Volatile Compounds in Tofu Obtained by Soy Milk Fermentation with Lactobacillus plantarum BAL-03-ITTG and Lactobacillus fermentum BAL-21-ITTG

Tofu is one of the main foods made with soybeans. The aim of this work was to evaluate the effect of L. plantarum and L. fermentum on the volatile compounds and sensorial profile of fermented tofu during ripening. The soy milk was fermented separately with two native strains (L. plantarum or L. fermentum) until reaching a pH of 5.5, and the fermented tofu was obtained. The tofu obtained by acidification with lactic acid was used as a control and was characterized by microbial survival (L. plantarum, L. fermentum, and P. freudenreichii) for 0, 20, and 40 days of storage at 15 degrees C. Moreover, the lactic and acetic acid content was determined by high-performance liquid chromatography (HPLC), and the volatile compounds were evaluated by gas. Chromatography-mass spectrometry (GC-MS). The results were analyzed by an ANOVA test (P < 0.05). After storage, the lactic acid bacteria (LAB) survived in the fermented tofu at a concentration higher than 8.0 log CFU/g after 40 days of storage. The shelf life of fermented tofu obtained by acidification was fewer than 20 days because of the presence of fungi and yeasts. The hexanal content was reduced by approximately 96% (P < 0.05) in the tofu obtained by fermentation compared with the control. This process for fermented tofu production employing two native strains could be used for industrial purposes.

Automated summary

This study evaluated the effect of L. plantarum and L. fermentum on the volatile compounds and sensory profile of fermented tofu. The results showed that the lactic acid bacteria survived well in the fermented tofu, with a longer shelf life compared to tofu obtained by acidification. Fermentation also resulted in a reduction of hexanal content, making the tofu more delicious.