Effects of mixed culture of Bacillus subtilis and Lactobacillus acidophilus on Cheonggukjang quality

초록

In this study, the quality characteristics of Cheonggukjang prepared with the mixed culture of Bacillus subtilis and Lactobacillus acidophilus were investigated. One of the most common characteristics of Cheonggukjang is the formation of viscous substance, which is the mixture of a fructose polymer and poly-gamma-glutamic acid. After the first Cheonggukjang fermentation, sucrose (0, 2.5, and 7.5 %) and a Lactobacillus acidophilus strain, containing the enzyme responsible for the production of exopolysaccharide, were supplemented, and then the second fermentation was carried out at 40°C for 48 h. Changes in soluble solid contents, extension of viscous substance, pH, reducing sugar, amino-type and ammonia-type nitrogen content, enzyme activities, including a-amylase and protease, and isoflavone content were evaluated. The presence of sucrose in the starting fermentation materials decreased pH, aglycone-formed isoflavone, amino-type nitrogen, and protease activity, however, increased extension of viscous substance. Growth of acid-producing microbes, including L. acidophilus KCTC 3925, was stimulated by sucrose. In conclusion, the present study indicated that the mixed culture of B. subtilis and L. acidophilus changes the quality characteristics of Cheonggukjang, increasing formation of viscous substance. © The Korean Society of Food Preservation. All rights reserved.

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