|
Zein is by-product of producting corn amylum. Because it has corn yellow colour,it was called“yellow powder”. It is lack of diaminocaproic acid and 2-amino-3-indole-propionic acid which are necessary amino acids to peopl,so its biological value is low, and its application in the food industry was reduced. However, zein was hydrolyzed corn peptide by germ fermentation, not only meet spacial functionality what people need, but also contribute to a series of food processing industry, moreover have energetic effect to environment protection.We obtain a kind of strain from Yong Chuan black curd beans by casein plate process, which can hydrolyze protein with higher ability. And research its physiological and biochemistrical functions. By acclimatization make it to ferment zein,produce corn peptide, and and good generation stability. Result: it is bacillus subtilis,and enzyme activity is 1468.7U/mL,zein degree of hydrolysis is 9.64%. Taking OD600 as evaluative index, the single factor experiment of different temperature, pH, rotation speed, starter age, inoculating amount, carbon source, nitrogen source, concentration of carbon and nitrogen source, metal ions and concentration of metal ions. The results of single factor experiment were made as zero level of two revolving orthogonal experiment, and the optimum growth medium is glucose 2.0%, soybean peptone 3.6%, MgSO4 0.16%, K2HPO4 0.28%, KH2PO4 0.28%, CaCl2 0.03%. The highest growth amount (OD600) could reach 1.869.Taking zein degree of hydrolysis as evaluative index, to begin with, the single factor experiment of different carbon source, nitrogen source, concentration of carbon and nitrogen source, surface acting agent, concentration of surface acting agent, metal ions and concentration of metal ions.The results of single factor experiment were made as zero level of two revolving orthogonal experiment, and the optimum growth medium is glucose 1.90%, soybean peptone 1.90%, SDS 0.12%,MgSO4 0.18%, MnSO4 0.32%。zein degree of hydrolysis is 11.84%。On the base of the optimum growth medium ,and then make sure the different of rotation speed, volume of medium, temperature, pH, concentration of zein, inoculating amount. Through the orthogonal combination experiment , the fermentation condition: rotation speed 200r/min, volume of medium 50mL, temperature 37℃, pH 6, concentration of zein 4%, inoculating amount 3%. zein degree of hydrolysis is 16.72%.Zein was took 96h to ferment by 10L fermentation tank, the antioxidant activity of corn peptide was determined by TBRAS method. The results indicate that the hydrolysis is 16.68% when the zein was fermented at 72h and the antioxidant activity of corn peptide is best. The broth of corn peptide was made to powder by drying spray and the composition are carbohydrate 3.27%, protide 74.47%, fat 11.33%, ash content 8.80%.The broth was separated by Sephadex G-25. The separating broth of five peaked were collected. Separating broth was made to power by vacuum freeze-drying. The antioxidant activity of separating broth is determined by TBRAS method. Through the reasearch for antioxidant activity mechanism of corn peptide, its reducibility was discovered, and had stronger ability to clear hydroxy radical and superoxide free radical, but had weaker ability to clear DPPH·.
|