A concentrated roxburgh pear fruit juice with good taste and high nutritional value, and a preparation method and application thereof

Abstract

The application provides a concentrated roxburgh rose juice with good taste and high nutritional value, and a preparation method and application thereof, and belongs to the technical field of roxburgh rose juice preparation.The preparation method of the roxburgh rose juice provided by the application comprises the following steps: after roxburgh rose fruits are crushed at low temperature, low-temperature belt pressing is performed, juice is taken, pH is adjusted, mixed with rice protein powder, stirred and adsorbed at 4-10 DEG C, then, standing is performed, food-grade laccase is added for reaction, enzyme is inactivated, centrifugation is performed, the clarified liquid is taken, and adsorption resin column is used for adsorption treatment; after concentration, filling is performed, and high-temperature instantaneous sterilization is performed.The preparation method provided by the application can efficiently remove the bitter and astringent taste of roxburgh rose juice, can retain the heat-sensitive nutritional ingredients such as vitamin C and SOD in the maximum degree, and the product has the activities of inhibiting thyroid tumor cell proliferation and enhancing the immunity of the body, has excellent sensory quality, high nutritional value and good physiological activity, and overcomes the technical problems that the existing roxburgh rose juice preparation process cannot simultaneously consider the astringency removal effect and heat-sensitive nutrient retention.

Description

Technical Field

[0001] This invention belongs to the field of prickly pear juice preparation technology, specifically relating to a concentrated prickly pear juice with excellent taste and high nutritional value, its preparation method, and its application. Background Technology

[0002] The prickly pear, the fruit of a plant in the genus Rosa of the Rosaceae family, is a plant resource used for both medicinal and edible purposes, mainly distributed in southwestern regions such as Guizhou, Yunnan, and Sichuan. The prickly pear fruit is rich in nutrients, earning it the reputation of "King of Vitamin C" due to its high vitamin C content. It is also rich in superoxide dismutase (SOD), ranking first among various fruits and vegetables. In addition, it contains flavonoids, prickly pear polysaccharides, triterpenoids, polyphenols, amino acids, and various minerals, among other bioactive components. Modern pharmacological studies have shown that the prickly pear possesses extremely high nutritional and development value.

[0003] However, the prickly pear fruit contains a large amount of tannins and various organic acids, resulting in a strong sour, astringent, and bitter taste in the raw prickly pear juice, leading to poor consumer acceptance and severely restricting the development of the prickly pear industry. Therefore, how to effectively improve the taste of prickly pear juice while preserving its heat-sensitive nutrients to the greatest extent is a key technical problem that urgently needs to be solved in the deep processing of prickly pear. Currently, existing methods for removing astringency and improving the taste of prickly pear juice mainly include physical adsorption, enzymatic deastringency, encapsulation deastringency, fermentation deastringency, and heat treatment. However, each has its own limitations. The core flaw is that while existing deastringency technologies improve the sour, bitter, and astringent taste of prickly pear juice, they inevitably lead to a significant loss of heat-sensitive nutrients such as vitamin C and SOD, resulting in a technical dilemma of deastringency leading to inactivation. Specifically, physical adsorption has limited deastringency efficiency, and non-specific adsorption leads to the simultaneous loss of beneficial components; enzymatic deastringency requires high temperature and long reaction time, resulting in severe loss of heat-sensitive components; fermentation deastringency is inefficient, has a long fermentation cycle, and suffers significant nutrient loss; and heat treatment severely damages heat-sensitive nutrients. In summary, existing prickly pear juice de-astringency technologies suffer from a fundamental technical contradiction: technologies with better de-astringency effects (such as enzymatic or heating methods) often require higher temperatures or longer processing times, leading to more severe damage to heat-sensitive nutrients like vitamin C and superoxide dismutase (SOD); while relatively milder technologies (such as physical adsorption) are insufficient in de-astringency efficiency and cannot completely solve the problem of the sour and bitter taste. Industry data shows that traditional de-astringency processes result in significant losses of vitamin C and SOD in prickly pear juice, which contradicts the product positioning of prickly pear juice as a high-nutrition and high-activity product and seriously weakens the core competitiveness of prickly pear products. Therefore, developing a preparation method that can efficiently remove the sour and bitter taste of prickly pear juice while maximally preserving heat-sensitive nutrients such as vitamin C and SOD is a technical challenge that urgently needs to be solved in this field. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a method for preparing prickly pear juice that can efficiently remove the sour and bitter taste of prickly pear juice while retaining heat-sensitive nutrients such as vitamin C and SOD to the greatest extent, so that the prepared prickly pear juice has a good taste and high nutritional value.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing prickly pear juice with excellent taste and high nutritional value, comprising the following steps: crushing prickly pear fruit at low temperature, performing low-temperature belt pressing, adjusting the pH of the juice to 3.8-4.2, mixing it with rice protein powder, stirring and adsorbing at 4-10℃, then allowing it to stand, adding food-grade laccase for reaction, centrifuging, taking the clarified liquid and adsorbing it with an adsorption resin column, collecting the resin effluent, concentrating it and filling it, and then sterilizing it at high temperature; the low temperature is 15-25℃; The method for preparing the rice protein powder includes the following steps: Rice was ground into a paste and mixed with α-amylase for enzymatic hydrolysis 1. After enzyme inactivation, alkaline protease was added for enzymatic hydrolysis 2. After enzyme inactivation, papain was added for enzymatic hydrolysis 3. After enzyme inactivation, the supernatant was collected, activated carbon was added for adsorption, the activated carbon was removed, and the mixture was concentrated and dried.

[0006] Preferably, the particle size of the low-temperature crushing is 3~6mm.

[0007] Preferably, the low-temperature belt pressing includes the following steps: pre-pressing at 0.3~0.5 MPa, then main pressing at 1.0~1.2 MPa, and finally deep pressing at 1.8~2.0 MPa; the filter belt running speed of the low-temperature belt press is 0.5~1.5 m / min, and the material spreading thickness is 20~30 mm.

[0008] Preferably, the volume-to-mass ratio of juice to rice protein powder is 100mL:0.4~0.8g; the stirring and adsorption speed is 150~200r / min, and the time is 25~35min; the settling time is 20~30min; the amount of food-grade laccase added is 100~500U per 1L of juice; the reaction temperature for adding food-grade laccase is 4~10℃, the stirring speed is 60~100r / min, and the time is 40~90min; the centrifugation speed is 6000~8000r / min, and the time is 10~15min.

[0009] Preferably, the adsorption resin is a macroporous weakly acidic cation exchange resin; the resin column diameter-to-height ratio is 1:6~10; the sample loading flow rate is 1~2 BV / h; and the resin adsorption temperature is 4~10℃.

