Vegetable Cool Chain

Adrian Dahlenburg SARDI Horticulture

Project Number: VG97016

VG97016

This report is published by Horticulture Australia Ltd to pass on information concerning horticultural research and development undertaken for the vegetable industry.

The research contained in this report was funded by Horticulture Australia Ltd with the financial support of the vegetable industry.

All expressions of opinion are not to be regarded as expressing the opinion of Horticulture Australia Ltd or any authority of the Australian Government.

The Company and the Australian Government accept no responsibility for any of the opinions or the accuracy of the information contained in this report and readers should rely upon their own enquiries in making decisions concerning their own interests.

ISBN 0 7341 0465 0

Published and distributed by: Horticultural Australia Ltd Level 1 50 Carrington Street Sydney NSW 2000 Telephone: (02) 8295 2300 Fax: (02) 8295 2399 E-Mail: horticulture@horticulture.com.au

© Copyright 2002

Horticulture Australia

Project Number: VG97016

Project Title: Vegetable Cool Chain

Project Leader: Adrian Dahlenburg

Organisation: SARDI

Report by Matthew Palmer and Adrian Dahlenburg

1

Project Number: VG97016

Project Title: Vegetable Cool Chain

Project Leader: Adrian Dahlenburg

Organisation: SARDI

Funding: Horticulture Australia

Vegetable Levy

Date: 17 June 2002

Adrian Dahlenburg

SARDI Horticulture

GPO Box 397

Adelaide South Australia 5001

dahlenburg.adrian@saugov.sa.gov.au

Phone: (08) 8303 9416 Fax: (08) 8303 9424

Acknowledgments and Collaborators

SARDI

Matthew Palmer

Maria Nechvoglod

Louise Chvyl

Agriculture Victoria

Robert Premier

Janine Jaeger

NTDPIF

Melinda Gosbee

Susan Marte

Disclaimer

Any recommendations contained in this publication do not necessarily represent current HAL policy. No person should act on the basis of the contents of this publication, whether as to

matters of fact or opinion or other content, without first obtaining specific, independent professional advice in respect of the matters set out in this publication.

2

Contents

CONTENTS 3

MEDIA SUMMARY 4

TECHNICAL SUMMARY 5

TECHNOLOGY TRANSFER STRATEGY 7

Industry Articles '

Project Publications "

Visits 11

Wholesale Market Meetings 13

RESEARCH AND DEVELOPMENT ACTIVITIES 14

Temperature Moni tor ing 14

Introduction 14

Temperature Monitoring Summary 14

Temperature Monitoring Data 14

Northern Territory Monitoring 17

Key Issues Identified Through Temperature Monitoring 19

Conducting future monitoring 20

Temperature Monitoring Outcomes 21

Warming and Cooling rates of palletised produce 22

Optimising storage temperature for selected Asian vegetables 23

NT Temperature Monitoring 29

Postharvest handling of 'Asian' vegetables in the Northern Territory 32

Inoculum of vegetables at time of harvest 38

Cool chain handling and microbial loads 42

Cool chain handling and microbial loads 43

Introduction 43

Methods 43

Results 44

Simulated Temperature Abuse 44

Results: Transport from Darwin to Melbourne 53

Temperature abuse during transport (Adelaide to Melbourne) 59

Media Summary

The Vegetable Cool chain project developed from an interest in understanding the current practices of

postharvest handling of Australian vegetables, and the impact that such practices have on produce quality

once it reaches the consumer. The project has investigated handling procedures by monitoring the

temperature of produce from when it is harvested in the field, through the marketing chain (including

packing, transport, markets and retail outlets). The results varied significantly between individuals, from

extremely good handling procedures - through to handling chains that require significant improvements.

Common problems noted included inadequate or under capacity cool rooms, inappropriate transport and

storage temperature (often linked to mixed produce) and extended periods of time out of cool storage at

wholesale and retail level.

Microbiological testing has been used to evaluate the impacts that breaks in the cool chain can have on

various produce types. Testing was carried out in laboratory situations and also during transport of

vegetables from Darwin to Melbourne and Adelaide to Melbourne. Vegetables exposed to various

temperatures and conditions to evaluate how the microbiological loads vary. Microbiological sampling

was used as a measure of produce quality (total aerobic counts, yeasts and moulds, fluorescent

pseudomonads) and the potential of human pathogens (Coliforms and fluorescent pseudomonads).

Controlled studies highlighted the importance of low temperatures to retard microbiological growth. The

results of monitoring samples during refrigerated transport were more variable, but also reinforced the

importance of temperature management, particularly precooling.

To communicate the importance of good cool chain management and the techniques and information to

implement them, a range of activities have been conducted. A series of publications (including a book,

information kits, fact sheets, posters, pocket guides and a web page) have been produced to assist all

those involved with handling vegetables. Regional meetings, presentations at conferences and site visits

- have also been used to convey the message of the project. Additionally, a series of articles prepared by

the project team have appeared in National and Regional newsletters and publications. Information

produced by the project can be found at http://www.sardi.sa.gov.au/coolchai/

4

Technical Summary

The Vegetable Cool chain project developed from an interest in understanding the current practices of

postharvest handling of Australian vegetables, and the impact that such practices have on produce quality

once it reaches the consumer. The project has investigated handling procedures by monitoring the

temperature of produce from when it is harvested in the field, through the marketing chain (including

packing, transport, markets and retail outlets). Electronic temperature data loggers were used on a range

of products primarily Broccoli, Lettuce, Carrots, Bitter Melon and Snake beans, as well as Leeks, Brussel

Sprouts, Beans, Cauliflowers, Chinese Cabbage, Cucumbers and Melons. The results varied significantly

between individuals, from extremely good handling procedures - through to handling chains that require

significant improvements. Common problems noted included inadequate or under capacity cool rooms,

inappropriate transport and storage temperature (often linked to mixed produce) and extended periods of

time out of cool storage at wholesale and retail level.

Microbiological testing has been used to evaluate the impacts that breaks in the cool chain can have on

various produce types. Testing was carried out in laboratory situations and also during transport of

vegetables Darwin-Melbourne and Adelaide-Melbourne. Vegetables exposed to various temperatures and

conditions to evaluate how the microbiological loads vary. Microbiological sampling was used as a

measure of produce quality (total aerobic counts, yeasts and moulds, fluorescent pseudomonads) and the

potential of human pathogens (Coliforms and fluorescent pseudomonads).

Field sampling was conducted to assess the variability of microbiological levels in the field. Samples

were taken of Snake Beans, Bitter Melon, Broccoli, Lettuce and Carrots in the field and assessed. There

was a large variability in micro levels measured. The single highest counts were obtained on bitter melon

at 40300000 CFU/g. Other bitter melon had values as low as 30 CFU/g. The vegetable types displayed

different numbers of organisms. For example, snakebeans displayed relatively higher counts of Yeasts

and Moulds. The Micro-organisms found in the greatest amounts were Total Aerobic Count, followed by

Yeasts and Moulds, with Coliforms and Fluorescent Pseudomonads.

Laboratory studies kept vegetables at various temperatures 4, 8 15, 25 and 35°C for 72 hours. During this

time, produce was periodically sampled to measure each of the four microbiological indicators.

Temperature was found to be a major factor in the growth rate of the organisms. Despite some variability,

the higher temperatures were found to have higher growth rates, except in some instances where an

increase in temperature reduced the rate of growth. This was true for the Yeasts and Moulds (peak at

25°C); Fluorescent Pseudomonads (peak at 15 - 25°C) and Lettuce (peak at 25°C). However in any

normal market handling practices (eg not 35°C for 3 days), the lower the storage temperature, the lower

the rate of microbiological growth. This was confirmed by the result that in all instances, the 4°C

treatment showed the lowest, or equal lowest growth of microbiological organisms.

To communicate the importance of good cool chain management and the techniques and information to

implement them, a range of activities have been conducted. A series of publications (including a book,

5

information kits, fact sheets, posters, pocket guides and a web page) have been produced to assist all

those involved with handling vegetables. Regional meetings, presentations at conferences and site visits

have also been used to convey the message of the project. Additionally, a series of articles prepared by

the project team have appeared in National and Regional newsletters and publications. Information

produced by the project can be found at http://www.sardi.sa.gov.au/coolchai/

Recommendations on future research, development and technology transfer activities for improved

vegetable cold chain handling would include:

• Continuing promotion of improved cold chain handling practices through out the market supply

chain.

• Encouragement and support for temperature monitoring activities that allow supply chain operators to

better understand the impact of their handling practices on product temperatures.

• Development and production of handling information and systems targeted at specific commodities

and market sectors including exports.

• Development of more cost effective and efficient small scale, on-farm cooling systems for small

volume producers.

• Analysis of the costs and returns associated with a range of different postharvest handling systems

and the use of this data in promoting to the industry improved supply chain handling systems.

• Projects specifically targeted at improving cold chain handling practices beyond the farm gate.

6

Technology Transfer Strategy

Industry Articles A strategy for increasing the awareness about the importance of good postharvest handling as well as the

project was the use of various publications. Four editions of the project newsletter "Vegetable Cool

News" were distributed throughout the life of the project. Initially the newsletter was distributed by the

project team directly through a limited contact database. This method was superseded by supplying

articles directly to industry newsletters. This method was much preferred as it enabled us to reach a much

larger audience, enabled colour printing and greatly reduced the workload of printing newsletters,

envelopes and mailing individual newsletters. Thanks particularly to "National Marketplace News" and

"Good Fruits and Vegetables" for their assistance in promoting and publicising the project. These

publications were useful in also reaching audiences beyond the growers with many inquiries from

Wholesalers and occasionally retailers.

The production of 2 Newsletter article CDs facilitated the distribution of articles along with relevant

photos. Selected comments from the Editors after the first CD can be seen below:

Fiona Douglas of The Victorian National Marketplace News has used three articles when she was

running an export feature. She has also accessed and used the packaging & handling and Cool Matters

articles on the internet. Basically she is happy with the productions but would prefer jpeg rather than tiff

files for the cushioning and photos as the tiff files are too large & require conversion before she can use

them.

Mr Mark Richards of WA Grower was very happy/pleased with the CD. He has not actually used any

of the articles etc in his publication but their IDO, David Element, has and they have shown it to many

growers. They have not published any of it as i) they only publish quarterly and ii) cool handling is not

such an issue as are some market problems at the moment. They expect they will do so in the future -

when the rain stops!

Publication in both jpeg and tiff would be better as they need to convert them to use but also have a web

page. Overall Mark thought the production a great one and looks forward to future ones.

In response to the previous comments, some small changes to the next edition were incorporated -

including multiple image formats, and more compatible interface.

A television spot on the combined cool chain projects was also featured on 2 episodes of Cross Country.

The programs focused on the projects activities, benefits to those involved with the project and the

benefits and techniques involved with temperature monitoring.

An example of the range of articles produced by, or written about the project are shown below.

7

Transporting Fresh Produce in Refrigerated Trucks

National Marketplace News Feb 2000

Poor Temperature control dogs industry

National Marketplace News, Feb 1999

Research warms to challenge

National Marketplace News May 1998

Cool Handling Web Site

Supermarket to Asia V4 No 4 2000/01

Cool Chain Project

Hort Report 1998 Cool Chain Article

The importance and benefits of cool chain handling

Australian Chamber Handbook 1999

Techniques for maintaining the cool chain

National Marketplace News, Feb 2000

Cool Chain good for sales

Stock Journal, March 2001

Transporting Fresh produce in refrigerated trucks

National Marketplace News, Feb 1999

Booklets assisting fruit and vegetable exports

Stock Journal, Dec 2000

Guides to assist Australian Exports

National Marketplace News, April 2002

Cool from shed to supermarket - new air freight container

National Marketplace News, April 2002

Project Publications Throughout the life of the project we have developed a range of publications covering a wide range of

postharvest handling topics. The simultaneous funding of fresh stone fruit / vegetable cool chain projects

has allowed a wider range of information to be produced, that is of benefit to both groups. The expertise

and experience we have gained has also allowed us to leverage further money from other organisations to

further the amount of publications we have been able to produce.

