A study on the heat stability of food enzyme induced by amino-carbonyl reaction.

1.研究了卵清蛋白与几种二糖(麦芽糖、异麦芽糖、纤维二糖、乳糖、蜂蜜二糖)在50ﾟC、65%RH条件下放置0-20天后与卵清蛋白的美拉德反应。异麦芽糖和蜂蜜二糖与蛋白质混合后强烈地诱导棕色变色、荧光化合物的产生和蛋白质聚合，而其他的诱导作用很弱。在麦芽糖、乳糖和纤维二糖体系中，高级美拉德反应产物如棕色和/或荧光化合物的产生较弱，这表明在葡萄糖的C-4OH键合的末端吡喃糖苷基团进一步延缓了Amadori重排产物中醛成分的进一步降解。用合成底物测定了美拉德反应中产生的胰酶-葡萄糖复合体的活性。在贮藏8d前，复合体的活性均高于天然复合体。贮藏4天的复合体热变性温度为64.5ﾟC，天然复合体的热变性温度为61.5ﾟC，Km值分别为0.428和0.932。这些结果表明，胰酶-葡萄糖复合体对热变性具有保护作用，对底物具有较强的亲和力。比较了胰酶-麦芽糖复合体和胰酶-葡萄糖复合体的活性。由于胰酶-麦芽糖复合体停留在美拉德反应的早期阶段，因此在较长时间内保持了较高的活性。用分批系统测定胰酶-葡萄糖复合体对酪蛋白的活性。胰酶-葡萄糖复合体在贮藏4d前表现出比天然复合体更高的稳定性。

1. The Maillard reaction of ovalbumin and several disaccharides (maltose, isomaltose, cellobiose, lactose, melibiose) was investigated by measuring several properties of the sugar-protein Maillard adducts after each sugar was kept with ovalbumin at 50ﾟC and 65% RH for 0-20 days. Isomaltose and melibiose mixed with the protein strongly induced brown colorization, production of fluorescent compounds, and protein polymerization, whereas the others did so very weakly. The weaker production of advanced Maillard reaction products such as brown color and/or fluorescent compounds in the maltose, lactose and cellobiose systems indicated that the terminal pyranoside groups bonded at the C-4 OH of glucose retarded further degradation to aldehyde components of the Amadori rearrangement products.2. The activity of trypsin-glucose complexes produced in the Maillard reaction was measured by the use of synthetic substrate. The activities of the complexes were higher than that of native one until 8-day storage. The heat denaturation temperature of the complex stored for 4 days was 64.5ﾟC whereas that of native one was 61.5ﾟC. The Km values of the complex and native one were 0.428 and 0.932, respectively. These results indicated that trypsin-glucose complex have protective effect for heat denaturation, and strong affinity of substrate.3. The activity of trypsin-maltose complex was compared with that of trypsin-glucose. The high activity of trypsin-maltose complex was maintained for long storage, because the complex stay in early stage of the Maillard reaction.4. The activity of trypsin-glucose complex against casein was measured by batch system. The trypsin-glucose complex showed higher stability than native one until 4-day storage.