Preparation process of Dornfelder sparkling grape juice

Abstract

The present invention relates to a preparation process of a novel Dänfelser sparkling grape juice, belonging to the technical field of grape juice preparation. Select fully ripe Dänfelser grape fruits with bright color, no rot and no pesticide residues, wash them clean in clear water, remove the fruit stalks after drying; freeze the grapes at low temperature and then crush them, and use a press to press the pulp after low-temperature impregnation to make all the juice flow out; first filter the squeezed juice through a filter screen, then fill it into a disinfected and sterilized container, add a clarifying agent, and clarify it naturally at low temperature; take the upper clarified liquid and perform fine filtration through a modified microfiltration membrane; adjust the sugar-acid ratio of the grape juice and then perform homogenization treatment, and then quickly cool it after ultra-high temperature instantaneous sterilization; cool the sterilized grape juice and add it to a soda mixer, fill it with carbon dioxide, and then pour it into a disinfected glass bottle and seal it for packaging; the novel Dänfelser sparkling grape juice prepared by the present invention contains a high content of procyanidins.

Description

Technical Field

[0001] The present invention relates to the technical field of grape juice preparation, and in particular to a preparation process of Dornfelder sparkling grape juice. Background Art

[0002] Dornfelder sparkling grape juice is a drink rich in carbon dioxide bubbles made from Dornfelder grapes. Dornfelder grapes are a popular red grape variety in Germany, which was hybridized and cultivated in 1956. It has dark-colored skin, rich phenolic substances, high sugar content, and the wine brewed from it has a deep color, appropriate acidity, and fruit aromas such as plum, cherry, blackberry, and floral aroma, and sometimes the coolness of mint can also be felt.

[0003] The Chinese patent application with the publication number CN110403109A discloses a preparation method of sparkling grape juice. The main differences compared with the traditional preparation method are as follows: First, freezing and macerating the grapes is beneficial to extracting various nutrients in the grapes; second, adding spirulina can significantly improve the nutritional value of the grape juice; third, low-temperature maceration is used for the grape juice, ultraviolet sterilization is used for disinfection, and the carbonation step is also processed at low temperature, which can reduce the damage to aromatic substances during the preparation process and enhance the fragrance of the grape juice.

[0004] The Chinese patent application with the publication number CN1033236A discloses a process method for producing grape juice. The picked grapes are subjected to removing impurities, washing, crushing and de-stemming, pulping, coloring, centrifugal separation with enzyme precipitation, degumming, de-calcium, fine filtration, sterilization, and finally filling to make the finished product.

[0005] The Chinese patent application with the publication number CN105838532A discloses a processing technology of grape juice wine beverage, belonging to the technical field of grape wine making, including raw material selection, preparation of grape liqueur, preparation of grape juice, adding fruit juice and proportionally blending the grape juice wine beverage.

[0006] The content of proanthocyanidins in the grape juice prepared by the above patents and the prior art is relatively low. Summary of the Invention

[0007] In order to solve the above problems, the present invention provides a preparation process of Dornfelder sparkling grape juice, including the following steps:

[0008] S1 Raw Material Selection:

[0009] Select fully mature, brightly colored Dornfelder grape fruits without rot and pesticide residues;

[0010] S2 Rinsing and De-stemming:

[0011] Rinsing: Rinse the selected grapes clean in clean water to remove the soil, impurities and residual pesticides on the surface;

[0012] Stem removal: Remove the fruit stems after air-drying;

[0013] S3 Crushing and pressing:

[0014] Freezing impregnation: Freeze the grapes at -25~-30°C and then crush them. Use ice crystals to destroy the cell structure and conduct low-temperature impregnation treatment;

[0015] Pressing: Press the impregnated pulp 3 - 8 times with a press to make all the juice flow out;

[0016] S4 Filtration and clarification:

[0017] Coarse filtration: First filter the squeezed juice through a filter screen to remove impurities such as peels, seeds, and pulp pieces in the juice;

