Application of Enzymes in Fruit and Vegetable Juice Processing In recent years, pectinase and other enzymes (such as cellulase) were used to treat vegetables and fruits, which greatly improved the juice yield of vegetables and fruits, simplified the process steps, and made transparent and clear fruit and vegetable juice, which can be made into various drinks and foods, such as carrot juice, apple juice, tomato juice, onion juice and so on. The juice treated by enzyme is relatively stable, which can prevent turbidity and protect its original color and flavor, thus prolonging the storage period. The technological process of fruit and vegetable juice processing includes peeling → juicing → clarification, filtration → extraction → storage (stability, color and flavor of fruit and vegetable juice) → peeling → juicing → clarification, filtration → extraction → storage, peeling and softening citrus, soaking fruits and vegetables with pressure or vacuum to make pectinase penetrate into cell gaps or cell walls. This method has been used to soften the whole orange, and the orange peel is easy to peel. Squeezing fruits and vegetables to improve the juice yield of fruits and vegetables 1) Pectinase is the most widely used enzyme to improve the juice yield of fruits and vegetables, followed by cellulase. Adding a certain amount of pectinase before juice extraction can effectively decompose pectin in pulp tissue, reduce the viscosity of juice, facilitate juice extraction and filtration, and thus improve juice yield. Cellulase can degrade macromolecular cellulose in fruits and vegetables into cellobiose and glucose molecules with smaller molecular weight, destroy plant cell walls, fully release intracellular soluble substances, improve juice yield and increase soluble solid content. At present, citrus peel residue has been successfully hydrolyzed by cellulase to produce fruit-containing beverage, in which 50% of crude fiber is converted into soluble sugar and the other 50% is degraded into short-chain oligosaccharide, which constitutes the dietary fiber of fruit-containing beverage, which has certain health care and medical value. In production, if the two enzymes are used in a proper proportion, the yield will be more effectively increased. 2) Atherosclerosis, also known as softening enzyme, is a compound enzyme obtained by solid-state fermentation of Aspergillus Niger, which is mainly composed of pectinase, cellulase and xylanase, and contains protease and amylase. In the process of fruit and vegetable processing, atherogenic enzyme can crush fruit and plant cells, so as to coagulate and soften the raw materials of fruits and vegetables, thereby improving the juice yield and clarity and reducing the viscosity of fruit and vegetable juice. For example, in the production of apple juice, the use of atherogenic enzyme will make the production process simpler and the addition cost will be greatly reduced. Pulping enzyme I was added in apple crushing and enzymolysis, and the cost of adding enzyme in fruit juice degumming was only 15% ~ 20% of that of foreign enzyme preparation. Adding Atherosclerosis Ⅰ can increase the juice yield of fruits and vegetables, degrade pectin, cellulose and protein, and increase the juice yield of cells by 15% ~ 25%. After the clarified fruit and vegetable juice is squeezed and filtered, there are still some extremely fine polymers and solid particles in the juice, which will cause the fruit and vegetable juice to be turbid. Such as gum, starch and other polysaccharides. They are the main reasons for 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), most of the above substances can be degraded into galacturonic acid, glucose, amino acids and other products, thus clarifying the fruit and vegetable juice, and at the same time obviously improving the nutritional components and stability of the clarified juice. 1) The role of pectinase in clarification of fruit and vegetable juice. When pectinase acts on fruit and vegetable juice, it can not only reduce viscosity, but also produce flocculation to clarify fruit and vegetable juice. The essence of clarification mechanism includes enzymatic hydrolysis of pectin and non-enzymatic electrostatic flocculation. The newly processed fruit and vegetable juice is generally a stable colloid system, and its main stabilizing factor is pectin. The viscosity of pectin can protect colloid and prevent protein in fruit and vegetable juice from reacting with polyphenols or suspended particles with opposite charges to precipitate. When pectinase in fruit and vegetable juice is partially hydrolyzed, the viscosity of the system decreases, and the colloid loses its stability, so that the positively charged protein particles originally wrapped in it are exposed and collide with other negatively charged particles, leading to flocculation. Many commercial pectinase preparations can be used to clarify apple juice. The results showed that when the mixed preparation of endopolygalacturonase and pectin esterase was added, 30% of ester bonds and 5% of glycosidic bonds in pectin were hydrolyzed, and apple juice was fully clarified. The experiment shows that the transmittance of apple juice can reach about 95% after adding 0.07% pectinase preparation and reacting at 45℃ for 2 hours. Transparent juice with absorbance of 0. 