111 results about "Polyphenol oxidase activity" patented technology

The present invention relates to a method for enhancing a plant's resistance to diseases and / or bruising by transforming the plant with sense and antisense polyphenol oxidase encoding sequences from potato. The invention also relates to transgenic plants and progeny thereof with reduced polyphenol oxidase activity.

The method for preprocessing Asiatic wormwood to preserve the color in combination with quick-freezing and unfreezing for keeping quality belongs to the technical field of fruit-vegetable food storage and processing. The process of the method is as follows: Asiatic wormwood with tender leaves and stalks is chosen, washed and then added with compound enzyme inhibitor, and by regulating the components, content and material-to-solution ratio of the enzyme inhibitor, the activity of polyphenol oxidase in the Asiatic wormwood is inhibited; the Asiatic wormwood is then blanched in boiled water, thepH value of the solution is regulated, the blanching time is adjusted, and while substances with bed flavor, such as absinthin, are completely removed, the loss of the Asiatic wormwood pigment is reduced; after cooling, metal ion color-preserving processing is carried out, and the dosage of metal ions and the pH value of color preservative are determined; after being sufficiently blanched, the Asiatic wormwood is pulped and filtered, vacuum packages are adopted for precooling and medium-frequency ultrasonic quick-freezing, and the Asiatic wormwood is refrigerated under the condition of negative 18 DEG C, and is ultrasonically unfrozen when being applied later. High-quality Asiatic wormwood product is produced by the method, the method is economic and practical, the cost investment is low,the process is simple and easy to implement, and the method can provide technical support for the industrialized production of Asiatic wormwood.

The invention discloses a method for brewing cherry fruit wine. The method is characterized by comprising the following steps of: after selecting, washing and stoning cherries serving as raw materials, obtaining primary pulp by juicing; adding the following substances such as pectinase, calcium citrate, vitamin C, and g / L kojic acid into the primary pulp; standing for 5 to 24 hours; preparing clear juice by performing centrifugal separation; inoculating 0.05 to 2 percent of fruit wine yeast based on the weight of the clear juice; controlling a temperature and fermenting, wherein the primary fermentation temperature is between 16 and 28 DEG C, the fermentation time is 7 to 15 days, the secondary fermentation temperature is between 15 and 20 DEG C, and the fermentation time is 20 to 40 days; aging for 3 to 6 months; clarifying and filtering by adopting an ultra-filtration method; and filling, sterilizing and packaging to obtain finished cherry fruit wine. The method effectively improves a production process of cherry wine, reduces the content of polyphenol fundamentally, inhibits the activity of polyphenol oxidase, reduces harsh taste and improves stability. Compared with the prior art, the cherry fruit wine produced by the method maintains effective nutrient components, reduces the harsh taste and has a pure flavor.

A genetically modified fruit-producing plant, said plant having sufficiently reduced total Polyphenol Oxidase (PPO) activity relative to a wild type of said plant to reduce browning in the fruit of said plant relative to said wild type, wherein the reduced total PPO activity results from a reduction in activity of at least two PPO isoenzymes in said plant relative to said wild type, or a cell, seed, seedling, part, tissue, cell, fruit or progeny of said plant.

The invention provides a method for inhibiting the activity of polyphenol oxidase in whole wheat flour, which is used for combined treatment on the whole wheat flour by utilizing an antioxidant and ultrasonic waves. The method comprises the following concrete steps of: (1) pretreatment; (2) combined treatment by using the antioxidant and the ultrasonic waves: adding ascorbic acid or reduced glutathione into a suspension liquid, stirring for 3min, and then carrying out ultrasonic treatment by using an ultrasonic crushing instrument under the working parameters that the ultrasonic power is 450-750w, every ultrasonic time is 20-28s, the chill time is 2-10s, and the total ultrasonic treatment time is 1-3min, wherein the ascorbic acid occupies 0.5-1.5% of the weight of the suspension liquid, and the reduced glutathione occupies 0.25-1% of the suspension liquid; and (3) filtering and drying. The method can be used for effectively inhibiting the activity of the polyphenol oxidase in whole wheat flour, lowering the brown stain degree of whole wheat noodles and prolonging the shelf life of the whole wheat noodles and is short in treatment time, high in efficiency, low in cost and capable of being applied to industrial production.