The range of publications have been distributed continuously through the life of the project, as they have

been produced. The main avenues for distribution have been through meetings and conferences, through

publicity generated by the Newsletter and articles, and through the Cool Handling web site.

The total list of publications produced by the project team is:

Information Kits

Forced Air Cooling

Hydrocooling

Vacuum Cooling

Cool Room Construction - Refrigeration

Cool Room Construction - Insulation

Refrigeration Systems

Choosing a refrigerated carrier

Temperature Data Loggers

Vegetable Physiology and Cooling

Fact Sheets and Articles

Managing your cooling requirements

Field Heat

Plastic Bins

Packaging and Cooling

Cool room construction for the vegetable grower

Cool room refrigeration checklist

Centre Line Loading

Thermometer Calibration

9

Posters Notes

Produce Handling Guidelines

* See Note Below.

4000 copies printed and distributed.

2000 reprint just produced.

Pathways for Exports - Sea Freight * See Note Below

Pathways for Exports - Air Freight * See Note Below

Pocket Guides Notes

Harvest, Packing and Dispatch Guide * See Note Below

Refrigerated Road Transport * See Note Below

Air freight of Perishables * See Note Below

Refrigerated Shipping * See Note Below

* Publications funded by the South Australian Air Freight Export Council, South Australian Freight

Council for Sea Cargo and the South Australian Land Freight Council.

Evaluation and Discussion on Publications

The posters in particular have been highly sought after and appear to be a successful mechanism to

deliver targeted messages to industry. The Produce Handling Guidelines were largely distributed to

transporters, wholesalers and retailers.

The project also made use of electronic media to distribute information. This proved successful with the

Cool Handling web page, from which, we have received much positive feed back. This has also proved to

be a time saving way of directing people to relevant information - rather than physically mailing

information to them. However, we have noted that paper copies of information are still important as only

a limited number of growers have ready access to web facilities. Other groups (agency, IDOs, consultants,

retailers) interested in information produced by the project generally had a high percentage of web access

and could more often could access relevant information from the site.

Information Kits and fact sheets were designed to address specific sections of cool chain handling. These

were publicised in a number of our publications and have been well accepted by individuals who were

interested in particular topics.

10

Visits One of the key components of the technology transfer program of the project relied on regional meetings

in the various growing regions throughout the country. These meetings would not have been possible

without the support and organisation of people in each of the districts who helped in organising venues,

inviting participants and promoting the work of the cool handling project.

Other information presented at the meetings included

• The benefits of temperature monitoring

• Some example temperature monitoring results

• Research results, including forced air cooling

Information, or information order forms were also distributed at each of the meetings. These included fact

sheets, information kits and most popularly and produce handling guidelines.

Another important aspect of the meetings was the discussion generated by the information presented.

Common points of discussion included:

Grower / Packer

• What are the benefits of cooling, when other temperature abuse is known to occur along the chain

• Cooling methods

Transport

• Mistrust between the parties involved

• Mixed loads, shipping with incompatible products

• Multiple pick up points affecting good temperature management

• The necessity of refrigerated transport over short transport distances

Wholesale Markets, Independent retailers and Supermarkets

• Mistrust between the parties involved

• Un-refrigerated fruit at the wholesale markets, upon delivery and during sale on the market floor

• The lack of cool chain management beyond the wholesale markets

• Mishandling of fruit in the retail store

11

Conference

21-Sep-99 NSW

22-Sep-99 NSW

6-Jun-OO NSW

25 - 28 Oct-00 WA

Meetings and Visits

29-Jun-98 SA

13-Oct-98 VIC

9-Mar-99 VIC

26 - 30/7 99 NT

25-28/5/99 VIC

1999 VIC

7-Jul-99 QLD

7-M-99 QLD

ll-Aug-99 SA

13-Aug-99 SA

Clarrie Beckingham, Agric. NSW

Conference Delegates Intl. Inst. Of Refrig. 20th Conference

Vegetable growers, ag industry

reps, agency staff

Lettuce growers, around Australia Lettuce Industry Conference

Carrot Conference WA

24-Aug-99 NSW

7-Sep-99 QLD

17-Sep-99 VIC

20-Oct-99 WA

9 -Jun-00 NT

13-Jun-00 QLD

13-Jun-00 QLD

14-Jun-00 QLD

14-Jun-00 QLD

14-Jun-00 QLD

14-Jun-00 QLD

15-Jun-00 QLD

15-Jun-00 QLD

15-Jun-00 QLD

Virginia growers and Researchers

Veg R&D committee

Various grower visits

Various grower visits and queries

Mildura Field Day

Werribee Field Days

Matt Hood, D.J. Hood Farmers

Steve Nimmo, Prime Haulage

Vegetable planning meeting, other

Vegetable planning meeting,

brassica, leafy

Clarrie Beckingham

Growers/packers

Growers, agency staff, IDO's

Vegetable Grower / Packers

Gatton Vegetable growers and

QDPI staff

Kevin Niemeyer

Fassifern Valley growers

Dan Hood, Rugby farm

Keith Jackwitz, Vege Fresh

Ian and Ann Rickus

John Brent, Bunnybites farm

Abbots

Kent and Narelle West

Craig Feutrill

Veg R&D commettee

Project Team

Melinda Gosbee

Peter Deuter, QDPI

Peter Deuter, QDPI

Craig Feutrill

Craig Feutrill

A Dahlenburg

Peter Deuter, QDPI

Riverlink, Adrian Dahlenburg

David Ellement, Veg IDO

Melinda Gosbee

Samantha Bray

Samantha Bray

Samantha Bray

Samantha Bray

Samantha Bray

Samantha Bray

Samantha Bray

Samantha Bray

Samantha Bray

12

Wholesale Market Meetings

An offer was made to all wholesale markets in regards to holding meetings during the second half of

2000. The chamber and/or Market company in each market were contacted to assist coordination of

meeting/workshops.

Only the Brisbane market responded positively to the offer of conducting a workshop. The Adelaide,

Perth and Sydney market both responded that there was little interest from their members, due to current

good understanding of cool chain issues through their quality management systems. As we were unable to

conduct workshops in these markets, information was sent to the chambers informing them of the

information and publications available and where their members can obtain more information on cool

chain handling.

A workshop was conducted by Adrian Dahlenburg at the Brisbane Market on November 17. Information

was delivered to each of the markets along with order forms so information can be ordered from us.

Evaluation and Discussion of meetings

The meetings were beneficial for the project, particularly in guiding research directions, and the

highlighting the need for information in different areas. It was also greatly beneficial to understand the

different needs and requirements for cool handling information and adoption throughout the country. For

those involved hopefully the result was a greater understanding about the need and reason for good cool

chain handling practices.

The most difficult thing in conducting the meetings were the time in organising and travelling to the

regions for the meetings. Much of the success of the meetings relied on regional people generating

interest in the project and the meetings.

13

Research and Development Activities

Temperature Monitoring

Introduction

The original premise of the temperature monitoring was for the project and for the individuals involved to

better understand the temperature of vegetables as they pass through the marketing chain. This

information could then be used to determine the most critical points along the handling chain. For the

project this enabled us to better focus our information to key areas, and for those directly involved in the

monitoring it allowed them to make improvements in their handling systems where appropriate.

Temperature Monitoring Summary

Most of the temperature runs were conducted from the field where the produce was harvested, through to

the wholesale markets. The markets provided the most reliable site for the loggers to be collected. Early

trials with loggers being transported through to retail outlets, caused a higher rate of logger loss than at

the wholesale markets. Some successful runs were conducted through to retail outlets where the

monitoring was well coordinated with wholesaler and retailer.

Temperature Monitoring Data

Temperature monitoring was undertaken with a range of different vegetable crops, particularly in the

early years of the project. The most extensive collection of temperature monitoring was undertaken as

part of the microbiological survey work from the Northern Territory and South Australia to Victoria. The

monitoring work was undertaken with collaborating producers and packers as identified by IDO's and

other industry organisations and from meetings in various regions around Australia.

- Temperature loggers were provided to interested parties to use as they wish for a period up to a month.

They were encouraged to use them from the field through to the market end of the supply chain. A logger

recovery service paid for by the project was provided in each of the wholesale markets in Australia.

Users were asked to keep a log sheet to record the logger use, and the dates and times relating to specific

produce handling activities to help interpret the logger data. Loggers were returned to the SARDI cool

chain team for down-loading and interpretation. Once the temperature data was down-loaded, the

information was linked with the data log sheets and hard copies of the information provided to the

industry collaborators. Interpretations and suggestions on improved cool chain handling practices were

often made on the reports or discussed with the collaborators.

Some examples of the types of information and temperature data colleted from the temperature

monitoring work are included below with some comments relating to the temperature management of the

produce for that particular set of data. The issues raised in the comments would be the type of issues

raised with the relevant supply chain operators in discussion of the data-logger information.

14

D I U O U I I I - n ts iu i u nc tcmc i

20.0

mo

o

(0

a. E ao'

4.0

. i i 1 ' i r — i 1 i i | i i i | 1 i i | i i i | i i i | i . . , . .

28Th 29Fr 30Sa 31Su Jun 2Tu • 3W6 4Th Time (starting 27/05/1998) ;

Comments:

• The 2 lines on this graph are air temperature and the core temperature of the head of broccoli.

• The room cooling for the produce is slow (36hrs from 12 to 0°C) and could impact on the market

quality and shelf life, particularly if the same cooling rates were to occur with warmer incoming

produce temperatures.

• Coolstore is holding produce at near to optimum temperature.

• Minimal increase in temperature during packing.

• Temperature rise in the retail situation was slow, possibly being held in coolroom at retail store

operating at around 10°C.

Carrots - Packingshed to 2 Retail Outlets (Adelaide)

• i i — i i i .

18b - 18V* Time (starting 17/02/1998 07:40:06)

Comments

• Rapid temperature reduction achieved in cooling.

• Produce warming during distribution centre handling and transport to the retail stores.

• Produce cooling again in cool room at one of the retail stores.

15

Carrots to Darwin - Carrot Core and Van Air Temps

—i 1 1 — — i — - ^ — — i 1 =i i— SSa 6Su 7Mo

Time (starting 4/09/1998 09:38:30)

Comments

• Carrots transported from Adelaide to Darwin

• Large temperature span for air temperature while truck in operation. Some small potential for frozen

produce directly in front of air off coil as temperature go down to minus 2°C.

• Carrot core temperatures higher than optimal at loading.

• Carrot core temperatures slowly decreased (approx 3°C) during transit till midday Sunday 6 , then

increased over the next day. What happened? Warm produce added to load / carton or pallet

relocated on load / load movement or re-stowage so all or part of load blocked from adequate airflow,

are all possibilities.

• Van air temperature shows a slight tendency to follow daily external temperature variations which

could indicate the van is loaded to very near the full refrigeration capacity of the equipment.

16

25.0

20.0

B is.o 8. E'

I— 10.0

S.0

0 .

- J»<»,«*<-vsJ-»*s-

I -• . I . 5 T h ;•

— | 1 1 1 1 1 1 1 1 —

6Fr 7Sa 8Su Time (starting 4/08/1999 17:59:00)

-i 1 ' 9 M o

Comments

• Produce not cooled before loading which impacted on air temperature and likely was responsible

(together with any other warm produce on the load) for elevated transport van temperatures for the

first 24 to 36 hours.

