Chinese wolfberry fruit primary pulp as well as preparation method and application thereof

Abstract

The invention discloses Chinese wolfberry primary pulp as well as a preparation method and application thereof, and belongs to the technical field of preparation of berry primary pulp. The preparation method is used for solving the technical problem that in the prior art, the content of nutrient substances in the Chinese wolfberry primary pulp needs to be improved. The preparation method of the Chinese wolfberry primary pulp comprises the steps of picking and acceptance inspection, winnowing and lifting, manual sorting, four-stage cleaning and sterilization, vibration draining and blow-drying, crushing, double-pass pulping, colloid milling, high-pressure homogenization, concentration, vacuum degassing, UHT sterilization, sterile filling, detection and warehousing and ex-warehousing. The Chinese wolfberry primary pulp prepared by the preparation method disclosed by the invention not only has rich nutrient substances, but also has better oxidation resistance compared with the Chinese wolfberry primary pulp prepared by a traditional preparation method.

Description

Technical Field

[0001] The invention relates to the technical field of berry puree preparation, and in particular to wolfberry puree and a preparation method and application thereof. Background Art

[0002] Lycium barbarum is the mature fruit of the small shrub Lycium barbarum of the Solanaceae family, also known as wolfberry. Lycium barbarum is rich in protein, Lycium barbarum polysaccharides, amino acids, betaine and flavonoid nutrients and bioactive substances, with special quality characteristics and pharmacological effects. As a traditional Chinese medicinal material, it is also an important food ingredient that is both medicinal and edible. It is worth noting that Lycium barbarum has the effects of inhibiting tumor growth and cell mutation, immune regulation, anti-aging, anti-fatigue, regulating blood lipids, lowering blood sugar and improving vision. Among them, Lycium barbarum polysaccharides contribute the most to the various pharmacological activities of Lycium barbarum, which can significantly improve liver damage and improve the antioxidant function of the liver. Because Lycium barbarum has irregular inflorescences, the fruits are harvested in batches, and fresh Lycium barbarum has a high water content, and the epidermis is easily damaged and infected, resulting in losses. Eating fresh Lycium barbarum directly can maximize its nutritional value, but the shelf life is short. In view of this, people process wolfberries to obtain wolfberry products, especially wolfberry dried fruit, which retains the nutritional value and function of fresh wolfberries. People stew, soak and boil wolfberry dried fruit, but the absorption rate is not high. The surface of wolfberries is covered with a waxy layer, which reduces the precipitation of active substances in wolfberries.

[0003] As people pay more attention to food safety, they hope to obtain wolfberry products that are easier for the human body to absorb and rich in nutrients without adding any preservatives. Common beverage products include wolfberry puree, wolfberry fermented beverages and wolfberry wine. Among them, wolfberry puree is fresh wolfberry juice obtained by screening, cleaning, crushing, beating, filtering and grinding. High-quality wolfberry puree usually has a red color and no odor. It can better retain the nutritional components of wolfberry and is convenient to carry and eat.

[0004] Chinese patent CN110074296A discloses a method for preparing black wolfberry pulp, comprising the steps of washing, cleaning, sorting and removing impurities from ripe black wolfberry fruits, squeezing juice or beating the pulp to obtain black wolfberry pulp with juice; grinding the black wolfberry pulp with a colloid mill to obtain a colloidal juice; subjecting the colloidal juice to low-temperature centrifugal separation or low-temperature standing, and filtering to obtain a pulp; homogenizing the pulp, and then filling and sterilizing to obtain black wolfberry pulp; the black wolfberry pulp prepared by the patent has stable color, is natural and healthy, and is nutritious and palatable, but the nutrient content of the black wolfberry pulp prepared by the patent needs to be further improved. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a wolfberry puree and a preparation method and application thereof, which solves the problem that the nutrient content of wolfberry puree in the prior art needs to be improved. The wolfberry puree prepared by the present invention has better antioxidant properties than the wolfberry puree prepared by the traditional preparation method.

[0006] In order to achieve the above object, the present invention provides a method for preparing wolfberry puree, comprising the following steps:

[0007] S1. Picking, acceptance, winnowing and manual sorting: Take wolfberries that have been picked within 8 days, inspect the intact wolfberries, send them to the winnowing machine for cleaning, and manually sort out the broken wolfberries;

[0008] S2, four-level cleaning and sterilization: including primary cleaning, secondary cleaning, tertiary cleaning and quaternary sterilization;

[0009] S3, vibration draining, drying, crushing and double-channel beating: adding the wolfberry fruit particles obtained in S2 into a vibration drainer for vibration draining and drying; sending them into a crusher for crushing; transferring them into a double-channel beating machine for beating to obtain a wolfberry slurry;

[0010] S4, colloid mill: the wolfberry slurry is ground by a colloid mill to obtain a colloid juice;

[0011] S5, high-pressure homogenization, concentration and vacuum degassing: the colloidal juice obtained in S4 is added to a high-pressure homogenizer, a color preservative is added, and homogenization is performed under a nitrogen atmosphere; the juice is then put into a low-temperature concentration device for concentration, and a degasser is used for degassing to obtain primary wolfberry puree;

[0012] S6, UHT sterilization;

[0013] S7, aseptic filling, testing, storage and delivery: the sterilized primary wolfberry puree will be transported to the aseptic filling machine through the pipeline, the filling head chamber will maintain a temperature of ≥98℃ to achieve aseptic conditions, and the pulp will be filled into a sterile bag to obtain wolfberry puree; the filling weight is controlled by a mass flow meter; the filling outlet temperature: <35℃; the sealing is tested to be complete, storage registration, and delivery records;

[0014] Wherein, the preparation of the ultrafiltration membrane in the low temperature concentration device includes the following steps;

[0015] The nano-additive and PES are added to N,N-dimethylacetamide, heated, stirred, ultrasonicated, and allowed to stand until bubbles are completely eliminated to obtain a uniform casting solution; the casting solution is poured onto a smooth and clean glass, and the film is scraped with a film scraper, and the scraped film is allowed to stand at room temperature for a period of time, and then immersed in a water bath together with the glass plate for phase inversion, and after the film falls off the glass plate, it is washed with deionized water and dried to obtain an ultrafiltration membrane;

[0016] Wherein, the preparation of the nano additive comprises the following steps:

[0017] Step (1) adding carboxymethyl chitosan and citric acid to acetone, heating, reacting, and after the reaction is completed, distilling under reduced pressure, washing, and drying to obtain modified carboxymethyl chitosan;

[0018] Step (2) under nitrogen atmosphere, adding cellulose nanocrystals to the vitamin C aqueous solution, heating for the first time, stirring for reaction, and completing the reaction; adding modified carboxymethyl chitosan aqueous solution, heating for the second time, stirring for reaction, and completing the reaction, washing with deionized water until neutral, and drying to obtain the nano additive.

