Pomegranate juice based on whole fruit utilization as well as preparation method and application thereof

Abstract

The invention relates to the technical field of food processing, and discloses a preparation method of grenadine juice based on full fruit utilization, the grenadine juice prepared by the method and application of the grenadine juice. Aiming at the problems of waste of pericarp and fruit seeds, low extraction efficiency, large loss of nutritional ingredients, poor clarity, influence on quality in a sterilization process and the like in traditional pomegranate juice processing, the preparation method comprises the following steps: crushing whole pomegranate fruits, and sequentially carrying out composite enzymolysis, pulsed electric field treatment and cold squeezing to obtain primary pomegranate juice and filter residues; performing pH regulation and ultrasonic-assisted extraction on filter residues to obtain a secondary extracting solution, mixing the primary pomegranate juice and the secondary extracting solution, performing microfiltration clarification through a ceramic membrane, performing combined sterilization through a pulsed electric field and ultrahigh pressure, and performing sterile filling, thereby realizing efficient utilization of the whole pomegranate fruits, improving the juice yield and the content of functional components, and reducing the production cost. The clarity, the stability and the sensory quality of the product are improved. The prepared pomegranate juice can be used for functional beverages, health-care products or food additives.

Description

Technical Field

[0001] This invention relates to the field of food processing technology. More specifically, this invention relates to a pomegranate juice based on the utilization of the whole fruit, its preparation method, and its application. Background Technology

[0002] Pomegranate( Punica granatum Pomegranate (L.) is a nutritious fruit, its juice rich in polyphenols (such as anthocyanins and ellagic acid), vitamins, and minerals, exhibiting excellent antioxidant activity and making it popular with consumers. Traditional pomegranate juice processing primarily aims to extract the pulp and juice. The conventional process typically includes washing, peeling, and removing the seeds from the fresh pomegranate, or crushing it whole, followed by mechanical pressing to extract the juice. Subsequent clarification (such as centrifugation and filtration) and heat sterilization (such as pasteurization or ultra-high temperature sterilization) are then performed to achieve commercial sterility and extend shelf life. However, this conventional processing model, centered on the pulp and juice, has several inherent technical problems and drawbacks, especially in the context of pursuing higher nutritional value, better sensory quality, and more comprehensive resource utilization.

[0003] From a raw material utilization perspective, the peel and seeds of pomegranate fruit account for approximately 30%-50% of the whole fruit's weight. Traditional processing methods often discard the peel and seeds as waste. Studies have shown that the content of bioactive substances such as polyphenols and flavonoids (e.g., ellagic acid and pungent glycosides) in pomegranate peel and seeds is much higher than in the pulp. Therefore, the traditional method of extracting only the pulp juice results in the loss of a large amount of high-value functional components, not only wasting resources but also limiting the further improvement of the nutritional value of the final product. Achieving efficient and high-value utilization of the entire pomegranate fruit is a challenge facing the industry. The difficulty lies in how to effectively release and retain these active ingredients from the dense peel and hard seeds, while avoiding the negative effects of rough texture and excessive astringency caused by the fiber and lignin abundant in these parts.

[0004] In terms of extraction efficiency and component retention, traditional single-pressing methods are not thorough enough in releasing intracellular contents, especially for the cell structures of the peel and seeds, resulting in a relatively low juice yield. To improve juice yield or extract by-products, heating or high-intensity mechanical treatment is sometimes used, but this can easily lead to the degradation and destruction of heat-sensitive active ingredients (such as anthocyanins and vitamin C), and may exacerbate the dissolution of off-flavor substances or produce a "cooked" taste due to high temperatures. Although enzymatic hydrolysis can be used to assist extraction, if the enzyme system is not properly selected or the process parameters are not well controlled (such as temperature, pH, and time), problems such as incomplete cell wall disruption, lack of specificity, or excessive hydrolysis leading to difficulties in juice clarification and abnormal release of flavor substances (such as the production of bitterness) may occur. How to achieve gentle, efficient, and selective cell wall disruption and release of intracellular contents is the key to improving juice yield and the extraction rate of functional components.