• Transport temperature too low for bitter melon. Probably shipped as a minor component of a mixed

commodity load.

Northern Territory Monitoring

Objective: To investigate the cool handling of Asian vegetables and the effects on quality.

The Vegetable Cool Chain project is funded by HRDC and is a joint project between the South Australian

Research and Development Institute, Agriculture Victoria and NT DPIF. Part of the project was the

temperature monitoring of bitter melon and snake bean during transport via road freight from Darwin to

Melbourne. Data loggers were placed in cartons at Darwin, and records of the quality of the produce

taken. In Melbourne, the consignment was met at the market, loggers removed for collection of data and

product quality again recorded. A total of 20 successful consignments of bitter melon were monitored,

and 13 of snake beans.

Data is presented in Graphs 1 and 2 as the proportion of the journey that the produce spent in three

selected temperature brackets. 7 to 10°C is the optimum storage temperature for physiological quality of

bitter melon and snake beans, however they are often transported at much lower temperatures to ensure

heat damage does not occur. Above 10°C bitter melon will start to ripen, and snake beans produce enough

heat through respiration to damage the product. A typical time interval is 80 to 100 hours, from produce

arriving at depot for consolidation to being sold in the Footscray markets.

17

Graph 1. Proportion of journey that temperatures of <7, between 7 and 10° and over 10°C were recorded

in boxes of bitter melon transported by road freighted to Melbourne. Initial vegetable temperatures are

displayed under each column.

c

o

c o '•c o Q. O

22710.728.1 a5 10.7123 11.920.1 17.7a0 ia6 1X713.9 11.4112 S7 12212911.91X3

• <7C D7to10C D>10C

Graph 2. Proportion of journey that temperatures of <7, between 7 and 10° and over 10°C were recorded

in boxes of snake beans transported by road freight to Melbourne. Initial vegetable temperatures are

displayed under each column.

100%

CD

c

o

c o t : o D. O

12.3 10.5 12.6 8.0 10.1 11.5 11.6 11.7 6.7

• <7Cn7to iocn>ioc

10.6 13.0 13.1 10.1

Of greatest concern is the proportion of time the temperature was recorded above 10°C. For all the times

recorded, bitter melon spent 20% of its transit time above 10°C. For snake beans, this proportion was

slightly higher at 24%. Snake beans and bitter melon spent 46 and 37% respectively in the optimum

temperature range, and the remaining 30 and 43% of the total recorded time at less than 7°C. Also of

concern are the high temperatures of bitter melon at the beginning of the trip. Such produce is not

18

adequately precooled. This affects not only the shelf life of the product but also the ability of the

refrigeration unit in the truck to cool the produce.

The quality of bitter melon was recorded in Darwin and Melbourne. In the Melbourne market, 1 carton

was recorded as excellent quality, 3 as good quality, 9 as satisfactory and 5 as non saleable. The main

reasons for loss of quality was physical damage to the product, usually insect or other preharvest damage,

and ripening. Often the seeds inside the bitter melon sampled were turning red.

Key Issues Identified Through Temperature Monitoring

Mixed Produce Loads

Mixed produce loads are when different commodities are transported in the same truck, or when the same

produce type is loaded at different temperatures.

Mixed commodity loads would ideally have a dedicated compartment running at the recommended

temperature for each commodity. However, transport vehicles with multiple temperature compartments

are more expensive and not commonly used. The temperature of the truck is usually set at a temperature

that will prevent chilling injury to any produce in the vehicle (often 5°C), but this is often a non-ideal

temperature for particular vegetables.

Alternatively, a problem also occurs when warm produce is loaded along with properly pre-cooled

produce. The cooled produce subsequently warms as the temperature equilibrates with the warm produce.

Temperature monitoring has demonstrated that cooling during transport is at best extremely slow, and

usually negligible. When warm produce is to be loaded onto the truck, transporters are left with the

decision to either reject the load (at a financial cost to themselves) or accept warm produce and

compromise the quality of the other produce on the vehicle.

From these results it has been justifiably argued "If the other produce on the vehicle isn't at the right

temperature", or "the vehicle is running at the wrong temperature", what is the point of properly cooling

my vegetables prior to transport. The response is not an easy one, other than to say that the longer the

vegetables spend at the optimum temperatures, the better it will be when it comes to sell. Alternatively,

there are steps that can be taken to reduce the effects of mixed loads. Pallet covers can reduce the effects

of small or short term breaks in the cool chain. Trials we conducted demonstrated their usefulness,

provided the produce is properly cooled prior to covering, they are required for a brief time only, and that

the covers are removed once the produce is returned to correct refrigeration temperature.

19

Wholesale Markets and Distribution Centres

The wholesale markets are of great importance in delivering vegetables to the consumer. Most produce

will pass through either the wholesale markets or distribution centre (or both) before reaching the

consumer. However, some of the current practices in storage and marketing of vegetables results in large

breaks in the cool chain. Delivery to unrefrigerated receival areas and long periods without refrigeration

(at delivery and on the market selling floor) result in significant temperature increases. Refrigerated

selling floors greatly reduce this problem and are beginning to be adopted. Coordinated deliveries and

pre-selling of produce also allows fruit to be kept in the cool room longer. Distribution centres often have

facilities available to maintain the cool chain (loading docks, large refrigerated holding rooms), but good

practices must still be implemented to ensure fruit is not left standing around outside of refrigeration.

Cooling techniques and facilities

Adequate precooling and storage facilities have been identified as a key issue in the temperature

monitoring of vegetables. Many of the cool rooms monitored were found to be under capacity, resulting

in slow cooling rates or even the inability to reach the target temperature. This was particularly true of

smaller operators. Small gains can be made by harvesting produce in the cool of the morning and quickly

cooling vegetables, but the only real solution is an upgraded coolroom or refrigeration system. Rapid

cooling facilities (hydrocooling, vacuum cooling or forced air cooling) is also a requirement for optimum

produce quality. These also require suitable equipment and refrigeration capacity. New cool rooms and

cooling equipment is usually an expensive proposition and often down the list of grower priorities.

Unfortunately there are no easy solutions to this problem, however there are successful examples of

cooperative packing sheds and cool store facilities, which effectively spreads the expense of new

equipment over a group of growers.

Conducting future monitoring

Many of the obstacles and challenges for successful temperature monitoring have been addressed in the

Temperature Data Loggers Information kit, available on the project web site. Some of the key points for

successful temperature monitoring include:

• Good communication between all parties. People sending loggers need to inform those receiving the

loggers prior to and at the time of sending the loggers. This can help avoid some of the loss (or theft,

or vandalism) of loggers that occurred during this project.

• Good record keeping to interpret logger results

• Well marked. It is easy to misplace loggers if they are not clearly visible. Particularly in loads with

multiple pallets, loggers can be easily missed. Bright or contrasting coloured stickers, tape or ribbon

should be used to identify the presence of a logger. It is important to label all four sides of a pallet.

• Providing a mechanism for returning the loggers. Providing a self addressed, prepaid envelope

enables quick and easy return of loggers by the receiver.

20

The most critical factors when temperature monitoring are good communication with the marketing chain

and good record keeping about the loggers movements. Without good records being kept, the logger

results become difficult, if not impossible to interpret. The records can be detailed, but in most situations

need only include the most critical movements of vegetables within the handling system.

A typical record sheet would look like

15/01 9:00 a.m. Broccoli Harvested

10:00 Arrived at Shed and into cool room

2:30 p.m. Onto grader (logger removed for 5 mins)

3:30 p.m. Packed and returned to cool room

16/01 6:00 p.m. Loaded on truck and transported to wholesale markets

9:30 p.m. Arrived at markets and logger removed

Temperature Monitoring Outcomes

One of the recurring results from the temperature monitoring was the surprise that the people expressed

when they saw the temperatures that occurred during the handling of their produce. Inevitably the results

were worse than they expected. This highlights the need for people to actually monitor produce

temperatures, rather than relying on feeling the produce, or simply relying on the temperature displayed

on the coolroom.

Monitoring temperatures also highlights where breaks are occurring in the handling chain. In speaking

with individuals in the handling chain, much of the blame was usually attributed to "everyone else" in the

chain. The objective results of the temperature logger demonstrate where problems need to be addressed.

Common grower complaints, particularly with mishandling at wholesale or distribution level, were

highlighted, but often an equally serious problem of slow cooling, or non-ideal shipping temperature were

also shown in the results.

While our results were not used or intended for dispute resolution, temperature monitoring can be highly

helpful for this process, particularly on export shipments or over long distances. Temperature monitoring

can be a highly beneficial in integrated supply chains, where all groups are well coordinated and

cooperative, to enable continual improvement. However, for less organised marketing arrangements

temperature monitoring is important to enable clear understanding of what the consequences are for

uncoordinated produce handling.

The results have been useful to highlight breaks in the cool chain and where improvements need to be

implemented.

21

Warming and Cooling rates of palletised produce Forced air cooling was found to offer many benefits in comparison to room cooling. All produce cooled

much faster and much more evenly with forced air cooling. Rapid cooling is beneficial for maintaining

postharvest quality. During room cooling of one pallet, individual pieces of produce took between 9 and

25 hours to properly cool. This uneven cooling can lead to uneven ripening/softening, water loss and

susceptibility to decay within a single pallet. If the produce is room cooled a number of times (in field

bins, prior to shipping, at wholesale markets etc) this can lead to produce with varying qualities being

presented to the consumer as a uniform line. Rapid cooling systems greatly reduce the variability in

product temperature. Forced air cooling is recommended as a system that offers rapid cooling, with the

benefit of being able to be used in conjunction with an existing cool room.

From temperature data logging and observation, there are times during the handling chain where product

is not under refrigeration and can warm quite rapidly. Pallet wraps can be of benefit in better maintaining

the cool chain, where these breaks occur. Three unperforated wraps were tested (thin plastic wrap, bubble

wrap and insulated foil) and all approximately doubled the time to reach 5°C compared with an

unwrapped pallet. However there are limitations to the use of pallet wraps. If product is not properly

precooled prior to applying the wrap, enclosing the product will rapidly lead to heat and ethylene build up

and subsequent product deterioration. Enclosed pallet wraps also prevent cooling if warm produce is

placed in a cool room. Some possible practical uses include

• Immediately prior to transport. Reusable pallet wraps could be used to cover produce if it is not

under refrigeration. These could be removed as the truck is being loaded.

• During transport. Wraps could be used on pallets of properly cooled vegetables that are to be carried

at non-ideal temperatures. This can occur if the truck is running at a higher temperature, or if warm

product is being loaded on the truck with cool product. Even with transport vehicles running at 5°C,

properly cooled vegetables at 0°C will warm extremely slowly if covered in pallet wrap.

• At the wholesale markets. If refrigeration facilities are a distance from the point of unloading or the

produce spends time with no refrigeration, pallet wraps will reduce the costs of refrigeration in re-

cooling the produce and better maintain quality.

22

Optimising storage temperature for selected Asian vegetables Project Officers: Melinda Gosbee and Susan Marte

Location: BARC

Objective: To determine optimum storage temperatures for some Asian Vegetable types.

This work was begun by TK Lim and sections of it have been reported in previous Annual Reports.The

following is an adaptation of a paper 'Postharvest handling of 'Asian' vegetables in the Northern

Territory ' by M. Gosbee and TK Lim. It summarises several years work and includes new information on

sinqua, snake beans and kang kong.

Materials and methods

Five types of Asian vegetables were chosen for this study. Bitter melon {Momordica charantia) and snake

beans (Vigna unguiculata cv. Group Sesquipedalis) are among the most commonly grown Asian

vegetables, and frequently have deterioration problems. Okra (Abelmoschus esculentus) also tends to

have similar problems, presumably due to its high respiration rate (Kader 1992). Sinqua, or angled luffa

(Luffa acutangula) was chosen to be representative of several types of melon which are considered by

growers to be less sensitive to temperature. Kang kong (Ipomoea aquatica) was chosen as a

representative of common leafy vegetables.