[0019] Preferably, primary cleaning: soak the wolfberry berries in distilled water at room temperature for 5-10 minutes.

[0020] Preferably, the secondary cleaning is: placing the wolfberry fruit particles into an ultrasonic cleaning machine, and cleaning them at room temperature and a frequency of 20-40kHz for 10-18 minutes.

[0021] Preferably, the third-stage cleaning is as follows: the wolfberry fruit particles are soaked in a chlorhexidine aqueous solution with a mass concentration of 1-3% for 10-14 minutes at room temperature.

[0022] Preferably, the fourth-level sterilization is as follows: the wolfberry fruit particles after the third-level washing are soaked in a sodium hypochlorite aqueous solution with a mass concentration of 0.1-0.5% for 12-16 minutes.

[0023] Preferably, in the vibrating drainer, the vibration frequency is 20-60kHz, the amplitude is 2-5mm, and the vibration time is 6-10min.

[0024] Preferably, the drying conditions are: drying at 40-60° C. and a speed of 1-2 m / s for 80-120 min.

[0025] Preferably, the rotation speed in the crusher is 1500-3500r / min, and the crushing time is 2-6min.

[0026] Preferably, the first screen in the double-pass pulping machine is 1-1.8 mm, and the second screen is 0.3-0.8 mm.

[0027] Preferably, the rotation speed of the double-pass beater is 1500-3500 r / min, and the beating time is 6-10 min.

[0028] Preferably, the material used for the fourth-level sterilization is a sodium hypochlorite aqueous solution; wherein the mass concentration of the sodium hypochlorite aqueous solution is 0.1-0.5%.

[0029] Preferably, the color protecting agent is any one or both of tea polyphenols and ascorbic acid.

[0030] Preferably, the pressure in the high-pressure homogenization is 40-60 MPa, and the processing time is 80-100 min.

[0031] Preferably, the grinding speed of the colloid mill is 12000-24000 r / min, and the grinding time is 40-60 min.

[0032] Preferably, the mass ratio of the colloidal juice to the color preservative is (99.5-99.9):(0.1-0.5).

[0033] Preferably, the low temperature concentration temperature is 50-60°C and the time is 30-60 min.

[0034] Preferably, the vacuum degree in the degasser is 0.08-0.1 MPa, the temperature is 60-75° C., and the degassing time is 10-20 min.

[0035] Preferably, UHT sterilization is carried out at 140-150°C for 2-6 seconds.

[0036] Preferably, the mass ratio of the nano-additive, PES and N,N-dimethylacetamide is (4-10):(14-28):(100-160); the heating temperature is 50-60° C., and the stirring time is 10-14 h.

[0037] Preferably, the mass ratio of carboxymethyl chitosan, citric acid and acetone is 100:(50-90):(300-500); the heating temperature is 60-80° C., and the reaction time is 8-10 h.

[0038] Preferably, the mass ratio of cellulose nanocrystals, vitamin C aqueous solution and modified carboxymethyl chitosan aqueous solution is (20-40):(600-1200):(1000-1800); wherein the mass concentration of the vitamin C aqueous solution is 10%; the concentration of the modified carboxymethyl chitosan aqueous solution is 3 mol / L;

[0039] The first heating temperature is 75-85°C, the stirring rate is 120-200 r / min, and the reaction time is 3-5 h; the second heating temperature is 75-85°C, the stirring rate is 120-200 r / min, and the reaction time is 3-5 h.

[0040] Preferably, the wolfberry puree is prepared by the method for preparing wolfberry puree.

[0041] Preferably, the wolfberry puree is used to improve antioxidant properties.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] 1. The present invention provides a newly prepared wolfberry puree with high nutritional value and good antioxidant properties; the four-stage sterilization step effectively kills microorganisms, prolongs the shelf life of the product, improves the safety of the product, ensures the preservation of the nutritional components of wolfberry, and is beneficial to human absorption; no preservatives are added to ensure food safety, and the addition of tea polyphenols increases antioxidant properties and inhibits browning.

[0044] 2. The preparation method of wolfberry puree provided by the present invention, through picking and acceptance, wind selection and lifting, manual selection, four-level cleaning and sterilization, vibration drainage and air drying, crushing, double-channel pulping, colloid mill, high-pressure homogenization, concentration, vacuum degassing, UHT sterilization, aseptic filling, testing, warehousing and outbound delivery, can obtain wolfberry puree in a uniform semi-fluid state, without foreign matter, good fluidity, uniform and delicate texture, showing a jujube red color, and having the taste and fragrance of mature wolfberry, without unpleasant odor caused by fermentation or other reasons, and without adding additives such as flavors, pigments and preservatives, to ensure food safety.

[0045] 3. The preparation method of wolfberry puree provided by the present invention reduces the bacteria on the surface of wolfberry after four-stage cleaning and sterilization, and effectively extracts the nutrients and juice of wolfberry through double-pass pulping after crushing, thereby improving the juice yield and the nutritional value of the product. The colloid mill can further effectively extract the nutrients of wolfberry. The high-pressure homogenization, concentration and vacuum degassing operations can make the wolfberry puree fine in texture and stable in properties. Tea polyphenols, as a natural antioxidant, are not only beneficial to the human body, but also further inhibit the browning of wolfberry puree, thereby ensuring the color appearance of the wolfberry puree.

[0046] 4. The preparation method of wolfberry puree provided by the present invention strictly controls the temperature below 100°C during operations such as crushing, double-pass beating, colloid mill, high-pressure homogenization, concentration, and vacuum degassing, so as to maintain the nutrition and flavor of wolfberry puree as much as possible; at the same time, the concentration adopts the method of low-temperature concentration, which reduces the impact on the heat-sensitive substances in the wolfberry components. And the sterilization effect of the present invention is relatively high, avoiding the loss of effective ingredients and nutrients, and can better maintain the natural flavor of the puree, while reducing the harm of chemical reagents to the human body. The ultrafiltration membrane used in the present invention does not destroy the components in the feed liquid, does not require heating, and has low energy consumption cost; it does not need to add other reagents, so it will not cause secondary pollution. The entire filtration process is relatively energy-saving and environmentally friendly, with a strong ability to intercept nutrients and excellent concentration effect. DETAILED DESCRIPTION

[0047] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0048] Example 1

[0049] This embodiment provides a method for preparing wolfberry puree, comprising the following steps:

[0050] S1. Picking, acceptance, winnowing and manual sorting: Take wolfberries that have been picked within 8 days, inspect the intact wolfberry berries, send them to the winnowing machine, and select them for 6 minutes at 0.1MPa, wind speed 8m / s, and sieve size 3mm. Manually select and remove the broken wolfberry berries;

[0051] S2, four-level cleaning and sterilization: including primary cleaning, secondary cleaning, tertiary cleaning and quaternary sterilization;

