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Thermal processing of acidified foods with pH 4.1 to pH 4.6

Breidt, Frederick, Kay, Kathryn, Osborne, Jason, Ingham, Barbara, Arritt, Fletcher
ARS USDA Submissions 2014 v.34 no.3 pp. 132
Escherichia coli O157, Listeria monocytogenes, Salmonella enterica, acid tolerance, acidity, bacterial contamination, food contamination, food processing, foods, heat, heat tolerance, heat treatment, pH, pathogens, vegetables
Shelf-stable acidified foods with a pH at or below 4.6 must be processed to achieve a 5-log reduction for vegetative bacterial pathogens. Published research does not exist to adequately support the Food and Drug Administration process filings for products with pH 4.1–4.6 or to define critical limits for acid and acidified foods with pH values in this range. Using a non-inhibitory vegetable-based medium, we developed models and data for the thermal destruction of acid-resistant vegetative microbial pathogens, including 5-strain cocktails of Escherichia coli O157:H7, Salmonella enterica, and Listeria monocytogenes in acidified foods with pH values of 4.1 to 4.6. Under the experimental conditions, Listeria monocytogenes was the most heat- and acid-resistant pathogen. A z-value of 16.7°F, an F-value (at 160°F) of 5.6 min, and a table of recommended processing conditions were estimated from the thermal processing data. This work addresses a lack of documentation that is challenging to all areas of the industry, especially small processors.