Bloater Formation by Gas-forming Lactic Acid Bacteria in Cucumber Fermentations

Abstract

The formation of “bloaters” (hollow stock) in cucumbers brined for salt-stock purposes at 5 to 10% salt has been associated with gaseous fermentation caused chiefly by yeasts. Recently, serious early bloater damage, not attributable to yeasts, has been observed in commercial-scale experiments on control of bloaters in overnight dill pickles brined in 50-gal barrels at 3.0 to 4.5% salt. Growth of fermentative species of yeasts was effectively controlled by the addition of 0.025, 0.05, and 0.1% sorbic acid or its sodium salt. In contrast to this, the fermenting brines showed extremely high populations of acid-forming bacteria, identified as Lactobacillus plantarum, L. brevis , and Pediococcus cerevisiae . The gas-forming species (i.e., L. brevis ) constituted a high proportion of the total populations. Representative isolates from 36 barrels of overnight dill pickles were tested for their ability to produce bloaters in 1-quart jars of pasteurized cucumbers equilibrated at 4 to 5% salt, 0.25% lactic acid, and p H 4.0. Bloaters, identical with those made by yeast cultures, were produced in all jars inoculated with L. brevis . No bloaters were produced by L. plantarum and P. cerevisiae . These results suggest that the control of bloater damage in cucumber fermentations, particularly at low salt concentrations, may necessitate inhibition of gas-forming lactic acid bacteria.