Determination of 5-Log Reduction Times for Escherichia coli O157:H7, Salmonella enterica, or Listeria monocytogenes in Acidified Foods with pH 3.5 or 3.8†

Abstract

A critical factor in ensuring the safety of acidified foods is the establishment of a thermal process that assures the destruction of acid-resistant vegetative pathogenic and spoilage bacteria. For acidified foods such as dressings and mayonnaises with pH values of 3.5 or higher, the high water phase acidity (acetic acid of 1.5 to 2.5% or higher) can contribute to lethality, but there is a lack of data showing how the use of common ingredients such as acetic acid and preservatives, alone or in combination, can result in a 5-log reduction for strains of Escherichia coli O157:H7, Salmonella enterica, and Listeria monocytogenes in the absence of a postpackaging pasteurization step. In this study, we determined the times needed at 10° C to achieve a 5-log reduction of E. coli O157:H7, S. enterica, and L. monocytogenes in pickling brines with a variety of acetic and benzoic acid combinations at pH 3.5 and 3.8. Evaluation of 15 different acid-pH combinations confirmed that strains of E. coli O157:H7 were significantly more acid resistant than strains of S. enterica and L. monocytogenes. Among the acid conditions tested, holding times of 4 days or less could achieve a 5-log reduction for vegetative pathogens at pH 3.5 with 2.5% acetic acid or at pH 3.8 with 2.5% acetic acid containing 0.1% benzoic acid. These data indicate the efficacy of benzoic acid for reducing the time necessary to achieve a 5-log reduction in target pathogens and may be useful for supporting process filings and the determination of critical controls for the manufacture of acidified foods.

Validation of Baking To Control Salmonella Serovars in Hamburger Bun Manufacturing, and Evaluation of Enterococcus faecium ATCC 8459 and Saccharomyces cerevisiae as Nonpathogenic Surrogate Indicators

“…3B). For validation of commercial food manufacturing processes as preventive control steps, a 5-log reduction of a specified pathogen population is often targeted (8,37,38). Microbial reductions of !5 log CFU/g on the injury-recovery media were achieved by 6.0, 5.0, 5.0, and 7.75 min for Salmonella serovars Senftenberg, Newport, and Typhimurium, and for E. faecium, respectively.…”

“…The a w s of the crumb and crust of baked buns were determined separately at 258C, using an AquaLab Series 4TEV a w meter (Decagon Devices, Inc., Pullman, WA). a w s were determined in the first study for pre-and postproof dough, along with separate crumb and crust measurements during baking (2,4,6,8,10,12, and 14 min) and after baking (treatment BþC) buns. At each sampling point, and within 10 s of removal from the oven, the crumb and crust of buns were separated by hand, placed into separate a w cups, sealed with Parafilm M (American National Can Group Inc., Chicago, IL), and analyzed within 30 min.…”

Use of phytic acid and hyper-salting to eliminate Escherichia coli O157:H7 from napa cabbage for kimchi production in a commercial plant

“…When Breidt et al (2007) acidified cucumbers with acetic acid (≤ pH 3.3), a 5-log reduction in the E. coli O157:H7 population was achieved after 5.7 and 1.4 days of storage at 10°C and 25°C, respectively. Also, Breidt et al (2013) reported that cucumbers pickled in acetic acid (2.5%) + benzoic acid (0.1%) (pH 3.5) required a minimum of 1.5 days storage at 10°C to achieve a 5-log reduction in the E. coli O157:H7 population. Finally, Lu et al (2013) showed that a mixture of 0.3% fumaric acid (25 mM), 0.06% benzoic acid (5 mM), 0.4% acetic acid (70 mM), and 2% NaCl (pH 3.8) achieved a 5-log CFU/g reduction in the E. coli O157:H7 population after 8.8 days of storage at 10°C, with no change in the sensory attributes of the product.…”

Survival and Growth of Probiotic Lactic Acid Bacteria in Refrigerated Pickle Products

“…Our hypothesis was that cultures with superior acid resistance would exhibit long‐term survival desirable for a commercial probiotic refrigerated cucumber pickle product. Cucumber juice medium was used as a generic vegetable broth medium that does not contain known antimicrobial compounds so that the results may be applied to a variety of brined vegetable products (Breidt and others , ).…”