the importance of disinfection for the hygiene in the dairy and beverage production

INTERNATIONAL

BIODETERIORATION &

BIODEGRADATION ELSEVIER International Biodeterioration & Biodegradation 41 (1998) 201-208

The importance of disinfection for the hygiene in the dairy and beverage production

Reinhard Orth*

Biological ResearchjDep. Microbiology, Henkel KGaA. Diisseldorf, Germany

Accepted; 29 January 1998

Abstract

The disinfectants used in the fields of unfermented and fermented milk products and in the alcoholic and nonalcoholic beverage production must achieve primarily the efficiency demands of the specific contamination flora. But besides this microbiological effects also the technological, toxicological, ecological and economical requirements are considered in detailed discussion. In this connection it is to be expected that in the future only those disinfectant types will play an important part which are corresponding to all legislative requirements like the European biocidal product directive and to the new European efficiency test standards. The main disinfectants

of the two concerned industries are discussed in the correlation to the cleaning and disinfection procedures i.e. for CIP, open surfaces, environmental areas with setting examples for specific hygienic plants. Modern disinfectants based on a new modified peracetic acid

product generation were characterized besides classical products based on chlorine, quaternary compounds, amphoterics, halogenated carbonic acids, aldehydes, biguanides, alcohols and considering also combined cleaning and disinfection products. 0 1998 Elsevier

Science Ltd. All rights reserved.

Keywords: Milk & milk products; Brewery; Nonalcoholic industry; ATP-bioluminescence; Disinfectant compounds; Efficacy; Technological conditions and procedures; Residue level; Ecological components.

1. Introduction

Discussing disinfectant procedures an agreement should be found on the definition and understanding of the term disinfection in order to eliminate confusion on the mean- ing of terms used to describe products and processes in the disinfectants industry or in the application field of the food industry. A well accepted and tolerated definition of disinfection was given by the British Standards Insti- tution (BSI 5283, 1986) in the following text:

The destruction of microorganisms, but not usually bacterial spores. It does not necessarily kill all microorganisms, but reduces them to a level acceptable for a defined purpose, for example, a level which is harmful neither to health nor to the

quality of perishable foods.

This general requirement on the efficacy of disinfectants must be achieved by the majority of the products used in the hygiene programs of dairy and beverage plants with the target to kill or reduce the plant specific harmful contamination flora. The applicability of disinfectants therefore is selected according to the spectrum of activity based on the chemical characterization of the

*Corresponding author.

SO964-8305/98/$19.00 $c 1998 Elsevier Science Ltd. All rights reserved. PII: SO964-8305(98)00036-5

agent and the suitability to different food production processes. But besides a broad spectrum of activity and a rapid efficiency a modern disinfectant for industrial hygiene must have additional properties for an efficacious application process:

low toxicological risk easily to rinse off without any residual problems low ecological risk, classification as readily biodegradable, concern to water hazard classes (O-3) compatibility with different technological surface material, no corrosion problems economical application

If the rating ‘readily biodegradable’ is awarded, it means that within 28 days 60% or 70% of the disinfectants will have been degraded depending on which measurement is made in terms of BODjCOD (= 60%) or DOC loss (= 70%) limiting value. The products are tested for this evaluation in accordance with OECD-test No. 301 A-F screening tests.

2. Disinfection technology for closed food contact surfaces

Considering the disinfection technology you have to distinguish between appropriate procedures of closed

202 R. Orthllnternational Biodeterioration & Biodegradation 41 (1998) 201-208

piping systems (CIP=cleaning in place) and containers with large quantities of circulated solution and good tur- bulence, good microbial suspension, simple temperature application between cold (4 or 1OC) to heated (40-60°C) and generally good pre-cleaning. The separate disinfection, carried out after the cleaning operation, deals with less soiling, but is an additional step. If the extent of soiling is not too excessive one would therefore normally carry out a combined cleaning and disinfecting step. In this context, the choice of cleaning and disinfecting agents must depend among other parameters on the type and intensity of soiling and contamination considering also the material quality of the process equipment. The CIP disinfection technology can be generally applied with low concentration of active ingredients.

