Application of enzymes in food industry

Enzyme is an efficient and safe biocatalator, which has been widely used in the food industry such as the development of food raw materials, quality improvement, process transformation, etc., with high efficiency, specificity, mild and other biological characteristics. With the deepening of research, enzymes are replacing traditional chemical reagents with their unique advantages, and are increasingly used in the food industry. Enzyme industry has become one of the most promising emerging industries in China.

1. Research progress of biological enzymes in food industry

Enzymes used in the food industry are diverse due to their roles and capabilities in food production. According to the type of reaction they catalyze, they can be divided into five categories: oxido-reductase (dehydrogenase, reductase or oxidase), transferase, hydrolase, isomerase (racemase, superisomerase, cis-isomerase, isomerase, tautomase, mutase, cyclic isomerase) and ligase (synthetase).

Among them, protease, glycoenzyme, esterase, fat oxidase, polyphenol oxidase, peroxidase and ascorbate oxidase are widely used. Protease is a kind of hydrolase, which can be divided into acidic protease and alkaline protease according to the optimal pH, and has been widely used in food industry. The common sugar enzymes are α-lake powder enzyme, β-amylase, glucose amylase, etc., which are mostly used in sweetener production industry; Esterase is a hydrolytic enzyme, and calcium salt can improve the stability of esterase. Polyphenol oxidase is used to control enzymatic Browning reaction and has great influence on the color value of the product.

The industrial production of enzymes for food processing dates back to 1874, when Danish scientist Christian Hansen extracted chymosin from a calf's stomach for use in cheese making. Chymosin is produced by recombinant deoxyribonucleic acid (rDNA) technology introduced by microorganisms containing the bovine tryptase gene. Chymosin, expressed in E. coli K-12, became a recombinant enzyme approved by the U.S. Food and Drug Administration (FDA) for use in foods. Many of the enzymes currently used in food processing are derived from recombinant microorganisms.

How to maintain the color, aroma, taste and structure of food during food processing is a very important issue, so it is necessary to avoid violent chemical reactions during processing. Enzymes are suitable for food processing due to mild reaction conditions, strong specificity, colorless and odorless itself, and easy to control the reaction, and bring new ideas to the traditional food industry.

The ideal enzymes and their functions in food mainly include: endogenous β-glycosidase, polyphenol oxidase (PPO), peroxidase (POD), esterase affecting ripening and flavor production; Cathepsin can be used for myofibrillar protein hydrolysis fermentation products, protease and transglutaminase can be used for food structure modification. Of these enzymes, endogenous PPO or endogenous lipase and lipoxygenase (LOX) cause rancor, resulting in dark discoloration of fresh fruits, vegetables and raw crustaceans. Enzymes are used as additives for a wide range of applications in food processing, such as coagulation, ripening, baking, brewing, cell cracking, hydrolysis, and molecular structural modification. At present, enzymes are widely used in dairy products, baked goods, beverages, oils, meat and functional foods.

2. Application of biological enzymes in food industry

2.1 Sugar industry and starch processing

Pectinase, α-amylase, glucanase, β-amylase and glucose isomerase are commonly used in sugar and starch processing, among which pectinase, glucanase and α-amylase are more widely used.

Pectinase is a kind of complex enzyme which can decompose pectin and hydrolyze pectin specifically to achieve the effect of clarification. α-amylase is an endonuclease that can indiscriminately break the α-1, 4-glucoside bond, acting on both amylose and amylopectin. α-amylase can effectively degrade the starch in the mixed juice, avoiding the increase of acidic flocculants caused by excessive starch content, and rapidly reducing the viscosity.

α-glucanase is a biological enzyme that can hydrolyze macromolecule glucan to glucose and other small molecules. There are two kinds of endo-dextran and exo-dextran enzymes. The hydrolyzing effect of endo-dexanase is better than exo-dexanase. Glucose isomerase, also known as xylose isomerase, refers to the isomerase that can isomerize aldose into the corresponding ketose, which can carry out the isomerization reaction of glucose to produce high fructose syrup in place of sucrose.