[0010] Preferably, the concentration includes vacuum concentration, wherein the vacuum concentration temperature is 45~75℃, the vacuum degree is -0.07~-0.09MPa, and the concentration is carried out to a soluble solids content of 70~72°Brix; the high-temperature instantaneous sterilization conditions are sterilization at 105℃ for 20~30s.

[0011] Preferably, the amount of α-amylase added is 0.6~1.2 U / g rice; the pH for enzymatic hydrolysis 1 is 6~7, the temperature is 50~60℃, and the time is 0.5~1.5h; the amount of alkaline protease added is 1000~2000 U / g rice; the pH for enzymatic hydrolysis 2 is 8.0~9.5, the temperature is 55~65℃, and the time is 2.5~4h; the amount of papain added is 2400~4800 U / g rice; and the pH for enzymatic hydrolysis 3 is 6~7, the temperature is 45~55℃, and the time is 1~3h.

[0012] Preferably, the enzyme inactivation conditions are: incubation at 100℃ for 8-10 min; the volume-to-mass ratio of supernatant to activated carbon is 100 mL: 0.1-0.2 g; the activated carbon adsorption conditions are: stirring and adsorption at 45-55℃ for 25-35 min; the activated carbon is removed by filtration using a 0.22 μm filter membrane; the concentration and drying include vacuum concentration and spray drying, wherein the vacuum degree of vacuum concentration is -0.07 to -0.09 MPa, the temperature is 45-50℃, and the concentration is reduced to 20%-25% solids; the inlet air temperature of spray drying is 160-170℃, the outlet air temperature is 75-80℃, and the atomization pressure is 1.8 MPa.

[0013] The present invention also provides prickly pear juice prepared by the above preparation method.

[0014] The present invention also provides the application of the above-mentioned prickly pear juice in any of the following: (1) preparing antioxidant products; (2) preparing products for the prevention and treatment of thyroid cancer; (3) preparing products for the relief of hangovers and liver protection; (4) preparing products for the improvement of sleep.

[0015] The beneficial effects of this invention are: This invention employs a complete process combining low-temperature crushing, low-temperature belt pressing, low-temperature targeted deastringency removal from rice protein powder, and purification with adsorption resin combined with high-temperature instantaneous sterilization. On one hand, it leverages the action of rice protein to efficiently remove astringent tannins, followed by further purification with resin, significantly improving the unpleasant sour and bitter taste of prickly pear juice. On the other hand, it avoids prolonged high-temperature processing throughout the entire process, maximizing the retention of heat-sensitive nutrients such as vitamin C and SOD enzymes. The prickly pear juice prepared using this method has a pure fruity aroma, excellent storage stability, and high food safety. Simultaneously, the product possesses activities that inhibit the proliferation of thyroid tumor cells and enhance the body's immunity, combining excellent sensory qualities, high nutritional value, and good physiological activity, overcoming the technical challenge of existing prickly pear juice preparation processes that struggle to simultaneously achieve deastringency removal and retain heat-sensitive nutrients. Detailed Implementation

[0016] This invention provides a method for preparing prickly pear juice with excellent taste and high nutritional value, comprising the following steps: crushing prickly pear fruit at low temperature, performing low-temperature belt pressing, adjusting the pH of the juice to 3.8-4.2, mixing it with rice protein powder, stirring and adsorbing at 4-10℃, then allowing it to stand, adding food-grade laccase for reaction, centrifuging, taking the clarified liquid and adsorbing it with an adsorption resin column, collecting the resin effluent, concentrating it and filling it, and then sterilizing it at high temperature; the low temperature is 15-25℃; The method for preparing the rice protein powder includes the following steps: Rice was ground into a paste and mixed with α-amylase for enzymatic hydrolysis 1. After enzyme inactivation, alkaline protease was added for enzymatic hydrolysis 2. After enzyme inactivation, papain was added for enzymatic hydrolysis 3. After enzyme inactivation, the supernatant was collected, activated carbon was added for adsorption, the activated carbon was removed, and the mixture was concentrated and dried.

[0017] This invention does not specifically limit the source of the prickly pear fruit; commercially available products commonly used in the field are acceptable. In this invention, the prickly pear fruit is preferably fresh fruit that is 80-90% ripe, with a greenish-yellow to golden-yellow color. Moldy, diseased, unripe, and overripe soft fruit are removed. After harvesting, the fresh fruit should preferably be processed within 4 hours, or temporarily stored at 0-4°C for no more than 24 hours. After obtaining the fresh prickly pear fruit, it is preferred to first rinse it with running water to remove surface mud, impurities, and thorns, with the water temperature controlled at 15-25°C, followed by low-temperature crushing.

[0018] In this invention, when performing low-temperature crushing, a low-temperature crusher is preferably used. The particle size of the low-temperature crushed material is preferably 3-6 mm, more preferably 4-5 mm. In this invention, the temperature of the low-temperature crushing is preferably 15-20°C. Crushing under low-temperature conditions can inhibit the activity of polyphenol oxidase (PPO) from the source, reducing vitamin C oxidation and browning. The crushing particle size set in this invention can avoid excessive crushing that could lead to seed breakage and increase the dissolution of bitter substances.

[0019] In this invention, a belt press is preferably used for low-temperature belt pressing. The width of the filter belt is preferably 800-1200 mm, more preferably 900-1100 mm. The low-temperature belt pressing preferably includes the following steps: pre-pressing and dehydration at 0.3-0.5 MPa, followed by main pressing and juice extraction at 1.0-1.2 MPa, and finally deep pressing at 1.8-2.0 MPa. More preferably, it includes the following steps: pre-pressing and dehydration at 0.4 MPa, followed by main pressing and juice extraction at 1.1 MPa, and finally deep pressing at 1.9 MPa. The operating speed of the filter belt in the low-temperature belt pressing is preferably 0.5-1.5 m / min, more preferably 0.8-1.2 m / min. The material spreading thickness in the low-temperature belt pressing is preferably 20-30 mm, more preferably 23-27 mm. This invention employs a low-temperature belt press, which maximizes the retention rate of Vitamin C and the activity of SOD enzyme, while also achieving a high juice yield. This reduces the mixing of fine particles from the fruit pomace, simplifying subsequent clarification. After pressing, the product is preferably coarsely filtered through an 80-100 mesh screen to remove large particles such as peel, seeds, and coarse fiber.