3. Disinfection technology for open food contact surfaces

The treatment of exposed open surfaces and containers with direct food contact is additional to the disinfection of flow through areas (CIP) of the same high importance. This type of surface can only be sprayed or covered by the low pressure foam system or treated with the new thin film cleaning product technology for (Duzounis, 1996) brief periods and only where the residual film is active for a longer period. The rapid cooling of warm solutions and the more difficult microbial suspension and precleaning must be considered. For a successful surface disinfection the concentrations of active substances are necessarily higher and the quantities of solution lower compared with CIP cleaning. Normally a quantity of at least 0.41 use solution of the applied disinfectant per rn’ treated surface (DVG, 1996) is calculated for this type of disinfection.

To minimize the risk for secondary contamination, from the food production environmental field, all surfaces which do not come into direct contact with beverage and dairy products have to be disinfected. For this procedure the choice for different active agents is larger also because of longer possible contact times.

4. Monitoring for cleanliness and critical control points

The cleaning and disinfection programs should be con- tinually and effectively monitored for their suitability and effectiveness with microbiological methods at various stages of production in compliance with council food hygiene directives like 93/43 EEC or for milk based products 92/46 EEC.

Different conditions of the practice, such as water hardness, temperature, soiling factors influence the disinfecting effects which have been integrated therefore in the lab test methods. Besides these factors the success of a chemical hygiene program depends also on the question

if all the surfaces of the equipment were reached, for example the critical ones like sealings, joints, openings and lids with the control on dead spaces and the need of dismantling of parts of the pipe system. As the use of disinfectants must be followed by thorough rinsing of the working equipment the bacteriological quality of the rinse-water must be controlled on quality of potable water to minimize the recontamination risk. Also according to the European standard prEN 1672 on the safety and hygiene requirements of food production the machinery surfaces shall be cleanable and where required capable of being disinfected.

For this purpose the hazards shall be eliminated or the associated risks reduced by ensuring that machinery is properly designed, constructed with smooth, continuous or sealed surfaces and capable of being properly installed, operated, cleaned and maintained.

In Germany the DINstandards 11483 and 11484 (1983) contribute to define the technological conditions and lim- its for the cleaning and disinfection of the dairy machinery considering the material of surfaces, joints and the CIP system (DIN Report 18/1988).

The validation of the cleaning procedures is an essen- tial part of successful hygiene maintenance and management. Validation provides the information that confirms the efficacy of the cleaning procedure and helps to identify problems or shortfalls in the cleaning regime. It should be pro-active, enabling immediate correction of problems or action to prevent potential product damage. Now, by the availability of ATP bioluminescence monitoring systems as proactive methods of validation, the cleanliness of food contact surfaces can be controlled within a few minutes by the operators on the line to detect in real time the cleaning efficacy. This rapid methodology measures ATP from both microbial contamination and product residues but does not identify numbers of organisms or identify them to species level. Results allow fast action to be taken on areas of non compliance where surfaces should be recleaned. This validation system cor- responds also to the check up requirement of cleaning and disinfection mentioned in the European council directive 92146 on milk hygiene and to guidelines for good hygiene practice of brewery and beverage associations.

5. Important aspects for the disinfection in the beverage production

The disinfectants used in the alcoholic and nonalcoholic beverage production must achieve primarily the efficiency demands of the specific contamination flora which is shown according to Back (1997) in Table 1. The most frequent types of active agents used in breweries, soft drink and fruit juice industries are listed in Table 2.

In CIP systems disinfectant formulations based on peracetic acid/hydrogen peroxide combinations as well as

R. Orth/International Biodeterioration & Biodegradation 41 (1998) ZOI-208 203

Table 1

Contamination flora in the beverage industry (Back, 1997)

Microorganisms

Beverage industry

Soft drink/

Brewery Fruit juice

Bacteria

Lactobacillus brevis

Lactobacillus lindneri

Leuconostoc mesenteriodes

Pediococcus damnosus

Enterobacter cloacae

Yeasts with Ascospores

Saccharomyces cerevisiae

Saccharomyces cerevisiae var. diastaticus

Zygosaccharomyces bailii

Pichia anomala

Moulds

Penicillium expansum

x x

x

x

x

x x

x x

x

x - x

x

halogenated carbonic acids like the monobromic acetic acid are the predominant product types, because they can be regulated by conductivity due to the combination with anorganic and organic acids.

