44-2

L. J. HARRIS, Department of Food Science & Technology, University of California, One Shields Avenue, Davis, CA 95616

Commercially-produced unpasteurized orange juice has been associated with three relatively large documented outbreaks of salmonellosis since 1995, two in the U.S. and one in Australia. Acidic foods, including citrus juices, were historically considered of minimal concern for foodborne illness because of the inability of human pathogens to multiply at low pH. The risk associated with consumption these foods is still thought to be relatively low. However, the survival of microbial pathogens in acidic products including orange juice is well documented. Survival is enhanced by refrigerated storage used to extend the shelf life of unpasteurized juices. This survival coupled with the low infectious dose of some pathogens makes these foods potential vehicles for foodborne illness if product contamination is not avoided. The likelihood of contamination of citrus fruit in the field is not well defined and potential levels of contamination are unknown. Survival of human pathogens on the fruit prior to harvest is also poorly understood. Salmonella spp. will survive on the surface of harvested intact oranges at ambient and refrigerated temperatures and this organism and other human pathogens have been shown to multiply on the surface of peeled oranges stored at room temperature. Whole fruit treatments such as washing and brushing, waxing, and immersion in hot water, can reduce surface contamination to varying degrees. All treatments are more effective when contamination is away from the stem scar area. Internalization of pathogens into the fruit through the stem scar has recently been questioned. Although demonstrable under laboratory conditions, it is not thought that this type of internalization would likely occur in sound fruit through packinghouse and juicing operations. The processing of fresh citrus into unpasteurized juice will be reviewed with emphasis on contamination, survival, and reduction of human pathogens on intact citrus and in finished products.