[0052] Among them, the first-level cleaning: soak the wolfberry berries in distilled water for 5 minutes at room temperature;

[0053] Among them, the second level cleaning: put the wolfberry fruit into an ultrasonic cleaning machine and clean it for 18 minutes at room temperature and 20kHz frequency;

[0054] Among them, the third-level cleaning: at room temperature, the wolfberry fruit particles are soaked in a 1wt% chlorhexidine aqueous solution for 14 minutes;

[0055] The fourth-level sterilization is as follows: the wolfberry fruit particles after the third-level washing are soaked in a 0.1wt% sodium hypochlorite aqueous solution for 16 minutes;

[0056] S3, vibration draining, drying, crushing and double-pass beating: add the wolfberry fruit particles obtained in S2 into a vibration drainer, vibrate and drain for 10 minutes at a vibration frequency of 20kHz and an amplitude of 2mm; blow dry for 120 minutes at 40°C and a speed of 1m / s; send to a crusher and crush at a speed of 1500r / min for 6 minutes; transfer to a double-pass beating machine and beat at a speed of 1500r / min for 10 minutes, filter through a first sieve of 1mm and a second sieve of 0.8mm to obtain a wolfberry slurry;

[0057] S4, colloid mill: the wolfberry slurry is ground in a colloid mill at a speed of 12000 r / min for 60 min to obtain a colloid juice;

[0058] S5, high-pressure homogenization, concentration and vacuum degassing: add the colloidal juice obtained in S4 into a high-pressure homogenizer, add tea polyphenols, and homogenize for 100 minutes at room temperature and 40MPa under a nitrogen atmosphere; enter the low-temperature concentration equipment, concentrate at 50°C for 60 minutes, and concentrate to 2MPa﹒s; degas in a degasser at a vacuum degree of 0.08Mpa and a temperature of 60°C for 20 minutes to obtain primary wolfberry puree;

[0059] Among them, the mass ratio of colloidal juice to tea polyphenols is 99.5:0.1;

[0060] S6, UHT sterilization: at 140°C, maintain for 6 seconds;

[0061] S7, aseptic filling, testing, storage and delivery: the sterilized primary wolfberry puree will be transported to the aseptic filling machine through the pipeline, the filling head chamber temperature is maintained at ≥98℃ to achieve aseptic conditions, the pulp is filled into a sterile bag to obtain wolfberry puree; the filling weight is controlled by a mass flow meter; the filling outlet temperature: <35℃; the seal is tested to be complete, the leakage rate is <0.05%, storage registration, and delivery record;

[0062] Wherein, the preparation of the ultrafiltration membrane in the low temperature concentration device includes the following steps;

[0063] The nano-additive, PES and N,N-dimethylacetamide were mixed in a mass ratio of 4:14:100, stirred at 50°C and a speed of 100 r / min for 14 hours, ultrasonicated at a frequency of 20 kHz for 20 minutes, and allowed to stand for complete elimination of bubbles to obtain a uniform casting solution; the casting solution was poured onto a smooth and clean glass, and the film was scraped with a film scraper. After the scraped film was allowed to stand at room temperature for 10 seconds, it was immersed in a 40°C water bath together with the glass plate for 20 minutes for phase inversion. After the membrane fell off the glass plate, it was washed with deionized water for 3 times, and dried at 50°C for 10 hours to obtain an ultrafiltration membrane with a thickness of 100 mm and a pore size of 30 nm;

[0064] Wherein, the preparation of the nano additive comprises the following steps:

[0065] Step (1) carboxymethyl chitosan, citric acid and acetone are mixed in a mass ratio of 100:50:300, reacted at 60° C. for 10 h, and after the reaction is completed, vacuum distilled at 0.08 MPa and 50° C. for 6 h, washed with deionized water for 3 times, and dried at 70° C. for 5 h to obtain modified carboxymethyl chitosan;

[0066] Step (2) under nitrogen atmosphere, adding cellulose nanocrystals to a 10 wt % vitamin C aqueous solution, reacting at 75° C. and a rotation speed of 120 r / min for 5 h, and completing the reaction; adding a 3 mol / L modified carboxymethyl chitosan aqueous solution, reacting at 75° C. and a rotation speed of 120 r / min for 5 h, and completing the reaction, washing with deionized water until neutral, and drying at 90° C. for 8 h to obtain a nano additive;

[0067] Wherein, the mass ratio of cellulose nanocrystals, vitamin C aqueous solution and modified carboxymethyl chitosan aqueous solution is 20:600:1000.

[0068] Example 2

[0069] This embodiment provides a method for preparing wolfberry puree, comprising the following steps:

[0070] S1. Picking, acceptance, winnowing and manual sorting: Take wolfberries that have been picked within 8 days, inspect the intact wolfberry berries, send them to the winnowing machine, and select them for 5 minutes at 0.3MPa, wind speed 9m / s, and 3mm screen. Manually select and remove the broken wolfberry berries;

[0071] S2, four-level cleaning and sterilization: including primary cleaning, secondary cleaning, tertiary cleaning and quaternary sterilization;

[0072] Among them, the first-level cleaning: soak the wolfberry berries in distilled water for 6 minutes at room temperature;

[0073] Among them, the second level cleaning: put the wolfberry fruit into an ultrasonic cleaning machine and clean it for 16 minutes at room temperature and 25kHz frequency;

[0074] Among them, the third-level cleaning: at room temperature, the wolfberry fruit particles are soaked in a 1.5wt% chlorhexidine aqueous solution for 13 minutes;

[0075] The fourth-level sterilization is as follows: the wolfberry fruit particles after the third-level washing are soaked in a 0.2wt% sodium hypochlorite aqueous solution for 15 minutes;

[0076] S3, vibration draining, drying, crushing and double-pass beating: add the wolfberry fruit particles obtained in S2 into a vibration drainer, vibrate and drain for 9 minutes at a vibration frequency of 30kHz and an amplitude of 3mm; blow dry for 110 minutes at 45°C and a speed of 1.2m / s; send to a crusher and crush for 5 minutes at a speed of 2000r / min; transfer to a double-pass beating machine and beat for 9 minutes at a speed of 2000r / min, filter through a first sieve of 1.2mm and a second sieve of 0.4mm to obtain a wolfberry slurry;

[0077] S4, colloid mill: the wolfberry slurry is ground in a colloid mill at a speed of 15000 r / min for 55 min to obtain a colloid juice;

[0078] S5, high-pressure homogenization, concentration and vacuum degassing: add the colloidal juice obtained in S4 into a high-pressure homogenizer, add tea polyphenols, and homogenize for 95 minutes at room temperature and 45MPa under a nitrogen atmosphere; enter the low-temperature concentration equipment, concentrate at 52°C for 53 minutes, and concentrate to 2.5MPa﹒s; degas for 18 minutes in a degasser with a vacuum degree of 0.08Mpa and a temperature of 63°C to obtain primary wolfberry puree;