Table 2

Disinfectants in the beverage production plant

Mainly in breweries they were integrated in a very economic and environmentally safe acid tank cleaning concept. In comparison to conventional tank cleaning the optimized new acid tank cleaning processes have obvious advantages in saving total process costs by reduced rinse water, time and without an alkaline detergent a reduced effluent charged. By the new generation of peracetic acid/ H,Oz based products combined with organic acid the fungicidal effects against a mixed yeast contamination flora could be enhanced and with the phosphorus-free acid cleaning and the AOX (adsorbable organic halogen compounds)-free disinfection this procedure has a high economic efficiency and environmental safety (Fig. 1).

5.1. Differences of resistance of yeasts and their ascospores to disinfectants

Whereas the majority of the beverage spoiling yeasts with many differences in natural resistances can be controlled for example by good killing effects of the mentioned acid disinfectants and quaternary ammonium compound based product types on vegetative cells, the activity on ascospores of the most common yeast contaminants are not considered in efficiency results. Wittich

Disinfectant type Brewery Soft drink/fruit juice

1 Hydrogen peroxide-Peracetic acid/H,O,

(a) PAA 2.5~15%

(b) with organic or anorganic acids and or

surfactants

2 Halogenes

(a) alkaline chlorine

(b) acid iodophores

3 Surface active agents

(a) quaternary ammonium compounds pH

4-9

(b) amphoterics

4 Halogenated carbonic acids

chlorine-iodine-bromine with anorganic

acids

5 Alkylamines

(foam disinfection)

6 Biguanidines

7 Aldehydes

formaldehyde-glutardialdehyde

8 Chlorine dioxide

brewhouse

fermentation-storage-pressure tanks

pipelines

filler

cask cellar

bottle washing (rinse water)

dialysis, reverse osmosis

malthouse

brewhouse

tanks and pipelines

hoses, fittings, filter cellar


general plant cleaning

malthouse, hoses, fittings

mixing machines, filler

tanks and pipelines tanks and pipelines

filler

environmental hygiene

soaking of small utensils and instruments

air sanitation by fogging (bottling hall)


tanks, filters, mixing machine, pipelines container,

bottle washing (rinse water), PET-bottles centrifuges

pasteurizer, conveyor chains, filler, crowner

tanks, filters. mixing machine, pipelines, container,

presses, filter cloths, general plant, cleaning, bottle

washing (rinse water)

general plant cleaning

centrifuges, pasteurizer

evaporator, filler, crowner

conveyor chains

filler

environmental hygiene

soaking of small utensils and instruments

air sanitation by fogging (bottling hall) environmental

hygiene


204 R. Orth/International Biodeterioration & Biodegradation 41 (1998) 201-208

Process A

Process B

Process c

Process steps

F-l freshwaterrhse

0 50 100 150 200 Time (minutes)

Fig. 1. Comparison of conventional and new processes for tank cleaning in breweries (Kluschanzoff, 1994).

1.0

0.8

0.6

0.4

0.2

0

-

1 1

0.61

0.48

i

Biguanide QAC Aldehyde Chlorine PAA

0.29

1 0

0.7 -

-

0.39

0.25

i

Active APcnts

0.43 0.43 II Halogensted Carbonic acids

Vegetative ceils I-1 Ascospores

Index of resistance = number of tests with reduction rates -Z 5 log total number of tests

Fig. 2. Comparison of the resistance of ascospores and vegetative cells against different disinfectants (Wittich and Kramer, 1992).

and Kramer (1992) and Neumayr et al. (1988) dem- tested and applied disinfectants than vegetative cells. The onstrated in the Fig. 2 and Table 3 that ascospores most distinct differences were observed with the bigu- showed a higher resistance against the majority of the anide containing disinfectant but also for the PAA and

