Studies on Ripenin Mechanisms of a Novel Fermented Food Prepared with Soybean Protein Gel

以大豆蛋白凝胶为原料，在微生物(红曲霉)的作用下，研制出一种具有淡淡奶油干酪风味的新型发酵食品。本研究对发酵食品的成熟机理进行了研究。首次采用平板SDS-聚丙烯酰胺凝胶电泳法(SDS-PAGE)研究了纯化的红曲霉蛋白水解酶对大豆蛋白的消化作用。大豆球蛋白中β-伴大豆球蛋白的α‘、α、β亚基和大豆球蛋白中的酸性亚基等多肽带消失，而大豆球蛋白的碱性亚基在整个酶反应过程中仍保持不变。不同成熟阶段的食品中水不溶部分的SDS-PAGE-图谱变化与上述酶反应的情况相似。发酵过程中，食品中蛋白质的溶解度增加。研究了发酵过程中产品物理性质的变化。在成熟过程中，产品的硬度和粘附性都有所下降。在发酵体系中加入微生物蛋白酶，可缩短陈化时间。还考察了发酵产物的精细结构与其物理性质的关系。

A novel fermented food which has a mild creamy cheese type flavor was made from soybean protein gel by the action of microorganism (Monascus fungus). In this study, ripening-mechanisms of the fermented food were investigated. For the first time, digestion of soybean protein by the purified Monascus-proteinase was examined by slab SDS-polyacrylamide gel electrophoresis (SDS-PAGE). Some polypeptide bands of soybean globulin such as alpha'-, alpha- and beta-subunits in beta-conglycinin and acidic subunit in glycinin disappeared, but that of basic subunit in glycinin still remained throughout the enzyme reaction.Changes in soybean protein and each nitrogen compound of the food prepared by Monascus fungus during fermentation were investigated. SDS-PAGE-pattern in water-insoluble fraction of the food at various ripening stages changed similarly to the case of enzyme reaction described above. Protein solubility ratio of the food increased during fermentation. Changes in physical properties of the product during fermentation were investigated. The values of hardness and cohessiveness of the product decreased during a ripening period. When the microbial proteinase was added to the fermentation system, the aging time could be shortened. The physical properties were also examined in relation to the fine structure of fermentation products.