Quality Characteristics of Bijijang in Different Fermentation Conditions

摘要

Changes in quality characteristics of Bijijang {fermented soybean curd residue) prepared at 35°C and 40°C for 0, 12, 24, 36, and 48 hr were investigated. Acidity of Bijijang increased, whereas pH and Hunter's color values decreased during fermentation. Immediately after Bijijang preparation, α- and β-amylase activities were very low, β-Amylase activity during fermentation increased rapidly, with those fermented at 40°C higher than at 35°C. Neutral protease activity was significantly higher than acidic protease activity, and increased gradually after 12 hr. Change in total nitrogen content in Bijijang was insignificant, whereas contents of amino-type and water-soluble nitrogens increased significantly during fermentation. Major free amino acids of Bijijang were Arg, Pro, Glu, Thr, Ser, and Lys at initial fermenting stage, and, as fermentation progressed, contents of Cys, Met, Glu, Ile, Leu, and Phe increased. Reducing sugar contents of Bijijang fermented at 40°C were higher than those fermented at 35°G. Sucrose content decreased and glucose content increased. Glucoside (genistin and daidzin) contents decreased and aglycone (genistein and daidzein) contents increased during preparation of Biji and fermentation of Bijijang. Contents of freesugars and isoflavones were higher in Bijijang fermented at 40°C than at 35°C. Based on these results, fermentation at 40°C for 48 hr was determined to be optimum fermentation condition for Bijijang.