[0018] Clarification: Pour the coarsely filtered juice into a sterilized container, add 1 - 5% of the clarifying agent based on the mass of the juice to help the fine particles in the juice precipitate; then let the juice stand at low temperature for a period of time to make the juice clarify naturally;

[0019] Fine filtration: Take the upper clarified liquid and further remove impurities in the juice through a modified microfiltration membrane, and filter to obtain clear and transparent grape juice;

[0020] S5 Adjusting the sugar-acid ratio:

[0021] Adjust the sugar-acid ratio to (13 - 15):1 to make the taste of the juice more balanced and palatable;

[0022] S6 Homogenization and sterilization:

[0023] Homogenization: Homogenize the juice with the adjusted sugar-acid ratio;

[0024] Sterilization: Adopt ultra-high temperature instantaneous sterilization method, and then quickly cool to 30 - 40°C within 10 - 20 s;

[0025] S7 Low-temperature carbonation:

[0026] Cool the sterilized grape juice to 0 - 5°C, then add it to a soda mixer and charge it with carbon dioxide to form uniform and fine bubbles in a saturated state;

[0027] S8 Bottling and packaging:

[0028] Pour the carbonated Dornfelder bubble grape juice into sterilized glass bottles and seal and package; The packaged product is stored and transported at a low temperature of 2 - 6°C;

[0029] The modified microfiltration membrane is prepared by reacting a microfiltration membrane, rapeseed polyphenols, and cysteine to obtain a polyphenol microfiltration membrane and then performing plasma treatment.

[0030] Further, the temperature of the low-temperature impregnation is 1-3°C, and the time is 12-24 hours.

[0031] Further, the clarifying agent is gelatin or pectinase.

[0032] Further, the low-temperature standing time is 24-48h.

[0033] Further, the temperature of the ultra-high temperature instantaneous sterilization method is 130-140°C, and the time is 3-5s.

[0034] Further, the carbon dioxide filling amount is 2-2.5 times the volume of the grape juice.

[0035] Further, the specific preparation method of the modified microfiltration membrane is as follows:

[0036] A1 Preparation of polyphenol microfiltration membrane:

[0037] By weight, add 100-140 parts of microfiltration membrane, 5-10 parts of rapeseed polyphenols, 2-5 parts of cysteine, and 2-4 parts of sodium bicarbonate to 1000-1200 parts of water, stir at 65-75°C for 100-150 minutes, take out and dry to obtain the polyphenol microfiltration membrane;

[0038] A2 Plasma treatment:

[0039] Place the polyphenol microfiltration membrane obtained in step A1 in a radio frequency plasma processor, using nitrogen as the plasma gas source; first evacuate the vacuum in the reaction chamber to 10-20 Pa, then let nitrogen flow into the reaction chamber at a flow rate of 30-50 sccm, after stabilizing for 5-10 minutes, adjust the power to 80-120 W and process for 5-15 minutes, during which control the pressure in the reaction chamber at 50-100 Pa; after the treatment, turn off the plasma generator and the nitrogen inlet valve, continue to evacuate for 5-10 minutes, and finally slowly introduce air to restore to normal pressure to obtain the modified microfiltration membrane.

[0040] Further, the microfiltration membrane is selected from one of CA microfiltration membranes 11104-013N, 11104-025N, 11106-013N, and 11106-025N.

[0041] Reaction mechanism:

[0042] Cysteine contains a mercapto group (-SH), and rapeseed polyphenols have an olefin group. Under the conditions of step A1, the mercapto hydrogen dissociates into a sulfur radical (-S·), which attacks the carbon-carbon double bond of rapeseed polyphenols, the π bond opens, the sulfur radical combines with one carbon atom, and the hydrogen atom combines with the other carbon atom, so that rapeseed polyphenols are grafted onto cysteine and finally grafted onto the surface of the microfiltration membrane. Sodium bicarbonate may adjust the pH to assist the reaction, and the microfiltration membrane serves as the reaction carrier.