15. 2) Application of compound enzyme in clarification of litchi juice The optimum technological conditions of compound enzyme clarification of litchi juice are cellulase 600U/ 100g, pectinase 1000U/ 100g, α -amylase 250U/ 100g and papain1000. After mixed enzymolysis, the light transmittance of clarified juice gradually increased within 0~24h, and then slowly decreased after 24~ 168h, and the final light transmittance remained at 80%. The transmittance of raw juice is basically maintained at about 50%. Pectin qualitative test of raw juice and clarified juice showed that there were many precipitates in raw juice, but there were no obvious precipitates in clarified juice. Enzymatic improvement of aroma of fruit and vegetable juice is the main factor affecting its quality, which is easy to be lost during processing. Recent studies have shown that adding enzyme preparation to fruit and vegetable juice can hydrolyze its flavor precursors and produce flavor substances. Flavor precursors are usually some flavor substances that form glycosides with sugar and exist in the form of bonds. Studies have shown that monoterpenoids are the most sensitive aromatic substances. Most monoterpenes in fruits and vegetables exist in the form of pyrans and furanose, and a large number of terpenoids in this bonded state are still not hydrolyzed after fruits and vegetables mature. Terpenol in fruit and vegetable juice can be released by adding β -glucosidase to increase aroma. Experiments show that α-L- pyranosidase or α-L- furan arabinosidase can release agallonol and geraniol from fruits, making the juice more fragrant. Previous studies have shown that it is very uneconomical to extract exogenous enzymes from fruits, but now flavor enzymes can be separated from Aspergillus and yeast. Shoseyov et al. isolated from Aspergillus Niger? 0? 8- glucosidase hydrolyzes passion fruit and vegetable juice, releasing a lot of linalool, benzaldehyde and phenylethanol. Will the glucose concentration in fruit juice be inhibited when it is high? 0? 8- glucosidase activity, a glucose values-resistant strain was isolated from Aspergillus oryzae by Riu et al? 0? 8- glucosidase, which can separate geraniol, nerol and linalool from the corresponding monoterpenoids in fresh grape juice. 0? Does not contain 8- glucoside. Gueguen et al. immobilized with DuoliteA-580 aldehyde? 0? The physical and chemical properties of 8- glucoamylase are similar to those of free enzyme. The apricot juice immobilized by the enzyme was detected by gas chromatography-mass spectrometry. It was found that α-r- terpineol, α-terpineol, 2- phenylethanol and α-pinene all increased significantly, and the flavor components of other fruit and vegetable juices also increased. Another experiment showed that isolated from yeast? 0? 8- glucosidase also has the ability to promote the flavor of fruit and vegetable juice. Dry the separated yeast? 0? Compared with acid hydrolysis, 8- glucosidase hydrolyzes mango and passion fruit juice, which will release bad terpenoids with hydrolysis, which is not conducive to juice processing. 0? 8- glucosidase can hydrolyze flavor precursors and degrade anthocyanins. 0? 8- glucoside is not conducive to the processing of red fruit and vegetable juice. Enzymatic deodorization of fruit and vegetable juice Citrus juice will become bitter soon after extraction, which is mainly caused by limonin and naringin. Enzymatic debittering mainly uses different enzymes to act on limonin and naringin respectively to generate substances without bitterness. Immobilized naringinase is often used in industrial production to reduce the content of naringin in citrus juice to remove bitter substances. This method has achieved good results. Naringinase can be obtained from commercially available citrus pectin preparation, Aspergillus, etc. Naringinase has two kinds of enzyme activities-rhamnosidase and glucosidase, which hydrolyze naringin into rhamnose and bitter-free glycoside-ligand grapefruit, thus playing a role in debittering. Tsen et al. immobilized naringinase with chitin in 1989, and studied the kinetic factors of immobilization. Manio'n et al. produced immobilized naringinase with hollow glass bed as carrier, DEAS dextran gel and tannin aminoethyl fiber as carrier.