Effect of acid and salt concentration in fresh-pack pickles on the growth of Clostridium botulinum spores

Abstract

The addition of various amounts of acetic acid to pureed cucumbers inoculated with Clostridium botulinum spores has shown that outgrowth is inhibited at pH 4.8 but not at pH 5.0. Inoculation experiments with whole cucumbers showed that as little as 0.9% acetic acid in the brine was sufficient to prevent outgrowth from spore inocula as high as 106/cucumber. It was further shown that the rapid rate of acetic acid penetration into fresh-pack pickles prevents the growth of any C. botulinum spores that may be present.

Cure Appearance Development in Pasteurized Cucumber Pickle Mesocarp Tissue Associated With Proteolysis

“…Intercellular spaces of cucumbers are apparently tightly enclosed in a nonporous protective barrier that resists permeation of liquid when tissues are exposed to acid brine and the pressures and temperatures of thermal processing. In contrast to the impermeability of intercellular spaces, the cells walls of pickles must be highly permeable because equilibration of tissues with process brines occurs within a few days after pasteurization (Bell et al 1972;Ito et al 1976). Pasteurization is known to modify the composition and physical properties of cucumber pickle and other plant cells walls (Howard and Buescher 1990;Kunzek et al 1999), which would account for enhanced hydration and expansion that we observed.…”

Survival of Escherichia coli O157:H7 in Cucumber Fermentation Brines

“…Acid and acidified foods are defined in the United States Code of Federal Regulations (21 CFR part 114) as having a pH value of ≤ 4.6. This is the pH upper limit that prevents Clostridium botulinum spore outgrowth and neurotoxin production (Ito and others 1976). Acidified foods, to which acid or acid food ingredients are added to lower the pH below 4.6, include pickled vegetables sold in hermetically sealed (anaerobic) containers.…”

Interaction of pH and NaCl on culture density of Clostridium botulinum 62A

“…Ever since a report by Dozier in 1924 (6) which stated that Clostridium botulinum cannot grow below pH 4.87, tremendous emphasis has been placed on determining the growth-limiting pH for this organism (8)(9)(10)12). Recent reports (14,17,19) of specialized circumstances of toxin production at pH < 4.6 have stimulated additional research.…”