自然发酵黄豆酱酱曲培养过程中蛋白酶的形成及蛋白质的分解

The proteases formation and proteolysis during the incubation of naturally fermented soybean Koji

豆酱是中国传统发酵的豆制品,酱曲是发酵的前期阶段,该过程中蛋白质被水解酶分解为氨基酸和肽类。水分含量及pH值变化可以影响酱曲培养,试验结果表明水分含量呈下降趋势,pH值第1～20天下降,第20～45天升高。中性蛋白酶活力最高,碱性蛋白酶活力最低,在发酵第30天时酸性、中性蛋白酶活力达到高峰而后降低,碱性蛋白酶活力则持续升高,蛋白质分解产物NSI、多肽氮含量持续上升,最终平均NSI可达53.98%(干基),多肽氮均值为28.35%(干基),氨态氮均值为0.45%(干基)。

Soybean paste is a Chinese traditional fermented product. The koji is the first period of producing soybean paste. The proteins are hydrolyzed into amino acids and peptides by proteases in the koji. The incubation of koji is affected by pH and moisture content. The moisture content of the koji is gradually decreased during the incubation, but the pH is decreased from 1-20 days and then increased from 20-45 days. During the koji incubation, neutral protease activity is the highest and alkali protease activity is the lowest in the proteases. During the incubation, the highest activity of neutral protease and acid protease are at 30 days, but alkali protease activity is continuously increased. In the koji, NSI, aminophenol nitrogen and peptides concentration are gradually increased. At the end, the NSI, aminophenol nitrogen and peptides concentration are 53.98%, 28.35% and 0.45% respectively.