Inhibitory Effect of Lactobacillus plantarum on Salmonella infantis, Enterobacter aerogenes and Escherichia coli during Tempeh Fermentation

Abstract

Growth and inhibition of Salmonella infantis, Enterobacter aerogenes and Escherichia coli in fermenting soybeans during tempeh production were studied in presence and absence of Lactobacillus plantarum. In fermenting unacidified soybeans S. infantis grew by 7 log units in 40 h. E. coli and E. aerogenes grew by 6 and 7 log units respectively. A similar pattern of growth of the three test organisms in fermenting acidified beans was also noted. Further inoculation of unacidified cooked beans with L. plantarum at a level of 106/g resulted in a complete inhibition of the test organisms in the product. On acidified cooked beans a lower level of L. plantarum inoculum (102/g) was enough to show a complete inhibitory effect. The lowering of the pH in fermenting beans by L. plantarum might have played a role in the destruction of the test organisms.