[0079] Among them, the mass ratio of colloidal juice to tea polyphenols is 99.6:0.2;

[0080] S6, UHT sterilization: at 142°C, maintain for 5 seconds;

[0081] S7, aseptic filling, testing, storage and delivery: the sterilized primary wolfberry puree will be transported to the aseptic filling machine through the pipeline, the filling head chamber temperature is maintained at ≥98℃ to achieve aseptic conditions, the pulp is filled into a sterile bag to obtain wolfberry puree; the filling weight is controlled by a mass flow meter; the filling outlet temperature: <35℃; the seal is tested to be complete, the leakage rate is <0.05%, storage registration, and delivery record;

[0082] Wherein, the preparation of the ultrafiltration membrane in the low temperature concentration device includes the following steps;

[0083] The nano-additive, PES and N,N-dimethylacetamide were mixed in a mass ratio of 5.5:17.5:115, stirred at 52°C and 120r / min for 13h, ultrasonicated at a frequency of 25kHz for 18min, and allowed to stand for complete elimination of bubbles to obtain a uniform casting solution; the casting solution was poured onto a smooth and clean glass, and the film was scraped with a scraper, and the scraped film was allowed to stand at room temperature for 12s and then immersed in a 42°C water bath together with the glass plate for 18min for phase inversion, and after the membrane fell off the glass plate, it was washed with deionized water for 3 times and dried at 55°C for 9.5h to obtain an ultrafiltration membrane with a thickness of 100mm and a pore size of 30nm;

[0084] Wherein, the preparation of the nano additive comprises the following steps:

[0085] Step (1) carboxymethyl chitosan, citric acid and acetone are mixed in a mass ratio of 100:60:350, reacted at 65° C. for 9.5 hours, and after the reaction is completed, vacuum distilled at 0.08 MPa and 52° C. for 5.5 hours, washed with deionized water for 3 times, and dried at 72° C. for 4.5 hours to obtain modified carboxymethyl chitosan;

[0086] Step (2) under nitrogen atmosphere, adding cellulose nanocrystals to 10 wt % vitamin C aqueous solution, reacting at 77° C. and 140 r / min for 4.5 h, and completing the reaction; adding 3 mol / L modified carboxymethyl chitosan aqueous solution, reacting at 77° C. and 140 r / min for 4.5 h, and completing the reaction, washing with deionized water until neutral, and drying at 92° C. for 7.5 h to obtain a nano additive;

[0087] Among them, the mass ratio of cellulose nanocrystals, vitamin C aqueous solution and modified carboxymethyl chitosan aqueous solution is 25:750:1200.

[0088] Example 3

[0089] This embodiment provides a method for preparing wolfberry puree, comprising the following steps:

[0090] S1. Picking, acceptance, winnowing and manual sorting: Take wolfberries that have been picked within 8 days, inspect the intact wolfberry berries, send them to the winnowing machine, and select them for 4 minutes at 0.5MPa, wind speed 10m / s, and sieve size 3mm. Manually select and remove the broken wolfberry berries;

[0091] S2, four-level cleaning and sterilization: including primary cleaning, secondary cleaning, tertiary cleaning and quaternary sterilization;

[0092] Among them, the first-level cleaning: soak the wolfberry berries in distilled water at room temperature for 7 minutes;

[0093] Among them, the second level cleaning: put the wolfberry fruit into an ultrasonic cleaning machine and clean it for 14 minutes at room temperature and 30kHz frequency;

[0094] Among them, the third-level cleaning: at room temperature, the wolfberry fruit particles are soaked in a 2wt% chlorhexidine aqueous solution for 12 minutes;

[0095] The fourth-level sterilization is as follows: the wolfberry fruit particles after the third-level washing are soaked in a 0.3wt% sodium hypochlorite aqueous solution for 14 minutes;

[0096] S3, vibration draining, drying, crushing and double-pass beating: add the wolfberry fruit particles obtained in S2 into a vibration drainer, vibrate and drain for 8 minutes at a vibration frequency of 40kHz and an amplitude of 3mm; blow dry for 100 minutes at 50°C and a speed of 1.5m / s; send to a crusher and crush for 4 minutes at a speed of 2500r / min; transfer to a double-pass beating machine and beat for 8 minutes at a speed of 2500r / min, filter through a first sieve of 1.4mm and a second sieve of 0.5mm to obtain a wolfberry slurry;

[0097] S4, colloid mill: the wolfberry slurry is ground in a colloid mill at a speed of 18000 r / min for 50 min to obtain a colloid juice;

[0098] S5, high-pressure homogenization, concentration and vacuum degassing: add the colloidal juice obtained in S4 into a high-pressure homogenizer, add tea polyphenols, and homogenize for 90 minutes at room temperature and 50MPa under a nitrogen atmosphere; enter the low-temperature concentration equipment, concentrate at 55°C for 45 minutes, and concentrate to 3MPa﹒s; degas for 15 minutes in a degasser with a vacuum degree of 0.09Mpa and a temperature of 67°C to obtain primary wolfberry puree;

[0099] Among them, the mass ratio of colloidal juice to tea polyphenols is 99.7:0.3;

[0100] S6, UHT sterilization: at 145°C, maintain for 4 seconds;

[0101] S7, aseptic filling, testing, storage and delivery: the sterilized primary wolfberry puree will be transported to the aseptic filling machine through the pipeline, the filling head chamber temperature is maintained at ≥98℃ to achieve aseptic conditions, the pulp is filled into a sterile bag to obtain wolfberry puree; the filling weight is controlled by a mass flow meter; the filling outlet temperature: <35℃; the seal is tested to be complete, the leakage rate is <0.05%, storage registration, and delivery record;

[0102] Wherein, the preparation of the ultrafiltration membrane in the low temperature concentration device includes the following steps;

[0103] The nano-additive, PES and N,N-dimethylacetamide were mixed in a mass ratio of 7:21:130, stirred at 55°C and 140r / min for 12h, ultrasonicated at a frequency of 30kHz for 15min, and allowed to stand for complete elimination of bubbles to obtain a uniform casting solution; the casting solution was poured onto a smooth and clean glass, and the film was scraped with a film scraper. After the scraped film was allowed to stand at room temperature for 15s, it was immersed in a 45°C water bath together with the glass plate for 15min for phase inversion. After the membrane fell off the glass plate, it was washed with deionized water for 3 times, and dried at 60°C for 9h to obtain an ultrafiltration membrane with a thickness of 100mm and a pore size of 30nm;

[0104] Wherein, the preparation of the nano additive comprises the following steps:

[0105] Step (1) carboxymethyl chitosan, citric acid and acetone are mixed in a mass ratio of 100:70:400, reacted at 70°C for 9 hours, and after the reaction is completed, vacuum distilled at 0.08Mpa and 55°C for 5 hours, washed with deionized water for 3 times, and dried at 75°C for 4 hours to obtain modified carboxymethyl chitosan;

[0106] Step (2) under nitrogen atmosphere, adding cellulose nanocrystals to 10 wt % vitamin C aqueous solution, reacting at 80° C. and 160 r / min for 4 h, and completing the reaction; adding 3 mol / L modified carboxymethyl chitosan aqueous solution, reacting at 80° C. and 160 r / min for 4 h, and completing the reaction, washing with deionized water until neutral, and drying at 95° C. for 7 h to obtain a nano additive;

[0107] Wherein, the mass ratio of cellulose nanocrystals, vitamin C aqueous solution and modified carboxymethyl chitosan aqueous solution is 30:900:1400.