[0043] The preparation process of a Dänfelser sparkling grape juice according to the present invention has the following remarkable effects compared with the prior art:

[0044] 1. The present invention adopts the freeze - maceration technique. By freezing the grapes at low temperature and then crushing them, the cell structure is damaged by ice crystals, and combined with low - temperature maceration, the release efficiency of polyphenolic substances and volatile aroma components in the peel can be significantly improved, enhancing the fruit aroma layer.

[0045] 2. The present invention adopts the ultra - high - temperature instantaneous sterilization technique, which can kill microorganisms while maximizing the retention of nutrients and flavors; by rapidly heating and cooling, the negative impacts of long - term high temperature on the color and taste of the fruit juice are avoided.

[0046] 3. The present invention adopts the low - temperature carbonation technique. Carbon dioxide is filled in a low - temperature environment, so that the fruit juice forms uniform and fine bubbles in a saturated state; by controlling the carbon dioxide filling amount, the aroma escape caused by high - temperature carbonation can be avoided, and the masking of the original flavor of the fruit juice by bubbles can be reduced.

[0047] 4. Pigment removal: The modified microfiltration membrane grafted with rapeseed polyphenols, with its phenolic hydroxyl and other active groups, adsorbs pigments (such as anthocyanins) in the grape juice through hydrogen bonds and π - π stacking to achieve removal, making the original juice clear and transparent.

[0048] 5. Other impurity interception: The microfiltration membrane screens by pore size, and the active groups of rapeseed polyphenols adsorb through hydrogen bonds, electrostatic interactions, etc., removing impurities such as particles, microorganisms, proteins, and polysaccharides, improving the purity and clarity of the original juice.

[0049] 6. Selective separation: The modified microfiltration membrane has different effects on impurities. Impurities with strong interactions (such as pigments, proteins, etc.) are more easily removed, and small - molecule active ingredients such as flavor substances and vitamins in the original juice are well retained, maintaining the flavor and nutrition of the original juice.

[0050] 7. The Dänfelser sparkling grape juice prepared by the present invention contains a relatively high content of proanthocyanidins, making the Dänfelser sparkling grape juice have certain antioxidant and anti - aging effects. Specific embodiments

[0051] To further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following is a detailed description in combination with examples and comparative examples:

[0052] 1. Proanthocyanidin content test: Determination is carried out by high - performance liquid chromatography.

[0053] 2. Total colony count test: The test is carried out with reference to the GBT4789.21 - 2003 food hygiene microbiological examination frozen printed matter, beverage inspection standard.

[0054] 3. Clarity Test: Randomly invite 50 people to rate the clarity of Dornfelder Sparkling Grape Juice, and take the average value of the ratings for statistics; the full score is 10 points.

[0055] Example 1: A preparation process of Dornfelder Sparkling Grape Juice, the operation steps are as follows:

[0056] S1 Raw Material Selection:

[0057] Select fully ripe, brightly colored Dornfelder grape fruits without rot and pesticide residues;

[0058] S2 Rinsing and Stem Removal:

[0059] Rinsing: Rinse the selected grapes thoroughly in clean water to remove the soil, impurities, and residual pesticides on the surface;

[0060] Stem Removal: Remove the stems after drying;

[0061] S3 Crushing and Pressing:

[0062] Freezing and Maceration: Freeze the grapes at -25°C and then crush them. Use ice crystals to destroy the cell structure and conduct low-temperature maceration treatment;

[0063] Pressing: Press the macerated pulp 3 times with a press to make all the juice flow out;

[0064] S4 Filtration and Clarification:

[0065] Coarse Filtration: First filter the squeezed juice through a filter screen to remove the peel, seeds, and pulp block impurities in the juice;