The invention discloses a method for controlling a blackheart disease of normal-temperature stored pineapples by an abscisic acid. The method comprises the steps that an abscisic acid solution of 5-500mg / L is sprayed on the surfaces of the pineapples; and the sprayed pineapplesare is packed with a polyethylene plastic film bag of 0.02-0.04 millimetres and moisturized for 6-9 hours, then the polyethylene plastic film bag is removed, and the pineapples are aired and stored in a storehouse at the temperature of 20-25 DEG C. According to the method, the abscisic acid solution of 5-500mg / L is sprayed on the surfaces of pineapple fruits, so that the polyphenol oxidase activity and the peroxidase activity of the pineapples can be reduced effectively, and the pineapples can be prevented from suffering from the blackheart disease. The method is simple in operation, low in cost and high in applying efficiency, and can be popularized easily; at the same time, the storage period of the pineapples is prolonged, the problem of a farmer that the pineapples are difficult to sell can be solved effectively, and the enthusiasm of the farmer for planting pineapples is protected; and good economic and social benefits are achieved. The pineapples are kept fresh without a refrigerating storage and being transported at a low temperature, so that the energy is saved, the environmental protection is facilitated, and the method is a low-carbon preservation technology.

A process in which cocoa polyphenol concentrate is obtained comprising the steps of: a) subjecting unfermented cocoa beans to a blanching step in water at a temperature in the range from 85-100 DEG C for a time period in the range from 3 to 15 minutes to give unfermented cocoa beans with reduced polyphenol oxidase activity; b) drying the unfermented cocoa beans with reduced polyphenol oxidase activity at a temperature of less than 85 DEG C to obtain dried unfermented cocoa beans with a moisture content of no more than 15%; c) subjecting the dried unfermented cocoa beans to a particle size reduction step to obtain dry unfermented cocoa bean intermediate whereby at least 99 wt% of the product has a particle size less than or equal to 300 m; e) extracting polyphenols from the dry unfermented cocoa bean intermediate to give a cocoa polyphenol extract and extracted solids; d) concentrating the cocoa polyphenol extract to yield a cocoa polyphenol concentrate; and wherein the process further includes a defatting step which is carried out prior to step d).

The invention discloses a method for coating preservation of Litchi chinensis bacterium by phellinus igniarius polysaccharide. The method comprises the following steps: classifying the harvested Litchi chinensis bacterium, picking the Litchi chinensis bacterium consistent in maturity and sizes and free of mechanical damage and plant diseases and insect pests, and soaking in a phellinus igniarius polysaccharide solution of which the concentration is 0.8 to 1.2% for 2 to 6min, carrying out air drying by cold air until the surfaces of the Litchi chinensis bacterium are dried and formed by films and then performing preservation at the temperature of 4 DEG C. The invention further discloses a preservation method of the Litchi chinensis bacterium by fumigating the phellinus igniarius polysaccharide solution on the surfaces of the Litchi chinensis bacterium, and further discloses a method for extracting the phellinus igniarius polysaccharide solution. In addition, the invention has the beneficial effects of lowering the respiration rate of the Litchi chinensis bacterium, inhibiting the activity of polyphenol oxidase of the Litchi chinensis bacterium, reducing internal moisture evaporation, delaying aging and having low cost and long preservation time; furthermore, the phellinus igniarius polysaccharide is high in nutritional values and has a variety of biological activities of oxidation resistance, immunity enhancement, tumor resistance and the like, and the films are coated on the surfaces of the Litchi chinensis bacterium, and free of any toxic and side effects to human bodies, thereby being natural and environment-friendly.