[0108] Example 4

[0109] This embodiment provides a method for preparing wolfberry puree, comprising the following steps:

[0110] S1. Picking, acceptance, winnowing and manual sorting: Take wolfberries that have been picked within 8 days, inspect the intact wolfberry berries, send them to the winnowing machine, and select them for 3 minutes at 0.7MPa, wind speed 11m / s, and sieve size 3mm. Manually select and remove the broken wolfberry berries;

[0111] S2, four-level cleaning and sterilization: including primary cleaning, secondary cleaning, tertiary cleaning and quaternary sterilization;

[0112] Among them, the first-level cleaning: soak the wolfberry berries in distilled water at room temperature for 8 minutes;

[0113] Among them, the second level cleaning: put the wolfberry fruit into an ultrasonic cleaning machine and clean it for 12 minutes at room temperature and 35kHz frequency;

[0114] Among them, the third-level cleaning: at room temperature, the wolfberry fruit particles are soaked in a 2.5wt% chlorhexidine aqueous solution for 11 minutes;

[0115] The fourth-level sterilization is as follows: the wolfberry fruit particles after the third-level washing are soaked in a 0.4wt% sodium hypochlorite aqueous solution for 13 minutes;

[0116] S3, vibration draining, drying, crushing and double-pass beating: add the wolfberry fruit particles obtained in S2 into a vibration drainer, vibrate and drain for 7 minutes at a vibration frequency of 50kHz and an amplitude of 4mm; blow dry for 90 minutes at 55°C and a speed of 1.8m / s; send to a crusher and crush for 3 minutes at a speed of 3000r / min; transfer to a double-pass beating machine and beat for 7 minutes at a speed of 3000r / min, filter through a first sieve of 1.6mm and a second sieve of 0.6mm to obtain a wolfberry slurry;

[0117] S4, colloid mill: the wolfberry slurry is ground in a colloid mill at a speed of 21000 r / min for 45 min to obtain a colloid juice;

[0118] S5, high-pressure homogenization, concentration and vacuum degassing: add the colloidal juice obtained in S4 into a high-pressure homogenizer, add tea polyphenols, and homogenize for 85 minutes at room temperature and 55MPa under a nitrogen atmosphere; enter the low-temperature concentration equipment, concentrate at 57°C for 38 minutes, and concentrate to 3.5MPa﹒s; degas for 12 minutes in a degasser with a vacuum degree of 0.09Mpa and a temperature of 71°C to obtain primary wolfberry puree;

[0119] Among them, the mass ratio of colloidal juice to tea polyphenols is 99.8:0.4;

[0120] S6, UHT sterilization: at 147°C, maintain for 3s;

[0121] S7, aseptic filling, testing, storage and delivery: the sterilized primary wolfberry puree will be transported to the aseptic filling machine through the pipeline, the filling head chamber temperature is maintained at ≥98℃ to achieve aseptic conditions, the pulp is filled into a sterile bag to obtain wolfberry puree; the filling weight is controlled by a mass flow meter; the filling outlet temperature: <35℃; the seal is tested to be complete, the leakage rate is <0.05%, storage registration, and delivery record;

[0122] Wherein, the preparation of the ultrafiltration membrane in the low temperature concentration device includes the following steps;

[0123] The nano-additive, PES and N,N-dimethylacetamide were mixed in a mass ratio of 8.5:24.5:145, stirred at 57°C and 160r / min for 11h, ultrasonicated at a frequency of 35kHz for 12min, and allowed to stand for complete elimination of bubbles to obtain a uniform casting solution; the casting solution was poured onto a smooth and clean glass, and the film was scraped with a scraper, and the scraped film was allowed to stand at room temperature for 17s and then immersed in a 47°C water bath together with the glass plate for 12min for phase inversion, and after the membrane fell off the glass plate, it was washed with deionized water for 3 times and dried at 65°C for 8.5h to obtain an ultrafiltration membrane with a thickness of 100mm and a pore size of 30nm;

[0124] Wherein, the preparation of the nano additive comprises the following steps:

[0125] Step (1) carboxymethyl chitosan, citric acid and acetone are mixed in a mass ratio of 100:80:450, reacted at 75°C for 8.5h, and after the reaction is completed, vacuum distilled at 0.08Mpa and 57°C for 4.5h, washed with deionized water for 3 times, and dried at 77°C for 3.5h to obtain modified carboxymethyl chitosan;

[0126] Step (2) under nitrogen atmosphere, adding cellulose nanocrystals to 10 wt% vitamin C aqueous solution, reacting at 82° C. and 180 r / min for 3.5 h, and completing the reaction; adding 3 mol / L modified carboxymethyl chitosan aqueous solution, reacting at 82° C. and 180 r / min for 3.5 h, and completing the reaction, washing with deionized water until neutral, and drying at 97° C. for 6.5 h to obtain a nano additive;

[0127] Among them, the mass ratio of cellulose nanocrystals, vitamin C aqueous solution and modified carboxymethyl chitosan aqueous solution is 35:1050:1600.

[0128] Example 5

[0129] This embodiment provides a method for preparing wolfberry puree, comprising the following steps:

[0130] S1. Picking, acceptance, winnowing and manual sorting: Take wolfberries that have been picked within 8 days, inspect the intact wolfberry berries, send them to the winnowing machine, and select them for 2 minutes at 1MPa, wind speed 12m / s, and sieve size 3mm. Manually select and remove the broken wolfberry berries;

[0131] S2, four-level cleaning and sterilization: including primary cleaning, secondary cleaning, tertiary cleaning and quaternary sterilization;

[0132] Among them, the first-level cleaning: soak the wolfberry berries in distilled water at room temperature for 10 minutes;

[0133] Among them, the second level cleaning: put the wolfberry fruit into an ultrasonic cleaning machine and clean it for 10 minutes at room temperature and 40kHz frequency;

[0134] Among them, the third-level cleaning: at room temperature, the wolfberry fruit particles are soaked in a 3wt% chlorhexidine aqueous solution for 10 minutes;