Table 3

The resistance of vegetative cells and ascospores against 3 disinfectant types based on peracetic acid, quaternary ammonium compound and biguanides

(Quantitative suspension test method at 20°C)

Disinfectant

Peracetic acid 0.5%

Quaternary ammonium compound 0.1%

Biguanides 0.6%

Peracetic acid 0.5% Quaternary ammonium compound 0.1%

Biguanides 0,6%

(Neumayr et al., 1988).

log reduction rates after 5 minutes 15 minutes

Yeast type log cfu test solution Vegetative cells Ascospores Vegetative cells Ascospores

Saccharomyces cerevisiae 25.7 4.3 > 5.7 a6.0 Vegetative cells 5.7 3.7 3.0 5.6 3.6 Ascospores 6.0 35.7 1.7 > 5.7 1.7

Saccharomyces uvarum 5.3 0.9 26.1 a6.4 Vegetative cells 6.5 36.5 3.9 2~6.5 4.1 Ascospores 6.5 36.5 0.5 36.5 > 1.7

R. Orth/International Biodeterioration & Biodegradation 41 (1998) 201-208 205

QAC based disinfectant types must be concentrations much higher and or the contact times longer to get good disinfection results under field conditions.

The Fig. 2 shows the resistance indices of ascospores and vegetative cells of a yeast group (Zygo- saccharomyces, Hansenula, Saccharomyces) against six frequently used disinfectant types in a comparison with nearly the same results shown in Table 3. These results are of special interest for the application of disinfectants in the soft drink industry where ascosporogenious yeast species belong to the frequently occurring contamination flora. Thus the higher resistance of the ascospores of yeast species to disinfectants could cause in some cases risk factors for the production hygiene and the disinfection procedure which can perhaps be explained by this knowledge.

5.2. Cold aseptic bottleJiIling with the integration ofper- acetic acid

The presence of new beverages with high bacteriological susceptibility especially in new creatively shaped packaging materials for refillable and non refillable bottles, very sensitive to temperatures, constituted a new hygienic filling system with the use of modern disinfectants in the bottle washer. This cold aseptic bottle filling technology for microbiologically sensitive products in packaging materials (i.e. plastic bottles PET) without the use of preservatives, bottle or can pasteurization, or hot filling is working with an improved killing efficacy by a peracetic acid based disinfection in combination with wetting agents.

Synergistic effects of both chemical components produce optimized killing results with short contact times on yeasts and moulds which could be confirmed by different equipment and system suppliers.

5.3. Specific safe, ecological and economical hygiene concepts

The most prevailing disinfectant group used in the beverage industry has the peracetic acid as active agent in different formulations and modification (Schroder, 1984). Besides the universal efficiency against all types of microorganisms and the good complete biodegradability into the components water, oxygen and acetic acid residues and even with the qualification as indirect food additive for no rinse procedures by the FDA this disinfectant type achieves also technological advantages in the field. With the new more acid product types they can be easily controlled in the cleaning process by conductivity measuring. This advantage is beneficial for example in the above mentioned acid tank cleaning process in breweries in presence of the CO* atmosphere. Residues which are added to the beverage product through disinfection without rinsing, by misapplication or because of special cir-

cumstances which could not be avoided technically are disintegrated quickly into harmless substances. Brewery institutes have certified by testing that minor residues as 3-5ppm PAA (threshold value in beer) are harmless (Versuchasstation schweizerischer Brauereien, Zurich 1977).

For disinfection concepts for fillers and conveyor belts also spraying systems for foaming procedures are used with sanitizers based on alkylamine with good disinfecting efficacy also at cold conditions. This disinfection technology is mostly combined with the innovative thin film alkaline or acid cleaning technology as a precondition for a successful disinfection.