[0005] In the clarification and stability of fruit juice, the pomegranate juice after pressing usually contains unstable components such as pulp particles, colloids, starch and soluble macromolecules (such as proteins, polysaccharides). Traditional clarification methods such as high-speed centrifugation may not completely remove small particles, and the use of filter aids may introduce foreign substances and increase costs. Membrane filtration technology (such as microfiltration) is an effective clarification method, but these unstable substances in the fruit juice can easily cause membrane pollution, leading to rapid decline in membrane flux, reduced filtration efficiency, frequent cleaning and increased operating costs. How to effectively and gently promote the aggregation and removal of these unstable substances before membrane filtration without relying on chemical filter aids or harsh physical treatments that may affect the quality is a technical difficulty in improving clarification efficiency and maintaining long-term stability of the product.

[0006] In the sterilization and quality maintenance, heat treatment (such as pasteurization) is the most commonly used sterilization method in the fruit juice industry, but its thermal effect inevitably causes damage to heat-sensitive color substances (such as anthocyanins), flavor substances and some vitamins in pomegranate juice, resulting in darkening of the color of the juice, generation of cooked and stale flavors, and decrease in nutritional value. Non-thermal sterilization techniques, such as ultra-high pressure (HPP) treatment, can better preserve the quality, but have limited effect on the killing of some pressure-resistant microorganisms (such as spores), which may affect the long-term microbial safety of the product. Pulse electric field (PEF) treatment has a certain inhibitory effect on microorganisms and has little effect on quality, but single use sometimes cannot achieve complete commercial sterility. Therefore, exploring a sterilization strategy that can ensure microbial safety while maximizing the preservation of the fresh quality of pomegranate juice is a problem that the industry continues to focus on.

[0007] In the process of pursuing full fruit utilization, secondary extract obtained from by-products such as fruit peels and seeds is rich in functional components such as polyphenols, but also often accompanied by a more intense astringency. If it is directly added back to the main product, although it can improve the nutritional value, it may lead to excessive astringency of the final product, affecting the sensory acceptance of consumers. How to effectively balance the nutritional functionality and sensory palatability of the product while utilizing these high-value by-products is another contradiction that needs to be solved in the development of pomegranate full fruit utilization technology. SUMMARY

[0008] An object of the present application is to solve at least the above problems and to provide at least the advantages to be explained later.

[0009] In order to achieve these objects and other advantages according to the present application, a preparation method of pomegranate juice based on full fruit utilization is provided, comprising: S1, crushing the pomegranate fresh fruit into pomegranate pulp after washing, the pomegranate pulp containing fruit peels, seeds and pulp; S2, adding a complex enzyme preparation to the pomegranate pulp, and enzymatically hydrolyzing at 35-50℃ for 1-3h; the complex enzyme preparation comprises the following mass percentages of enzymes: pectinase 40%-50%, cellulase 20%-25%, hemicellulase 10%-15%, β-glucosidase 8%-12%, and xylanase 5%-8%; the complex enzyme preparation is added in an amount of 0.01%-0.05% of the mass of the pomegranate pulp; S3, treating the enzymatically hydrolyzed pomegranate pulp under the conditions of an electric field intensity of 15-40kV / cm, a pulse width of 10-100μs, and a pulse frequency of 100-500Hz for 100-500μs; S4, cold-pressing the pomegranate pulp treated by the pulsed electric field, at a pressure of 0.5-2MPa, and filtering the pressed pulp through a 100-200 mesh screen to obtain primary pomegranate juice and residue; S5, adding pure water to the residue obtained in the step S4 in a mass ratio of 1: (5-10), adjusting the pH of the solution to 3.0-4.0 using citric acid, and performing ultrasonic-assisted extraction at an ultrasonic power of 300-600W, a temperature of 50-70℃, and for a time of 10-30min, and then performing solid-liquid separation to obtain secondary extract; S6, mixing the primary pomegranate juice obtained in the step S4 with the secondary extract obtained in the step S5, and then microfiltering the mixed juice through a ceramic membrane with a pore size of 0.1-0.5μm to obtain clarified pomegranate juice; S7, first performing pulsed electric field treatment on the clarified pomegranate juice obtained, at an electric field intensity of 25-35kV / cm and for a treatment time of 50-100μs, and then performing ultrahigh pressure treatment at a pressure of 400-600MPa, a pressure maintaining time of 3-5min, and a temperature of 20-25℃, wherein the interval between the pulsed electric field treatment and the ultrahigh pressure treatment is not more than 60s; S8, filling the pomegranate juice sterilized by the ultrahigh pressure into a container in a sterile environment to obtain the pomegranate juice.

