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Abstract
Outbreaks associated with the consumption of contaminated juices have stressed the relevance of introducing a microbial killing step during processing of these products. Nonetheless, some unanswered questions regarding the application of pasteurization and nonthermal technologies, such as UV light, to ensure the safety of beverages with a pH below 4.6 have been identified. Hence, this research project aimed to address some of these existing gaps of information and therefore assist the food industry, regulatory agencies and process authorities with the establishment of critical limits for the safe thermal or UV processing of low-pH drinks. The thermal tolerance of E. coli O157:H7 in apple-carrot juice blends, using different acids and at variable pH values was determined. Then, the effect of different methodologies of acid adaptation and acid shock on the thermal tolerance and survival of three Shiga toxin-producing E. coli strains was assessed. Furthermore, the impact of the concentration of insoluble solids and the darkening of juice after apple pressing, on the efficiency of UV treatments were studied and, the influence of the addition of selected additives and preservatives on the efficiency of the UV treatment of apple juice and the impact of UV radiation over those compounds was additionally evaluated. This dissertation will provide the juice and beverage industries with relevant information to meet some of the science-based rules stated in current and new regulations, including the Food Safety Modernization Act.