[0020] After coarse filtration, the pH is adjusted to preferably 3.9-4.1 before being mixed with rice protein powder. This invention does not have specific limitations on the type of solvent used for pH adjustment; in some embodiments, sodium citrate solution is used. This invention utilizes the hydrophobic interaction and hydrogen bonding between rice protein and tannin molecules to form a protein-tannin complex precipitate, thereby directionally removing astringent large-molecule tannins while having minimal impact on nutrients such as vitamin C, SOD, and small-molecule flavonoids. Furthermore, rice protein is a natural food ingredient with no risk of enzyme residues, aligning with the trend towards clean labeling. In this invention, the volume-to-mass ratio of juice to rice protein powder is preferably 100mL:0.4~0.8g, more preferably 100mL:0.5~0.7g; the stirring and adsorption speed is preferably 150~200r / min, more preferably 170~180r / min; the stirring and adsorption time is preferably 25~35min, more preferably 28~32min; after the stirring and adsorption is completed, it is preferably allowed to stand to allow the complex to fully flocculate and precipitate, the standing time is preferably 20~30min, more preferably 22~28min; in the process of removing astringency using rice protein powder, this invention maintains a low temperature (15~20℃) throughout the process, avoiding the loss of VC and SOD caused by the high temperature of 45℃ in the traditional enzymatic method. In this invention, after the adsorption and settling period, food-grade laccase is added for reaction. After the reaction, centrifugation is performed to remove the protein-tannin complex precipitate and other suspended impurities to obtain a clear liquid. The centrifugation is preferably performed using a disc centrifuge, the centrifugation speed is preferably 6000~8000 r / min, more preferably 6500~7500 r / min, the centrifugation time is preferably 10~15 min, more preferably 12~14 min, and the centrifugation temperature is preferably ≤10℃. In this invention, the amount of food-grade laccase added is 100-500U per 1L of juice, more preferably 200-400U per 1L of juice; the preferred reaction temperature for adding food-grade laccase is 4-10℃, the preferred stirring speed is 60-100r / min, more preferably 70-90r / min, and the preferred time is 40-90 min, more preferably 50-80 min; the enzyme inactivation method is ultraviolet irradiation for 10-15 min; after adding laccase, this invention can decompose the lignin in prickly pear, reduce the irritation of prickly pear juice to the intestines, increase bioavailability, and further help improve the tannin removal rate and clarification effect.

[0021] In this invention, the clarified liquid obtained after centrifugation is treated with an adsorption resin column. The core function is to remove trace amounts of free rice protein remaining after centrifugation, solving the problems of turbidity during storage, protein allergies, and a ricey taste caused by small amounts of residual rice protein. Furthermore, the cation exchange resin has strong protein selectivity, minimizing the loss of water-soluble nutrients from the prickly pear. This invention adds rice protein for de-astringency, achieving a total de-astringency effect of over 90%. Moreover, the purification process using the adsorption resin after de-astringency does not alter the chemical structure of the nutrients, achieving the triple effects of de-astringency, aroma preservation, and nutrient stabilization. In this invention, the adsorption resin is preferably a macroporous, weakly acidic cation exchange resin. The weakly acidic resin carries a negative charge under acidic conditions of pH 3.8-4.2, adsorbing positively charged free rice protein. Neutral / weakly acidic prickly pear polyphenols, vitamin C, and tannins are mostly absorbed, precisely removing protein without significant nutrient loss. After adsorption by the cation exchange resin, protein flocculation and precipitation during storage are completely avoided, while reducing the risk of plant protein allergies. In this invention, the macroporous weakly acidic cation exchange resin is preferably food-grade D113-FG macroporous adsorption resin. In this invention, the resin column diameter-to-height ratio is preferably 1:6~10, more preferably 1:7~9; the feed flow rate is preferably 1~2 BV / h; and the resin adsorption temperature is preferably 4~10℃.

[0022] In this invention, the concentration method preferably includes vacuum concentration, wherein the vacuum concentration temperature is preferably 45~75℃, the vacuum degree is preferably -0.07~-0.09MPa, and the concentration to a soluble solids content preferably reaches 70~72°Brix. In this invention, the headspace is preferably controlled ≤5% during filling to reduce the oxygen content in the filling container. In this invention, the high-temperature instantaneous sterilization condition is preferably 105℃ for 20~30s. This invention uses high-temperature instantaneous sterilization, which, due to its extremely short sterilization time, can largely retain nutrients (VC, SOD enzyme activity, total phenols) and maintain flavor authenticity (preserving the fresh flavor of the prickly pear juice). The prickly pear juice prepared using the method of this invention has a shelf life of 3~6 months under refrigeration at 4℃.

[0023] In the preparation process of rice protein powder of the present invention, before grinding the rice into a slurry, it is preferable to mix the rice and water at a material-liquid ratio of 1g:5~7mL and then grind the rice into a colloid mill until it passes through an 80-mesh sieve. After grinding, the rice is heated to gelatinize, which fully breaks down the starch particles and facilitates the action of α-amylase. In the present invention, the heating temperature is preferably 90°C and the gelatinization time is preferably 20min.

[0024] In this invention, the preferred amount of α-amylase added is 0.6~1.2 U / g rice, more preferably 0.8~1.0 U / g rice; the preferred pH for enzymatic hydrolysis 1 is 6~7, the preferred temperature is 50~60℃, more preferably 52~58℃, and the preferred time is 0.5~1.5h, more preferably 0.8~1.2h. This invention uses α-amylase for enzymatic hydrolysis to remove rice starch, release protein, and improve protein purity.

[0025] In this invention, the preferred amount of alkaline protease added is 1000-2000 U / g rice; the preferred pH for enzymatic hydrolysis 2 is 8.0-9.5, the preferred temperature is 55-65℃, more preferably 58-62℃, and the preferred time is 2.5-4 h, more preferably 2.8-3.5 h. This invention uses alkaline protease for enzymatic hydrolysis, which can initially cleave large rice protein molecules and improve protein solubility.

[0026] In this invention, the preferred amount of papain added is 2400-4800 U / g rice, more preferably 2600-4200 U / g rice; the preferred pH for enzymatic hydrolysis 3 is 6-7, the preferred temperature is 45-55℃, more preferably 48-52℃, and the preferred time is 1-3 h, more preferably 1.5-2.5 h. This invention uses papain for enzymatic hydrolysis, which can cleave hydrophobic bitter peptides, optimize the binding ability of protein and tannins, and is suitable for removing astringency from prickly pear juice.

