Technology For The Remove Of Bitter Peptides Hydrolyzated From Milk Protein With Enzymatic Preparations

Milk protein is an important source of human dietary protein, and milk is known as the nearly "perfect" food. Protein content of the milk is in the 2.8-3.3%, the most of it is casein protein, accounting for 78.8 % of the total protein. Milk protein peptide is the biological activity peptide fragments, which is inherent sequence of milk protein and released from hydrolyzed of it. In recent years as many different functions of milk biological activity peptide were identified, milk peptide research was beyond the scope of nutrition and became a focus of food industry, involved physiology and nutrition ,and other researchs. The bitter produced in hydrolysis has been a choke point of milk peptide applying in industrialization.Therefore, this dissertation has studied three debitter methods base on optimizing condition of hydrolysis; choosing the debittering microorganism and optimizing technology.Besides that we have developed a milk activity peptides drink . The results were showed as follows:(1)Firstly,choosing suitable protease to hydrolysis milk protein was carried out, finally Papain and Neutral protease were adopted as optimizing enzyme to make hydrolyte . experiment data was analysed with DPS data work flat, the effect of hydrolysis by adding Papain and Neutral protease simultaneously was the best processing. The optimum hydrolysis conditions are hydrolysis for 210min, concentration of substrate was 8%, enzyme /substrate ratio is Papain 3000U/g and Neutral protease 4800U/g, under 52.3℃. TCA-SNI is 53.69%, DH is 21.37%, average length of peptides is 5.(2)Debittering with active carbon,β-CD,Flavourzyme respectively were compared one another. A better way of active carbon was indicated as: dosage was 1%, temperature was 40℃, reaction time was 1h, bitter wais gone, however the lossing of protein N was 22.58%; The effect ofβ-CD was obvious. There was peculiar smell when dosage arrives at 2% and bitter was 1, an additional substance was introduced. The debittering of Flavourzyme was better comparatively, , it's convenient and have a little nutrition gone, enzyme dosage 750U/g,50℃,6h was suitable technics of deittering, the bitter value is 3.(3)After determination of three indexes: bitter value,TCA-SNI,total protease activity,Bifidobacterium was choosen from seven strains which preserved in our lab to be a tool of debittering. Protracting the culture curve of Bifidobacterium, the biggest total protein activity appeared on the point of 36h; the fermentation substrate with FOS 0.5% and 9% of strains inoculate to MRS substrate was the best debitter dose. Conditions of orthonogal experiment was: dose of inoculate fermentation was 5%, incubation for 5h, and residued bitter value of solution was 3.(4) Processing and formulation of milk debitter peptides drink: sugar8.00%,mixture of acid ( the portion of malic acid to citric acid was 1:1) 0.15%,chocolate flavour 0.5%, sensory index was 9.1. Bifidobacterium number was 2.2×10~6 cfu/ml, it meets the demand of health care standard .