Bloater Formation by Gas-forming Lactic Acid Bacteria in Cucumber Fermentations1

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 pH 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.