Vegetables were packed into boxes containing 3 to 10 kg of produce. Pack sizes were chosen to simulate

current industry practices. They were either commercial size (for bitter melon and sinqua) or scaled down

but still a representative size (snake beans, okra and kang kong). Vegetables were sourced from local

growers and repacked into packaging treatments. Produce packed in paper wrapping had a double

thickness placed at the top and bottom, of the carton. Plastic bags were made of low density natural

polyethylene. Perforated bags had large holes (10 mm diameter) 20 mm apart over most of the area, while

peakfresh® bags were microperforated plastic bags with gas exchange properties. Again, specific

treatments were chosen depending on the type of vegetable and the types of packaging used by growers

(Table 1). They were then placed in a coolroom at 5, 10, 15 or 20°C.

Vegetables were assessed twice a week for quality, and once a week for weight loss. Quality was scored

on a 1 to 5 subjective scale of 1 = excellent, 2 = good, 3 = saleable, 4 = poor and 5 = very poor. Shelf life

was determined as the number of days a product took from harvest to reach a score of less than 3. Ratings

were continued until produced reach a score of less than 2. Weight loss is expressed as the percentage of initial

fresh weight remaining. This was determined in a slightly different manner in each experiment (Table 1).

Two boxes of each packaging x temperature treatment were used. Unfortunately the effect of temperature could not

be statistically analysed as only one coolroom was available at each temperature. Analysis of the effect of packaging

on quality score was analysed using general linear models. Weight loss was significantly affected by packaging and

data was analysed by analysis of deviance.

23

Table 1. Packaging and pack size used in the assessment of optimum storage life and temperature of five Asian vegetables.

Bitter Melon Okra Sinqua Snake beans Kangkong

Packaging

Paper wrapping / / / / /

Perforated Bag / / / /

PeakfreshBag / / • /

Plastic Bag • / / / /

Pack size 10 kg 5 kg 10 kg 5 kg 3 kg

Weight loss combined weight combined individual total weight of total weight of

of 5 fruit weight of 10 weight of 5 fruit 5 kg box 3 kg box

fruit

Results and Discussion

Temperature had by far the greater effect on quality and shelf life than packaging. Differences in quality

score of vegetables stored at different temperatures (Figure 1 a, c-f) were greater than that observed

between vegetables stored in different types of packaging (Figure lb).

Figure 1. Effect of temperature (a, c - f) and packaging (b) on the quality of various 'Asian' vegetables

during storage. Vertical bars (b) represent LSD (P<0.05).

24

a) Sinquar - temperature

e) Snake beans

•—• - •

0 5 10 15 20 25 30 35 40

Days after harvest

b) Sinquar - packaging

o Newspaper • Perforated Bac A Peakfresh Bag o Plastic Bag

d) Okra

0 5 10 15 20 25 30 35 40

Days after harvest

25

Table 2. Weight loss (% initial fresh weight) after approx. two weeks in storage. Results are averaged across the four temperatures. Values followed by different letters within

columns are significantly different (P < 0.05).

Bitter Melon Okra Sinqua Snake beans Kang kong

Days after harvest: 14 14 16 13 13

Packaging

Paper wrapping 97.61a 91.76 a 93.97 a 89.59 a 85.39 a

Perforated Bag 97.81a 95.03 a 94.14 b 93.27 b

PeakfreshBag 98.54 b 97.90 b 99.56 c 99.91c

Plastic Bag 99.12 b 98.20 b 98.71b 99.59 c 100.44 c

At any one temperature, however, packaging had a distinct effect on the rate of water loss. Vegetables

stored in plastic lost significantly less water than product stored without any plastic covering. Perforated

bags were intermediate (Table 2). The rates for okra, <2% for produce in bags, and 8.2% for okra in paper

wrapping, were similar to that reported by Perkins-Veazie and Collins (1992). The use of peakfresh bags

did not significantly increase the storage life of any of these products over the use of plastic bags. As

peakfresh bags are considerably more expensive, this information should save the grower significant and

unnecessary cost.

Table 3. Optimum storage temperature and packaging combinations for maximising shelf life for five selected vegetables.

Temperature Packaging Shelf Life

Bitter melon 5°C Paper wrapping 3 weeks

Okra 10°C Plastic bag 3 weeks

Sinqua 5°C Any 2.5 weeks

Snake beans 5 - 10 °C Plastic bag 2.5 weeks

Kang kong 5°C • Plastic bag 2 weeks

The simple conclusion that every vegetable is best stored at 5°C in a plastic bag was not the case (Table

3). The use of plastic bags to reduce water loss is only recommended when the temperature can be

accurately controlled. Warm produce packaged in plastic bags is difficult to cool, due to the decreased

ventilation. If temperature is not well controlled during transport, packaged in plastic bags are more likely

to 'cook' due to the heat produced as the vegetables respire. For product like snake beans with a very high

respiration rate (Zong et al 1992), we currently recommend the use of perforated plastic bags as these

have greater air flow capacity when the product is being cooled. This also highlights the importance of

completely cooling produce prior to packaging.

26

The use of plastic bags for bitter melon poses a different problem. These fruit are close to maturity at

harvest, are producers of ethylene and are also sensitive to ethylene (Zong et al 1992). Optimum stage of

harvest is difficult to determine, and is clouded by the desire of growers to harvest heavier and therefore

more profitable vegetable. As the bitter melon ripen, the flesh rapidly turns a brilliant yellow and splits

open. This may induce the rest of the melons in the box to likewise ripen. Bitter melon are consumed

immature, and such ripe fruit are unmarketable. Temperature reduces the rate of ripening and loss of

quality (Figure lc), but packing bitter melon in paper wrapping increases ventilation within the box and

reduces the possibility ethylene triggering the fruit to ripen.

In this trial, okra stored in paper wrapping succumbed to fungal decay more readily than that in plastic

bags. It may be that the paper wrapping was a source of inoculum, or that water loss from the okra

predisposed them to decay. From these results, plastic packaging is more beneficial than paper wrapping

(Table 3).

Sinqua was different because the shelf life of vegetables stored at 20°C were not greatly different to that

of vegetables stored at 15 or 10°C. This would be why sinqua, and other melons, have a reputation among

growers for longer shelf life. Sinqua stored at 5°C had a significantly longer shelf life than that stored at

any other temperature (Figure la).

Kang kong is a leafy vegetable with a very short shelf life. Low temperatures of 5 to 10°C were beneficial

in prolonging shelf life (Figure 1 f). Water loss was significantly greater in paper wrapping and perforated

bags from day 6, and the use of plastic bags is strongly recommended. At 15 and 20°C, breakdown in

kang kong was seen as wilting and yellowing of the lower leaves and fungal decay. At lower temperatures

colour and turgor were maintained for longer.

Chilling injury was observed in bitter melon and okra after 3 weeks at 5°C. Dark watery pits first

appeared on the bitter melon at this time and increased with time in storage. Zong et al (1992) suggested

that none of these vegetables should be stored at less than 10°C for more than two weeks, due to chilling

injury. That observation is more accurate as the vegetables were removed to 20° and chilling injury

observed after 2 to 3 days. This was not attempted in our experiment and symptoms may have been more

obvious had we held the vegetables at 20°C after removal from cooler temperatures.

At the present time, most growers cool their produce to 4 to 8°C, and temperatures of 4 to 6°C are used in

road freight for periods of 3 days. While these temperatures may seem a bit low, the lower temperatures

reduce the possibility of the vegetables heating up within packaging. The transit time of 4 days to

southern markets is short enough to minimise the risk of developing chilling injury. When vegetables are

properly precooled, vegetable quality is maintained and produce reaches markets in a good condition.

Technology in terms of temperature and packaging exist for a range of vegetables. It is, however,

important to match these not only to each vegetable in the case of its particular physiology but also to the

capability of the growers and available transport options. Our recommendations may well change as the

skill of the growers in postharvest handling and managing the cool chain increase.

27

Acknowledgments

Thanks to Carole Wright for statistical analysis. Funding for this project by HRDC and RIRDC is

gratefully appreciated.

References

Bureau of Meteorology, Commonwealth of Australia. 1999.

http://www.bom.gov.au/climate/averages/tables

Kader A.A. 1992. Postharvest biology and technology: an overview. In: Postharvest Technology of

Horticultural Crops, pg 15 to 20. University of California, USA

Perkins-Veazie, P. and Collins, J.K. 1992. Cultivar, packaging, and storage temperature differences in

postharvest shelf life of okra. HortTechnology 2:350-352.

Zong, R.J., Cantwell, M., Morris, L. and Rubatzky, V. 1992. Postharvest studies on four fruit-type

Chinese vegetables. Acta Horticulturae 318:345-354.

28

NT Temperature Monitoring Project Officers: Melinda Gosbee and Susan Marte

Location: BARC

Objective: To investigate the cool handling of Asian vegetables and the effects on quality.

The Vegetable Cool Chain project is funded by HRDC and is a joint project between the South Australian

Research and Development Institute, Agriculture Victoria and NT DPIF. Part of the project was the

temperature monitoring of bitter melon and snake bean during transport via road freight from Darwin to

Melbourne. Data loggers were placed in cartons at Darwin, and records of the quality of the produce

taken. In Melbourne, the consignment was met at the market, loggers removed for collection of data and

product quality again recorded. A total of 20 successful consignments of bitter melon were monitored,

and 13 of snake beans.

Data is presented in Graphs 1 and 2 as the proportion of the journey that the produce spent in three

selected temperature brackets. 7 to 10°C is the optimum storage temperature for physiological quality of

bitter melon and snake beans, however they are often transported at much lower temperatures to ensure

heat damage does not occur. Above 10°C bitter melon will start to ripen, and snake beans produce enough

heat through respiration to damage the product. A typical time interval is 80 to 100 hours, from produce

arriving at depot for consolidation to being sold in the Footscray markets.

29

Graph 1. Proportion of journey that temperatures of <7, between 7 and 10° and over 10°C were recorded in boxes of bitter melon transported by road freighted to Melbourne. Initial

vegetable temperatures are displayed under each column.

o c 3

c o

'•£ O Q. O 0.

22.710.728.1 a5 1Q7123 11.920.1 17.7a0 ia6 ia7ia911.4 112 a7 12212911.9ia3

• <7C D 7 t o 1 0 C D > 1 0 C

Graph 2. Proportion of journey that temperatures of <7, between 7 and 10° and over 10°C were recorded in boxes of snake beans transported by road freight to Melbourne. Initial

vegetable temperatures are displayed under each column.

CD C

o

c g o Q. o

12.3 10.5 12.6 8.0 10.1 11.5 11.6 11.7 6.7 10.6 13.0 13.1 10.1

• <7Cn7to 10Crj>10C

Of greatest concern is the proportion of time the temperature was recorded above 10°C. For all the times

recorded, bitter melon spent 20% of its transit time above 10°C. For snake beans, this proportion was

slightly higher at 24%. Snake beans and bitter melon spent 46 and 37% respectively in the optimum

temperature range, and the remaining 30 and 43% of the total recorded time at less than 7°C. Also of

concern are the high temperatures of bitter melon at the beginning of the trip. Such produce is not

30

adequately precooled. This affects not only the shelf life of the product but also the ability of the

refrigeration unit in the truck to cool the produce.

The quality of bitter melon was recorded in Darwin and Melbourne. In the Melbourne market, 1 carton

was recorded as excellent quality, 3 as good quality, 9 as satisfactory and 5 as non saleable. The main

reasons for loss of quality was physical damage to the product, usually insect or other preharvest damage,

and ripening. Often the seeds inside the bitter melon sampled were turning red.

