A bulletin for the Australian Food Industry May 2000
Contents: Packaged minimally-processed fresh-cut vegetables | Decontamination of fresh fruit and vegetables | Improving the safety of fresh produce | Use of sanitisers at low temperature
Use of sanitisers at low temperature
A validated sanitation program is an essential support for any HACCP food safety program. While it is not an integral part of the HACCP plan, which is restricted to process steps, the sanitation program must be in place before a HACCP plan can be properly introduced. Hence the use in the United States of the term pre-requisite program.
In Food Safety and Hygiene, November 1998, we reported a study on the effectiveness of fifteen sanitisers against yeasts and moulds. This study showed that some widely used sanitisers were relatively ineffective as fungicides and sounded a warning to food manufacturers to investigate carefully their choice of sanitiser.
A study reported in Journal of Applied Microbiology 1999 87 718 reinforces this warning. The authors from Campden and Chorleywood Food Research Association point out that many chilled foods are produced at chill temperatures to optimise product quality and ensure food safety. Yet the biocidal efficacy of common sanitisers may not have been validated at these temperatures.
The paper describes work which investigates the efficacy of eighteen proprietary products used in the food industry and examines the effect of lower temperatures on disinfection efficacy.
Pseudomonas aeruginosa was used as a test organism because of its known resistance to sanitisers and Escherichia coli 0157: H7 was also included in the study. The tests were carried out according to the bactericidal suspension test incorporated in the European Standard BS EN 1276. No comparable Australian Standard exists. The standard test temperature is 20°C and in this study 10°C was included as an additional test temperature. The products were tested at three concentrations in both "clean" and "dirty" conditions.
Products which performed satisfactorily against Ps. aeruginosa also performed satisfactorily against E. coli 0157:H7 but products which failed against Ps. aeruginosa did not necessarily fail against E. coli 0157:H7. Importantly, only 11 of the 18 products achieved a pass result under all parameters tested.
Two types of product gave a clear difference in activity with temperature - amphoterics and quarternary ammonium compounds though this was brand specific rather than class specific. Another result of note was the relatively poor performance of chlorine dioxide at the three concentrations tested.
The authors conclude that, under the test conditions, E. coli 0157:H7 is not particularly resistant to most common sanitisers used in the food industry. Just as importantly, they recommend that, especially for high risk chilled food processing, final assurance of sanitiser performance can only be validated by undertaking studies in a food processing environment using a comprehensive microbiological program with environmental sampling.
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