6. Important aspects for the disinfection in the milk

processing industry

According to the council directive 92/46 EEC where the health rules for the production of raw milk, heat treated milk and milk based products are laid down the manager of a milk processing plant has to take all measures necessary to ensure at all stages of production a sufficient hygiene. That means also that all the premises, equipment and tools, tanks, pipelines in contact with milk must be cleaned and disinfected at regular intervals before use. Only a successful cleaning and disinfection as a precondition for a successful critical control point concept contribute to minimise the risk factors by microbial recontamination of milk products (Wildbrett, 1996). Also some technological factors in the milk processing like the bactericidal effects of pasteurization, the sterilization process for inactivating all microbial life including heat resistant bacterial spores in the UHT milk, and the fermentation of milk to yogurt by using starter organisms produce preservation effects which have the purpose to lengthen the shelf life of milk products. The chemicals of cleaning procedures play on the other hand an important part to reduce and kill the contamination flora of each milk production stage. Representative species of these microorganisms were also considered for the evaluation of the activity of a disinfectant in the dairy field (Table

4).

6.1. Monitoring for cleanliness and critical control points

Technological critical points in the three way valves or rubber joints in modern installations are often hard to reach with cleaning products or working sectors in which automation is hard to achieve, where human intervention is indispensable are risk factors difficult to keep under control. Those hazards for good hygiene results must be integrated in a monitoring program with regular check up. Personal hygiene training for hand hygiene and the awareness of the possible microbiological consequences of direct human contacts in sensitive production zones

206 R. Orth/International Biodeterioration & Biodegradation 41 (1998) 201-208

Table 4 Contamination flora in the dairy industry (according to the european CEN/TC 216 test standards for disinfectants and DLG-test guidelines)

Bacteria: Escherichia coli Pseudomonas aeruginosa Salmonella typhimurium Enterococcus hirae Staphylococcus aureus (Listeria monocytogenes)

Spore forming bacteria: Bacillus subtilis Bacillus cereus

Bacteriophages: Lactobacillus lactis subsp. lactis-bacteriophage PO01 Lactococcus lactis, subsp. lactis-bacteriophage PO08

Fungi: Geotrichum candidum Kluyveromyces sp. Penicillium roqueforti Mucor sp. Aspergillus niger

must develop the sensitivity for a hygienic behaviour of the staff. It must be well translated to the operators on the machines what is the right time for application of hand disinfectants and how to use the mostly alcohol based products.

The cleaning success as the main precondition for the following disinfection step can be controlled in a similar way as it was recommended for the beverage industry by the ATP-bioluminescence monitoring on organic residues. Those residues are able to inactivate partially disinfectant use solutions on the base of chlorine and peroxides.

6.2. Dairy cleaning technology with integrated disinfection

A very sensitive hygienic zone of the milk processing is at the end of the production line the packages or containers in which the milk products are filled up and the filling machines belonging to it.

High concentrated hydrogen peroxide combined with temperatures of 70430°C is a technological system to sterilize the interior surface of carton packages within N 6 seconds integrated in a high speed filling process. Only the biocide application together with an adapted technology is able to keep the microbial hazards under control in this field. But the security of this process is also depending on the sterility of the internal surfaces of the filling machine which is mostly achieved by the use of peracetic based disinfectants. Because of the universal efficiency against all types of contaminants this type of disinfectant with different new modifications considering conductivity and surface activity is widely distributed in dairies for the disinfection of precleaned CIP surfaces, pipelines, tanks, fillers, evaporators, pasteurizers. Already every classical cleaning step in the milk processing industry is to be regarded in addition to the concomitant removal of microbial contamination as a partial ster-

ilisation. The application of hot alkaline or acid deter- gents which have primarily the purpose to remove organic and mineral residues are able in the same time to reduce and to kill the harmful bacteria in rates of 99.9 to 99.99 percent. But higher product quality mostly requires still a separate disinfection step to kill the residual germ content. For equipment like a bulk milk tanker or storage milk tanks with low level soiling it is sufficient to use a combined cleaning and disinfecting step as a standard procedure. Products for this purpose are based on alkaline active chlorine or formulated with organic or an organic acids combined with surface active agents. With increased temperatures of 50°C these products show also sufficient bactericidal effects of a 510g microbial reduction.

6.3. Selection criteria for the right process adapted disinfectant

Generally there is a lot of disinfectants available for the milk processing industry with different active agents which are summarized in Table 5 with the conditions and fields of application (Wildbrett, 1996).