The present invention discloses a frozen penaeus vannamei with heads processing method which is realized by the scheme as follows: timely killing live penaeus vannamei, cleaning and disinfecting, soaking to preserve fresh, freezing, and ice glazing. The soaking fresh preserving process contains biological preservative water or ice and ice glazing water which contains 0.3-0.5 g / L nisin, 0.5-1.0 g / L chitosan, 3-5 g / L epsilon-polylysine (epsilon-PL), 0.005-0.01 g / L 4-hexylresorcinol (4-HR), and 0.5-1.0 g / L L-ascorbic acid (Vc). By low-temperature control and complex biological preservation technology, polyphenol oxidase activity and microbial proliferation in the penaeus vannamei head can be inhibited, the problems of easy appeared black and red heads of the frozen penaeus vannamei with heads during the thawing process can be resolved, and the quality and appearance of the frozen penaeus vannamei with heads are enhanced.

The invention relates to a method for improving the activity of polyphenol oxidase in apples by virtue of hexadecyl trimethyl ammonium bromide and dodecyl trimethyl ammonium bromide, belonging to the technical field of preparation of enzyme catalysts in bioengineering. The method comprises the step of extraction of polyphenol oxidase (PPO) crude enzyme liquid. The method is characterized in that catalytic reaction is carried out by taking polyphenol oxidase as a catalyst in the presence of hexadecyl trimethyl ammonium bromide (CTAB) or dodecyl trimethyl ammonium bromide (DTAB). According to the method, the activity of polyphenol oxidase in the apples is improved by virtue of hexadecyl trimethyl ammonium bromide or dodecyl trimethyl ammonium bromide.

The invention relates to the technical field of enzymatic activity, in particular to an apple polyphenol oxidase accelerative activator and application thereof. The apple polyphenol oxidase accelerative activator comprises a mixture of dodecyltrimethylammonium bromide or hexadecyl trimethyl ammonium bromide and a Gemini surfactant according to the weight ratio of 10-2,000: 1-4; and the Gemini surfactant is dibromo-bis(dimethyl dodecyl) pentyl diammonium or dibromo-bis(dimethyl hexadecyl) pentyl diammonium. The invention further provides application of the apple polyphenol oxidase accelerative activator in improvement of apple polyphenol oxidase activity. The apple polyphenol oxidase activity can be increased to be 240%, and the use amount level of the apple polyphenol oxidase accelerative activator is low.

The invention provides a method for keeping cordyceps sinensis fresh by using an irradiation method, and relates to the technical field of cordyceps sinensis fresh-keeping. The method includes soakingfresh cordyceps sinensis in a fresh-keeping solution; performing modified atmosphere packaging; and performing irradiation on the modified atmosphere packaged cordyceps sinensis with <60>Co[gamma] rays or 5-10 MeV electron beams, irradiation dose being 0.1-1.5 kGy, and ununiformity being less than or equal to 1.25 so that the fresh-keeping of the cordyceps sinensis can be realized. According to the embodiments, compared with the prior art, the weight loss rate, soluble protein content decreasing rate and polyphenol oxidase activity growth rate of the cordyceps sinensis can be significantly reduced by adopting the method to perform fresh-keeping processing on the fresh cordyceps sinensis, and the fresh-keeping time at least can reach 75 d; and long-time and effective fresh-keeping on animal-fungal tissue complexes like the cordyceps sinensis can be realized under limited irradiation dose, and obvious damage to the cordyceps sinensis can be avoided.

The present invention relates to a process for reducing the polyphenol oxidase activity in cocoa beans comprising the step of steaming non-fermented, non-roasted raw cocoa beans with water vapor.

A DNA sequence including a gene coding polypeptide having polyphenol oxidase (PPO) activity, or a fragment thereof.

