Sorbic acid as a selective agent in cucumber fermentations. II. Effect of sorbic acid on the yeast and lactic acid fermentations in brined cucumbers.

Previous studies (Costilow et al., 1955) demonstrated that the yeasts found to be most prevalent in cucumber fermentations were completely inhibited by 0.01 per cent sorbic acid in an 8 per cent salt (NaCl) medium at pH 4.6. As the pH was increased and/or the salt concentration decreased, more sorbic acid was required for complete inhibition of some of the yeasts tested. Cultures of Pediococcus cerevisiae, Lactobacillus plantarum and Lactobacillus brevis isolated from cucumber fermentations (Costilow et al., 1956) were not affected appreciably by sorbic acid in concentrations up to 0.1 per cent. Phillips and Mundt (1950) and Jones and Harper (1952) reported that 0.1 per cent sorbic acid would prevent the growth of surface yeasts on cucumber fermentations without interfering with acid fermentation. The former authors found that concentrations less than 0.1 per cent were not completely effective. Borg et al. (1955) observed that 0.1 per cent sorbic acid would inhibit the growth of fermentative yeasts in cucumber fermentations; but, also, markedly inhibited the acid fermentation. Furthermore, the treatment was found to impair the curing and the color of the fermented cucumbers. As a result of our laboratory experiments, it was decided to test a number of sorbic acid concentrations in experimental cucumber fermentations to determine their effect on the yeast and acid fermentations.