[0066] Clarification: Pour the coarsely filtered juice into a sterilized container, add 1% of the clarifying agent based on the mass of the juice to help the fine particles in the juice precipitate; then let the juice stand at low temperature for a period of time to make the juice naturally clarify;

[0067] Fine Filtration: Take the upper clarified liquid and further remove the impurities in the juice through a modified microfiltration membrane, and filter to obtain clear and transparent grape juice;

[0068] S5 Adjusting the Sugar-Acid Ratio:

[0069] Adjust the sugar-acid ratio to 13:1 to make the taste of the juice more balanced and palatable;

[0070] S6 Homogenization and Sterilization:

[0071] Homogenization: Homogenize the juice with the adjusted sugar-acid ratio;

[0072] Sterilization: Adopt ultra-high temperature instantaneous sterilization method, and then quickly cool to 30°C within 10 s;

[0073] S7 Low-Temperature Carbonation:

[0074] Cool the sterilized grape juice to 5°C, then add it to a soda mixer and charge it with carbon dioxide to form uniform and fine bubbles in a saturated state.

[0075] S8 Bottling and packaging:

[0076] Fill the carbon dioxide-charged Dornfelder sparkling grape juice into sterilized glass bottles and seal them; store and transport the packaged products at a low temperature of 6°C.

[0077] The temperature of the low-temperature maceration is 1°C and the time is 12 hours.

[0078] The clarifying agent is gelatin.

[0079] The low-temperature standing time is 24h.

[0080] The temperature of the ultra-high temperature instantaneous sterilization method is 130°C and the time is 3s.

[0081] The carbon dioxide filling amount is 2 times the volume of the grape juice.

[0082] The specific preparation method of the modified microfiltration membrane is as follows:

[0083] A1 Preparation of polyphenol microfiltration membrane:

[0084] Add 100g of microfiltration membrane, 5g of rapeseed polyphenols, 2g of cysteine, and 2g of sodium bicarbonate to 1000g of water, stir at 65°C for 100 minutes, take out and dry to obtain the polyphenol microfiltration membrane.

[0085] A2 Plasma treatment:

[0086] Place the polyphenol microfiltration membrane obtained in step A1 in a radio frequency plasma treatment instrument, using nitrogen as the plasma gas source; first evacuate the reaction chamber to a vacuum of 10Pa, then let nitrogen flow into the reaction chamber at a flow rate of 30sccm, after stabilizing for 5 minutes, adjust the power to 80W and treat for 5 minutes, controlling the pressure in the reaction chamber at 50Pa during this period; after the treatment, turn off the plasma generator and the nitrogen inlet valve, continue to evacuate for 5 minutes, and finally slowly introduce air to restore to atmospheric pressure to obtain the modified microfiltration membrane.

[0087] The microfiltration membrane is selected from CA microfiltration membrane 11104-013N.

[0088] Example 2: A preparation process of Dornfelder sparkling grape juice, the operation steps are as follows:

[0089] S1 Raw material selection:

[0090] Select fully ripe, brightly colored, non-rotten and pesticide-free Dornfelder grape fruits.

[0091] S2 Rinsing and Stem Removal:

[0092] Rinsing: Rinse the selected grapes thoroughly in clean water to remove the soil, impurities, and residual pesticides on the surface;

[0093] Stem Removal: Remove the stems after drying;

[0094] S3 Crushing and Pressing:

[0095] Freezing and Maceration: Freeze the grapes at -28°C and then crush them. Use the ice crystals to break the cell structure and conduct low-temperature maceration treatment;

[0096] Pressing: Press the macerated pulp 5 times using a press to make all the juice flow out;

[0097] S4 Filtration and Clarification:

[0098] Coarse Filtration: First filter the squeezed juice through a strainer to remove the peel, seeds, and pulp lumps in the juice;

[0099] Clarification: Pour the coarsely filtered juice into a sterilized container, add 3% of the clarifying agent based on the mass of the juice to help the fine particles in the juice precipitate; then let the juice stand at low temperature for a period of time to clarify naturally;