The choice of the right disinfectants and its handling has to be determined for each process stage in the hygiene plan according to the typical contamination and spoilage flora but also considering the compatibility with the technology, material-, temperature- and time conditions.

A special microbiological problem arising during yogurt manufacture and other milk fermentation processes is the danger emanating from bacteriophages. Initially slight contamination results in the possibility of leading to slow acidification or even to a stop of the process (FIL- IDF, 1991).

There are only chlorine and peracetic acid based disinfectants which have a sufficient rapid efficiency on lactococcal bacteriophages which shows a efficiency comparison of 5 different disinfectant in Table 6 (Lembke and Teuber, 1981). The reduction of bacteriophages by hydrogen peroxide, formalin and quaternary compounds are after 10 minutes too low to be recommended for practical application. But this virus based contamination problem is too complex to be solved only by very efficient disinfectants. It’s also an appropriate example that nearly bacteriophage free production area can be reached only by a total hygienic management of the plant excluding all possible infection sources. In addition to the disinfection of the technological equipment and environmental surfaces after each production without neglecting the staff hygiene washing and disinfection of hands and changing shoes and clothes each time a job routine is changed, there are also other following measures against phage contamination for example necessary:

0 application of multiple cultures as starter l defined cultures with rotation

R. Orthjlnternational Biodeterioration & Biodegradation 41 (1998) 201-208 207

Table 5

Disinfectants in the milk processing industry (Wildbrett, 1996)

Disinfecting active agents Conditions and fields of application

1 Hydrogen Peroxide CIP-Vapourisation-Spray disinfection

- 100~10000 mg/l cold disinfection

- lO~lOOOmg/l hot disinfection

- 30-300 g/l hot disinfection of packaging surfaces

tanks, pipelines, filters, fillers, external disinfection of machines and equipment

CIP-spray-short time disinfection

- 50-200 mg/l cold disinfection

-40&2000mg/l hot disinfection spores, bacteriophages, viruses

tanks, pipelines, pasteurizer, filter, fillers. cationic exchanger ultrafiltration

2 Peracetic acid (PAA) HzOz

(a) PAA 2.5-15%(b) with organic or anorganic acids and or

surfactants

3 Halogenes UP-spray disinfection

(a) active alkaline chlorine anorganic and organic carrier systems - 0.3 mg/llO mg/l water circulation system

- 25-50 mg/l CIP-disinfection

(b) acid iodophors

- 1 OQ-400 mg/l combined cleaning and disinfection

- 1000-5000 mg/l open surfaces

pipelines, tanks, fillers, rinse water bottle washing machine

CIP-spray disinfection cold-40°C temperature limit

- 15-50 mg/l CIP-disinfection

- 50-200 mg/l combined cleaning and disinfection

-30&l 000 mg/l open surfaces

tanks, pipelines. fillers

4 Surface active agents

(a) quaternary ammonium compounds

CIP-spray disinfection pH 5-10

- 100 mg/l grampositive bacteria. yeasts

- lO&lOOO mg/l grammegative bacteria

mould-open surface

(b) amphoterics

pipelines, tanks, fillers. external disinfection of machines/equipment floors

CIP-Spray disinfection

- 250-2000 mg/l CIP disinfection


5 Biguanidines CIP-spray disinfection pH 5-7

-200-l 000 mg/l CIP-disinfection

- 5Ot&3000 mg/l open surfaces

6 Alkylamines foam disinfection of open surfaces

fillers-environmental hygiene


7 Aldehydes

formaldehyde-glutardialdehyde

spray disinfection

- 100&10000 mg/l cold disinfection of open surfaces

floors, walls, general disinfection of machinery and equipment

Table 6

Efficiency of various disinfectants against lactococcal bacteriophages (Lembke and Teuber 1981)