[0135] The fourth-level sterilization is as follows: the wolfberry fruit particles after the third-level washing are soaked in a 0.5wt% sodium hypochlorite aqueous solution for 12 minutes;

[0136] S3, vibration draining, drying, crushing and double-pass beating: add the wolfberry fruit particles obtained in S2 into a vibration drainer, vibrate and drain for 6 minutes at a vibration frequency of 60kHz and an amplitude of 5mm; blow dry for 80 minutes at 60°C and a speed of 2m / s; send to a crusher and crush for 2 minutes at a speed of 3500r / min; transfer to a double-pass beating machine and beat for 6 minutes at a speed of 3500r / min, filter through a first sieve of 1.8mm and a second sieve of 0.8mm to obtain a wolfberry slurry;

[0137] S4, colloid mill: the wolfberry slurry is ground in a colloid mill at a speed of 24000 r / min for 40 min to obtain a colloid juice;

[0138] S5, high-pressure homogenization, concentration and vacuum degassing: add the colloidal juice obtained in S4 into a high-pressure homogenizer, add tea polyphenols, and homogenize for 80 minutes at room temperature and 60MPa under a nitrogen atmosphere; enter the low-temperature concentration equipment, concentrate at 60°C for 30 minutes, and concentrate to 4MPa﹒s; degas for 10 minutes in a degasser with a vacuum degree of 0.1Mpa and a temperature of 75°C to obtain primary wolfberry puree;

[0139] Among them, the mass ratio of colloidal juice to tea polyphenols is 99.9:0.5;

[0140] S6, UHT sterilization: at 150°C, maintain for 2s;

[0141] S7, aseptic filling, testing, storage and delivery: the sterilized primary wolfberry puree will be transported to the aseptic filling machine through the pipeline, the filling head chamber temperature is maintained at ≥98℃ to achieve aseptic conditions, the pulp is filled into a sterile bag to obtain wolfberry puree; the filling weight is controlled by a mass flow meter; the filling outlet temperature: <35℃; the seal is tested to be complete, the leakage rate is <0.05%, storage registration, and delivery record;

[0142] Wherein, the preparation of the ultrafiltration membrane in the low temperature concentration device includes the following steps;

[0143] The nano-additive, PES and N,N-dimethylacetamide were mixed in a mass ratio of 10:28:160, stirred at 60°C and 180r / min for 10h, ultrasonicated at a frequency of 40kHz for 10min, and allowed to stand for complete elimination of bubbles to obtain a uniform casting solution; the casting solution was poured onto a smooth and clean glass, and the film was scraped with a film scraper, and the scraped film was allowed to stand at room temperature for 20s and then immersed in a 50°C water bath together with the glass plate for 10min for phase inversion, and after the membrane fell off the glass plate, it was washed with deionized water for 3 times and dried at 70°C for 8h to obtain an ultrafiltration membrane with a thickness of 100mm and a pore size of 30nm;

[0144] Wherein, the preparation of the nano additive comprises the following steps:

[0145] Step (1) carboxymethyl chitosan, citric acid and acetone are mixed in a mass ratio of 100:90:500, reacted at 80°C for 8h, and after the reaction, vacuum distilled at 0.08Mpa and 60°C for 4h, washed with deionized water for 3 times, and dried at 80°C for 3h to obtain modified carboxymethyl chitosan;

[0146] Step (2) under nitrogen atmosphere, adding cellulose nanocrystals to a 10 wt % vitamin C aqueous solution, reacting at 85° C. and 200 r / min for 3 h, and completing the reaction; adding 3 mol / L modified carboxymethyl chitosan aqueous solution, reacting at 85° C. and 200 r / min for 3 h, and completing the reaction, washing with deionized water until neutral, and drying at 100° C. for 6 h to obtain a nano additive;

[0147] Among them, the mass ratio of cellulose nanocrystals, vitamin C aqueous solution and modified carboxymethyl chitosan aqueous solution is 40:1200:1800.

[0148] Comparative Example 1

[0149] This comparative example provides a method for preparing wolfberry puree, comprising the following steps:

[0150] S1. Picking, acceptance, winnowing and manual sorting: Take wolfberries that have been picked within 8 days, inspect the intact wolfberry berries, send them to the winnowing machine, and select them for 6 minutes at 0.1MPa, wind speed 8m / s, and sieve size 3mm. Manually select and remove the broken wolfberry berries;

[0151] S2, four-level cleaning and sterilization: including primary cleaning, secondary cleaning, tertiary cleaning and quaternary sterilization;

[0152] Among them, the first-level cleaning: soak the wolfberry berries in distilled water for 5 minutes at room temperature;

[0153] Among them, the second level cleaning: put the wolfberry fruit into an ultrasonic cleaning machine and clean it for 18 minutes at room temperature and 20kHz frequency;

[0154] Among them, the third-level cleaning: at room temperature, the wolfberry fruit particles are soaked in a 1wt% chlorhexidine aqueous solution for 14 minutes;

[0155] The fourth-level sterilization is as follows: the wolfberry fruit particles after the third-level washing are soaked in a 0.1wt% sodium hypochlorite aqueous solution for 16 minutes;

[0156] S3, vibration draining, drying, crushing and double-pass beating: add the wolfberry fruit particles obtained in S2 into a vibration drainer, vibrate and drain for 10 minutes at a vibration frequency of 20kHz and an amplitude of 2mm; blow dry for 120 minutes at 40°C and a speed of 1m / s; send to a crusher and crush at a speed of 1500r / min for 6 minutes; transfer to a double-pass beating machine and beat at a speed of 1500r / min for 10 minutes, filter through a first sieve of 1mm and a second sieve of 0.8mm to obtain a wolfberry slurry;

[0157] S4, colloid mill: the wolfberry slurry is ground in a colloid mill at a speed of 12000 r / min for 60 min to obtain a colloid juice;

[0158] S5, high-pressure homogenization, concentration and vacuum degassing: the colloidal juice obtained in S4 is added to a high-pressure homogenizer, and homogenized for 100 minutes at room temperature and 40 MPa under a nitrogen atmosphere; it is then put into a low-temperature concentration device, and concentrated for 60 minutes at 50°C to 2 MPa﹒s; it is degassed for 20 minutes in a degasser at a vacuum degree of 0.08 MPa and a temperature of 60°C to obtain primary wolfberry puree;

[0159] S6, UHT sterilization: at 140°C, maintain for 6 seconds;

[0160] S7, aseptic filling, testing, storage and delivery: the sterilized primary wolfberry puree will be transported to the aseptic filling machine through the pipeline, the filling head chamber temperature is maintained at ≥98℃ to achieve aseptic conditions, the pulp is filled into a sterile bag to obtain wolfberry puree; the filling weight is controlled by a mass flow meter; the filling outlet temperature: <35℃; the seal is tested to be complete, the leakage rate is <0.05%, storage registration, and delivery record;

