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Title: Thermal processing of acidified foods with pH 4.1 to pH 4.6

item Breidt, Frederick
item KAY, KATHRYN - North Carolina State University
item OSBORNE, JASON - North Carolina State University
item INGHAM, BARBARA - University Of Wisconsin
item ARRITT, FLETCHER - North Carolina State University

Submitted to: Food Protection Trends
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/24/2014
Publication Date: 5/1/2014
Publication URL:
Citation: Breidt, F., Kay, K.L., Osborne, J., Ingham, B., Arritt, F. 2014. Thermal processing of acidified foods with pH 4.1 to pH 4.6. Food Protection Trends. 34(3):132-138.

Interpretive Summary: For producers of acidified foods, the Food and Drug Administration requires that a scheduled process be submitted to the agency. This filing must be returned for commercial production of acidified foods, according to acidified foods regulations 21 CFR part 114. The process filings must have scientific data to show that the product is free of bacteria that can cause human disease, some of which are acid resistant. The research has shown time and temperature conditions needed to assure safety for thermal processing of acidified foods with pH values of up to 4.6, the upper pH limit for acidified food products. These data expand on previous published results for products with a pH of 4.1 or below. This work fills a critical gap in the scientific knowledge about the safe processing of these products. The results can be used by processors for FDA filings, and will assure safe production practices.

Technical Abstract: 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.