[0027] In the preparation process of the rice protein powder of the present invention, the enzyme inactivation condition is preferably 100℃ for 8-10 min; after enzyme inactivation, the supernatant is taken for activated carbon adsorption to remove bitterness and color, wherein the activated carbon is food-grade activated carbon. The volume-to-mass ratio of the supernatant to the activated carbon is preferably 100 mL: 0.1-0.2 g, and the activated carbon adsorption condition is preferably 45-55℃ with stirring for 25-35 min, more preferably 48-52℃ with stirring for 28-32 min. In this invention, the preferred method for removing activated carbon is filtration using a 0.22 μm filter membrane. The concentration and drying methods preferably include vacuum concentration and spray drying. The vacuum concentration is preferably performed at a vacuum degree of -0.07 to -0.09 MPa, more preferably -0.08 MPa, with a temperature of 45 to 50°C, more preferably 47 to 49°C, and the concentration is preferably achieved to a solid content of 20% to 25%. The spray drying is preferably performed at an inlet air temperature of 160 to 170°C, more preferably 162 to 168°C, with an outlet air temperature of 75 to 80°C, more preferably 76 to 78°C, and an atomization pressure of 1.8 MPa. In this invention, the rice protein powder preferably has a protein content of ≥82%, a degree of hydrolysis (DH) of 18% to 26%, and a solubility of ≥90%.

[0028] The present invention also provides prickly pear juice prepared by the above preparation method.

[0029] The present invention also provides the application of the above-mentioned prickly pear juice in any of the following: (1) preparation of antioxidant products; (2) preparation of products for the prevention and treatment of thyroid cancer; (3) preparation of products for hangover relief and liver protection; (4) preparation of products for improving sleep. In the present invention, the products preferably include pharmaceuticals, food or cosmetics.

[0030] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0031] Unless otherwise specified, the following embodiments are all conventional methods.

[0032] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0033] The α-amylase used in the following examples was purchased from Shandong Longket Enzyme Preparation Co., Ltd., the alkaline protease was purchased from Beijing Kangruina Biotechnology Co., Ltd., and the papain was purchased from Nanning Pangbo Biotechnology.

[0034] Example 1 A method for preparing prickly pear juice with excellent taste and high nutritional value, the steps are as follows: Select fresh prickly pears that are 80-90% ripe and range in color from greenish-yellow to golden yellow. Remove any moldy, diseased, unripe, or overripe prickly pears. First, rinse the prickly pears with running water to remove surface dirt, impurities, and thorns. Then, feed the washed prickly pears into a low-temperature crusher for crushing. The particle size is controlled at 4mm, and the crushing temperature is 15℃~17℃. Spread the crushed material onto a belt press for low-temperature belt pressing. The belt speed is 1.0m / min, and the material thickness is 25mm. A low-temperature cooling system maintains the pressing temperature at 15℃~17℃ throughout the process. First, pre-press at 0.4MPa to dehydrate, then main press at 1.1MPa to extract juice, and finally deep press at 1.9MPa. Collect the pressed juice and coarsely filter it through an 80-mesh sieve to remove large particles such as peel, seeds, and coarse fiber. Collect the juice, adjust the pH to 4.0, and mix it with rice protein powder. The volume-to-mass ratio of juice to rice protein powder is... The ratio of 100 mL to 0.6 g was used. The mixture was stirred and adsorbed at 4-6℃ and 170 r / min for 30 min. After adsorption, the mixture was allowed to stand for 25 min. Then, 300 U of food-grade laccase was added per 1 L of juice. The mixture was stirred at 8℃ and 80 r / min for 60 min. The mixture was then centrifuged at 7000 r / min for 13 min. The clarified liquid was then adsorbed onto a food-grade D113-FG macroporous weakly acidic cation exchange resin column with a column diameter-to-height ratio of 1:8 and a sample loading flow rate of 1.5 BV / h. The resin effluent was collected and vacuum concentrated at 55℃ and -0.08 MPa until the soluble solids content reached 71°Brix. The mixture was then bottled, with the headspace controlled to be ≤5%. Finally, it was sterilized at 105℃ for 25 s to obtain prickly pear juice with excellent taste and high nutritional value.

[0035] The preparation method of the rice protein powder used in the above preparation method is as follows: Rice and water were mixed at a ratio of 1g:6mL and then ground in a colloid mill until the fineness reached 80 mesh. The mixture was then gelatinized at 90℃ for 20 minutes, and the pH was adjusted to 6.5. α-Amylase was then added at a rate of 1.0U / g of rice for enzymatic hydrolysis 1. The enzymatic hydrolysis 1 was carried out at a temperature of 55℃, a stirring speed of 180r / min, and a time of 1.0h. After the enzymatic hydrolysis 1 was completed, the enzyme was inactivated at 100℃ for 9 minutes.

[0036] Then adjust the pH to 8.5, add alkaline protease at a rate of 1500 U / g rice, and stir to perform enzymatic hydrolysis 2. The temperature of enzymatic hydrolysis 2 is 60℃ and the time is 3h. After enzymatic hydrolysis 2 is completed, inactivate the enzyme at 100℃ for 9min.

[0037] The pH was adjusted to 6.5, and papain was added at a rate of 3000 U / g of rice for enzymatic hydrolysis 3. The hydrolysis 3 was performed at 50℃ for 2 hours. After hydrolysis 3, the enzyme was inactivated at 100℃ for 9 minutes. The mixture was cooled to room temperature and centrifuged at 6000 rpm for 15 minutes to remove the bottom starch and fiber precipitates. The supernatant was collected. Activated carbon was added to the supernatant at a volume-to-mass ratio of 100 mL:0.2 g. The mixture was then stirred at 50℃ for 30 minutes for adsorption. After filtration through a 0.22 μm filter to remove the activated carbon, the clarified protein solution was collected and concentrated under vacuum at -0.08 MPa and 48℃ to 23% solids. The solution was then spray-dried at an inlet air temperature of 165℃, an outlet air temperature of 78℃, and a misting pressure of 1.8 MPa. The dried powder was passed through a 100-mesh sieve to obtain rice protein powder.

[0038] Example 2 A method for preparing prickly pear juice with excellent taste and high nutritional value, the steps are as follows: Select fresh prickly pears that are 80-90% ripe and range in color from greenish-yellow to golden yellow. Remove any moldy, diseased, unripe, or overripe prickly pears. First, rinse the prickly pears with running water to remove surface dirt, impurities, and thorns. Then, feed the washed prickly pears into a low-temperature crusher for crushing. The particle size is controlled at 3mm, and the crushing temperature is 16℃~18℃. Spread the crushed material onto a belt press for low-temperature belt pressing. The belt speed is 1.5m / min, and the material thickness is 30mm. A low-temperature cooling system maintains the pressing temperature at 16℃~18℃ throughout the process. First, pre-press at 0.3MPa to dehydrate, then main press at 1.0MPa to extract juice, and finally deep press at 1.8MPa. Collect the pressed juice and coarsely filter it through an 80-mesh sieve to remove large particles such as peel, seeds, and coarse fiber. Collect the juice, adjust the pH to 3.8, and mix it with rice protein powder. The volumetric mass ratio of the juice to the rice protein powder is... The ratio of 100mL to 0.4g was used for adsorption by stirring at 6-8℃ and 150r / min for 25min. After adsorption, the mixture was allowed to stand for 20min. Then, 100U of food-grade laccase was added per 1L of juice, and the mixture was stirred at 4℃ and 60r / min for 90min. The mixture was then centrifuged at 6000r / min for 10min. The clarified liquid was then adsorbed onto a food-grade D113-FG macroporous weakly acidic cation exchange resin column with a column diameter-to-height ratio of 1:6 and a sample loading flow rate of 1 BV / h. The resin effluent was collected and vacuum concentrated at 45℃ and -0.07MPa until the soluble solids content reached 70°Brix. The mixture was then bottled, with the headspace controlled to be ≤5%. Finally, it was sterilized at 105℃ for 20s to obtain prickly pear juice with excellent taste and high nutritional value.