[0100] Fine Filtration: Take the upper clarified liquid and further remove the impurities in the juice through a modified microfiltration membrane, filter, and obtain clear and transparent grape juice;

[0101] S5 Adjusting the Sugar-Acid Ratio:

[0102] Adjust the sugar-acid ratio to 14:1 to make the taste of the juice more balanced and palatable;

[0103] S6 Homogenization and Sterilization:

[0104] Homogenization: Homogenize the juice with the adjusted sugar-acid ratio;

[0105] Sterilization: Adopt the ultra-high temperature instantaneous sterilization method and then quickly cool it to 35°C within 15 s;

[0106] S7 Low-Temperature Carbonation:

[0107] Cool the sterilized grape juice to 3°C, then add it to a soda mixer and charge it with carbon dioxide to form uniform and fine bubbles in a saturated state;

[0108] S8 Bottling and Packaging:

[0109] Pour the carbonated Dornfelder sparkling grape juice into sterilized glass bottles and seal and package; Store and transport the packaged products at a low temperature of 4°C.

[0110] The temperature of the low-temperature impregnation is 2°C and the time is 16 hours.

[0111] The fining agent is gelatin.

[0112] The time of low-temperature standing is 32 h.

[0113] The temperature of the ultra-high temperature instantaneous sterilization method is 135°C and the time is 4 s.

[0114] The carbon dioxide filling amount is 2.1 times the volume of the grape juice.

[0115] The specific preparation method of the modified microfiltration membrane is as follows:

[0116] A1 Preparation of polyphenol microfiltration membrane:

[0117] Add 110 g of microfiltration membrane, 6 g of rapeseed polyphenols, 3 g of cysteine, and 3 g of sodium bicarbonate to 1050 g of water, stir at 68°C for 110 minutes, take out and dry to obtain the polyphenol microfiltration membrane;

[0118] A2 Plasma treatment:

[0119] Place the polyphenol microfiltration membrane obtained in step A1 in a radio frequency plasma processor with nitrogen as the plasma gas source; first evacuate the reaction chamber to a vacuum of 13 Pa, then introduce nitrogen into the reaction chamber at a flow rate of 40 sccm. After stabilizing for 6 minutes, adjust the power to 90 W and treat for 8 minutes, while controlling the pressure in the reaction chamber at 60 Pa; after the treatment, turn off the plasma generator and the nitrogen inlet valve, continue to evacuate for 6 minutes, and finally slowly introduce air to restore to atmospheric pressure to obtain the modified microfiltration membrane.

[0120] The microfiltration membrane is selected from CA microfiltration membrane 11104-025N.

[0121] Example 3: A preparation process of Dornfelder sparkling grape juice, and its operation steps are as follows:

[0122] S1 Raw material selection:

[0123] Select fully ripe, brightly colored, non-rotten and pesticide-free Dornfelder grape fruits;

[0124] S2 Rinsing and stalk removal:

[0125] Rinsing: Rinse the selected grapes clean in clean water to remove the soil, impurities and residual pesticides on the surface;

[0126] Stalk removal: Remove the stalks after drying;

[0127] S3 Crushing and pressing:

[0128] Freezing impregnation: The grapes are quickly frozen at -29°C and then crushed. The cell structure is damaged by ice crystals for low-temperature impregnation treatment;

[0129] Pressing: The impregnated pulp is pressed 7 times using a press to make all the juice flow out;

[0130] S4 Filtration and clarification:

[0131] Coarse filtration: The squeezed juice is first filtered through a filter screen to remove impurities such as peels, seeds, and pulp chunks in the juice;

[0132] Clarification: The coarsely filtered juice is filled into a sterilized container, and a clarifying agent accounting for 4% of the juice quality is added to help the fine particles in the juice precipitate; then the juice is left to stand at low temperature for a period of time to clarify naturally;

