Fate of Salmonella species and E. coli in Fresh-Prepared Orange, Avocado, Papaya and Pine Apple Juices

Abstract

Background: Fruits are consumed for their various nutritional qualities. They contain organic acids in quantities that are generally sufficient to produce pH values of 4.6 or lower and the large majority of fruits are considered high acid products. Some fruits, such as avocado, are rich in fat. The aim of this study was to evaluate the microbiological safety of fruit juices by determining the growth potential of some food-borne pathogens in the juices at different holding temperatures. Methods: Juices were prepared from fresh ripened papaya, pine apple, avocado and orange fruits in Addis Ababa between February and May, 1999. They were separately inoculated with young cultures of Salmonella typhimurium, Salmonella choleraesuis, and E. coli (strains 9637 and 25922). Counts of test strains were made at intervals for 48 hours at ambient and refrigeration temperatures. Results: Papaya and avocado juices had initial pH values of >5.7 and allowed all test strains to reach numbers >107 cfu/ml at ambient temperature holding. At refrigeration temperatures, at least no elimination was observed. In pine apple juice (pH 3.8), the E. coli test strains were eliminated at both holding temperatures within 16 h whereas slight increase in counts of Salmonella test strains was observed at ambient temperature holding. Orange juice (pH 3.1) did not allow the survival or growth of the test organisms at both holding temperatures. Conclusion: Although pasteurization may not be practical in the Ethiopian fruit juice market, it may be useful to require fruit juice vendors to have procedures in place to reduce the number of disease-causing microorganisms to the same level achievable by pasteurization. Microbial reduction methods other than pasteurization, including washing, scrubbing, antimicrobial solutions, alternative technologies or a combination of techniques are suggested. In addition, it would be appropriate to determine the microbiological quality and safety of other fruit juices sold in various vending houses as made available for consumption in order to establish their role in the epidemiology of food- borne diseases in the country. Ethiop J Health Sci Vol. 11, No. 2 July 2001