Abstract
In order to prevent spoilage of okara, a by-product of tofu manufacturing, the use of lactic acid fermentation was investigated. Lactobacillus casei L-14 and Weissella paramesenteroides HM25 were selected as starter cultures of okara fermentation. The optimum fermentation conditions, such as inoculum levels and mixing ratios, of the two lactic acid bacteria (LAB) were determined in order to realize rapid LAB growth and high organic acid levels in the okara. When okara was inoculated with 106cfu/g mixed LAB and incubated at 30°C for 7 days, almost no microorganisms except for the LAB inoculated were detected in the okara. However, okara contaminated with large numbers of microorganisms at the tofu manufacturers and fermented under identical conditions showed significant numbers of bacteria, especially spore-formers. Therefore, semi-anaerobic incubation was attempted to effectively prevent okara spoilage. Okara was inoculated with mixed LAB and then packaged into airtight containers at 0.92kg/L. After 7-day incubation, no spore-forming bacteria, coliforms or fungi were detected in the okara. These results indicated that the combination of mixed LAB and semi-anaerobic incubation using airtight containers were effective in preventing the spoilage of okara.
