A bulletin for the Australian Food Industry September 1996
Contents: Salmonella: more unusual incidents | Ciguatera poisoning | Phthalates in foods | Ozone treatment of mineral water | Effective sanitation programs | Thermal processing of foods | Transfer of allergens in genetic manipulation of foods | National food hygiene standards
Effective sanitation programs
Yeasts and moulds are common spoilage organisms of many foods including acid products such as mayonnaise and semi-dry products such as cheese and bread. The use of preservatives is not permitted in many foods and in those to which preservatives may be added, their presence may reduce consumer demand. A thorough sanitation programme is necessary in production facilities used in the manufacture of all foods but particularly those which do not incorporate a terminal thermal process or which do not possess any inherent inhibitory properties such as reduced water activity.
It is a relatively common practice in food production for sanitation programmes to incorporate the use of at least two disinfectants on a rotating basis. This helps to control a wider range of microorganisms and to reduce the risk of a selection of resistant microflora in a production facility. The basis for this practice has been confirmed in a recent paper published by Danish workers, Bundgaard-Nielsen and Nielsen (Journal of Food Protection 59:1996 268-75). In a study of fifteen disinfectants against twenty-five fungal contaminants of bread and cheese, these authors found that the resistance of yeasts and moulds to a given disinfectant varied considerably with the strain and species of the isolate.
Of equal importance to food manufacturers and sanitiser suppliers was their finding that some widely used disinfectants were relatively ineffective as fungicides. These included 0.1% potassium hydroxide, 3.0% hydrogen peroxide and 0.3% peracetic acid. When making this assessment, one has to relate the effectiveness of a disinfectant to its method of use. In the work reported a contact time of 10 minutes at 20°C was used between 1 ml of mould or yeast suspension and 9.0 ml of the disinfectant solution. The disinfectant was made up in accordance with manufacturers' instructions.
While the disinfectants were therefore being challenged with a high population of microorganisms, it should be remembered that in many sanitation programs, the contact time between sanitiser and working surface may be much less than 10 minutes unless a soaking step is included in the program. The results sound a warning to manufacturers to investigate their choice of sanitiser, the concentration at which it is used and its contact time.
Food Science Australia
PO Box 52, North Ryde 1670. Tel +61 2 9490 8397 Fax +61 2 9490 8499
Email enquiries@csiro.au