2.2 Dairy product processing

Rennet, lactase, protease, lipase and lactoperoxidase are the most commonly used enzymes in dairy products processing.

Rennet turns liquid milk into near-solid cheese; Lactase can hydrolyze the lactose in milk, which brings good news to lactose intolerant people. Protease and lipase can accelerate cheese ripening and improve cheese properties. Lactoperoxidase can remove hydrogen peroxide and prolong the shelf life, which has a remarkable effect on the preservation of goat milk.

So far, lactoperoxidase preservation method is recognized as the most ideal preservation method. Zhang Cong reviewed the application of lipase, complex flavor protease and glucosidase. Cheese, known as cheese, contains very rich nutrients and will play a major role in improving food structure and strengthening body quality for people in the country.

In order to meet people's growing demand for high-quality dairy products, the development of special cheese suitable for Chinese consumption, in cheese processing to add a variety of enzymes to make cheese taste more delicious. The experiments of Zhang Shuo et al. showed that endogenous lipase, transglutaminase, flavor protease combined with complex protease and lactoperoxidase played an obvious role in cheese processing. The amount of transglutaminase has a significant effect on the hardness, elasticity and yield of cheese, and it can improve the nutritional titer of protein by introducing lysine, so that the processed dairy products have a good appearance and texture.

2.3 Juice and beverage processing

In the production and processing of fruit juice, adding enzymes can play a role in clarifying, improving juice yield, reducing non-enzymatic Browning and determining the organic acid content in fruit juice. In juice and beverage processing, α-amylase, glycosylase, protease, complex enzyme made of pectinase, glucanase and amylase in a certain proportion, and glucose oxidase are widely used.

Gao Yujun et al. from Zhengzhou Institute of Light Industry applied double enzyme method (high temperature α-amylase and saccharase) to corn juice, which improved the phenomenon of precipitation during storage of corn beverage. Sun Wei et al summarized that limonin dehydrogenase, limonin lyase, limonin deoxyase, nomiline dehydrogenase and nomiline deoxyase could be used to remove the lime base bitterness of orange juice.

Jia Jinglin et al. from Tarim University acted a variety of proteases on walnut protein to hydrolyze the protein into polypeptide, which provided reference for the subsequent production of walnut protein polypeptide products.

Wang Jihui et al. prepared walnut polypeptide by combining neutral protease and papain on walnut meal. Some studies have been conducted to reduce turbidity, viscosity and absorbance of three kinds of fruit juices by polygalacturonic acid exonuclide, which is of great significance for the clarification of fruit juices.

2.4 Meat processing

Meat is the main source of daily energy intake of the human body, with the improvement of people's pursuit of a better life, people's requirements for meat is not only the demand for human energy, but also in the taste, fresh and health and safety have a higher pursuit.

As an efficient biocatalyst, enzymes have entered the field of vision of researchers. With the findings of various studies, enzymes play a very important role in the preslaughter and processing and transportation of meat products, among which protease, transglutaminase, endogenous enzyme and lysozyme play a particularly obvious role, gradually replacing chemical agents and becoming an indispensable part in the processing of meat products.

Preslaughter factors have a variety of effects on the quantity, distribution and type of connective tissue. After slaughter, the activity of protein enzymes in muscle changes, which will greatly affect the tenderness of meat. The enzyme is injected before slaughter and spreads throughout the body after blood circulation. The enzyme is static in the meat. When the temperature reaches the optimal temperature of the enzyme during cooking, it catalyzes to increase the expansion rate of the meat, increase water absorption, change the tissue structure, tenderize the meat and enhance the taste.

In 2007, the United States approved the use of rice kojase and other microbial proteases, and then Swift Co., Ltd. produced food-grade protease Proten, the usage is the same as papain, it gives priority to the hydrolysis of tissue protein, and the activity of other proteins is very low. Tenderize the meat without affecting the original taste of the meat.

At present, countries are doing further research on microbiological egg white enzymes, and in the near future, better food-grade microbial proteases will be applied to meat processing to improve human living standards.

