Studies On Optimization Of Whey Protein Enzymic Hydrolysis Technology Parameters And Characteristics Of Enzymic Hydrolysis Product

Whey protein is rich in nutrition bioactive peptides,which have important roles on regulation of cell metabolism and physiological function. In this experiment, took whey powder(WPC80) as the raw material, using single factor experiment, multiple factors combination experiment and DPS(6.01) statistics software to do analysis of variance and multiple comparison, optimized the technology parameters of whey protein hydrolysis, and tested the functions of hydrolyzate, with purpose to build the technology of whey protein hydrolysis into peptide, and defined the characteristics of whey protein hydrolysis peptides. The research content and results were as following:1. Research on single enzyme enzymolysis condition on whey protein. took whey protein powder as raw materials, pepsase, trypsinase and alkaline proteinase as the hydrolytic enzymes, NSI and DH as the evaluation indexes, single factor experiment was carried out, based on single factor experiment, single enzyme well-distributed design experiment were carried out, the results showed: the best hydrolysis enzyme was alkaline proteinase. The optimized Technology parameters were: temperature 53.25℃, pH8.42, concentration of substrate was 5.5%, the ratio of enzyme to substrate was 1/25, enzymolysis time was 414min, degree of hydrolysis was 20.73%.2. Optimization the enzyme enzymolysis condition of double enzyme hydrolysis whey protein. Based on single factor experiment, mixed enzymes hydrolysis experiment were carried out, that was the pepsase + trypsinase, pepsase + alkaline proteinase, trypsinase+ alkaline proteinase 3 kinds of mixed double enzyme experiment, using orthogonal experiment, variance analysis, factor importance analysis, compared and defined the best hydrolysis conditions. The result showed: trypsinase+ alkaline proteinase were the best combination, the enzymes hydrolysis time was 232min和146min, the ratio of enzyme to substrate was 1/25, the quality of two enzyme was 1:3.3. Detection of whey peptides molecular weight distribution. Used alkaline proteinase to prepare whey protein digest, and after precipitated with trichloracetic acid, and were centrifugated to separate macromolecule protein, filted with 5KDa and 1KDa ultrafiltration membrane,the filtrate was taken vacuum concentration and freeze drying, finally obtained little peptides mixture(M). Diluted the little peptides mixture(M).to some concentration, separated and purified M with C18 HPLC, compared the chromatogram of little peptides mixture(M)with standard peptide chromatogram, classified the little peptides mixture(M) into A,B,C three kinds according to retention time, and offered the material for the later experiment. The results showed that the molecular weight of the little peptides mixture A,B,C was 200Da～530Da,530Da～750Da,750Da～1000Da,separately the absorption peak of B occupy 78.6%.4. physico-chemical property and function test of whey peptides. Took the little peptides mixture under test and measurement of solubility and thermostability, at the same time, took the rats as model to do anti- fatigue test of he little peptides mixture. Took the little peptides mixture under bacteriostasis experiment and ACE inhibitory activity in vitro and detected whether it contained bacteriostasis factor and ACE suppression activity. The result showed that: the little peptides mixture can improve the solubility and thermostability of whey protein, and enhanced the endurance ability of rats. The little peptides mixture A, B, C have a certain activity of ACE inhibition, B was the strongest and its inhibition of ACE was (92.37±2.19)%.It indicated that all the three A,B,C peptides contained antibacterial factors.