The invention discloses a method for prolonging the refreshing time of yellow peach slices. The method comprises the following steps of: (1) preparing a film solution : dissolving chitosan into distilled water, stirring, then, adding glacial acetic acid to prepare a chitosan solution, stirring at the temperature of 18-22 DEG C, adding glycerol and Tween 80 into the chitosan solution and stirring, regulating the pH value to be 5.6 by using a NaOH water solution, and filtering to obtain the film solution; and (2) carrying out film coating treatment: immersing the slices into the film solution, and taking out the slices and draining. According to the method, the loss of vitamin C in the yellow peach slices can be effectively reduced, the increases of the activity of polyphenol oxidase and the relative conductivity are retarded, the browning is inhibited, and the loss of juice is reduced; and the shelf lives of the yellow peach slices are obviously prolonged, so that the yellow peach slices have excellent shelf quality.

The invention provides a method for keeping cordyceps sinensis fresh through the recombination of modified atmosphere packaging and ultraviolet irradiation, and relates to the technical field of cordyceps sinensis fresh-keeping. The method includes soaking fresh cordyceps sinensis in a fresh-keeping solution; taking out the cordyceps sinensis to soak in a tectorial membrane liquid after drying; forming a layer of protective membrane on the surfaces of the cordyceps sinensis; and performing ultraviolet irradiation on the coated cordyceps sinensis after modified atmosphere packaging so that thefresh-keeping of the cordyceps sinensis can be realized. Through the adoption of a comprehensive processing mode of fresh-keeping with the fresh-keeping solution, coating with the tectorial membrane liquid, modified atmosphere packaging and ultraviolet irradiation, the reduction of weight loss rates of the cordyceps sinensis can be significantly inhibited, the reduction of soluble protein contentcan be alleviated, and the increasing of the activity of polyphenoloxidase can be delayed; and compared with conventional fresh-keeping methods, the fresh-keeping time at least can reach 75 d; so thatbetter effects of maintaining the color and fragrance of the fresh cordyceps sinensis can be achieved.

The invention provides a potato whole starch preparation method. Color fixatives are not added in the preparation process. The preparation method includes the steps: performing vacuum pumping packaging on potato blocks with the volume smaller than or equal to 5cm<3>, and treating the vacuum packaging potato blocks for 20-60min under the ultrahigh pressure condition; freezing the potato blocks treated under the ultrahigh pressure condition to the temperature ranging from -50 DEG C to -40 DEG C, performing vacuum freezing drying on the potato blocks to obtain dewatered potatoes, and crushing the potatoes to 90-150 meshes to obtain potato whole starch. According to the preparation method, the potato blocks are treated under the ultrahigh pressure condition, the activity of oxidase, particularly, polyphenol oxidase in the potatoes can be passivated, and poor color and luster caused by oxidation and browning is effectively prevented in the preparation process of the potato whole starch, so that the potato whole starch with good color and luster can be acquired without adding any additives by the preparation method.

The invention discloses a polyphenol oxidase passivation method based on dielectric barrier discharge low-temperature plasma. The dielectric barrier discharge low-temperature plasma is applied to shrimp processing at a processing voltage of 55-60kV for 60-70s. The method has the following beneficial effects: the polyphenol oxidase is passivated by utilizing the dielectric barrier discharge low-temperature plasma, the plasma contains highly-active substances such as electrons, ions, excited-state atoms, metastable-state atoms, and free radicals, and the substances change the secondary structureand the tertiary structure of the polyphenol oxidase, thereby leading to the loss of the activity of the polyphenol oxidase.

