Examples of enzyme preparations used in food processing

Enzyme preparations are special proteins with biocatalytic enzyme characteristics. They have the characteristics of small addition amount, high catalytic efficiency, and mild reaction. They are essential auxiliary processing aids in the food industry to accelerate food processing and improve the quality of food products. Enzyme preparations approved for use in the food industry in my country include α-amylase, saccharifying enzyme, papain, bromelain, alkaline protease, pectinase, cellulase, etc., which are mainly used in protein peptide processing, fruit and vegetable processing, dairy processing and other fields.

Enzyme preparations used in protein processing

1. Peptides have many biologically active functions. Enzyme preparations are used in protein hydrolysis to decompose proteins into peptides and amino acids, increasing the solubility and absorbability of proteins. Enzymatic protein hydrolysis to produce peptides is one of the examples of industrial application of bio-enzymes. At present, peptide products have been widely used in the pharmaceutical and food industries, such as infant formula, peptide oral liquid and other products.
2. Yeast extract has the functions of improving food flavor, enhancing freshness and flavor, reducing salt and saltiness, and balancing odor. Yeast extracts soluble components (such as proteins, amino acids, peptides, nucleotides, etc.) from yeast cells through enzymatic autolysis. Due to different yeast fermentation, the activity of endogenous enzymes varies. By adding exogenous enzymes, the indicators of various aspects of the product can be improved. In the process of autolysis and enzymatic hydrolysis, papain is added to help yeast cells break the wall, accelerate the dissolution of endolysates, and improve the utilization rate of effective ingredients, which is also more conducive to protein hydrolysis and nucleic acid hydrolysis.
Enzyme preparations used in fruit and vegetable processing
1. Improve the juice yield of fruit pulp. The most widely used enzyme in improving the juice yield of fruits and vegetables is pectinase, followed by cellulase. Adding a certain amount of pectinase before juicing the pulp can effectively decompose the pectin substances in the pulp tissue, reduce the viscosity of the juice, make it easier to squeeze and filter, and thus increase the juice yield. Cellulase can degrade the macromolecular cellulose in fruits and vegetables into cellobiose and glucose molecules with smaller molecular weights, destroy the plant cell walls, fully release the intracellular dissolved substances, and increase the juice yield. And increase the soluble solid content.

2. Clarify fruit and vegetable juice. After the pulp is squeezed and filtered, there are still some very small polymers and solid particles in the juice that can cause turbidity in the fruit and vegetable juice. For example, pectin substances, starch, and other polysaccharides are the main causes of turbidity and browning of fruit and vegetable juice. If pectinase, cellulase, α-amylase, and papain are added to fresh fruit and vegetable juice (or sterilized fruit and vegetable juice) (one or more can be selected according to the turbidity components), most of the above substances can be degraded into galacturonic acid, glucose, amino acids and other products, making the fruit and vegetable juice clear, and at the same time significantly improving the nutritional content and stability of the clarified juice.

3. Enhance aroma and remove odor. During the processing of fruit and vegetable juice, salty substances are lost, but flavor precursor substances still exist. Studies have shown that monoterpenoid compounds are the most sensitive aromatic substances to the sense of smell. Most monoterpenoid substances in fruits and vegetables exist in the form of pyranose and furanose in a bonded state, and a large number of such bonded terpenes are still not hydrolyzed after the fruits and vegetables mature. By adding β-glucosidase, terpene alcohols in fruit and vegetable juice can be released to increase aroma. Experiments have shown that α-L-pyranose arabinosidase or o-L-furanose arabinosidase can release linalool and geraniol in fruits to enhance the aroma of juice. Enzyme preparations can remove the bitterness caused by naringin and limonin analogs in citrus juice. For example, adding naringinase can hydrolyze naringin into safflower and rhamnose; adding limonin dehydrogenase can oxidize citric acid bitterness into limonin ring alkaloids. Thus, the purpose of removing bitterness and reducing bitterness is achieved.

2. Application of enzyme preparations in baked foods
1. Application of α-amylase in bread. Adding an appropriate amount of α-amylase to bread flour can increase the volume of bread by about 10% compared with blank bread. This is because when baking bread, α-amylase hydrolyzes part of the starch to produce dextrin and sugar, which reduces the viscosity of the dough, resulting in an increase in the dough expansion rate, an increase in the volume of the bread after baking, and a better softness of the bread core. Zhou Sumei et al. (1998) experimentally proved that adding a maltose α-amylase obtained from genetically modified bacteria to bread flour showed a significant anti-bread aging effect and could extend the shelf life of bread.
2. Application of protease in baked foods. Protease is added to flour to degrade the protein in the dough into peptides and amino acids to a certain extent, resulting in a decrease in the protein content in the dough. The dough gluten strength is weakened, meeting the requirements of biscuits, cookies, pizza, etc. for weak gluten dough. At the same time, the degradation of protein is more conducive to the absorption of nutrients by the human body. Fungal protease is used in bread making, which can hydrolyze the chemical bonds at a certain position inside the gluten, thereby improving the extensibility of the dough, improving the symmetry and uniformity of the bread, and improving the structure and flavor of the bread.
3. Glucose oxidase is used in bread production. Glucose oxidase can significantly enhance the dough strength due to its good oxidizing property, making the dough non-sticky and elastic; after proofing, the dough is white and shiny, with delicate texture; after baking, the volume is expanded, the pores are uniform, it is tough and non-sticky. At the same time, with the increase of the amount of glucose oxidase added, the anti-aging effect of bread also increases, and the effect is more significant than potassium bromide.

3. Enzyme preparations used in dairy products
1. Raw milk is used to make cheese through the action of rennet. The specific process is: raw milk-sterilization-lactic acid fermentation-add rennet to stand and coagulate-cut-filter and separate whey-add salt to make curd-press-mature-cheese. Principle of rennet: (1) Casein forms paracasein under the action of rennet; (2) Paracasein forms "calcium bridges" between paracasein molecules in the presence of free calcium, causing the paracasein particles to aggregate and produce a gel.

2. Lactase decomposes lactose. Lactose is a sugar found in mammalian milk, and cow's milk contains about 4.6% to 4.7% lactose. Lactose is not easy to ferment and has low solubility. It is easy to form crystals in frozen products and affect the processing performance of food. When liquid milk is sterilized by ultra-high temperature instantaneous sterilization through pipes, the presence of lactose will produce colloids that block the pipes. If lactase is added to cow's milk, lactose can be hydrolyzed to produce glucose and galactose. It greatly improves the processing performance and is more conducive to the production of yogurt by lactic acid fermentation, overcoming "lactose intolerance", improving the digestion and absorption rate of lactose, and improving the taste of the product.
3. Remove bad odors. When heating and sterilizing milk, it is easy to produce a cooking smell. The main reason for this is that the β-lactoglobulin in the whey protein produces sulfhydryl groups due to heating. If sulfhydryl oxidase is added to the raw milk before heating, the sulfhydryl group can be converted into disulfide to avoid the cooking smell caused by high-temperature sterilization. If trypsin is added to milk, it can hydrolyze polypeptides, amides and esters, and produce peptides with relatively low molecular weight, which can effectively inhibit the milk oxidation smell caused by adverse conditions of milk fat.