[0161] Wherein, the preparation of the ultrafiltration membrane in the low temperature concentration device includes the following steps;

[0162] The nano-additive, PES and N,N-dimethylacetamide were mixed in a mass ratio of 4:14:100, stirred at 50°C and a speed of 100 r / min for 14 hours, ultrasonicated at a frequency of 20 kHz for 20 minutes, and allowed to stand for complete elimination of bubbles to obtain a uniform casting solution; the casting solution was poured onto a smooth and clean glass, and the film was scraped with a film scraper. After the scraped film was allowed to stand at room temperature for 10 seconds, it was immersed in a 40°C water bath together with the glass plate for 20 minutes for phase inversion. After the membrane fell off the glass plate, it was washed with deionized water for 3 times, and dried at 50°C for 10 hours to obtain an ultrafiltration membrane with a thickness of 100 mm and a pore size of 30 nm;

[0163] Wherein, the preparation of the nano additive comprises the following steps:

[0164] Step (1) carboxymethyl chitosan, citric acid and acetone are mixed in a mass ratio of 100:50:300, reacted at 60° C. for 10 h, and after the reaction is completed, vacuum distilled at 0.08 MPa and 50° C. for 6 h, washed with deionized water for 3 times, and dried at 70° C. for 5 h to obtain modified carboxymethyl chitosan;

[0165] Step (2) under nitrogen atmosphere, adding cellulose nanocrystals to a 10 wt % vitamin C aqueous solution, reacting at 75° C. and a rotation speed of 120 r / min for 5 h, and completing the reaction; adding a 3 mol / L modified carboxymethyl chitosan aqueous solution, reacting at 75° C. and a rotation speed of 120 r / min for 5 h, and completing the reaction, washing with deionized water until neutral, and drying at 90° C. for 8 h to obtain a nano additive;

[0166] Wherein, the mass ratio of cellulose nanocrystals, vitamin C aqueous solution and modified carboxymethyl chitosan aqueous solution is 20:600:1000.

[0167] Comparative Example 2

[0168] This comparative example provides a method for preparing wolfberry puree, comprising the following steps:

[0169] S1. Picking, acceptance, winnowing and manual sorting: Take wolfberries that have been picked within 8 days, inspect the intact wolfberry berries, send them to the winnowing machine, and select them for 6 minutes at 0.1MPa, wind speed 8m / s, and sieve size 3mm. Manually select and remove the broken wolfberry berries;

[0170] S2, four-level cleaning and sterilization: including primary cleaning, secondary cleaning, tertiary cleaning and quaternary sterilization;

[0171] Among them, the first-level cleaning: soak the wolfberry berries in distilled water for 5 minutes at room temperature;

[0172] Among them, the second level cleaning: put the wolfberry fruit into an ultrasonic cleaning machine and clean it for 18 minutes at room temperature and 20kHz frequency;

[0173] Among them, the third-level cleaning: at room temperature, the wolfberry fruit particles are soaked in a 1wt% chlorhexidine aqueous solution for 14 minutes;

[0174] The fourth-level sterilization is as follows: the wolfberry fruit particles after the third-level washing are soaked in a 0.1wt% sodium hypochlorite aqueous solution for 16 minutes;

[0175] S3, vibration draining, drying, crushing and double-pass beating: add the wolfberry fruit particles obtained in S2 into a vibration drainer, vibrate and drain for 10 minutes at a vibration frequency of 20kHz and an amplitude of 2mm; blow dry for 120 minutes at 40°C and a speed of 1m / s; send to a crusher and crush at a speed of 1500r / min for 6 minutes; transfer to a double-pass beating machine and beat at a speed of 1500r / min for 10 minutes, filter through a first sieve of 1mm and a second sieve of 0.8mm to obtain a wolfberry slurry;

[0176] S4, colloid mill: the wolfberry slurry is ground in a colloid mill at a speed of 12000 r / min for 60 min to obtain a colloid juice;

[0177] S5, high-pressure homogenization, concentration and vacuum degassing: the colloidal juice obtained in S4 is added to a high-pressure homogenizer, and homogenized for 100 minutes at room temperature and 40 MPa under a nitrogen atmosphere; it is then put into a low-temperature concentration device, and concentrated for 60 minutes at 50°C to 2 MPa﹒s; it is degassed for 20 minutes in a degasser at a vacuum degree of 0.08 MPa and a temperature of 60°C to obtain primary wolfberry puree;

[0178] S6, UHT sterilization: at 140°C, maintain for 6 seconds;

[0179] S7, aseptic filling, testing, storage and delivery: the sterilized primary wolfberry puree will be transported to the aseptic filling machine through the pipeline, the filling head chamber temperature is maintained at ≥98℃ to achieve aseptic conditions, the pulp is filled into a sterile bag to obtain wolfberry puree; the filling weight is controlled by a mass flow meter; the filling outlet temperature: <35℃; the seal is tested to be complete, the leakage rate is <0.05%, storage registration, and delivery record;

[0180] Among them, the filter membrane in the low-temperature concentration equipment is a commercially available filter membrane from Shenzhen Yulin Environmental Engineering Co., Ltd. with a pore size of 0.1μm.

[0181] Comparative Example 3

[0182] This comparative example provides a method for preparing wolfberry puree, comprising the following steps:

[0183] Step 1: After the ripe wolfberry fruits are washed, cleaned, sorted and impurities removed, the juice is squeezed to obtain a wolfberry slurry with juice.

[0184] Step 2: Grind the wolfberry slurry once with a colloid mill at a rotor speed of 20,000 r / min to obtain a colloidal juice.

[0185] Step 3: The colloidal juice is centrifuged at 1000 r / min and 10° C. for 60 min, and then filtered through a 4-mesh filter cloth to remove precipitates and foam to obtain a slurry.

[0186] Step 4: The slurry is homogenized for 10 minutes using a continuous high-pressure homogenizer at a pressure of 150 MPa, and then irradiated and sterilized and filled in 5 ml blue plastic bottles; after filling, it is pasteurized to obtain wolfberry slurry.

[0187] Comparative Example:

[0188] Comparative Example 1 lacks tea polyphenols compared to Example 1;

[0189] Comparative Example 2 Compared with Comparative Example 1, the filter membrane used in the low-temperature concentration is a commercially available filter membrane from Shenzhen Yulin Environmental Engineering Co., Ltd., with a pore size of 0.1 μm;

[0190] Comparative Example 3 is compared with Example 1 in that the wolfberry puree is prepared using a traditional preparation method.

[0191] In the embodiments and comparative examples, tea polyphenols are from Shanghai Tiankuo Biotechnology Co., Ltd.; PES is from BASF, with a molecular weight of 60,000; N,N-dimethylacetamide is from Nanjing Pinyoudao Chemical Technology Co., Ltd., CAS No.: 127-19-5; carboxymethyl chitosan is from Ningxia Hengpeptide Bioengineering Co., Ltd., with a content of >98%; cellulose nanocrystals are from Shanghai MacLean Biochemical Technology Co., Ltd.; citric acid and vitamin C are from Shanghai Aladdin Biochemical Technology Co., Ltd.; wolfberry berries are from Ningxia; and the others are all commercially available products.