[0039] The preparation method of the rice protein powder used in the above preparation method is as follows: Rice and water were mixed at a ratio of 1g:5mL and then ground in a colloid mill until the fineness reached 80 mesh. The mixture was then gelatinized at 90℃ for 20 minutes, and the pH was adjusted to 6. α-amylase was then added at a rate of 0.6U / g of rice for enzymatic hydrolysis 1. The enzymatic hydrolysis 1 was carried out at a temperature of 50℃, a stirring speed of 180r / min, and a time of 0.5h. After the enzymatic hydrolysis 1 was completed, the enzyme was inactivated at 100℃ for 9 minutes.

[0040] Then adjust the pH to 8.0, add alkaline protease at a rate of 1000 U / g of rice, and stir to perform enzymatic hydrolysis 2. The temperature of enzymatic hydrolysis 2 is 55℃ and the time is 2.5h. After enzymatic hydrolysis 2 is completed, inactivate the enzyme at 100℃ for 9min.

[0041] The pH was adjusted to 6, and papain was added at a rate of 2400 U / g of rice for enzymatic hydrolysis 3. The hydrolysis 3 was performed at 45℃ for 1 hour. After hydrolysis 3, the enzyme was inactivated at 100℃ for 9 minutes. The mixture was cooled to room temperature and centrifuged at 6000 rpm for 15 minutes to remove the bottom starch and fiber precipitates. The supernatant was collected. Activated carbon was added to the supernatant at a volume-to-mass ratio of 100 mL:0.1 g. The mixture was then stirred at 45℃ for 25 minutes for adsorption. After filtration through a 0.22 μm filter to remove the activated carbon, the clarified protein solution was collected and concentrated under vacuum at -0.07 MPa and 45℃ to 20% solids. The solution was then spray-dried at an inlet air temperature of 160℃, an outlet air temperature of 75℃, and a nebulization pressure of 1.8 MPa. The dried powder was then passed through a 100-mesh sieve to obtain rice protein powder.

[0042] Example 3 A method for preparing prickly pear juice with excellent taste and high nutritional value, the steps are as follows: Select fresh prickly pears that are 80-90% ripe and range in color from greenish-yellow to golden yellow. Remove any moldy, diseased, unripe, or overripe prickly pears. First, rinse the prickly pears with running water to remove surface dirt, impurities, and thorns. Then, feed the washed prickly pears into a low-temperature crusher for crushing. The particle size is controlled at 6mm, and the crushing temperature is 18℃~20℃. Spread the crushed material onto a belt press for low-temperature belt pressing. The belt speed is 0.5m / min, and the material thickness is 20mm. A low-temperature cooling system maintains the pressing temperature at 18℃~20℃ throughout the process. First, pre-press at 0.5MPa to dehydrate, then main press at 1.2MPa to extract juice, and finally deep press at 2.0MPa. Collect the pressed juice and coarsely filter it through an 80-mesh sieve to remove large particles such as peel, seeds, and coarse fiber. Collect the juice, adjust the pH to 4.2, and mix it with rice protein powder. The volume-to-mass ratio of juice to rice protein powder is... The ratio of 100 mL to 0.8 g was used. The mixture was stirred and adsorbed at 6-8℃ and 200 r / min for 35 min. After adsorption, the mixture was allowed to stand for 30 min. Then, 500 U of food-grade laccase was added per 1 L of juice. The mixture was stirred and reacted at 10℃ and 100 r / min for 40 min. The mixture was then centrifuged at 8000 r / min for 15 min. The clarified liquid was then adsorbed onto a food-grade D113-FG macroporous weakly acidic cation exchange resin column with a column diameter-to-height ratio of 1:10 and a feed flow rate of 2 BV / h. The resin effluent was collected and vacuum concentrated at 75℃ and -0.09 MPa until the soluble solids content reached 72°Brix. The mixture was then bottled, with the headspace controlled to be ≤5%. Finally, it was sterilized at 105℃ for 30 s to obtain prickly pear juice with excellent taste and high nutritional value.

[0043] The preparation method of the rice protein powder used in the above preparation method is as follows: Rice and water were mixed at a ratio of 1g:7mL and then ground in a colloid mill until the fineness reached 80 mesh. The mixture was then gelatinized at 90℃ for 20 minutes, and the pH was adjusted to 7. α-Amylase was then added at a rate of 1.2U / g of rice for enzymatic hydrolysis 1. The enzymatic hydrolysis 1 was carried out at a temperature of 60℃, a stirring speed of 180r / min, and a time of 1.5h. After the enzymatic hydrolysis 1 was completed, the enzyme was inactivated at 100℃ for 9 minutes.

[0044] Then adjust the pH to 9.5, add alkaline protease at a rate of 2000 U / g of rice, and stir to perform enzymatic hydrolysis 2. The temperature of enzymatic hydrolysis 2 is 65℃ and the time is 4h. After enzymatic hydrolysis 2 is completed, inactivate the enzyme at 100℃ for 9min.

[0045] The pH was adjusted to 7, and papain was added at a rate of 4800 U / g rice for enzymatic hydrolysis 3. The hydrolysis 3 was performed at 55℃ for 3 hours. After hydrolysis 3, the enzyme was inactivated at 100℃ for 10 minutes. The mixture was cooled to room temperature and centrifuged at 6000 rpm for 15 minutes to remove the bottom starch and fiber precipitates. The supernatant was collected. Activated carbon was added to the supernatant at a volume-to-mass ratio of 100 mL:0.2 g. The mixture was then stirred at 55℃ for 35 minutes for adsorption. After filtration through a 0.22 μm filter to remove the activated carbon, the clarified protein solution was collected and concentrated under vacuum at -0.09 MPa and 50℃ to 25% solids. The solution was then spray-dried at an inlet air temperature of 170℃, an outlet air temperature of 80℃, and a nebulization pressure of 1.8 MPa. The dried powder was then passed through a 100-mesh sieve to obtain rice protein powder.