Active agents Cont. %

Log reduction rates

After 10 min After 60 min Number of test phages

Formalin 0.6 0.5 4.5-9 6

Sodium-hypochlorite 0.5 4-9 5-9 6

Peracetic acid product 0.5 6.8-9 9 6

Hydrogen-Peroxide 6.0 0.1-0.3 0.551 2

Quaternary ammonium coumpound 0.5 No effect 4 1

l application of resistant bacterial cultures l use of direct set cultures l total elimination of whey residues as nutrient factor

for lactic acid bacteria

l blocking the infection sources by using only plastic pallets

l all recycled packing must be cleaned and disinfected daily

208 R. Orthllnternational Biodeterioration Br Biodegradation 41 (1998) 201-208

l separation of hygiene zones between raw materials and manufactured and limited access to production rooms

Therefore the application of disinfectants must always be regarded with the integration in a plant hygiene concept. The prevailing disinfectants group in the dairy field is similar to the beverage industry as already mentioned the peracetic acid based products because of the broad microbicidal spectrum even against viruses and bacterial spores but also because of the excellent ecological properties as the biodegradibility (readily biodegradable). The ecological challenge factor on the environment and the waste water system has today already the same importance on the scale of field requirements for disinfectants as the efficacy.

Surface active agents like quaternary ammonium compounds and alkylamines are mostly used for foam disinfection of the external sites of the equipment and the environmental surfaces around the production lines or the transport conveyor systems. They are not so much preferred in fermented milk based production because of growth inhibition risk factors of low residues on the development of lactic acid bacteria.

In contrast, to the beverage industry halogenated carbonic acids don’t belong to the routine disinfection procedures in the dairy field among others because of their protein precipitating property.

7. Future prospects

After the acceptance of the European CEN TC 216 standard test methods for the efficiency of disinfectants used in the area of food production as obligatory international accepted normes, the application of disinfectants differ only in the concern of plant and technology specific

factors which should be regulated by a hygiene plan. The European Biocidal Product Directive with the option of a catalogue of requirements for a future common European product approval point out that the safety factors for human health, the foodstuffs, and the environment will be more placed into the foreground for the application of disinfectants.

References

British Standard 5283, 1996. Glossary of terms relating to disinfectants (CEN/TC 216 HWG N 2).

DIN-Norm 11 483, 1983. Reinigung und Desinfektion von mil- chwirtschaftlichen Anlagen-Beriicksichtigung der Einflilsse auf nichtrostenden Stahl, Teil 1. Beuth-Verlag, Berlin.

DIN-Fachbericht 18, 1988. Milchwirtschaftliche Anlagen, Reinigung und Desinfektion nach dem CIP-Verfahren, Beuth-Verlag, Berlin.

DVG, 1996. 4. Desinfektionsmittelliste der deutschen Vet- erinarmeedizinischen Gesellschaft fur den Lebensmittelbereich, Deutsches Tierarzteblatt 44 Nov. 1996.

FIL-IDF-Bulletin, 1991. Practical phage control. Bulletin of the Inter- national dairy federation No 263.

Kluschanzoff, H., 1994. Cleaning and disinfection concepts in view of environmental aspects, EBC-monograph, London.

Lembke, I., Teuber, M., 1981. Inaktivierung von Bakteriophagen durch Desinfektionsmittel. Deutsche Molkereizeitung. 102,4.

Neumayr, L., Heyderhoff, G., Kramer, I., 1988. Resistenzunterschiede zwischen vegetativen Zellen und Ascosporen von Saccharomyces spp. gegentiber Desinfektionmitteln auf der Basis von Peressigslure. Biguaniden und quart&en Ammoniumverbindungen, Brauwiss. 41, 428-434.

Ouzounis, Dr., 1996. ‘TFC’ setzt MaDstabe bei der Obertlachenhygiene, ZFL 47(No 10).

Schroder, W.. 1984. Peracetic acid-disinfectant for the foodstuff industry, Brauwelt International Z(Heft 1) 115-120.

Wildbrett, G., 1996. Reinigung und Desinfektion in der Leb- ensmittelindustrie, B. Behr’s-Verlag, Hamburg.

Wittich, G., Kramer, I., 1992. Studies on the differences in resistance of yeast harmful to beverages and their ascospores to disinfectant agents. Monatsschrift fur Brauwissenschaft. 45(5), 156160.

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the importance of disinfection for the hygiene in the dairy and beverage production