Protozoal contamination of water used in Thai frozen food industry

Abstract

Water is involved in nearly all steps of food preparation. If contaminated or improperly treated it may lead to contaminated food products. This study evaluated the prevalence of contamination of water that was used for food preparation. Since protozoal cysts can be found in small number in water, 1,000 liters of either untreated or treated water were filtered through activated carbon block filters (1 mm nominal porosity). Identification of protozoa was performed using specific monoclonal antibodies against Giardia and Cryptosporidium parasites followed by fluorescence microscopy. Twelve of 20 untreated water samples (60%) were found to be contaminated by Giardia cysts, with an average of 53.33cysts/ 1,000 L (geometric mean 39.44), whilst 7 samples (35%) were contaminated by Cryptosporidium oocysts, with an average of 28.57 oocysts/1,000L (geometric mean 26.92). Three samples of untreated water (15%) were positive for both organisms. In contrast, none of treated water samples was contaminated. Untreated water is a potentialsource of food contamination, thus, treated water should be promoted for use in all steps of food preparation in each frozen food industry.