31

Postharvest handling of 'Asian' vegetables in the Northern Territory M.J. Gosbee and T.K. Lim

Abstract

In the Northern Territory of Australia a significant proportion of vegetable production is based on 'Asian'

type vegetables. These are mainly grown in the dry season (April to October) and are sold locally and

interstate. Interstate markets are 4000 km distant from the place of production. Most vegetables are

transported south by refrigerated road freight, which takes up to four days. This has necessitated careful

handling and cooling of the vegetables to ensure they reach the market in an acceptable condition.

Most popular vegetables grown in the NT are bitter melon {Momordica charantia), snake beans (Vigna

unguiculata cv. Group Sesquipedalis), okra {Abelmoschus esculentus), angled luffa or sinqua {Luffa

acutangula) long, hairy and winter melon (all types of Benincasa hispida), kang kong {Ipomoea aquatica)

and basil {Ocimum basilicum). These vegetables have different postharvest storage requirements.

Storage experiments testing the shelf life of some of these vegetables have been carried out over several

years. Boxes of vegetables stored in several different types of packaging at 5, 10, 15 and 20°C were

evaluated for overall quality, chilling injury, water loss and decay. Bitter melon and sinqua were best

stored at 5°C in paper wrapping or a perforated plastic bag. Okra and snake beans developed chilling

injury at 5°C, and the best storage condition found were 10°C and in a plastic bags. Kang kong

maintained its quality when stored at 5°C. Generally, vegetables need to be cooled to less than 12°C

before packaging. A more difficult issue has been educating the growers to thoroughly cool produce

before packing to ensure the vegetables remain cool during transport.

Introduction

Temperature control is the single most important factor in maintaining the shelf life and quality of

vegetables after harvest (Kader 1992). In the Northern Territory (NT), ambient daytime temperatures

during the main vegetable production season (May to October) are hot and dry, in the range of 19.3 to

33.1°C, with humidities of 38 to 78 % (Bureau of Meteorology 1999). Vegetables from both "European"

and "Asian" origins are grown in the NT. The "Asian" vegetables are mainly tropical cucurbits, along

with others requiring similar tropical climates. Interstate markets for these commodities are 4000 km

away. Produce is generally transported by refrigerated road freight which takes up to 4 days. Information

on the medium term storage of these vegetables is limited. This paper describes several storage

experiments conducted to determine the optimum temperature for freighting these vegetables, and some

of the problems encountered with their postharvest handling.

Materials and methods

Five types of Asian vegetables were chosen for this study. Bitter melon {Momordica charantia) and snake

beans {Vigna unguiculata cv. Group Sesquipedalis) are the most commonly grown vegetables (H. Ngo,

32

NT DPIF Economist, 1999., pers. comm.), and frequently have deterioration problems. Okra

(Abelmoschus esculentus) also tends to have similar problems, presumably due to its high respiration rate

(Kader 1992). Sinqua, or angled luffa (Luffa acutangula) was chosen to be representative of several types

of melon which are considered by growers to be less sensitive to temperature. Kang kong (Ipomoea

aquatica) was chosen as a representative of common leafy vegetables.

Vegetables were packed into boxes containing 3 to 10 kg of produce. Pack sizes were chosen to simulate

current industry practices. They were either commercial size (for bitter melon and sinqua) or scaled down

but still a representative size (snake beans, okra and kang kong). Vegetables were sourced from local

growers and repacked into packaging treatments. Produce packed in paper wrapping had a double

thickness placed at the top and bottom, of the carton. Plastic bags were made of low density natural

polyethylene. Perforated bags had large holes (10 mm diameter) 20 mm apart over most of the area, while

peakfresh® bags were microperforated plastic bags with gas exchange properties. Again, specific

treatments were chosen depending on the type of vegetable and the types of packaging used by growers

(Table 1). They were then placed in a coolroom at 5, 10, 15 or 20°C.

Vegetables were assessed twice a week for quality, and once a week for weight loss. Quality was scored

on a 1 to 5 subjective scale of 1 = excellent, 2 = good, 3 = saleable, 4 = poor and 5 = very poor. Shelf life

was determined as the number of days a product took from harvest to reach a score of less than 3. Ratings

were continued until produced reach a score of less than 2. Weight loss is expressed as the percentage of

initial fresh weight remaining. This was determined in a slightly different manner in each experiment

(Table 1).

Two boxes of each packaging x temperature treatment were used. Unfortunately the effect of temperature

could not be statistically analysed as only one coolroom was available at each temperature. Analysis of

the effect of packaging on quality score was analysed using general linear models. Weight loss was

significantly affected by packaging and data was analysed by analysis of deviance.

Results and Discussion

Temperature had by far the greater effect on quality and shelf life than packaging. Differences in quality

score of vegetables stored at different temperatures (Figure 1 a, c-f) were greater than that observed

between vegetables stored in different types of packaging (Figure lb).

At any one temperature, however, packaging had a distinct effect on the rate of water loss. Vegetables

stored in plastic lost significantly less water than product stored without any plastic covering. Perforated

bags were intermediate (Table 2). The rates for okra, <2% for produce in bags, and 8.2% for okra in paper

wrapping, were similar to that reported by Perkins-Veazie and Collins (1992). The use of peakfresh bags

did not significantly increase the storage life of any of these products over the use of plastic bags. As

peakfresh bags are considerably more expensive, this information should save the grower significant and

unnecessary cost.

33

The simple conclusion that every vegetable is best stored at 5°C in a plastic bag was not the case (Table

3). The use of plastic bags to reduce water loss is only recommended when the temperature can be

accurately controlled. Warm produce packaged in plastic bags is difficult to cool, due to the decreased

ventilation. If temperature is not well controlled during transport, packaged in plastic bags are more likely

to 'cook' due to the heat produced as the vegetables respire. For product like snake beans with a very high

respiration rate (Zong 1992), we currently recommend the use of perforated plastic bags as these have

greater air flow capacity when the product is being cooled. This also highlights the importance of

completely cooling produce prior to packaging.

The use of plastic bags for bitter melon poses a different problem. These fruit are close to maturity at

harvest, are producers of ethylene and are also sensitive to ethylene (Zong et al 1992). Optimum stage of

harvest is difficult to determine, and is clouded by the desire of growers to harvest heavier and therefore

more profitable vegetable. As the bitter melon ripen, the flesh rapidly turns a brilliant yellow and splits

open. This may induce the rest of the melons in the box to likewise ripen. Bitter melon are consumed

immature, and such ripe fruit are unmarketable. Temperature reduces the rate of ripening and loss of

quality (Figure lc), but packing bitter melon in paper wrapping increases ventilation within the box and

reduces the possibility ethylene triggering the fruit to ripen.

In this trial, okra stored in paper wrapping succumbed to fungal decay more readily than that in plastic

bags. It may be that the paper wrapping was a source of inoculum, or that water loss from the okra

predisposed them to decay. From these results, plastic packaging is more beneficial than paper wrapping

(Table 3).

Sinqua was different because the shelf life of vegetables stored at 20°C were not greatly different to that

of vegetables stored at 15 or 10°C. This would be why sinqua, and other melons, have a reputation among

growers for longer shelf life. Sinqua stored at 5°C had a significantly longer shelf life than that stored at

any other temperature (Figure la).

Kang kong is a leafy vegetable with a very short shelf life. Low temperatures of 5 to 10°C were beneficial

in prolonging shelf life (Figure 1 f. Water loss was significantly greater in paper wrapping and perforated

bags from day 6, and the use of plastic bags is strongly recommended. At 15 and 20°C, breakdown in

kang kong was seen as wilting and yellowing of the lower leaves and fungal decay. At lower temperatures

colour and turgor were maintained for longer.

Chilling injury was observed in bitter melon and okra after 3 weeks at 5°C. Dark watery pits first

appeared on the bitter melon at this time and increased with time in storage. Zong et al (1992) suggested

that none of these vegetables should be stored at less than 10°C for more than two weeks, due to chilling

injury. That observation is more accurate as the vegetables were removed to 20° and chilling injury

observed after 2 to 3 days. This was not attempted in our experiment and symptoms may have been more

obvious had we held the vegetables at 20°C after removal from cooler temperatures.

34

At the present time, most growers cool their produce to 8 to 10°C, and temperatures of 4 to 6°C are used

in road freight for short periods. While these temperatures may seem a bit low, the lower temperatures

reduce the possibility of the vegetables heating up within packaging. The transit time of 4 days to

southern markets is short enough to minimise the risk of developing chilling injury. When vegetables are

properly precooled, vegetable quality is maintained and produce reaches markets in a good condition.

Technology in terms of temperature and packaging exist for a range of vegetables. It is, however,

important to match these not only to each vegetable in the case of its particular physiology but also to the

capability of the growers and available transport options. Our recommendations may well change as the

skill of the growers in postharvest handling and managing the cool chain increase.

Acknowledgments

Thank you to Susan Marte who helped with the experiments and preparation of this paper. Carole Wright

for statistical analysis. Funding for this project by HRDC and RIRDC is gratefully appreciated.

References

Bureau of Meteorology, Commonwealth of Australia. 1999.

http://www.bom.gov.au/climate/averages/tables

Kader A.A. 1992. Postharvest biology and technology: an overview. In: Postharvest Technology of

Horticultural Crops, pg 15 to 20,. University of California, USA

Perkins-Veazie, P. and Collins, J.K. 1992. Cultivar, packaging, and storage temperature differences in

postharvest shelf life of okra. HortTechnology 2:350-352.

Zong, R.J., Cantwell, M., Morris, L. and Rubatzky, V. 1992. Postharvest studies on four fruit-type

Chinese vegetables. Acta Horticulturae 318:345-354.

35

Table 4. Packaging and pack size used in the assessment of optimum storage life and temperature of five Asian vegetables.

Bitter Melon Okra Sinqua Snake beans Kang kong

Packaging

Paper wrapping / • / / /

Perforated Bag / / / /

Peakfresh Bag / / / /

Plastic Bag / S / / /

Pack size 10 kg 5 kg 10 kg 5 kg 3 kg

Weight loss combined weight of 5 fruit

combined weight of 10

fruit

individual weight of 5 fruit

total weight of 5 kg box

total weight of 3 kg box

Table 5. Weight loss (% initial fresh weight) after approx. two weeks in storage. Results are averaged across the four temperatures. Values followed by different letters within

columns are significantly different (P < 0.05).

Bitter Melon Okra Sinqua Snake beans Kang kong

Days after harvest: 14 14 16 13 13

Packaging

Paper wrapping 97.61 a 91.76 a 93.97 a 89.59 a 85.39 a

Perforated Bag 97.81 a 95.03 a 94.14 b 93.27 b

Peakfresh Bag 98.54 b 97.90 b 99.56 c 99.91 c

Plastic Bag 99.12 b 98.20 b 98.71 b 99.59 c 100.44 c

Table 6. Optimum storage temperature and packaging combinations for maximising shelf life for five selected vegetables.

Temperature Packaging Shelf Life

Bitter melon 5°C Paper wrapping 3 weeks

Okra 10°C Plastic bag 3 weeks

Sinqua 5°C Any 2.5 weeks

Snake beans 5 - 10 °C Plastic bag 2.5 weeks

Kang kong 5°C Plastic bag 2 weeks

36

a) Sinquar - temperature

0 5 10 15 20 25 30 35 40

Days after harvest

o o Q.

CD >

C _CD

"35 o X CD

in

o o

CO

O

~- 4

1

b) Sinquar - packaging

o Newspaper D Perforated Bag ^ Peakfresh Bag o Plastic Bag

d) Okra

f) Kang kong

0 5 10 15 20 25 30 35 40

Days after harvest

Figure 1. Effect of temperature (a, c - f) and packaging (b) on the quality of various 'Asian' vegetables during storage. Vertical bars (b) represent LSD (P<0.05).

