Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/13/2007
Publication Date: 11/1/2007
Citation: Breidt, F., Hayes, J.S., Mcfeeters, R.F. 2007. Determination of 5-log reduction times for food pathogens in acidified cucumbers during storage at 10 and 25°C. Journal of Food Protection. 70(11):2638-2641.
Interpretive Summary: This study was carried out to determine the holding time needed to assure the safety of acidified vegetable products. While most bacteria on fresh vegetables do not cause disease, disease causing bacteria can be present. If vegetables are fermented the disease causing bacteria are eliminated. However, if fresh vegetables are directly acidified and not fermented, the manufacturers are responsible for treating the products to assure that disease causing bacteria (if present) will be killed. Some products have so much acid in them that they do not need a heat treatment to assure the elimination of disease causing bacteria. For these products, results from this study give the time needed for acid alone (without heat) to kill several kinds of acid resistant disease causing bacteria. Results from this study will help assure the safety of acidified vegetable products.
Technical Abstract: Outbreaks of acid-resistant food pathogens in acid foods with pH values below 4.0, including apple cider and orange juice, have raised concerns about the safety of acidified vegetable products. For acidified vegetable products with pH values between 3.3 and 4.6, previous research has demonstrated that thermal treatments are needed to achieve a 5-log reduction in the numbers of Escherichia coli O157:H7, Listeria monocytogenes, or Salmonella enterica. For some acidified vegetable products with a pH of 3.3 or below, heat processing can result in unacceptable product quality. The purpose of this study was to determine the holding times needed to achieve a 5 log reduction in E. coli O157:H7, L. monocytogenes, and S. enterica strains in acidified vegetable products with acetic acid as the primary acidulant, a pH of 3.3 or below and a minimum equilibrated temperature of 10 degrees C. We found E. coli O157:H7 to be the most acid resistant microorganism for the conditions tested, with a predicted time of 5.7 days to achieve a 5 log reduction in viable cell numbers at 10 degrees C.