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

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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.