[0046] Comparative Example 1 The difference from Example 1 is that the step of removing the astringency of rice protein powder is replaced by adsorption using macroporous adsorption resin, while the rest is the same as in Example 1.

[0047] Comparative Example 2 The difference from Example 1 is that the rice protein powder was not subjected to sequential enzymatic hydrolysis by alkaline protease and papain during preparation; all other aspects are the same as in Example 1.

[0048] Comparative Example 3 The difference from Example 1 is that the volume-to-mass ratio of juice to rice protein powder is 100mL:1g, while the rest is the same as Example 1.

[0049] Comparative Example 4 The difference from Example 1 is that the food-grade D113-FG macroporous weak acid cation exchange resin column was not used for adsorption treatment; otherwise, it is the same as Example 1.

[0050] Comparative Example 5 The difference from Example 1 is that the amount of α-amylase added during the preparation of rice protein powder is 1.5 U / g, while the rest is the same as in Example 1.

[0051] Comparative Example 6 The difference from Example 1 is that no activated carbon was added for adsorption during the preparation of rice protein powder; otherwise, they are the same as in Example 1.

[0052] Example 4 Fresh prickly pear fruit (from Longli, Guizhou, at 80-90% ripe) from the same batch were used to prepare prickly pear juice products according to the methods of Example 1 and Comparative Examples 1 to 6. Three parallel experiments were set up for each group, and the final results were averaged.

[0053] The detection indicators were tannin content, vitamin C (VC) content, and SOD enzyme activity. Tannin content was detected using the Folin-phenol colorimetric method (calculated as gallic acid), VC content using the 2,6-dichlorophenolindophenol titration method, and SOD enzyme activity using the pyrogallol autoxidation method (with 50% inhibition rate defined as one unit of enzyme activity, U). The tannin removal rate, VC retention rate, and SOD retention rate were calculated for each group. The tannin removal rate (%) = (tannin content of the original juice after coarse filtration - tannin content of the finished product) ÷ tannin content of the original juice after coarse filtration × 100%; the VC retention rate (%) = VC content of the finished product ÷ VC content of the original juice after coarse filtration × 100%; and the SOD retention rate (%) = SOD activity of the finished product ÷ SOD activity of the original juice after coarse filtration × 100%. The original juice after coarse filtration refers to the juice collected after coarse filtration following low-temperature belt pressing.

[0054] The results are shown in Table 1, indicating that the prickly pear juice prepared by the complete process of this invention has the highest tannin removal rate, and at the same time, the VC retention rate and SOD retention rate are both high, achieving a balance between efficient deastringency removal and high retention of heat-sensitive nutrients.

[0055] Table 1. Detection results for different groups

[0056] Comparative Example 7 The difference from Example 1 is that the low-temperature belt pressing process is a direct pressing at 2.2 MPa, while the rest is the same as Example 1.

[0057] Example 5 After the same batch of fresh prickly pear fruit was crushed at low temperature using the method in Example 1, it was divided into six equal parts. The low-temperature belt pressing of Example 1 and the low-temperature belt pressing of Comparative Example 7 were then performed separately. Three parallel experiments were conducted on each group. The coarse filtrate was collected and the tannin content, vitamin C content, SOD enzyme activity and juice yield were tested. The final results are expressed as mean ± standard deviation.

[0058] The results are shown in Table 2. The three-stage gradient slow extrusion method provided by this invention results in gradual juice extraction; single-stage high pressure easily causes compaction and caking of the pomace, sealing of pores, and lower juice yield. Single-stage instantaneous high pressure causes intense friction of the pulp and localized instantaneous heating, leading to ascorbic acid oxidation and degradation, a significant decrease in vitamin C content, and sudden pressure also causes denaturation and inactivation of SOD enzyme protein, resulting in a significant reduction in activity.

[0059] Table 2. Effects of different low-temperature belt pressing methods on prickly pear juice.

[0060] Example 6 Using the same batch of fresh prickly pear fruit, prickly pear juice was prepared according to the methods of Example 1 and Comparative Examples 1 to 7. Three parallel experiments were conducted for each group. Ten professionally trained food sensory evaluators (five men and five women, aged 22-40 years) were selected. All participants had no olfactory or gustatory impairments and were prohibited from consuming spicy or irritating foods for 24 hours prior to the evaluation, and from smoking or eating for 1 hour prior to the evaluation.

[0061] The evaluation was conducted in a standard sensory evaluation room (natural light, temperature 20-25℃, relative humidity 50%-60%), with single-person, single-room setups to avoid mutual interference. Each group's prickly pear juice samples were placed in identical colorless, transparent tasting cups, 30mL per cup, and randomly numbered with three digits. The evaluations were conducted blindly. Purified water was provided for rinsing the mouth during the evaluation process, and adjacent samples were evaluated at least 3 minutes apart. A 9-point scale was used for scoring, and the specific scoring criteria are shown in Table 3 below.

[0062] Table 3 Scoring Criteria

[0063] The average score from 10 evaluators was taken as the final result, rounded to one decimal place. The results are shown in Table 4. This indicates that the prickly pear juice prepared by the complete preparation method of this invention has better sensory quality, with almost no obvious astringency, very weak bitterness, a harmonious balance of sweet and sour, a rich fruity aroma, a bright golden color, and high overall acceptability, significantly superior to all comparative examples. The results presented by each comparative example show that this invention, through a dual astringency removal system of targeted deastringency removal with rice protein powder and adsorption with macroporous adsorption resin, can effectively remove the sour and bitter taste of prickly pear juice while retaining the natural fruity aroma of prickly pear, resulting in excellent sensory quality. The three-step enzymatic hydrolysis preparation process of rice protein powder and the post-treatment of debittering and decolorizing with activated carbon are necessary conditions to ensure the purity of the rice protein powder flavor and prevent the introduction of off-flavors. The three-stage gradient low-temperature pressing helps maintain the color and aroma of the juice, and the appropriate amount of rice protein added is the optimal balance point between the astringency removal effect and flavor harmony. The various technical features work together synergistically to give the prickly pear juice of this invention excellent sensory quality: low sourness and astringency, rich fruity aroma, bright color, and harmonious taste.

[0064] Table 4 Sensory evaluation results for each group

[0065] Example 7 After preparing prickly pear juice using the method of Example 1, the following tests were conducted on prickly pear juices that were freshly processed (0 days), refrigerated at 4℃ for 30 days, and refrigerated at 4℃ for 60 days: (1) Microbial safety test: Total colony count test shall be conducted in accordance with GB 4789.2, coliform bacteria test shall be conducted in accordance with GB 4789.3, Salmonella test shall be conducted in accordance with GB 4789.4, Staphylococcus aureus test shall be conducted in accordance with GB 4789.10, Listeria monocytogenes test shall be conducted in accordance with GB 4789.30, and mold and yeast test shall be conducted in accordance with GB 4789.15.