The invention discloses two-phase aqueous extraction combined with forward osmosis condensation and extraction technology for blueberry leaf anthocyanidin. The technology comprises the following steps: (1) dried blueberry leaves are crushed, blueberry leaves and an extraction solvent are mixed for extraction, a crude extract of anthocyanidin is obtained, and a polyphenol oxidase active inhibitor is added into the crude extract; (2) polyethylene glycol and magnesium chloride are added into the crude extract prepared in the step (2), mixed extraction time is set, after balancing, a top phase anda bottom phase are separated, a two-phase aqueous extraction system is used for carrying out multitime repeat extraction of the top phase obtained by separation in order to remove sugar in the crudeextract, polyethylene glycol in the top phase is removed, and mixed liquor is obtained; (3) membrane permeation distillation and condensation is carried out for the mixed liquor in the step (2), a penetration solution is a calcium chloride solution, the volume ratio of material liquid to the penetration solution is 1:3-5, and the material liquid is the mixed liquor in the step (2); (4) an ultrafiltration method is used for clarifying the crude extract product of anthocyanidin, and a forward osmosis solution is a sodium chloride solution.

The invention discloses a production method of flour special for low-bacterial raw and wet flour products, and belongs to the field of flour processing. The production method comprises the following steps that wheat is cleaned and wetted in reverse osmosis water or slightly-acidic electrolytic water with pH being 5.8-6.2 and effective chlorine concentration being 40-70ppm in a steam or mixing wheat wetting mode, decrustation and wheat scouring are conducted after wheat wetting, wheat cortex removing and grinding are performed, a tube cell with low polyphenol oxidase activity is selected for flour taking, and the flour is mixed to obtain the flour special for the low-bacterial raw and wet flour products. The preparation technology is simple and mild. The total number of bacterial colony ofobtained flour is less than or equal to 6.0*10<3>CFU / g, the total number of mold and yeast is less than or equal to 7.0*10<2>CFU / g, the total number of heat-resistant spores is less than or equal to 70CFU / g, enzyme activity is less than or equal to 360U / g.min, and the damaged starch content is 20-29UCD. The obtained flour special for the low-bacterial raw and wet flour products by the productionmethod is low in microbial content, is not liable to brown, and is not prone to water returning. The processing quality is stable, the flour is suitable for production and processing of the raw and wet flour products, and the application prospect is wide.

The invention provides a method for fresh keeping of guava fruits by film coating with rhizoma kaempferiae essential oil, rhizoma alpiniae officinarum essential oil and fresh ginger essential oil. According to the method disclosed by the invention, various substances having antibacterial activity, such as the rhizoma kaempferiae essential oil, the rhizoma alpiniae officinarum essential oil, the fresh ginger essential oil, and chitosan are used as fresh keeping agents. The method comprises the following steps of selecting fruits, performing disinfection, performing air drying for the first time, performing film coating, performing air drying for the second time, and performing packaging. The substances having antibacterial activity, such as the rhizoma kaempferiae essential oil, the rhizoma alpiniae officinarum essential oil, the fresh ginger essential oil and the chitosan are merged, so that films compounded from the rhizoma kaempferiae essential oil, the rhizoma alpiniae officinarum essential oil, the fresh ginger essential oil and the chitosan have obvious fresh-keeping effects on storage of picked guava fruits, and changes of mouth feel and flavor of the picked guava fruits can be notably delayed. Respiration peak can be delayed, the increment of the content of propanedial can be notably restrained, and the rise of relative electrical conductivity and the rise of polyphenol oxidase activity can be notably restrained, so that the fresh-keeping time is greatly prolonged. The method is simple and convenient, materials are easy to obtain, the cost is low, and the method is easy to popularize.

The invention discloses a method for controlling a pineapple's blackheart disease by low-temperature treatment. The method comprises the steps that pineapples picked within 24 hours are soaked with cold water at the temperature ranging between 3 DEG C and 6 DEG C for 20-50 minutes, then aired, and stored in a refrigerator at the temperature of 3-6 DEG C. The method can reduce the activity of polyphenol oxidases and the activity of peroxidases of the pineapples effectively, so that the pineapple's blackheart disease can be controlled effectively, and the pineapples can be stored for 30 days and prevented from suffering from the blackheart disease. The method is simple in operation and low in cost, and can be popularized easily; at the same time, the storage period of the pineapples is prolonged, and the loss of the pineapples after picking is reduced effectively; the economic loss of a dealer is reduced effectively, the problem of a farmer that the pineapples are difficult to sell is solved, and the enthusiasm of the farmer for planting pineapples is protected; and the pineapples can be sold to countries all over the world by ship, more foreign currencies are earned for the country of the farmer, and good economic and social benefits are achieved.

