1. TrypsinrnTrypsin is the main protease in the pancreas and is the most thoroughly studied of all proteases. Mainly because it is not only widely used in the food industry, it is also an important digestive enzyme. It is white to light brownish yellow amorphous powder, soluble in water, almost insoluble in ethanol, glycerin, chloroform and ether. Trypsin has high specificity and can only act on a few peptide bonds. It is usually extracted from the pancreas of pigs or cattle. Although the number and sequence of amino acid residues in mammalian
trypsin vary slightly with different animal species, they are all serine proteases and the mechanism of action is also the same. Trypsin is very stable when the pH is lower than 6, and the most stable when the pH is 3. Higher pH values will produce autocatalysis, that is, self-digestion and be destroyed. The optimum pH range for enzymes acting on proteins and most synthetic substrates is 7-9. Trypsin can inhibit the oxidized flavor of milk, produce hydrolyzed protein, and is also used for roasting and meat tenderization.
2. PapainrnCompared with other proteases, papain has higher thermal stability.
Papain has a strong ability to hydrolyze protein and can be used to improve the nutritional value or functional properties of vegetable protein.
(1) Mainly used for cold resistance of beer, that is, to hydrolyze the protein in beer to avoid turbidity after cold storage. The dosage is 0.5ï½5mg/kg, and immobilized papain has been used. The advantage is that the enzyme treatment is arranged after beer pasteurization, and the use of immobilized enzymes can more accurately control the degree of protein degradation, so that some protein can be retained in the beer, which is very beneficial to stabilizing the beer foam. Meat tenderization, that is, the collagen in the hydrolyzed muscle protein, is used for post-mortem injection of 0.5-5 mg/kg. Used for loosening biscuits and cakes, it can replace sulfite, which has the effect of reducing gluten and improves safety.
(2) In the processing of animal and plant protein foods, such as protein hydrolysates and high-protein beverages, it can improve product quality and nutritional value, and improve product digestion and absorption rate. Adding this product and other enzymes to soy sauce brewing can increase the yield and amino acid content. When making beer wort, adding this product and other enzymes can reduce the amount of malt and reduce costs.
(3) It can be used as a substitute for rennet and a coagulant for cheese.
3. ChymosinrnThere are three main sources of rennet used in cheese production: animal rennet (such as calf rennet, lamb rennet, pepsin, etc.); plant rennet (such as papain, ficin, etc.); Microbial rennet (such as mucor rennet, bacterial rennet, etc.). Among them, animal rennet was the earliest and most widely used in cheese production. Renal enzyme is one of the most valuable enzymes in the food industry because it is widely used to produce cheese. It is a carboxyl protease, which is mainly extracted from the fourth stomach water of unweaned calves, goats or lambs to obtain inactive zymogen. The zymogen undergoes partial hydrolysis and turns into active enzymes, and its molecular weight is reduced from 360,000 to 31,000. Clear amber to dark brown liquid, or white to light brown-yellow powder, slightly salty and hygroscopic. The dried product has stable activity and is unstable in solution. The pH value of the aqueous solution is about 5.8, the optimum coagulation pH value for milk is 5.8, and the optimum temperature is 37-43°C. It is inactive below 15°C and above 55°C. This enzyme cleaves between phenylalanine and leucine in casein in cow's milk, resulting in curdling. 1g of commercial rennet can be coagulated within 40 minutes at 35°C by adding 10 liters of milk.
In recent years, the world's cheese production has increased year by year, and the demand for
chymosin has also been increasing. People's attention has been paid to plant rennet and microbial rennet, which are widely sourced and inexpensive.
4. ProteasernProtease is almost white to light brownish yellow amorphous powder or liquid. It is soluble in water, and the aqueous solution is generally pale yellow. But it is almost insoluble in ethanol, chloroform and ether. The main function is to hydrolyze protein into low molecular weight peptone, peptides and amino acids. Natural products exist in animals, plants and microorganisms, and industrial applications are mainly produced by molds. The optimum temperature for products made from Aspergillus oryzae at pH 6.0 is 45-50°C. The product made from Aspergillus niger is also called acid
protease, with an optimum pH of 2.5 and an optimum temperature of 45°C. Copper ions or manganese ions with a concentration of 2Ã10-3mol have a strong activation effect, while silver ions and mercury ions have an inhibitory effect.
5. LipasernLipase is mainly used in cheese manufacturing to defat and produce special flavors (mainly to increase volatile acids and flavor fatty acids), fat modification, and lipid hydrolysis to prevent the fats and oysters in some dairy products and chocolate products from being spoiled. It is an excellent preparation to make milk chocolate and cream cake produce special flavor. Add the protein to break down the fat that may be mixed into it, thereby improving its foaming ability. In winemaking, adding lipase can shorten the winemaking time and improve the flavor of wine.