Preparation of whey protein peptides by protease hydrolysis

Whey protein is the main component of bovine whey liquid. It is rich in protein, minerals and trace elements, low in fat, cholesterol and lactose, and has a reasonable amino acid ratio, which is close to the human body's demand ratio. Whey is a by-product of the production process of cheese and casein. Its output is large. Generally, processing 1 ton of cheese will produce about 9 tons of whey liquid. Whey protein is a heat-sensitive protein. After heat denaturation, its solubility in water decreases significantly, which will affect its functional properties and its scope of use is also greatly limited. Enzyme hydrolysis is an effective method to improve the solubility of whey protein.
Whey protein peptides, also known as hydrolyzed whey protein, are a process of cutting intact whey protein into peptides and amino acids by adding protease enzymatic hydrolysis with whey protein liquid as the substrate. Different enzymes, enzyme activity, enzyme-substrate ratio, enzymatic hydrolysis temperature, pH value, time and other factors can form products with different degrees of hydrolysis. According to the degree of hydrolysis, it can be divided into moderate hydrolysis, partial hydrolysis and deep hydrolysis of whey protein. During the enzymatic hydrolysis process, the degree of hydrolysis is controlled according to the needs, and the size of the peptide, the yield of the peptide, and the taste and flavor should be considered. The molecular weight of whey polypeptide is between 1000 and 10000 Da, which is relatively large; whey oligopeptides are a mixture of small molecule peptides, and the molecular weight is mainly concentrated below 1000 Da. The solubility and thermal stability of whey protein peptides are better than those of whey protein. Its molecules are small, easy to absorb, and reduce the occurrence of milk protein allergies.
The type of enzyme is one of the important factors affecting the biological activity of enzymatic hydrolysis products. Different enzymes have different effects on the hydrolysis degree and product properties of whey protein due to their different cleavage sites. The composite enzymatic hydrolysis method is to use two or more proteases to hydrolyze proteins in a restricted manner. Compared with the enzymatic hydrolysis of a single enzyme, the composite enzymatic hydrolysis method increases the hydrolysis rate of protein, which can not only improve its emulsification and foaming properties, but also make the obtained whey peptides easier to be absorbed, transported and utilized by the body.