[0133] Fine filtration: The upper clear liquid is taken and further filtered through a modified microfiltration membrane to remove impurities in the juice, and clarified and transparent grape juice is obtained;

[0134] S5 Adjusting the sugar-acid ratio:

[0135] The sugar-acid ratio is adjusted to 14:1 to make the taste of the juice more balanced and palatable;

[0136] S6 Homogenization and sterilization:

[0137] Homogenization: The juice with the adjusted sugar-acid ratio is subjected to homogenization treatment;

[0138] Sterilization: The ultra-high temperature instantaneous sterilization method is adopted, and then it is quickly cooled to 35°C within 15 s;

[0139] S7 Low-temperature carbonation:

[0140] The sterilized grape juice is cooled to 2°C, then added to a soda mixer and carbon dioxide is filled in to form uniform and fine bubbles in a saturated state;

[0141] S8 Bottling and packaging:

[0142] The Dornfelder sparkling grape juice filled with carbon dioxide is poured into a sterilized glass bottle and sealed; the packaged product is stored and transported at a low temperature of 3°C.

[0143] The temperature of the low-temperature impregnation is 2°C and the time is 20 hours.

[0144] The clarifying agent is pectinase.

[0145] The low-temperature standing time is 43 h.

[0146] The temperature of the ultra-high temperature instantaneous sterilization method is 135°C and the time is 4 s.

[0147] The carbon dioxide filling amount is 2.4 times the volume of the grape juice.

[0148] The specific preparation method of the modified microfiltration membrane is as follows:

[0149] A1 Preparation of polyphenol microfiltration membrane:

[0150] Add 130 g of microfiltration membrane, 8 g of rapeseed polyphenols, 4 g of cysteine, and 3 g of sodium bicarbonate to 1150 g of water, stir at 73 °C for 140 minutes, take out and dry to obtain the polyphenol microfiltration membrane;

[0151] A2 Plasma treatment:

[0152] Place the polyphenol microfiltration membrane obtained in step A1 in a radio frequency plasma processor, using nitrogen as the plasma gas source; first evacuate the reaction chamber to a vacuum of 18 Pa, then introduce nitrogen into the reaction chamber at a flow rate of 45 sccm, after stabilizing for 8 minutes, adjust the power to 110 W and treat for 13 minutes, while controlling the pressure in the reaction chamber at 90 Pa; after the treatment, turn off the plasma generator and the nitrogen inlet valve, continue to evacuate for 8 minutes, and finally slowly introduce air to restore to atmospheric pressure to obtain the modified microfiltration membrane.

[0153] The microfiltration membrane is selected from CA microfiltration membrane 11106-013N.

[0154] Example 4: A preparation process of Dornfelder sparkling grape juice, and its operation steps are as follows:

[0155] S1 Raw material selection:

[0156] Select fully ripe, brightly colored, non-rotten and pesticide-free Dornfelder grape fruits;

[0157] S2 Rinsing and stalk removal:

[0158] Rinsing: Rinse the selected grapes thoroughly in clean water to remove the soil, impurities and residual pesticides on the surface;

[0159] Stalk removal: Remove the stalks after drying;

[0160] S3 Crushing and pressing:

[0161] Freezing impregnation: Freeze and crush the grapes at -30 °C, use ice crystals to destroy the cell structure, and carry out low-temperature impregnation treatment;

[0162] Pressing: Press the impregnated pulp 8 times with a press to make all the juice flow out;

[0163] S4 Filtration and clarification:

[0164] Coarse filtration: The squeezed juice is first filtered through a strainer to remove impurities such as peel, seeds, and pulp pieces in the juice; Clarification: The coarsely filtered juice is filled into a sterilized container, and a clarifying agent accounting for 1 - 5% of the juice mass is added to help the fine particles in the juice precipitate; Then the juice is allowed to stand at a low temperature for a period of time to clarify naturally;