[0066] The results showed that the total bacterial count was <10 CFU / mL at 0 days; <10 CFU / mL at 30 days; and <20 CFU / mL at 60 days. Coliform bacteria, Salmonella, Staphylococcus aureus, and Listeria monocytogenes were not detected, and molds and yeasts were <5 CFU / mL throughout the entire period.

[0067] (2) Changes in soluble protein content and turbidity during storage: The results showed that the soluble protein content of the product in Example 1 was extremely low, the turbidity increase was minimal after 60 days of storage, and there was no large amount of visible protein flocculent precipitate. This indicates that most of the rice protein was bound to tannins to form precipitates, which were removed by centrifugation, resulting in a low free protein content in the finished product. Furthermore, no protein flocculents were continuously generated during storage, eliminating any safety or sensory risks associated with protein precipitation.

[0068] (3) Detection of lead, arsenic, cadmium, mercury and common organophosphate and pyrethroid pesticide residues.

[0069] In accordance with the provisions of GB 2762-2022 "National Food Safety Standard - Limits of Contaminants in Food" under the category of "Fruit and Vegetable Juices and Beverages", the prickly pear juice prepared in Example 1 was tested for lead (Pb), cadmium (Cd), total arsenic (As), and total mercury (Hg). The test results showed that the lead content was far below 0.05 mg / kg, the cadmium content was far below ≤0.03 mg / kg, the total arsenic content was far below 0.1 mg / kg, and total mercury was not detected. All test results complied with the provisions of GB 2762-2022.

[0070] Meanwhile, in accordance with the provisions of GB 2763-2021 "National Food Safety Standard Maximum Residue Limits for Pesticides in Food", this product underwent multi-pesticide residue scanning testing (referring to testing methods such as GB 23200.121). All detected pesticide residues were below the corresponding limit values, meeting the standard requirements.

[0071] Example 8 Example 1: Effect Test on the Prevention and Treatment of Thyroid Cancer by Prickly Pear Juice 1. Group settings: Blank control group: equal volume of physiological saline / complete culture medium; Positive control group: Sorafenib (5 μM, in vitro) / 20 mg / kg (in vivo); Low-dose group of prickly pear juice: prickly pear juice concentrate diluted 2 times (in vitro) / 10 mL / kg (in vivo); Medium-dose group of prickly pear juice: 20 mL / kg of undiluted prickly pear juice (in vitro); High-dose group of prickly pear juice: prickly pear juice concentrated 2 times (in vitro) / 40 mL / kg (in vivo).

[0072] 2. In vitro cell experiments 2.1 Inhibitory effect of prickly pear juice on the proliferation of human papillary thyroid carcinoma cells TPC-1 (CCK-8 assay) Take TPC-1 cells in logarithmic growth phase and use 5 × 10⁻⁶ cells. 3 Cells were seeded per well in a 96-well plate and cultured for 24 h. Then, different concentrations of prickly pear juice samples were added to each well, with 6 replicates per group. After culturing for another 24 h, 48 h, and 72 h, 10 μL of CCK-8 solution was added to each well and incubated for 2 h. The absorbance at 450 nm was measured using a microplate reader, and the cell proliferation inhibition rate was calculated.

[0073] The results, shown in Table 5, indicate that the prickly pear juice of the present invention has a significant inhibitory effect on the proliferation of TPC-1 cells, and this effect is time- and dose-dependent. After 72 h of treatment, the inhibition rate of the medium-dose group of prickly pear juice reached 56.2%, and the inhibition rate of the high-dose group reached 72.8%, which is close to the effect of the positive control sorafenib.

[0074] Table 5. Results of the inhibitory effect of prickly pear juice on TPC-1 cell proliferation.

[0075] 2.2 Effect of prickly pear juice on TPC-1 cell apoptosis (flow cytometry) Take TPC-1 cells in logarithmic growth phase, at 2×10 5 Cells were seeded per well in 6-well plates and cultured for 24 h. Various concentrations of prickly pear juice were then added, and the cells were cultured for another 48 h. Cells were collected, washed twice with PBS, and double-stained with Annexin V-FITC and PI. Apoptosis rate was detected by flow cytometry.

[0076] The results are shown in Table 6. Prickly pear juice significantly induced apoptosis in TPC-1 cells in a dose-dependent manner. The total apoptosis rate in the high-dose group reached 45.7%, which was superior to the positive control group, suggesting that prickly pear juice mainly exerts its anti-thyroid cancer effect by inducing apoptosis.

[0077] Table 6. Effects of prickly pear juice on TPC-1 cell apoptosis.

[0078] 2.3 Effects of prickly pear juice on TPC-1 cell migration and invasion (Transwell assay) Migration assay: Transwell chamber (uncoated with Matrigel), add 200 μL of cell suspension (containing 1×10⁻⁶ cells) to the upper chamber. 5 (100 cells), add 600 μL of culture medium containing 10% fetal bovine serum to the lower chamber, culture for 24 h, fix and stain, and count the number of cells that have penetrated the membrane.

[0079] Invasion test: Transwell chambers (Matrigel coated), same method as above, count after 48 h of incubation.

[0080] The results are shown in Table 7. Prickly pear juice significantly inhibited the migration and invasion of TPC-1 cells in a dose-dependent manner. The high-dose group showed a migration inhibition rate of 68.8% and an invasion inhibition rate of 69.4%, suggesting that prickly pear juice has a potential role in inhibiting thyroid cancer metastasis.

[0081] Table 7. Effects of prickly pear juice on TPC-1 cell migration and invasion.

[0082] 3. In vivo animal experiments 3.1 Inhibitory effect of prickly pear juice on the growth of TPC-1 xenografts in nude mice Take TPC-1 cells in logarithmic growth phase and adjust the concentration to 5 × 10⁻⁶. 6 0.2 mL / mouse was subcutaneously injected into the right back of BALB / c nude mice; the tumor volume was increased to approximately 100 mm. 3 At that time, the nude mice were randomly divided into 5 groups of 8 mice each: Blank control group: 0.2 mL of normal saline was administered by gavage to each animal once daily; Positive control group: Sorafenib 20 mg / kg by gavage, once daily; Low-dose group of prickly pear juice: 10 mL / kg by gavage, once daily; Medium-dose group of prickly pear juice: 20 mL / kg by gavage, once daily; High-dose group of prickly pear juice: 40 mL / kg by gavage, once daily; The drug was administered continuously for 28 days, and the long diameter (a) and short diameter (b) of the tumor were measured every 14 days. The tumor volume V was calculated as V = 1 / 2 × a × b. 2 ; Twenty-four hours after the last administration, nude mice were euthanized by cervical dislocation, tumors were removed and weighed, and tumor inhibition rate was calculated.