[0010] Preferably, before the pulsed electric field treatment in the step S7, 5%-15% of the secondary extract of the step S5 is added back to the clarified pomegranate juice, and the secondary extract is concentrated to a soluble solid content of 40-50°Brix at 50-60℃ and (-0.08)-(-0.10)MPa.

[0011] Preferably, the operation temperature of the ceramic membrane microfiltration in the step S6 is controlled at 15-25℃.

[0012] Preferably, the ultrasonic-assisted extraction in the step S5 is performed in an intermittent ultrasonic mode, with a working-to-interval time ratio of (1-3):1, and a single ultrasonic working time of not more than 5s.

[0013] Preferably, the enzymatic process in step S2 is divided into two steps, the first step is to add 60%-70% of the total mass of the complex enzyme preparation to the pomegranate pulp, and the enzymatic process is carried out at 38-42 DEG C and pH 3.5-4.0 for 40-60 min, and the second step is to add the remaining complex enzyme preparation, and the enzymatic process is carried out at 45-50 DEG C and pH 4.0-4.5 for 20-40 min, and the stirring is continuously carried out at a speed of 50-150 rpm during the enzymatic process.

[0014] Preferably, before the pulsed electric field treatment in step S3, the pomegranate pulp after enzymatic treatment is pre-filtered through a 50-100 mesh screen, and the screened pomegranate pulp is subjected to the subsequent pulsed electric field treatment in step S3. The components on the screen include the peel and the seeds, which are crushed by a wall breaking machine, and then mixed with the pomegranate pulp after the pulsed electric field treatment in step S3.

[0015] Preferably, after the cold pressing in step S4, the obtained primary pomegranate juice is aged at 4-10 DEG C for 12-24 h, and then subjected to the microfiltration operation in step S6.

[0016] Preferably, in step S5, after the ultrasonic-assisted extraction, the obtained secondary extraction liquid is subjected to astringency removal treatment before being added back, and the astringency removal treatment is carried out by embedding with beta-cyclodextrin, and the addition amount of the beta-cyclodextrin is 0.5%-1.5% of the mass of the secondary extraction liquid.

[0017] The application provides a pomegranate juice prepared by the method.

[0018] The application provides an application of the pomegranate juice in preparing a functional beverage, a health product or a food additive.

[0019] The application at least has the following beneficial effects: Firstly, the application effectively solves the technical problem of serious waste of peel and seeds in the traditional pomegranate juice processing by means of whole fruit crushing and secondary extraction process. The traditional process only uses the pulp and discards the peel and seeds which account for a high proportion of the whole fruit mass, resulting in a large loss of high-value functional components such as polyphenols and flavonoids. The application crushes the whole fresh pomegranate into pulp, and carries out ultrasonic-assisted extraction on the filter residue after pressing, adjusts the pH to an acidic environment by means of citric acid, fully releases the bioactive substances in the peel and seeds, and realizes efficient utilization of the whole pomegranate. This not only significantly improves the utilization rate of raw materials and reduces resource waste, but also enriches the final product with more functional components such as polyphenols, greatly improves the nutritional value and functionality of the pomegranate juice, and overcomes the nutritional limitations caused by the discarding of by-products in the traditional mode.

[0020] Secondly, the present application effectively solves the technical problems of low extraction efficiency and easy degradation of heat-sensitive components in traditional pressing method through the synergistic effect of complex enzymatic hydrolysis and pulsed electric field treatment. Traditional single pressing is not thorough in releasing the cell contents, especially for the dense structure of fruit peel and fruit seeds, resulting in low juice yield and easy damage to heat-sensitive active components during high-intensity treatment. The present application uses a complex enzyme preparation containing pectinase, cellulase, hemicellulase, β-glucosidase and xylanase for enzymatic hydrolysis at a mild temperature, which specifically degrades the cell wall components; combined with pulsed electric field treatment, the high-voltage electric pulse is used to instantaneously destroy the cell membrane structure, promoting the release of the contents. Subsequent cold pressing avoids thermal damage, thereby improving the juice yield while maximizing the retention of anthocyanins, vitamin C and other heat-sensitive functional components, achieving efficient and gentle extraction.