[0165] Fine filtration: Take the upper clarified liquid and further remove impurities in the juice through a modified microfiltration membrane, and filter to obtain clear and transparent grape juice;

[0166] S5 Adjust the sugar - acid ratio:

[0167] Adjust the sugar - acid ratio to 15:1 to make the taste of the juice more balanced and palatable;

[0168] S6 Homogenization and sterilization:

[0169] Homogenization: Homogenize the juice with the adjusted sugar - acid ratio;

[0170] Sterilization: Adopt ultra - high - temperature instantaneous sterilization method and then quickly cool to 35°C within 15 s;

[0171] S7 Low - temperature carbonation:

[0172] Cool the sterilized grape juice to 0°C, then add it to a soda mixer and fill it with carbon dioxide to form uniform and fine bubbles in a saturated state;

[0173] S8 Bottling and packaging:

[0174] Fill the carbonated Dornfelder grape juice into sterilized glass bottles and seal and package; The packaged products are stored and transported at a low temperature of 2°C.

[0175] The temperature of the low - temperature maceration is 3°C and the time is 24 hours.

[0176] The clarifying agent is pectinase.

[0177] The low - temperature standing time is 48 h.

[0178] The temperature of the ultra - high - temperature instantaneous sterilization method is 140°C and the time is 5 s.

[0179] The carbon dioxide filling amount is 2.5 times the volume of the grape juice.

[0180] The preparation method of the modified microfiltration membrane is as follows:

[0181] A1 Preparation of polyphenol microfiltration membrane:

[0182] Add 140 g of microfiltration membrane, 10 g of rapeseed polyphenols, 5 g of cysteine, and 4 g of sodium bicarbonate to 1200 g of water, stir at 75 °C for 150 minutes, take out and dry to obtain a polyphenol microfiltration membrane;

[0183] A2 plasma treatment:

[0184] Place the polyphenol microfiltration membrane obtained in step A1 in a radio frequency plasma processor, using nitrogen as the plasma gas source; first evacuate the vacuum in the reaction chamber to 20 Pa, then let nitrogen flow into the reaction chamber at a flow rate of 50 sccm. After stabilizing for 10 minutes, adjust the power to 120 W and treat for 15 minutes, while controlling the pressure in the reaction chamber at 100 Pa; after the treatment, turn off the plasma generator and the nitrogen inlet valve, continue to evacuate for 10 minutes, and finally slowly introduce air to restore to normal pressure to obtain a modified microfiltration membrane.

[0185] The microfiltration membrane described above is selected from CA microfiltration membrane 11106 - 025N.

[0186] Comparative example 1: Do not modify the microfiltration membrane, and the others are the same as in Example 1.

[0187] Comparative example 2: Do not add rapeseed polyphenols, and the others are the same as in Example 1.

[0188] Comparative example 3: Do not add cysteine, and the others are the same as in Example 1.

[0189] Table 1: Detection results of each example and comparative example

[0190] Through the data analysis of the above examples and comparative examples, the Dänfelser sparkling grape juice prepared by the present invention contains a relatively high content of proanthocyanidins, making the Dänfelser sparkling grape juice have certain antioxidant and anti - aging effects.