37

Inoculum of vegetables at time of harvest An investigation of the microbial levels of vegetables at time of harvest was carried out for all five

commodities chosen, ie. lettuce, broccoli, carrots, snake beans and bitter melon. Several farms were

selected for sampling and several samples were collected from each farm and tested for total aerobic

microorganisms, coliforms, yeasts and moulds, and fluorescent Pseudomonads.

An indication of the variability of microbial inoculum from one plant to the next was provided by these

tests. Total aerobic counts were used to give a general indication of the numbers of microorganisms on

vegetables. Coliform counts give some idea of the possibility of human pathogens present on the

vegetables, especially if Escherichia coli were found. Yeast and moulds, and fluorescent Pseudomonads

are indicators of the presence of plant spoilage organisms.

Method

Several samples of each commodity were collected from several farms in Victoria and Nortem Territory.

The number of samples and farms was dependent on the availiability of commodities in an area and the

restriction of how many samples could be processed on the same day as picking. Samples were placed in

sterile bags and were transported back to the laboratory with ice packs in an esky.

Victoria

Four or five carrots were picked from three locations in one field from each of three farms. Two or three

heads of broccoli were picked from three locations in one field from each of four farms. One head of

lettuce was picked from three locations in one field from each of three farms.

Northern Teritory

Eight to ten snakebeans were picked from five locations in one field from each of three farms. Two or

three bitter melons were picked from three locations in one field from five farms.

Samples were tested on the same day as picking and the numbers counted as appropriate for each test

over the next few days. All counts were then calculated as Colony Forming Units per gram (CFU/g) of

produce.

Results

Microbial level on vegetables at time of harvest are shown in the following graphs. There was a large

variability in micro levels measured. The single highest counts were obtained on bitter melon were

40300000 CFU/g. Other bitter melon had values as low as 30 CFU/g.

The vegetable types displayed different numbers of organisms. For example, snakebeans displayed

relatively higher counts of Yeasts and Moulds. The Micro-organisms found in the greatest amounts were

Total Aerobic Count, followed by Yeasts and Moulds, with Coliforms and Fluorescent Pseudomonads.

38

The results are shown below, and graphically on the following pages.

Total aerobic Coliforms Yeasts & Fluorescent

Moulds

Bitter Melon Average Log 30337 20 2577 5

Min 30 2 476 0

Max 40300000 15200 15200 539

Broccoli Average Log 25940 290 301 7

Min 1260 13 71 0

Max 815000 4050 2750 180

Carrots Average Log 137229 8 141 5

Min 873 0 40 0

Max 5380000 88 745 58

Lettuce Average Log 43318 18 327 85

Min 986 0 31 1

Max 5380000 3370 55700 10800

Snakebeans Average Log 81849 123 5495 25

Min 1530 0 943 0

Max 3570000 3870 16000 5810

39

100000000

10000000

1000000

100000

10000

1000

100

10

1

Bitter Melon Total aerobic count

1 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 4 5

100000

10000

1000

100

10

Bitter Melon Conforms

1

MM 1 I . I 1 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 4 5

100000

10000

1000

100

Bitter Melon Yeasts & Moulds

100000

10000

1000

100

10

1

Bitter Melon Fluorescent

1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 4 5

Broccoli Total aerobic count

10000000

1000000

100000

10000

1000

100-

10

1

1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 4

100000

10000

Broccoli Coliforms

100000

10000

1000

100 --

10 +

1

Broccoli Yeasts & Moulds

1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 4

100000

10000

1000

100

10

Broccoli Fluorescent

JEL 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 4

Lettuce Total aerobic count

1onnnono

1000000 -

100000 -

10000 -

1000-

100 -

10 -

1

1000000 -

100000 -

10000 -

1000-

100 -

10 -

1

1000000 -

100000 -

10000 -

1000-

100 -

10 -

1

1000000 -

100000 -

10000 -

1000-

100 -

10 -

1

1000000 -

100000 -

10000 -

1000-

100 -

10 -

1

1 2 3 1 2 3 1 2 3 1 2 3

Lettuce Coliforms

100000

10000

1000

100

10

1

r - i r - i

— -

, , ,n, — -

1 2 3 1 2 3 1 2 3 1 2 3

Lettuce Yeasts & Moulds

1QOOOO

10000 -

1000 -

100 -

10 -

1 .

100 -

10 -

1 .

1 2 3 1 2 3 1 2 3 1 2 3

Lettuce Fluorescent

100000

10000

1000

100

10

l_1

f-i

n

n

f-i

n i - i

1 2 3 1 2 3 1 2 3 1 2 3

1QOOOOOO -,

Snake Beans Total aerobic count

1000000 -

100000 -

10000 -

1000 •

100 -

10-1 .

1000000 -

100000 -

10000 -

1000 •

100 -

10-1 .

H 1000000 -

100000 -

10000 -

1000 •

100 -

10-1 .

1000000 -

100000 -

10000 -

1000 •

100 -

10-1 .

1 1

1000000 -

100000 -

10000 -

1000 •

100 -

10-1 .

1 1 1 1

1000000 -

100000 -

10000 -

1000 •

100 -

10-1 .

S 1 jT

1000000 -

100000 -

10000 -

1000 •

100 -

10-1 . 1 1 1 1

1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 4 5

Snake Beans Coliforms

100000

10000

1000

100

10

1 unnnn

1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 4 5

Snake Beans Yeasts & Moulds

100000

10000

10 --

1000-*-™- -

100 --

Snake Beans Fluorescent

100000

IOOOOOOO -*

Carrot Total aerobic count

1000000 -

iooooo -

10000 -

•

—

1000 -

100 -

10-

•

1 2 3 1 2 3 1 2 3 1 2 3

100000

10000

1000

100

10

Carrot Coliforms

nn JUL 1 2 3 1 2 3 1 2 3 1 2 3

100000 -

Carrot Yeasts & Moulds

10000 -

1000 •

100 •

10 -

1 .

10000 -

1000 •

100 •

10 -

1 .

10000 -

1000 •

100 •

10 -

1 .

-

^

10000 -

1000 •

100 •

10 -

1 . -

- -—

-

1 2 3 1 2 3 1 2 3 1 2 3

100000

10000

1000

100

10

1

Carrot Fluorescent

is

3 1 2 3 2

42

Cool chain handling and microbial loads Investigations into the response of microbial loads of vegetables to transport and breaks in the cool chain

were carried out in three ways. Firstly, simulated temperature abuse trials were conducted in coolrooms

with controlled temperature environments, over time. Secondly, temperatures were monitored from the

distributor in Darwin to Melbourne Market and samples tested from each end. Thirdly, simulated

temperature abuse transport was carried out from Adelaide to Melbourne.

Introduction

The microbiological monitoring was used to investigate the effect of temperature and handling conditions

on the microbiological load found on vegetables. Four analyses were done on each vegetable sample,

representing different aspects of quality and safety.

Total Aerobic counts: Quality

Coliforms: Indicator of Human Pathogens

Yeasts and Moulds: Quality and Spoilage Organisms

Fluorescent Pseudomonads: Quality and Human Pathogens

In some instances microbiological levels will be causative in the deterioration of produce, usually a

particular bacteria, or plant pathogenic fungi. Alternatively, microbiological levels can be indicative of

morphological and physiological condition of the plant tissue, that is, high microbiological levels can be a

result of deteriorating tissue, but not necessarily to cause of it. Either way, the results presented can give

some indication of postharvest vegetable health.

A range of temperatures was used in the simulated abuse trials to represent conditions that may be

experienced during handling practices.

The transport from Darwin to Melbourne measured microbiological levels before and after transport to

investigate how commercial transport conditions impact on microbiological levels.

The Adelaide to Melbourne transport monitored microbiological levels, before and after transport at 2

temperatures (2° and 8°C) and with or without precooling, to determine how these practices impact on

microbiological levels and ultimately food quality and saftey.

Methods

Simulated temperature abuse (Cool room experiments)

This experiment has been conducted with broccoli, lettuce, carrots and snakebeans. Coolrooms were set at

five different temperatures (4, 8, 15, 25, 35°C) and bulk boxes stored at each temperature. Samples were

collected from each box at four times (0, 24, 48 and 72 hours) and tested for Total aerobic counts,

coliforms, yeasts and moulds, and fluorescent Pseudomonads.

43

Transport from Darwin to Melbourne

Snakebeans and bitter melon were intercepted at the distributor in Darwin. Temperature loggers were

inserted into produce and a sample taken from the same box. This sample was couriered to IHD,

Knoxfield overnight with ice. The boxes continued through to Melbourne market via the normal

distribution chain. Temperature loggers and a sample of produce were collected from Melbourne Market.

The samples were tested at IHD Knoxfield for total aerobic counts, coliforms, yeasts and moulds, and

fluorescent Pseudomonads.

Refrigerated transport (Adelaide to Melbourne)

Lettuce, broccoli and carrots were transported from Adelaide to Melbourne. Produce was collected from a

grower taken to SARDI, temperature loggers were set up and the produce stored at ambient or coolroom

temperatures until couriered at 8°C or 2°C. Samples from before storage were couriered overnight with

ice to IHD, Knoxfield. Samples after storage were tranported with ice in the 2°C courier truck. Finally

samples and temperature loggers were collected from Melbourne market and taken to IHD, Knoxfield.

All samples were tested for total aerobic counts, coliforms, yeasts and moulds, and fluorescent

Pseudomonads.

Results

Results are shown graphically on the following pages.

Simulated Temperature Abuse

Temperature was found to be a major factor in the growth rate of the organisms. Despite some variability,

the higher temperatures were found to have higher growth rates, except in some instances where an

increase in temperature reduced the rate of growth. This was true for the Yeasts and Moulds (peak at

25°C); Fluorescent Pseudomonads (peak at 15 - 25°C) and Lettuce (peak at 25°C). However in any

normal market handling practices (eg not 35°C for 3 days), the lower the storage temperature, the lower

the rate of microbiological growth. This was confirmed by the result that in all instances, the 4°C

treatment showed the lowest, or equal lowest growth of microbiological organisms.

44

Figure la: Microbial loads on Broccoli when stored at different temperatures for different times, to

40000000

35000000

30000000

25000000 "5 u.

o ~ 20000000 c a o o

15000000

10000000

5000000

Broccoli - Total Aerobic Count

24 48

Time (hours)

72

- © - 4 9 C

-B-89C

~*-25BC -*- 358C

45000

40000

35000

30000

g 25000 O

c o 20000

15000

10000

5000

Br

Figure la: Microbial loads on Broccoli when stored at different temperatures for different times, tot

Broccoli - Total Aerobic Count

40000000

35000000

30000000

25000000

3 U.

O r 20000000 c o o

15000000

10000000

5000000

•*-4 sC

9 -8 9 C

259C

35SC

24 48

Time (hours)

72

Bro

45000

40000

35000

30000

01 g 25000 p

20000

15000

10000

5000

Figure 2a: Microbial loads on Carrots when stored at different temperatures for different times, total aer

Carrot - Total Aerobic Count

40000000

35000000

30000000

25000000

3 U. Ji 20000000 c 3 o o

15000000

10000000

5000000

4SC

8fiC

15SC

25fiC

35SC

6 24 48 72

Time (hours)

Carro

30000

25000

20000

3 LL

2. 15000 c 3 o o

10000

5000

Figure 2b: Microbial loads on Carrots when stored at different temperatures for different times, yeast and counts.