[0192] The wolfberry puree prepared in Examples 1-5 and Comparative Examples 1-3 was subjected to sensory evaluation, including color, smell, and state, with reference to GB 7101-2015; the wolfberry polysaccharides and soluble sugars in the nutrients were determined by GB / T 18672-2014 "Wolfberry"; betaine was determined by NY / T2947-2016 "Determination of betaine content in wolfberry by high performance liquid chromatography" method; flavonoids were determined according to NY / T 3903-2021 and GB / T8410-2011 "Determination of flavonoids in wolfberry" methods; total phenols were determined according to T / NAIA097-2021 "Determination of total phenol content in wolfberry by photometric method"; the test results are shown in Table 1:

[0193] Table 1

[0194]

[0195] As shown in Table 1, the wolfberry pulp prepared in Examples 1-5 has good sensory evaluation and good nutrients. Comparative Example 1 lacks tea polyphenols compared to Example 1, which reduces the antioxidant properties of wolfberry pulp and weakens the ability to delay browning in wolfberry pulp; the ability of the filter membrane in the low-temperature concentration equipment in Comparative Example 2 to intercept nutrients is not as good as that in Comparative Example 1, so the nutrients including wolfberry polysaccharides, soluble sugars, betaine, flavonoids and total phenols are all lower than those in Comparative Example 1; Comparative Example 3 is not sterilized before juicing, which is not conducive to removing microorganisms on the surface, and there will be foreign matter in the wolfberry pulp. Single grinding cannot fully break the wolfberry cells, resulting in incomplete release of effective ingredients and reduced nutrient content. It can be seen from the table that the nutrient content prepared in Example 1 is higher than that in Comparative Example 3, indicating that the preparation method of wolfberry pulp provided by the present invention is better than the traditional preparation method of wolfberry pulp, and the antioxidant components contained in Example 1 are higher than those in Comparative Example 3, so the antioxidant property of Example 1 is better than that of Comparative Example 3.

[0196] Although the embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that all equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A method for preparing wolfberry puree, characterized in that: The following steps are involved: S1. Picking, acceptance, winnowing and manual sorting: Take wolfberries that have been picked within 8 days, inspect the intact wolfberries, send them to the winnowing machine for cleaning, and manually sort out the broken wolfberries; S2, four-level cleaning and sterilization: including primary cleaning, secondary cleaning, tertiary cleaning and quaternary sterilization; S3, vibration draining, drying, crushing and double-channel beating: adding the wolfberry fruit particles obtained in S2 into a vibration drainer for vibration draining and drying; sending them into a crusher for crushing; transferring them into a double-channel beating machine for beating to obtain a wolfberry slurry; S4, colloid mill: the wolfberry slurry is ground by a colloid mill to obtain a colloid juice; S5, high-pressure homogenization, concentration and vacuum degassing: the colloidal juice obtained in S4 is added to a high-pressure homogenizer, a color preservative is added, and homogenization is performed under a nitrogen atmosphere; the juice is then put into a low-temperature concentration device for concentration, and a degasser is used for degassing to obtain primary wolfberry puree; S6, UHT sterilization; S7, aseptic filling, testing, storage and delivery: the sterilized primary wolfberry puree will be transported to the aseptic filling machine through the pipeline, the filling head chamber will maintain a temperature of ≥98℃ to achieve aseptic conditions, and the pulp will be filled into a sterile bag to obtain wolfberry puree; the filling weight is controlled by a mass flow meter; the filling outlet temperature: <35℃; the sealing is tested to be complete, storage registration, and delivery records; Wherein, the preparation of the ultrafiltration membrane in the low temperature concentration device includes the following steps; The nano-additive and PES are added to N,N-dimethylacetamide, heated, stirred, ultrasonicated, and allowed to stand until bubbles are completely eliminated to obtain a uniform casting solution; the casting solution is poured onto a smooth and clean glass, and the film is scraped with a film scraper, and the scraped film is allowed to stand at room temperature for a period of time, and then immersed in a water bath together with the glass plate for phase inversion, and after the film falls off the glass plate, it is washed with deionized water and dried to obtain an ultrafiltration membrane; Wherein, the preparation of the nano additive comprises the following steps: Step (1) adding carboxymethyl chitosan and citric acid to acetone, heating, reacting, and after the reaction is completed, distilling under reduced pressure, washing, and drying to obtain modified carboxymethyl chitosan; Step (2) under nitrogen atmosphere, adding fiber nanocrystals to a vitamin C aqueous solution, heating for the first time, stirring for reaction, and completing the reaction; adding a modified carboxymethyl chitosan aqueous solution, heating for the second time, stirring for reaction, and completing the reaction, washing with deionized water until neutral, and drying to obtain a nano additive.

2. The method for preparing wolfberry puree according to claim 1, characterized in that: The first screen in the double-pass pulping machine is 1-1.8 mm, and the second screen is 0.3-0.8 mm.

3. The method for preparing wolfberry puree according to claim 1, characterized in that: The material used for the fourth-level sterilization is a sodium hypochlorite aqueous solution, wherein the mass concentration of the sodium hypochlorite aqueous solution is 0.1-0.5%.

4. The method for preparing wolfberry puree according to claim 1, characterized in that: The pressure in high-pressure homogenization is 40-60MPa and the processing time is 80-100min.

5. The method for preparing wolfberry puree according to claim 1, characterized in that: The mass ratio of the colloidal juice to the color preservative is (99.5-99.9):(0.1-0.5).

6. The method for preparing wolfberry puree according to claim 1, characterized in that: The mass ratio of the nano-additive, PES and N,N-dimethylacetamide is (4-10):(14-28):(100-160); the heating temperature is 50-60° C., and the stirring time is 10-14 hours.

7. The method for preparing wolfberry puree according to claim 1, characterized in that: The mass ratio of carboxymethyl chitosan, citric acid and acetone is 100:(50-90):(300-500); the heating temperature is 60-80°C, and the reaction time is 8-10h.

8. The method for preparing wolfberry puree according to claim 1, characterized in that: The mass ratio of cellulose nanocrystals, vitamin C aqueous solution and modified carboxymethyl chitosan aqueous solution is (20-40):(600-1200):(1000-1800); the mass concentration of the vitamin C aqueous solution is 10%; the concentration of the modified carboxymethyl chitosan aqueous solution is 3 mol / L.

9. A wolfberry puree prepared by the method for preparing wolfberry puree according to any one of claims 1 to 8.

10. Use of the wolfberry puree according to claim 9 in improving antioxidant properties.

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