Preparation of high Fischer ratio oligopeptide by proteolysis of corn gluten meal
2008
Ma, Y.,Institute of Technology, Harbin (China). Coll. of Food Science and Engineering | Lin, L.,Beijing Sanyuan Foods Co., Ltd. (China). Technical Center | Sun, D.W.,Institute of Technology, Harbin (China). Coll. of Food Science and Engineering
Corn gluten meal (CGM) was hydrolysed with Alcalase 2.4L using a two-step hydrolysis in order to obtain an oligopeptide with high Fischer ratio. In the first-step hydrolysis, the enzyme reaction conditions for hydrolysing CGM were optimised by using the orthogonal experimental design; pH = 8.0, temperature 55 deg C, enzyme to substrate ratio 3:97 w/w, substrate concentration 5% were identified as the optimum conditions, under which up to 11.62% degree of hydrolysis (DH) could be obtained. The hydrolysate was then fractionated by ultrafiltration using a membrane with the molecular weight cutoff of over 10 kD at 20 kPa. For the second-step hydrolysis, the filtrate was adjusted to pH 6.0, then papain was added at 50 deg C and the mixture was maintained for 3 hours. The hydrolysate was obtained after inactivating papain and centrifuging. Then the salt (mainly NaCl) in the hydrolysate was removed with an ion exchange resin at the speed of 8 times bed volume per hour, and aromatic amino acids were removed through absorption by active carbon. By using Sephadex G-25 gel filtration chromatography, a peptide mixture with low molecular weights between 1,000 and 1,300 was obtained. Finally, tests on amino acid composition and free amino acid concentration of oligopeptide solution showed that the oligopeptide had a high Fischer ratio of 34.71 and the yield of 11.59%.
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