[0021] Thirdly, the present application effectively solves the technical problems of difficult clarification, poor stability and serious membrane pollution of pomegranate juice through the optimization of ceramic membrane microfiltration and the previous process. Traditional clarification methods such as centrifugation or filter aid are difficult to completely remove colloidal, protein and other unstable substances, and may introduce foreign impurities or cause membrane flux decline. In the present application, the primary pomegranate juice is mixed with the secondary extraction liquid, then microfiltration is carried out using ceramic membranes with precise pore size, combined with previous enzymatic hydrolysis, pulsed electric field treatment and cold pressing and standing aging steps, to promote the complete flocculation and sedimentation of unstable substances, reducing the impurity load directly entering the microfiltration. This not only significantly improves the clarity and transparency of the juice, but also effectively alleviates membrane pollution, prolongs the service life of the membrane, enhances the stability of the product during storage, and avoids the generation of sediment.

[0022] Fourthly, the present application uses a combination of pulsed electric field and ultra-high pressure sterilization strategy to effectively solve the technical problems of quality destruction by traditional heat sterilization and possible incomplete inactivation by single non-thermal sterilization. Heat treatment can lead to the degradation of heat-sensitive color, flavor substances and vitamins in pomegranate juice, while single ultra-high pressure treatment has limited effect on some pressure-resistant microorganisms. In the present application, pulsed electric field treatment is first carried out in the sterilization stage to weaken the microbial cell activity by electroporation, followed by ultra-high pressure treatment in a very short time, and the synergistic effect of the two achieves more complete microbial inactivation without the use of high temperature, meeting the commercial sterility requirements. This combined process maximizes the retention of fresh color, typical flavor and active ingredients (such as anthocyanins, polyphenols) in pomegranate juice, significantly improving the microbial safety and quality retention of the product.

[0023] Fifth, the present application optimizes the extraction conditions in the whole fruit utilization process, improves the nutritional value while considering the sensory palatability, effectively solves the technical problem that the excessive astringency of the by-product extraction liquid affects the taste. In the traditional whole fruit utilization, although the peel and seed extraction liquid is rich in polyphenols, it also introduces a large amount of astringent substances, resulting in strong astringency of the final product. In the secondary extraction liquid, citric acid is used to adjust the pH to an acidic environment, and ultrasonic assisted extraction is combined, which effectively dissolves the functional components such as polyphenols, and avoids excessive extraction of astringent substances through process parameter control (such as temperature, time); subsequent mixing and microfiltration further balance the components. This makes the final product retain high total phenol content and functionality, and the astringency is reasonably controlled, the taste is more coordinated, the sensory acceptance of consumers is improved, and a good balance between nutrition and taste is achieved.

[0024] Other advantages, objects, and features of the present application will be apparent from the following description, and will be understood by persons skilled in the art. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The preparation process schematic diagram of pomegranate juice of one of the technical solutions of the present application; Figure 2 The preparation process schematic diagram of pomegranate beverage of one of the technical solutions of the present application; Figure 3 The preparation process schematic diagram of pomegranate flavored yogurt of one of the technical solutions of the present application. DETAILED DESCRIPTION

[0026] The following examples and Figures 1 to 3 The present application is further described in detail to enable those skilled in the art to implement it with reference to the description.

[0027] It should be noted that the experimental methods described in the following embodiments are conventional methods, and the reagents and materials are commercially available unless otherwise specified.

[0028] <Embodiment 1> Preparation of pomegranate juice based on whole fruit utilization, including: Raw materials and equipment: 10 kg of fresh pomegranate fruit without rot; the complex enzyme preparation is composed of pectinase (45%), cellulase (22%), hemicellulase (12%), beta-glucosidase (10%), and xylanase (6%); citric acid, beta-cyclodextrin, and pure water are all food grade.

[0029] Main equipment: crusher, constant temperature stirring reaction tank, pulse electric field (PEF) treatment instrument, cold press, ultrasonic extraction instrument, ceramic membrane microfiltration system, ultra-high pressure (HPP) sterilization equipment, vacuum concentration tank, sterile filling line.