The invention discloses a method for extracting longan seed polyphenol, and belongs to the field of natural product extraction method. The method comprises the following steps: 1) peeling and crushing; 2) filtering; 3) extracting; and 4) concentrating to obtain the polyphenol. The invention has the advantages of reasonable control of drying level of the longan seed, reduction of activity of polyphenol oxidase in longan seed, reduction of the loss of polyphenol in the production process, easiness to operate, high extraction efficiency and low production cost. The method has important meaning for expanding the use of longan seed and increasing their added value, not only is conducive to the full use of longan resources, but also helps promoting the development of longan planting.

The invention discloses a method for controlling pineapple black-heart by using salicylic acid. The method comprises the following steps of: spraying 1-200mg / L of a salicylic acid solution onto the surfaces of pineapple fruits 25-40 days before picking pineapples; and airing and storing the pineapples in a refrigerator of 8-12 DEG C after picking the pineapples. According to the method, 1-200mg / L of the salicylic acid solution is sprayed onto the surfaces of the pineapple fruits 25-40 days before picking of the pineapples, so that the polyphenol oxidase activity and peroxidase activity of the pineapples can be lowered effectively, and the pineapple black-heart is controlled effectively. The method has the advantages of easiness in operating, low cost, high application efficiency and easiness in popularizing; meanwhile, the storage period of the pineapples is prolonged, the economic losses of dealers can be effectively reduced, the problem of difficulty for peasants to sell pineapples is solved, and the enthusiasm of pineapple planting of the peasants is protected; and the pineapples can also be sold to countries all over the world by adopting shipping, so that more foreign currencies are earned for China, and a good economic benefit and a good social benefit are achieved.

The invention discloses a method for rapidly guaranteeing the quality of dried honeysuckle flower, and belongs to the technical field of agricultural product drying processing. The method is characterized in that organic matter steam and preferably ethanol steam is introduced in the initial stage of the gas conditioning of the dried honeysuckle flower for 10-20min, and the volume fraction of the ethanol steam in a gas conditioning drying medium is 1-5%. The method combines the organic matter steam gas conditioning drying with nitrogen gas conditioning drying, nitrogen introduction and organic matter steam spraying respectively reduce the oxygen content in drying environment, effectively reduce the number of oxygen molecules involved in an enzymatic oxidation reaction, and inhibit the enzymatic reaction; and the organic matter steam further reduces the rate of the enzymatic oxidation reaction by inhibiting the activity of polyphenol oxidase in honeysuckle flower to realize the protection of an active ingredient chlorogenic acid and the maintenance of the product color and maximally guarantee the quality of dried honeysuckle flower products.

The invention provides a method for preserving mulberry fruits with a coating film prepared from essential oil of three types of ginger. Multiple substances including Kacmpferia galangal essential oil, galangal essential oil, fresh ginger essential oil, chitosan and the like with antimicrobial activity are taken as a preservative. The method comprises steps as follows: fruit selection, disinfection, primary air drying, coating, secondary air drying and packaging. The multiple substances such as Kacmpferia galangal essential oil, galangal essential oil, fresh ginger essential oil, chitosan and the like with antimicrobial activity are integrated, the film prepared by compounding essential oil of three types of ginger and chitosan has a remarkable preservation function on mulberry fruits during postharvest storage, the postharvest taste and flavor change of the mulberry fruits can be significantly delayed, the breathing peak can be postponed, and increase of the malondialdehyde content and rise of the relative electrical conductivity and the activity of polyphenol oxidase can be notably inhibited, so that the preservation time is greatly prolonged. The method is simple, convenient, lower in cost and easy to popularize, and materials are easy to obtain.

