Spinning Disc Reactors - Flanders' FOOD · Akhtar, M . and Krishnan, S. S. Preparation of oil-water-oil multiple emulsions using spinning disc reactor technology, an oral presentation

Flanders’ FOOD Technology day 2010

IRMH ProcesstechNovel Processing Consultant

Spinning Disc Reactors

A novel processing machine for the food and chemical industry

Flanders FOOD Technology Day 2010


Basically a rotating disc, that can be heated or cooled, is fed with one or more liquids at its centre.

The liquids mix and spread over the disc and are collected at the edge. Mixing, heat transfer and mass transfer occurs on the disc












SDRs and Food processing; key characteristics

Ability to very rapidly heat and cool fluids, especially viscous fluids; pasteurisation, fine crystal formation. Very low delta T gives less thermal damage. Film coefficients up to 50kW/m2K, overall 10kW/m2K.

Self cleaning/easy clean characteristic

Enhanced mass transfer for evaporation and odour removal with less thermal damage

Effective use of UV radiation (sunshine treated!)

Unique combination of shear and draw gives opportunities for “structure manipulation”




And there’s more

Fundamentally easy to scale

Surface can be catalyst coated

Surface can be modified to alter residence times

Precipitation and crystallisation can be carried out without scaling

Non foaming

Especially good at handling viscous fluids particularly in cooling heat

transfer

Pure plug flow; no back mixing



SDRs and viscous fluids

A unique ability to manage viscous fluids thanks to a combination of shear, draw and high temperatures.

Feed Pipe

Angular Draw

Radial Shear

Increased Area of Coverage

Rotation of Disc

Normal Entangled Polymer Drawn Disentangled Polymer

The liquid film is “drawn” which tend to align and orientate long molecules




Removal of water (dissolved and as separate phase) from oil

Cloudy moist organicCloudy moist organicaround 1000ppm Haround 1000ppm H22OO

Clear processed organicClear processed organicaround 25ppm Haround 25ppm H22OO

SDR ProcessingSDR Processing

•• Organic heated rapidly to 200Organic heated rapidly to 200ooCC

•• Water removed with counterWater removed with counter--current current

gas flow. No spitting, no foaminggas flow. No spitting, no foaming

•• Organic cooled on walls.Organic cooled on walls.

•• Increased vapour pressure, water Increased vapour pressure, water

easily stripped with modest gas flow or easily stripped with modest gas flow or

vacuum.vacuum.

•• Exposure time short enough to avoid Exposure time short enough to avoid

degrading despite temperaturedegrading despite temperature

•• Result : Product is clear and dry.Result : Product is clear and dry.

An example of heat and mass transfer



SDR in the Food Industry; work carried out at Leeds University

Mayonnaise

Emulsions

Ice Cream

Fruit Juices




Mayonnaise (70% Oil)Lemon juice, vinegar, mustard, black pepper and egg yolk were mixed and passed over the reactor disc. The temperature was increased to 30, 40, 50 and 58 oC.

Conclusion: Slowly increasing the temperature to 58 oC, could produce pasteurised, consistent, smooth and homogeneous mayonnaise .

A high viscosity and creamy mayonnaise was produced.

Salmonella test has been confirmed negative.

Particle Size Distribution

0.01 0.1 1 10 100 1000 3000

Particle Size (µm)

0

2

4

6

8

10

Volu

me (

%)

70% oil SDR mayonaise 58 C, 04/05/05 12:32:40 SDR-mayonnaise, 03/27/05 19:14:58

at 25 oCat 58 oC



Comparison with Commercial Mayonnaise

Hellmann’s Real Mayonnaise

SDRMayonnaise

Microbiology tests confirmed that the mayonnaise was negative for Salmonella.

Aver. droplet size ~ 7 µmAver. droplet size ~ 25 µm Particle Size Distribution

0.01 0.1 1 10 100 1000 3000

Particle Size (µm)

0

2

4

6

8

10

Vo

lum

e (

%)

SDR-mayonnaise, 03/27/05 19:14:58 Hellman's mayonnaise repeat, 03/27/05 19:30:30

SDR mayonnaise is more consistent, smoother and

softer than Hellmann’s real mayonnaise.

Hellmann’sSDR




Multiple emulsions

water (W)

an O1/W/O2

multiple emulsiona W1/O/W2

multiple emulsion

water (W2)

water (W1)

oil (O)

oil (O1)

oil (O2)

There are two distinct forms of simple multiple emulsion.

- a water-in-oil-in-water (W/O/W) and

- an oil-in-water-in-oil (O/W/O).



Primary Emulsion

Jet Homogenizer

primary emulsion (W/O)

oil+lipophilic emulsifier(80 vol%)

aqueous phase(20 vol%)

average droplet size ~ 0.5 -1 µm

Pressure

350 bar

Secondary Emulsionprimary emulsion

(20 vol%)Spinning disc

reactor

W+hydrophilic emulsifier aqueous phase

(80 vol%)8 ml/s,

2000 rpm

a W/O/W multiple emulsion

average droplet size ~ 2 –10 µm

Stage I

Stage II

W/O/W multiple emulsions




inner aqueous phase

oil phase

primary emulsifier

secondary emulsifier

The SDR-processed multiple emulsionThe SDR-processed multiple emulsion

Confocal laser scanning microscopy

Confocal microscopy confirms that indeed mono-disperse multiple

emulsions were formed.