[0083] The results of tumor volume changes are shown in Table 8, and the results of tumor weight and tumor inhibition rate are shown in Table 9. This indicates that the prickly pear juice of the present invention can significantly inhibit the growth of TPC-1 xenografts in nude mice in a dose-dependent manner. The tumor inhibition rate in the high-dose group reached 65.1%, which was superior to the positive control sorafenib group (61.9%), suggesting that prickly pear juice has a good anti-thyroid cancer effect in vivo.

[0084] Table 8 Tumor volume changes

[0085] Table 9 Results of tumor weight and tumor inhibition rate

[0086] 3.2 Effects of prickly pear juice on the immune function of tumor-bearing mice After the last administration, blood was collected by enucleation, serum was separated, and the TNF-α content in the serum was detected by ELISA. After sacrifice, the spleen was collected and the spleen index was calculated. Splenic lymphocytes were separated and the NK cell killing activity was detected by MTT assay.

[0087] The results are shown in Table 10. Unlike the positive control sorafenib (a chemotherapy drug that suppresses immunity), prickly pear juice significantly increased the spleen index of tumor-bearing mice, increased serum TNF-α and other cytokine levels, and enhanced NK cell killing activity. This suggests that prickly pear juice not only directly inhibits tumor cells, but also exerts an indirect anti-tumor effect by enhancing the body's immune function. This is an important advantage that distinguishes it from traditional chemotherapy drugs.

[0088] Table 10 Effects of prickly pear juice on immune function in tumor-bearing mice

[0089] 4. Safety evaluation of prickly pear juice (organ index and liver and kidney function) After sacrifice, the heart, liver, kidneys, and lungs were harvested, and organ indices were calculated. Serum ALT, AST, BUN, Cr, and other liver and kidney function indicators were measured. The results are shown in Table 11. There were no significant differences in organ indices and liver and kidney function indicators between the high-dose prickly pear juice group and the blank control group (P>0.05), while the positive control sorafenib group showed significant liver and kidney function impairment. This suggests that prickly pear juice has good safety within its effective dose range and no significant toxic side effects.

[0090] Table 11 Safety evaluation results of prickly pear juice

[0091] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing prickly pear juice with excellent taste and high nutritional value, characterized in that, The process includes the following steps: After low-temperature crushing of the prickly pear fruit, low-temperature belt pressing is performed. The juice is adjusted to pH 3.8-4.2, mixed with rice protein powder, stirred and adsorbed at 4-10℃, then allowed to stand. Food-grade laccase is added for reaction, centrifuged, and the clarified liquid is treated with an adsorption resin column. The resin effluent is collected, concentrated, and then bottled. High-temperature instantaneous sterilization is then performed; the low-temperature process is 15-25℃. The method for preparing the rice protein powder includes the following steps: Rice was ground into a paste and mixed with α-amylase for enzymatic hydrolysis 1. After enzyme inactivation, alkaline protease was added for enzymatic hydrolysis 2. After enzyme inactivation, papain was added for enzymatic hydrolysis 3. After enzyme inactivation, the supernatant was collected, activated carbon was added for adsorption, the activated carbon was removed, and the mixture was concentrated and dried.

2. The preparation method according to claim 1, characterized in that, The particle size of the low-temperature crushing is 3~6mm.

3. The preparation method according to claim 1, characterized in that, The low-temperature belt pressing includes the following steps: first, pre-pressing at 0.3~0.5 MPa, then main pressing at 1.0~1.2 MPa, and finally deep pressing at 1.8~2.0 MPa; the filter belt running speed of the low-temperature belt pressing is 0.5~1.5 m / min, and the material spreading thickness is 20~30 mm.

4. The preparation method according to claim 1, characterized in that, The volume-to-mass ratio of juice to rice protein powder is 100mL:0.4~0.8g; the stirring and adsorption speed is 150~200r / min, and the time is 25~35min; the settling time is 20~30min; the amount of food-grade laccase added is 100~500U per 1L of juice; the reaction temperature for adding food-grade laccase is 4~10℃, the stirring speed is 60~100r / min, and the time is 40~90min; the centrifugation speed is 6000~8000r / min, the time is 10~15min, and the temperature is ≤10℃.

5. The preparation method according to claim 1, characterized in that, The adsorption resin is a macroporous weakly acidic cation exchange resin; the column diameter-to-height ratio is 1:6~10; the feed flow rate is 1~2 BV / h; and the resin adsorption temperature is 4~10℃.

6. The preparation method according to claim 1, characterized in that, The concentration includes vacuum concentration, wherein the vacuum concentration temperature is 45~75℃, the vacuum degree is -0.07~-0.09MPa, and the concentration is carried out to a soluble solids content of 70~72°Brix; the high-temperature instantaneous sterilization conditions are sterilization at 105℃ for 20~30s.

7. The preparation method according to claim 1, characterized in that, The amount of α-amylase added was 0.6~1.2 U / g rice; the pH for enzymatic hydrolysis 1 was 6~7, the temperature was 50~60℃, and the time was 0.5~1.5h; the amount of alkaline protease added was 1000~2000 U / g rice; the pH for enzymatic hydrolysis 2 was 8.0~9.5, the temperature was 55~65℃, and the time was 2.5~4h; the amount of papain added was 2400~4800 U / g rice; the pH for enzymatic hydrolysis 3 was 6~7, the temperature was 45~55℃, and the time was 1~3h.

8. The preparation method according to claim 1, characterized in that, The enzyme inactivation conditions are: incubation at 100℃ for 8-10 min; the volume-to-mass ratio of supernatant to activated carbon is 100 mL: 0.1-0.2 g; the activated carbon adsorption conditions are: stirring and adsorption at 45-55℃ for 25-35 min; the activated carbon is removed by filtration through a 0.22 μm filter membrane; the concentration and drying include vacuum concentration and spray drying; the vacuum degree of vacuum concentration is -0.07 to -0.09 MPa, the temperature is 45-50℃, and the concentration is reduced to 20%-25% solids; the inlet air temperature of spray drying is 160-170℃, the outlet air temperature is 75-80℃, and the atomization pressure is 1.8 MPa.

9. The prickly pear juice prepared by the preparation method according to any one of claims 1 to 8.

10. The use of the prickly pear juice according to claim 9 in any of the following, characterized in that: (1) Prepare antioxidant products; (2) Prepare products for the prevention and treatment of thyroid cancer; (3) Prepare products for the relief of hangovers and liver protection; (4) Prepare products for the improvement of sleep.

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