[0030] Preparation steps: S1, raw material processing: 10 kg of pomegranate fresh fruit is washed and broken into pomegranate pulp as a whole, which contains peel, seeds and pulp.

[0031] S2, complex enzymolysis: add complex enzyme preparation to the pomegranate pulp, the addition amount is 0.03% of the mass of the pomegranate pulp. The enzymolysis process is divided into two steps: First step: add 65% of the total mass of the complex enzyme preparation, and enzymolysis at 40℃, pH 3.8, with 100 rpm stirring for 50 min; Second step: add the remaining 35% of the complex enzyme preparation, and enzymolysis at 48℃, pH 4.2, with 100 rpm stirring for 30 min.

[0032] S3, pre-filtration and pulse electric field treatment: the pomegranate pulp after enzymolysis is pre-filtered through an 80-mesh screen, and the undersize part is sent to the pulse electric field treatment chamber for treatment under the conditions of electric field intensity 30 kV / cm, pulse width 50 μs, pulse frequency 300 Hz for 300 μs. The oversize components (mainly peel and seeds) are crushed by a wall breaking machine and mixed with the pomegranate pulp after pulse electric field treatment.

[0033] S4, cold pressing and standing aging: the mixed pomegranate pulp is cold pressed at a pressure of 1.2 MPa, and after pressing, it is filtered through a 150-mesh screen to obtain primary pomegranate juice and filter residue. The primary pomegranate juice is aged at 6℃ for 18 h.

[0034] S5, filter residue extraction and astringency removal treatment: the filter residue is added with pure water at a mass ratio of 1:8, and the solution pH is adjusted to 3.5 using citric acid. Intermittent ultrasonic assisted extraction is used: ultrasonic power 450 W, temperature 60℃, total time 20 min, work / intermittent time ratio 2:1, single ultrasonic working time 3 s.

[0035] After extraction, solid-liquid separation is carried out to obtain secondary extract. Add β-cyclodextrin with a mass of 1.0% to the secondary extract, and stir to dissolve for astringency removal treatment.

[0036] S6, mixing and microfiltration: mix the primary pomegranate juice obtained in S4 with the secondary extract after astringency removal obtained in S5. The mixed juice is micro-filtered through a ceramic membrane with a pore size of 0.2 μm, and the operation temperature is controlled at 20℃ to obtain clear pomegranate juice.

[0037] S7, Concentrate back-blending and non-thermal sterilization: The secondary extract obtained in S5 was concentrated under vacuum at 55℃ and -0.09 MPa to a soluble solid content of 45 °Brix.

[0038] Before pulsed electric field treatment, 10% of the concentrate described above was back-blended into the clarified pomegranate juice.

[0039] Pulsed electric field treatment was immediately performed thereafter: electric field strength 30 kV / cm, treatment time 80 μβ.

[0040] Immediately after pulsed electric field treatment, ultra-high pressure treatment was performed within an interval of no more than 60 s: pressure 500 MPa, pressure holding time 4 min, temperature maintained at 22℃.

[0041] S8, Aseptic filling: The pomegranate juice after ultra-high pressure sterilization was filled in a sterile environment, thereby obtaining the final product of pomegranate juice based on whole fruit utilization.

[0042] <Comparative Example 1> Pomegranate fresh fruit 10 kg, no rot; The complex enzyme preparation was composed of pectinase (61.4%), cellulase (26.4%), and hemicellulase (12.2%). (The ratio was recalculated by removing the shares of β-glucosidase (10%) and xylanase (6%) in Example 1 and ensuring the relative ratio of original pectinase, cellulase, and hemicellulase unchanged, while the total amount of enzyme preparation was unchanged); Citric acid, β-cyclodextrin, pure water, etc. were all food grade.

[0043] Preparation steps: S1, Raw material treatment: 10 kg of pomegranate fresh fruit was washed and then broken into pomegranate pulp, which contained peel, seeds, and pulp.