Ice Cream Making Process Using SDR

Water, xanthan gum, sugar, unsalted

butter, lecithin, milk, double cream,

skimmed milk powder

Homogenisation Pasteurisation

The mix was passed continuously over the disc at

85 °C; 3000 rpm; flow rate 6 ml/s; inlet temperature 20 °C

Freezing/aeration

Model ice cream

Heated at 55 °C

0-18 hr ageing

Ice Cream Base

Samples were collected

for micro analysis




Mixing(Pre-heating to 60°C)

Pasteurisation79.5°C for 15 seconds

Homogenisation

Cooling<7.2°C within 15 sec

AgeingTypical 18 hours

Conventional HTST

Freezing/aeration

The commercial process for making ice cream requires separate Pasteurisation and

Homogenisation stages followed by 18 hours ageing of the mixture.

Mixing(Pre-heating to 60°C)

Pasteurisation85°C for 0.43 seconds

Cooling<7.2°C

Balance tank0 hours

Freezing/aeration

SDR



Challenge TestingIce cream base was spiked with E. coli K-12. The mix was passed over the SDR and

samples were collected in aseptic containers.

E. coli K-12 is a weak strain and is widely used as a model organism in research.

The samples processed at 90°C indicate that sufficient heat has been applied to achieve a reduction in microbial loading associated with a safe product.

Microbiology of Ice Cream

0

3

6

9

12

60 70 80 90

disc temperature ( oC)

E.

co

li x

10 3

(cfu

/g)

E. coli K-12




ice cream base Particle Size Distribution

0.01 0.1 1 10 100 1000 3000

Particle Size (µm)

0

2

4

6

8

10

Vo

lum

e (

%)

Ian's ice cream, 06/26/07 17:18:38

Zero-hour Taste panel sample (1% lecithin), 06/26/07 17:34:51

SDR

Commercial

Particle Size Distributions

The SDR generates a stable emulsion that requires zerohours ageing to subsequently produce an ice cream product.



Sensory Assessment of Ice Cream

Model ice cream at zero-hour ageing was found to be very acceptable to the panellists.

0

1

2

3

4

5

6

7

8

9

0 h 18 h commercial

ice cream at different ageing time

mean

valu

es

smoothness

stickness

meltability

coldness




Pasteurisation of Fruit Juice

Prepared Fresh juice

Passed over the disc at various temperatures (75-95 °C); 2500 rpm; flow rate 6 ml/s; inlet temp. 5-10 °C

Samples were collected in aseptic containers and stored in Fridge at 5 °C

Microbiological analysis

Pasteurisation Homogenisation



Microbiology of Fruit Juice

0

800

1600

2400

3200

4000

1 2 3 5 6 8

Time (day)

TV

C x

10

3 (c

fu/g

)

Pasteurised

Un-pasteurised

Commercial

(a)

0

200

400

600

800

1 2 3 5 6 8

Time (day)

co

lifo

rm x

10

3 (

cfu

/g)

Pasteurised

Un-pasteurised

Commercial

(b)

The spinning disc reactor using a processing temperature of 90°C achieves a microbiologically safe fruit juice.




Sensory Assessment of Fruit Juice

The results show that the SDR technology doesn’t have detrimental effecton the perceived aroma, flavour and colour.

The SDR pasteurised juice is preferable to the commercial sample.

0

2

4

6

8

10

SDR-

Pasteurised

UnPasteurised Commercial

mea

n v

alu

es

Aroma

Flavour

Smoothness

Thickness

Colour



In Summary…

A controllable and scalable processor that has the potential to enhance the production of existing products and to produce unique products




Akhtar, M. and Krishnan, S. S. Preparation of oil-water-oil multiple emulsions using spinning disc reactor technology, an oral presentation in the World Emulsion Congress

to be held in Lyon (France) 11-13th October (2010).Akhtar, M. Chan, P. S. K. and Dinakaran, B. S. (2010). Pasteurization of carrot juice

using spinning disc reactor technology, submitted to LWT April.Akhtar, M., Chan, P. S. K., and Clayton, G. (2010). Concentration of apple juice using spinning disc reactor technology is being considered for a patent application, University

of Leeds (2010).Akhtar, M., Blakemore, I., Clayton, G. & Knapper, S. (2009). The use of spinning disc reactor for processing ice cream base – effect of ageing in making model ice cream.

International Journal of Food Science and Technology, 44, 1139–1145.Akhtar, M., Chan, P. S. K., Clayton, G., Kanjee, U. & Koutsidis, G. (2009). Physical and chemical properties of dark chocolate processed using spinning disc reactor technology

– effects of disc temperature and residence time. Journal of Food Engineering Efficiency, 3 (1), 7-14.

Akhtar, M. (2008). Evolution in chocolate technology. Published in Food & Beverage International, February (2008) pp. 27-28.

Akhtar, M. (2008). Scientists raise the bar for greener chocolate. YORKSHIRE POST, Tuesday, 15th January, (2008).

References



Contacts

Ian Henderson +44 (0)1642 711227

Mahmood Akhtar + 44 (0) 1133 43 2952

Robert Addleman +44 (0) 1438 717886

Documents

Spinning Disc Reactors - Flanders' FOOD · Akhtar, M . and Krishnan, S. S. Preparation of oil-water-oil multiple emulsions using spinning disc reactor technology, an oral presentation