The invention relates to a freshness keeping method of dry bamboo shoots. The polyphenol oxidase of the dry bamboo shoots is inactivated by using a vacuum microwave technology; and in a microwave energy generating area of vacuum microwave equipment, the activity of the polyphenol oxidase of the dry bamboo shoots is destroyed by ultrahigh frequency electromagnetic waves and thermal effect. Meanwhile, because the processing process is carried out under highly vacuum environment, the temperature int he microwave energy generating area cannot exceed 50 DEG C in the polyphenol oxidase inactivatingprocess. Therefore, the polyphenol oxidase can be inactivated without deepening color of the dry bamboo shoots to affect the product quality due to temperature rising. By using the technology provided by the invention to inactivate the polyphenol oxidase of the dry bamboo shoots, the whiteness and mouth feels of the processed dry bamboo shoots reach the premium grade; and the processed dry bambooshoots can be preserved for 12 months at normal temperature without changing color and deteriorating. The difficulties that the dry bamboo shoots are easy to change color and deteriorate, which perplex the producing enterprises for a long time and are to be solved, are solved; moreover, no sulfur dioxide is contained in the product.

The invention relates to the technical field soil remediation and particularly relates to a soil heavy metal deactivator and a preparation method of the soil heavy metal deactivator. The soil heavy metal deactivator improves the furfural residue, increases the content of soil humus, improves the activities of polyphenol oxidase, cellulase and peroxidase, improves the activity of the microorganismsin the soil, and promotes the dissolution of the active substance in the soil deactivator, the alkaline substance and a clay mineral modifier inhibit the activity of the heavy metal in the soil, butthe decline of the soil fertility, the soil hardening and the worsen constitutive property are possibly caused, the soil structure is improved, the soil is kept in the loose ventilated state, a microcrystal ground phosphate rock with finer particle size is added in white vinasse and the furfural residue to ferment, the surface activity of the ground phosphate rock is greatly reinforced, the nutrients of the waste are balanced and regulated through fermentation while the acid-base property of the waste is improved, so that the white vinasse and the furfural residue are efficiently utilized, nosecondary pollution is caused, the adsorbing and complexing of the heavy metals in the soil is promoted, and the deactivating effect is achieved.

It is intended to provide a method for producing a non-browning apple. Apples in which total polyphenol content is not more than 40 mg / 100 g fresh weight in terms of catechin when extracted from apple flesh using methanol and assayed by the Folin-Denis method are used as cross parents and by crossing and breeding them, using a low level of the browning degree of fruit flesh as an index and performing selection based on the index, the non-browning apple is produced. The non-browning apple has a non-browning characteristic that browning of flesh is less likely to occur and a polyphenol oxidase activity is significantly lower than that of a conventional cultivar.

The invention discloses a method for passivating the activity of dissolved polyphenol oxidase and membrane-bound polyphenol oxidase. The method comprises the following steps: step 1, taking fruit andvegetable materials, and carrying out first ultrahigh pressure treatment; step 2, performing ultrahigh-pressure homogenization treatment on the fruit and vegetable materials for 1-3 times at room temperature under a pressure value of 100-400MPa and an inlet temperature of 35-55 DEG C; and step 3, after a citric acid solution or a tartaric acid solution is added, performing secondary ultrahigh-pressure treatment at a room temperature under a pressure value of 150-600 MPa for a pressure maintaining time of 10-30 min. According to the invention, the activity of PPO in the juice can be effectivelypassivated, the sPPO activity inhibition rate is 98%, and the mPPO activity inhibition rate is 95%. Compared with traditional heat treatment, the method not only has a good passivation effect and maintains the flavor of the fruit juice, but also facilitates the improvement of the sensory quality of the fruit juice by an ultrahigh-pressure homogenization technology.