Transglutaminase can catalyze protein gelling, increase protein molecular size and change its functional properties. The gelling ability of transglutaminase on casein is better than that of soybean protein. Transglutaminase is a new protein function modifier, which can improve the elasticity and tenderness of meat products and can replace the role of phosphate

The addition of transglutaminase in ham sausage can increase the gelling of casein, thus improving its taste, flavor, structure and nutrition. Compared with exogenous enzymes, the system of endogenous enzymes is more complex, and there are many factors affecting their activity. Therefore, in recent years, exogenous enzymes have been studied more and more, so as to decompose the nutrients of meat products, thus achieving the purpose of tenderizing meat and forming unique flavor.

2.5 Beer Production

Beer is an alcoholic beverage made from malt by saccharification and fermentation. The malt contains various enzymes necessary for the degradation of raw materials to produce fermentable substances, mainly amylase, protease, β-glucanase, cellulase and nucleic acid decomposition enzyme.

Rational use of biological enzymes can not only significantly improve the quality of beer, but also reduce production costs and bring good news to the beer industry.

Papain, high temperature resistant α-amylase, acetyllactate decarboxylase and proline endonuclease play different roles in beer production.

Papain acting on raw malt protein can prevent protein from binding with polyphenols and precipitate, and has a good filtering effect, thereby improving the stability of beer, clarifying beer to a certain extent, and does not affect the taste characteristics of beer. Ethyl et al. used 0.08 mg/dL papain to reduce the turbidity of beer by 68.75% and increase the beer foam. The high-temperature resistant α-amylase and α-acetyllactate decarboxylase are applied to the gelatinization process of excipient. The high-temperature resistant α-amylase can liquefy starch well, and the α-acetyllactate decarboxylase can accelerate the reduction rate of acetyl and reduce the content of diacetyl in finished beer to a certain extent.

2.6 Condiment processing

Condiments are auxiliary foods that can increase the color, aroma and taste of dishes, promote appetite and benefit human health.

Lin Zusen reviewed the application of enzyme preparations in the brewing condiment industry, and separately described the process flow of enzyme preparations in the production of sweet sauce, soy sauce, vinegar, fermented bean curd and other condiments. The use of enzyme preparations to replace the traditional "koji" process in the production process has broad application prospects for improving product quality and environmental health.

Wan reviewed the use of enzymes in meat condiments, which can be used by condiment manufacturers to break down or combine protein chains, sugars and fats so that reactions occurring during cooking (such as the common Maillard reaction) produce only those desired flavor components.

Wei made a summative comparison between the traditional production process of soy sauce, vinegar and fermented bean curd and modern biotechnology using enzymes, and found that enzymatic processes can shorten the production cycle and reduce pollution.

Zhang Zhiguo et al. reviewed non-aqueous enzyme catalysis and its application in the synthesis of flavors and fragrances.

Zhang Zhongping et al. clarified pear vinegar with pectinase, and finally obtained pear acetic acid with unique and clear taste.

Du Guojun et al. applied pectinase to the brewing process of mixed fruit vinegar of sand fruit and kiwi fruit, and also had good clarification and modification.

Wu Yanwen et al., Tianjin University of Science and Technology, applied lipase to different types of cream, cheese and milk, hydrolyzed it in non-aqueous medium, and obtained milk flavor with excellent effect.

3 Conclusion

Enzymes have been widely used in the food industry, in addition to the above several categories, but also can be used in many aspects.

Jiang Guolong et al. reviewed the application of enzymes in the preparation of baked food; Yu Liping et al. summarized the application of enzymes in brewing, seasoning, oil processing and other fields; Hou Jin et al. introduced the application of enzymes in fruit and vegetable food processing; Wang Wei et al. reviewed the application of enzymes in lipid making, tea beverage, bean processing, egg processing and other industries.

It can be expected that with the rapid development of biotechnology, the types of enzymes that can be used in food will be greatly increased, and the vigorous research on complex enzymes, new enzymes and immobilized enzymes will be the future development trend. However, it must also be pointed out that the action mechanism of various enzymes in the food industry needs to be further studied, and enzyme preparations have broad application prospects.