[0191] The above - mentioned are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art, without departing from the scope of the technical solution of the present invention, can make some changes or modifications to the above - disclosed technical content to obtain equivalent embodiments with equivalent changes. However, as long as it does not depart from the content of the technical solution of the present invention, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A process for preparing Dornfelter sparkling grape juice, characterized in that: The following steps are involved: S1 Raw material selection: Choose fully ripe, brightly colored, free of rot and pesticide residues. S2 flushing and stem removal: Rinse: Rinse the selected grapes in clean water to remove dirt, impurities and residual pesticides on the surface; Destemming: Remove the fruit stems after drying; S3 Crushing and Pressing: Freeze immersion: The grapes are quickly frozen at -25~-30℃ and then crushed, using ice crystals to destroy the cell structure and perform low-temperature immersion treatment; Squeezing: Use a squeezer to squeeze the soaked pulp 3-8 times to make all the juice flow out; S4 Filtration Clarification: Coarse filtration: The squeezed juice is first filtered through a strainer to remove impurities such as peel, seeds and pulp from the juice; Clarification: put the coarsely filtered juice into a sterilized container and add 1-5% of the juice mass of a clarifier to help the fine particles in the juice settle; Then let the juice stand at low temperature for a while to make the juice clarify naturally; Fine filtration: Take the upper clarified liquid, pass it through a modified microfiltration membrane to further remove impurities in the juice, and filter it to obtain clear and transparent juice; S5 adjusts the sugar-acid ratio: Adjust the sugar-acid ratio to (13-15):1 to make the taste of the juice more balanced and palatable; S6 homogenization sterilization: Homogenization: homogenize the juice with adjusted sugar-acid ratio; Sterilization: Use ultra-high temperature instantaneous sterilization method, and then quickly cool to 30-40℃ within 10-20s; S7 Low Temperature Carbonation: Cool the sterilized juice to 0-5℃, then add it to the soda mixer and inject carbon dioxide into it to form uniform and fine bubbles in the juice under saturated state; S8 bottling packaging: The Danfit sparkling juice filled with carbon dioxide is poured into sterilized glass bottles and sealed; the packaged products are stored and transported at a low temperature of 2-6°C; The modified microfiltration membrane is prepared by reacting a microfiltration membrane, rapeseed polyphenols and cysteine ​​to prepare a polyphenol microfiltration membrane, and then subjecting the membrane to plasma treatment; The specific preparation method of the modified microfiltration membrane is: A1 Preparation of polyphenol microfiltration membrane: According to weight, 100-140 parts of microfiltration membrane, 5-10 parts of rapeseed polyphenol, 2-5 parts of cysteine, and 2-4 parts of sodium bicarbonate are added to 1000-1200 parts of water, stirred at 65-75° C. for 100-150 minutes, taken out and dried to obtain a polyphenol microfiltration membrane; A2 Plasma Treatment: The polyphenol microfiltration membrane obtained in step A1 is placed in a radio frequency plasma treatment instrument, and nitrogen is used as a plasma gas source; first, the vacuum degree in the reaction chamber is evacuated to 10-20Pa, and then nitrogen is introduced into the reaction chamber at a flow rate of 30-50sccm. After stabilization for 5-10 minutes, the power is adjusted to 80-120W for 5-15 minutes, during which the pressure in the reaction chamber is controlled at 50-100Pa; after the treatment, the plasma generator and the nitrogen inlet valve are closed, and the vacuum is continued for 5-10 minutes, and finally air is slowly introduced to restore the pressure to normal pressure to obtain a modified microfiltration membrane.

2. The process for preparing Dornfelde sparkling grape juice according to claim 1, characterized in that: The temperature of the low-temperature immersion is 1-3°C and the time is 12-24 hours.

3. The process for preparing Dornfelde sparkling grape juice according to claim 1, characterized in that: The clarifier is gelatin or pectinase.

4. The process for preparing Dornfelde sparkling grape juice according to claim 1, characterized in that: The low-temperature standing time is 24-48h.

5. The process for preparing Dornfelde sparkling grape juice according to claim 1, characterized in that: The ultra-high temperature instantaneous sterilization method has a temperature of 130-140° C. and a time of 3-5 seconds.

6. The process for preparing Dornfelde sparkling grape juice according to claim 1, characterized in that: The carbon dioxide filling amount is 2-2.5 times the volume of the grape juice.

7. The process for preparing Dornfelde sparkling grape juice according to claim 1, characterized in that: The microfiltration membrane is selected from one of CA microfiltration membranes 11104-013N, 11104-025N, 11106-013N, and 11106-025N.