8000

7000

6000

5000

u. o 4000

c 3 o o 3000

2000

1 0 0 0 -

Carrots - Yeast and Mould Count

6 24 48

Time (hours)

72

4SC

8fiC

15eC

25SC

35fiC

Carrots - Fluo

300000

250000

200000

u. O

150000

I 100000

50000

Figure 3a: Microbial loads on Lettuce when stored at different temperatures for different times, total aero

Lettuce - Total Aerobic Count

1600000000

1400000000 -

1200000000

1000000000

u.

~ 800000000 (0

o O

600000000 -

400000000

200000000 -

24 48

Time (hours)

72

* - 4 f i

e-8sc i« i-15eC

* - 2 5 B C 35fiC

Lettuc

1800000

1600000

1400000

1200000

£ 1000000 o,

i 800000 o o

600000

400000

200000

Figure 3b: Microbial loads on Lettuce when stored at different temperatures for different times, yeast and counts.

Lettuce - Yeasts and Mould Count

800000

700000

600000

24 48

Time (hours)

72

• 4 s

-B-89C

-A-15SC

-X-259C

-*-359C

Lettuce - Fluor

16000000

14000000 -

12000000

10000000

3 U.

~ 8000000 c 3 o o

6000000

4000000

2000000

Figure 4a: Microbial loads on Snakebeans when stored at different temperatures for different times, total

Snakebeans - Total Aerobic Count

100000000

90000000

80000000

70000000

^ 60000000 - -

5 IL

" 50000000 f c 3 0 ° 40000000

30000000

20000000

10000000

24 48

Time (hours)

72

^-4°C

a — 8fic A-15 9C

*- 2 5 s C

358C

Snake

600000

550000

500000

450000

400000 -

3 350000 1

5 u.

~ 300000 -'c 3 O ° 250000

200000

150000

100000

50000

Figure 4a: Microbial loads on Snakebeans when stored at different temperatures for different times, yeast Pseudomonad counts.

450000

400000

350000

Snakebeans - Yeast & Mould Count

24 48

Time (hours)

72

^ - 4 9 C

B—8SC

* - 1 5 9 C

* - 2 5 9 C

359C

Snakebeans -

25000

22500

20000

Results: Transport from Darwin to Melbourne

Results from the Darwin studies demonstrate the variability between runs with some samples

rapidly increasing in numbers over the transport time, while others decreasing at a rapid rate.

53

Figure 5a : Microbial loads on bitter melon before (initial) and after (final) transport, total aerobic and c

Bittermelon - Total Aerobic Count

600000

500000-

400000-

O) D li. o — 300000" c 3 o O

200000 -

100000"

initial final

- e — R u n 1

-S—Run 2

-A—Run 3

-*—Run 4

Hi—Run 5

-6—Run 6

-#—Run 7

-X—Run 8

- -O-•Run 9

- -O--Run 10

80000

70000"

60000-

^ 50000 O) D li. O ^ 40000 +J

c 3 O

o 30000

Bitterm

20000

10000

initial

Figure 5b: Microbial loads on bitter melon before (initial) and after (final) transport, yeast and mould an

Bittermelon - Yeast & Mould Count

900000

800000

700000-

600000-

D LL

o c 3 o o

500000"

400000 -

300000-

200000 "

100000-

p

/ ...

. . .

...

. . .

...

. . .

"1 ...

"1 ...

"1 ...

--•O-^-Run 9

- - O - - R u n 10 7

--•O-^-Run 9

- - O - - R u n 10 1

--•O-^-Run 9

- - O - - R u n 10 1

& a

initial final

Bittermelon -

5000 -

4500 "

4000 "

3500"

B 3000 -

4000 "

3500"

B 3000 -

4000 "

3500"

B 3000 -

4000 "

3500"

B 3000 -D IL

o w 2500"

D IL

o w 2500"

D IL

o w 2500" c 3 c 3 O 2000 " O 2000 "

1500-

1000 "

500"

1000 "

500"

o • ™ initial

Figure 6a: Microbial load on snakebeans before (initial) and after (final) transport, total aerobic and coli

Snakebeans - Total Aerobic Count

35000000 '

30000000 " - •—Run 1 30000000 " - •—Run 1

\ - e - R u n 2

25000000 -\ -T&-Run3 25000000 - \

-T&-Run3

\ - * - R u n 4 .—s \

D 20000000-U. O

\ - • - R u n 5

- e - R u n 6

D 20000000-U. O \

- • - R u n 5

- e - R u n 6 +•> \ c § 15000000 -

\ —•—Run 7 c § 15000000 - \

—•—Run 7

O \ - * - R u n 8

10000000 • \ —h- Run 9

10000000 • V —h- Run 9

\ - • - R u n

5000000 -V 10

5000000 -V

5000000 -

^i5 initial final

Snakebe

450000

400000-

350000-

300000 -

95 2 250000

3 200000 o O

150000

100000"

50000"

initial

Figure 6b: Microbial load on snakebeans before (initial) and after (final) transport, yeast and mould and

Snakebeans - Yeast & Mould Count

800000

700000-

600000-

~ 500000 -•5*

IL

o — 400000" c 3 o o 300000 -

200000

100000-

initial final

Snakebeans-

12000

10000-

8000-

D LL O — 6000 4-1

c 3 O O

4000 -

2000"

initial

Temperature abuse during transport (Adelaide to Melbourne)

Results of the transport studies were more variable than the laboratory studies. Full results are presented

graphically on the following pages.

A summary of the results was achieved by ranking the microbiological counts at the end of each run, to

determine which combination of handling conditions of precooling and transport temperature were better

for each vegetable.

Precooling prior to transport resulted in lower microbiological levels than uncooled produce, except in the

case of lettuce which had higher microbiological in the uncooled produce.

Interestingly, on average the 8°C transport temperature resulted in lower microbiological levels than the

2°C temperature, although the differences were quite small. Coliforms and Fluorescent Pseudomonads

showed no difference with temperature while Total Aerobic counts and Yeasts and Moulds showed lower

levels at 8°C.

59

Figure 7a: Total aerobic counts of Broccoli before and after storage and after transport from

Melbourne to Adelaide.

Runl

before after storage after transport

"precooled, 2"C transport

'uncooled, 2"C transport '

"precooled, 8"C transport

"uncooled, 8°C transport

Run 3 70000

60000

before after storage after transport

"precooled, 2°C transport

"uncooled, 2"C transport

"precooled, 8°C transport

"uncooled, 8°C transport

Run 2 4000000

3500000

before after storage after transport

"precooled, 2°C transport

"uncooled, 2°C transport

"precooled, 8°C transport

•uncooted, 8°C transport

R u n 4

before after storage after transport

"precooled, 2°C transport S— precooled, 8°C transport

"uncooled, 2°C transport ~~*~~uncooled, 8°C transport

Run 5

2500000

2000000

-5? 3 1500000 u. U

5 1000000 u

500000

before after storage, after transport

"precooled, 2°C transport"

"uncooled, 2"C transport *

"precooled, 8°C transport

"uncooled, 8°C transport

60

Figure 7b: Coliform counts of Broccoli before and after storage and after transport from

Melbourne to Adelaide.

Runl

before after storage after transport ""pre-cooled, 2°C transport"

"" uncooled, 2°C transport

"pre-cooled, 8"C transpor

"uncooled, 8"C transport

Run 3 600

500

400

r 300

200

100

0

before after storage after transport —pre-cooled, 2°C transport

"uncooled, 2°C transport

"pre-cooled, 8°C transpor

~ uncooled, 8"C transport

Run 2 25000

before after storage after transport

"pre-cooled, 2°C transport"

"uncooled, 2"C transport *"

"pre-cooled, 8°C transpor

"uncooled, 8"C transport

Run 4 800

700

600

g 50° r 4oo u 300

200

100

before after storage after transport

"pre-cooled, 2°C transport"

" uncooled, 2°C transport "

"pre-cooled, 8°C transpor

"uncooled, 8°C transport

Run 5

before after storage after transport

~ pre-coded, 2°C transport

'uncooled, 3*C transport

"pre-cooled, 8*C transport

"uncooled, 8"C transport

61

Figure 7c: Yeast and moould counts of Broccoli before and after storage and after transport from

Melbourne to Adelaide.

Run 1

before after storage after transport

"pre-cooled, 2 X transport '

-uncooled, 2°C transport '

"pre-cooled, 8"C transport

"uncooled, 8°C transport

40000

35000

30000

3 25000 f

B 20000 f

10000 t

5000

Run 2

before after storage after transport

"pre-cooled, 2"C transport '

"uncooled. 2°C transport '

"pre-cooled, 8°C transport

~ uncooled. 8°C transport

Run 3

before after storage after transport

"pre-cooled, 2"C transport '

"uncooled, 2°C transport '

"pre-cooled, 8°C transport

"uncooled, 8"C transport j

Run 4 35000

30000

,-, 25000 t CO

U, 20000 f o c 15000 3 O

0 10000

5000

before after storage after transport

-pre-cooled, 2*C transport

-uncooled. 2*C transport

-pre-cooled, 8"C transport

-uncooled, 8°C transport

Run 5 9000

before after storage after transport

~ pre-cooled, 2"C transport "

"uncooled, 2°C transport

•pre-cooled, B°C transport

"uncooled, 8°C transport

62

Figure 7d: Fluorescent Pseudomonad counts of Broccoli before and after storage and after

transport from Melbourne to Adelaide.

30

25

20 3

2 15

10

Run 1

before after storage after transport "pre-cooled, 2°C transport"

"uncooted, 2°C transport

~ pre-cooled, 8°C transpor

"uncooled, 8°C transport

Run 2 1200

1000

-3 800

3 | 600 c 3

5 400

200

o- "pre-cooled, 2°C transport"

"uncooted, 2°C transport ""

"pre-cooled, 8°C transpor

"uncooled, 8°C transport

Run 3 70

60

50

40

30

20

10

o-H "pre-cooled, 2°C transport"

"uncooled, 2°C transport oeiore

"pre-cooled, 8°C transpor

"uncooled, 8"C transport

atter storage—atter transport

Run 4 400

350

300

| 250

r 200

8 150

100

50

"pre-cooled, 2°C transport'

"uncooled, 2°C transport

oerore

"pre-cooled, 8°C transpor

"uncooled, 8°C transport

atter storage—alter transport

Run 5

250-

a 20oJ

3

I 150-C 3 O U

loo­

se­

250-

a 20oJ

3

I 150-C 3 O U

loo­

se­

\

250-

a 20oJ

3

I 150-C 3 O U

loo­

se­

\

250-

a 20oJ

3

I 150-C 3 O U

loo­

se­

\ \ / "

250-

a 20oJ

3

I 150-C 3 O U

loo­

se­

^\ / r

250-

a 20oJ

3

I 150-C 3 O U

loo­

se­

250-

a 20oJ

3

I 150-C 3 O U

loo­

se­ W /̂̂ **-ly n

before after storase after transport * pre-cooled, 2°C transport ' " pre-cooted, 8°C transpor

* uncooled, 2"C transport ' * uncooled, 8"C transport

63

Figure 8a: Total aerobic counts of Carrots before and after storage and after transport from

Melbourne to Adelaide.

Runl 1800000 "i

X

•3 1200000 ' D

= 800000 ' 0

A

200000 ^S> n • •— H 0

before after storage after transport

~ precooled, 2°C transport '

"uncooled, 2°C transport '

"precooled, 8°C transport

"uncooled, 8°C transport

Run 3 7000000

6000000

5000000

•5?

g 4000000

u I 3000000 o U

2000000

1000000

before after storage after transport

"precooled, 2"C transport '

"uncooled, 2"C transport '

"precooled, 8"C transport

"uncooled. 8"C transport

Run 4

1200000 "

1000000 • S 0 800000- s

CF

U/(

> * ^ - * <s c

d 0

U 400000-

/ c d 0

U 400000- X „ —==ft c d 0

U 400000-^s_——a-

200000 "

0 J 1 • 0 J

' ^ precooled, 2°C transport ** precooled, 8"C transport

A " uncooled, 2°C transport ' * uncooled, 8°C transport

4000000

3500000

3000000

4? 2500000 3 ~ 2000000

O 1500000

1000000

500000

0

Run 5

before after storage after transport

"precooled, 2"C transport.'

"uncooled. 2°C transport '

"precooled, 8"C transport

"uncooled, 8"C transport

64

Figure 8b: Coliform counts of Carrots before and after storage and after transport from

Melbourne to Adelaide.

Run 1 yuuu -

8000-

7000-

6000-

5000

4000-

3000-

2000

1000

yuuu -

8000-

7000-

6000-

5000

4000-

3000-

2000

1000

)K

yuuu -

8000-

7000-

6000-

5000

4000-

3000-

2000

1000

yuuu -

8000-

7000-

6000-

5000

4000-

3000-

2000

1000

yuuu -

8000-

7000-

6000-

5000

4000-

3000-

2000

1000

yuuu -

8000-

7000-

6000-

5000

4000-

3000-

2000

1000

yuuu -

8000-

7000-

6000-

5000

4000-

3000-

2000

1000

yuuu -

8000-

7000-

6000-

5000

4000-

3000-

2000

1000

yuuu -

8000-

7000-

6000-

5000

4000-

3000-

2000

1000 A o J 1 • i B i B

before after storage after transport

"precooled, 2°C transport

"uncooled. 2°C transport '

"precooled, 8°C transport

"uncooled, 8°C transport

Run 2

7000 "

6000-

5000

'Si 2 4000-

1 3000 o U

2000

1000

7000 "

6000-

5000

'Si 2 4000-

1 3000 o U

2000

1000

/v 7000 "

6000-

5000

'Si 2 4000-

1 3000 o U

2000

1000

7 xv

7000 "

6000-

5000

'Si 2 4000-

1 3000 o U

2000

1000

/ V*

7000 "

6000-

5000

'Si 2 4000-

1 3000 o U

2000

1000

/ \

7000 "

6000-

5000

'Si 2 4000-

1 3000 o U

2000

1000 7

7000 "

6000-

5000

'Si 2 4000-

1 3000 o U

2000

1000

o -I before after storage after transport

* precooled, 2°C transport ^ precooled, 8°C transport

~~* uncooled, 2°C transport ~~*"~ uncooled, 8"C transport

Run 3

before after storage after transport

"precooled, 2°C transport ~~H precooled, 8"C transport

"uncooled, 2°C transport * uncooled, 8"C transport

Run 4

before after storage after transport

"precooled, 2°C transport *

"uncooled, 2"C transport

•precooled, 8°C transport

"uncooled, 8°C transport

25000-

20000-

'SS

3 15000-

1 10000-

5000-

Run 5 25000-

20000-

'SS

3 15000-

1 10000-

5000-

_X . _

25000-

20000-

'SS

3 15000-

1 10000-

5000-

____2Z____ 25000-

20000-

'SS

3 15000-

1 10000-

5000-

.........JLL......

25000-

20000-

'SS

3 15000-

1 10000-

5000-

-----yC^----

25000-

20000-

'SS

3 15000-

1 10000-

5000-* - — - ^ ^

o -i before after storage after transport

• precooled, 2°C transport B precooled, 8°C transport

* uncooled, 2°C transport * uncooled, 8"C transport

65

Figure 8c: Yeast and mould counts of Carrots before and after storage and after transport from

Melbourne to Adelaide.

Run 1

3000

2 5 0 0 -

•~ 2000 00

1500 X

before after storage after transport

"prccooled, 2°C transport '

"uncooled, 2"C transport '

"precooled, 8°C transport

"uncooled, 8"C transport

Run 3

30000

25000

- 20000

15000 •-

10000

5000

before after storage after transport

"prccooled, 2"C transport '

"uncooled, 2*C transport '

•precooled, 8°C transport

"uncooled, 8*C transport

Run 2

9000

before after storage after transport

•precooled, 2°C transport '

" uncooled, 2°C transport '

"precoolcd, 8°C transport

"uncooled, 8°C transport

Run 4

12000

before after storage after transport

*" prccooled, 2°C transport

"uncooled, 2°C transport

"precooled, 8°C transport

"uncooled, 8°C transport

30000

25000-

o. 20000-

10000-

5 0 0 0 -

R u n 5

before after storage after transport

"prccooled, 2"C transport''

"uncooled. 2°C transport '

"precooled, 8"C transport

"uncooled. 8"C transport

66

Figure 8d: Fluorescent Pseudomonad counts of Carrots before and after storage and after

transport from Melbourne to Adelaide.

Run 1 1400

1 2 0 0 -

1000

800

600 --

4 0 0 -

2 0 0 -

-A-

X

before after storage after transport

"precooled, 2°C transport '

"uncooled, 2"C transport '

"precooled, 8°C transport

"uncooled, 8°C transport

Run 3 5000

4500

4000

3500 'So 3 3000 o 2500 -

2000

1500

1000

500

0

before after storage after transport

"precooled, 2°C transport '

"uncooled, 2"C transport '

"precooled, 8°C transport

"uncooled, 8°C transport

Run 2

before after storage after transport

•precooled, 2°C transport '

"uncooled, 2*C transport '

•precooled, 8°C transport

"uncooled, 8°C transport

Run 4 1600

1400

1 2 0 0 -

1000

8 0 0 -

tj 600

400

2 0 0 -

before after storage after transport

"precooled, 2°C transport '

"uncooled, 2°C transport '

•precooled, 8°C transport

•uncooled, 8°C transport

Run 5

before after storage after transport

"precooled, 2°C transport '

"uncooled, 2°C transport

•precooled, 8°C transport

"uncooled, 8"C transport

67

Figure 9a: Total aerobic counts of Lettuce before and after storage and after transport from

Melbourne to Adelaide.

Run 1

W 25000000 -- A-

^ 20000000 --2? r~~~77vT""" ^- 15000000 • 3 C

U 10000000 - •f/\--^- 15000000 • 3 C

U 10000000 -• • • ~ ~ / / ~ - \ - "

5000000 •

n • - - / • \ -

before after storage after transport "precooled, 2"C transport '

"uncooled, 2°C transport '

"precooled, 8"C transpon

"uncooled, 8°C transport

Run 3 2500000

2000000 • -

3 1500000 •X

g

o 1000000

500000 - -

"precooled, 2°C transport '

"uncooled, 2*C transport '

"precooled, 8°C transport

"uncooled. 8°C transport

6000000-

5000000 -

<-. 4000000 -so

u. ^ 3000000 -3 O

° 2000000 -

1000000 -

°r

Run 2

6000000-

5000000 -

<-. 4000000 -so

u. ^ 3000000 -3 O

° 2000000 -

1000000 -

°r

2* 6000000-

5000000 -

<-. 4000000 -so

u. ^ 3000000 -3 O

° 2000000 -

1000000 -

°r w

6000000-

5000000 -

<-. 4000000 -so

u. ^ 3000000 -3 O

° 2000000 -

1000000 -

°r —+— precooled, 2°C transport — - a — precooled, 8"C transport

" " ^ ^ u n c o o l e d , 2"C transport * "uncooled, 8"C transport

Run 4 3500000

3000000 - -

2500000 • -

£ 2000000

y, 1 1500000-o U

1000000

500000

"precooled, 2"C transport '

"uncooled, 2"C transport '

"precooled, 8°C transport

"uncooled. 8"C transport

14000000

12000000 --

10000000

I £ 8000000 u 6000000 - -

4000000 - -

2000000

Run 5

before after storage after transport "precooled, 2°C transport '

"uncooled, 2"C transport '

" precooled, 8"C transport

"uncooled. 8*C transport

68

Figure 9b: Coliform counts of Lettuce before and after storage and after transport from

Melbourne to Adelaide.

12000

10000

5 8000

" 6000

4000

2000

Run 1

before after storage after transport

"precooled, 2"C transport '

•uncooled. 2*C transport '

•precooled, 8°C transport

•uncooled, 8°C transport

1000

900

800

700

600

• 500

400

300

200

100

Run 2

before after storage after transport

"precooled, 2"C transport '

•uncooled, 2*C transport '

"precooled, 8°C transport

•uncooled, 8"C transport

80

70

60

| 50

| 40

° 30

20

10

Run 3

"precooled, 2"C transport '

"•uncooled, 2*C transport '

"precooled, 8°C transport

"uncooled, 8°C transport

400

350

300

£ 2 5 0 •—

" 200

150

100

50

Run 5

12000

10000

8000 3 LL.

O 6000

4000

2000

o - f -

Run4

"precooled, 2"C transport '

"uncooled, 2"C transport *

•precooled, 8°C transport

"uncooled, 8*C transport nui -uuiupui L

"precooled, 2°C transport '

"uncooled, 2"C transport '

"precooled, 8°C transport

"uncooled, 8*C transport

69

Figure 9c: Yeast and mould counts of Lettuce before and after storage and after transport from

Melbourne to Adelaide.

35000

30000 -

Run 1

before after storage after transport

-prccooled, 2°C transport '

"uncooled, 2°C transport '

"precooled, 8°C transport

"uncooled, 8°C transport

Run 2

before after storage after transport

"precooled, 2°C transport '

"uncooled, 2°C transport '

"precooled, 8°C transport

"uncooled, 8°C transport

Run 3

before after storage after transport

"precooled, 2°C transport '

"uncooled, 2°C transport '

"precooled, 8°C transport

"uncooled, 8°C transport

Run 4

before after storage after transport

"precooled, 2°C transport '

"uncooled, 2°C transport '

"precooled, 8°C transport

"uncooled, 8°C transport

Run 5

before after storage after transport

"precooled, 2"C transport '

"uncooled, 2°C transport '

"precooled, 8"C transport

"uncooled, 8°C transport

70

Figure 9d: Fluorescent Pseudomonad counts of Lettuce before and after storage and after

transport from Melbourne to Adelaide.

Run 1 3000

2500

2000

before after storage after transport

"precooled, 2°C transport '

"uncooled, 2°C transport '

"precooled, 8°C transport

"uncooled, 8°C transport

Run 3 6000

5000

--, 4000

u. ~ 3000

2000-

1000-

before after storage after transport

"precooled, 2°C transport '

"uncooled, 2°C transport '

"precooled, 8"C transport

"uncooled, 8°C transport

Run 2 8000

7 0 0 0 -

6 0 0 0 -

•S? 5 0 0 0 -3

before after storage after transport

"precooled, 2°C transport '

"uncooled, 2"C transport '

"precooled, 8°C transport

"uncooled, 8°C transpon

Run 4

before after storage after transport

"precooled, 2*C transport '

""uncooled, 2"C transport '

"precooled, 8"C transport

'uncooled, 8"C transport

Run 5

before after storage after transport

"precooled, 2°C transport

"uncooled, 2'C transport

"precooled, 8"C transport

"uncooled, 8°C trdnsport

71

Temperature and Microbiological monitoring through the marketing chain

30X

2TC

20X

15X

10X

5*C

OX

20000

J- 15000

• - p

o TJ cz

-f 10000

+ 5000

0 days 1 days

Pre- c o ole d after p ac kin§

2 days 3 days

B Not pre-cooled

Notes:

Carrot Temperature - line. Microbiological level - column

Microbiological samples were taken at packing, prior to transport and at the markets. Microbiological

level is coliforms, an indicator of human pathogen growth.

Implications: There was a rapid increase in microbiological levels when carrots were not pre-cooled.

Adequate pre-cooling is critical in slowing the growth rate of spoilage organisms and minimising the

chance of food safety problems.

72