[0044] S2, Complex enzymatic hydrolysis: The complex enzyme preparation described above was added to the pomegranate pulp, with an addition amount of 0.03% of the mass of the pomegranate pulp. The enzymatic hydrolysis process was divided into two steps: First step: 65% of the total mass of the complex enzyme preparation was added, and the enzymatic hydrolysis was carried out at 40℃ and pH 3.8 with 100 rpm stirring for 50 min; Second step: the remaining 35% of the complex enzyme preparation was added, and the enzymatic hydrolysis was carried out at 48℃ and pH 4.2 with 100 rpm stirring for 30 min.

[0045] S3, pre-filtration and pulse electric field treatment: the pomegranate pulp after enzymatic hydrolysis was pre-filtered through an 80-mesh screen, and the undersize fraction was fed into a pulse electric field treatment chamber. The treatment was performed under the conditions of an electric field intensity of 30 kV / cm, a pulse width of 50 μs, and a pulse frequency of 300 Hz for 300 μs. The oversize fraction (mainly peel and seeds) was crushed by a cell crusher and mixed with the pomegranate pulp after pulse electric field treatment.

[0046] S4, cold pressing and standing aging: the mixed pomegranate pulp was cold-pressed at a pressure of 1.2 MPa, and the pressed product was filtered through a 150-mesh screen to obtain primary pomegranate juice and filter residue. The primary pomegranate juice was aged at 6°C for 18 h.

[0047] S5, filter residue extraction and astringency removal treatment: the filter residue was added with pure water at a mass ratio of 1:8, and the pH of the solution was adjusted to 3.5 using citric acid. Intermittent ultrasonic-assisted extraction was performed at an ultrasonic power of 450 W, a temperature of 60°C, a total time of 20 min, a work / interval time ratio of 2:1, and a single ultrasonic working time of 3 s.

[0048] After extraction, solid-liquid separation was performed to obtain secondary extract.

[0049] β-cyclodextrin was added to the secondary extract at a mass fraction of 1.0%, and the mixture was stirred and dissolved for astringency removal treatment.

[0050] S6, mixing and microfiltration: the primary pomegranate juice obtained in S4 was mixed with the secondary extract after astringency removal obtained in S5.

[0051] The mixed juice was micro-filtered through a ceramic membrane with a pore size of 0.2 μm at an operating temperature of 20°C to obtain clear pomegranate juice.

[0052] S7, concentrate back-adding and non-thermal sterilization: the secondary extract obtained in S5 was vacuum concentrated at 55°C and -0.09 MPa to a soluble solid content of 45°Brix.

[0053] Before pulse electric field treatment, the clear pomegranate juice was back-added with the above-mentioned concentrate at a mass fraction of 10%. Pulse electric field treatment was immediately performed at an electric field intensity of 30 kV / cm for 80 μs. After pulse electric field treatment, ultra-high pressure treatment was immediately performed within an interval of no more than 60 s at a pressure of 500 MPa for 4 min while maintaining the temperature at 22°C.

[0054] S8, sterile filling: the pomegranate juice after ultra-high pressure sterilization was filled in a sterile environment to obtain the final pomegranate juice product.

[0055] <Comparative Example 2> Pomegranate fresh fruit 10 kg, no rot; Compound enzyme preparation: composed of pectinase (45%), cellulase (22%), hemicellulase (12%), β-glucosidase (10%), xylanase (6%); Citric acid, β-cyclodextrin, pure water, etc. are all food grade; Preparation steps: S1, raw material processing: 10 kg of pomegranate fresh fruit is washed and broken into pomegranate pulp as a whole, which contains peel, seeds and pulp.

[0056] S2, compound enzymolysis: add compound enzyme preparation to the pomegranate pulp, the addition amount is 0.03% of the mass of the pomegranate pulp. The enzymolysis process is divided into two steps: First step: add 65% of the total mass of the compound enzyme preparation, and enzymolysis at 40℃, pH 3.8, with 100 rpm stirring for 50 min; Second step: add the remaining 35% of the compound enzyme preparation, and enzymolysis at 48℃, pH 4.2, with 100 rpm stirring for 30 min.

[0057] S3, pre-filtering and mixing: the enzymolyzed pomegranate pulp is pre-filtered through an 80-mesh screen. (This comparative example omits the pulsed electric field treatment step here. The undersize part is not treated by PEF, but directly mixed with the oversize component.) The oversize component (mainly peel and seeds) is crushed by a cell wall breaking machine and mixed with the undersize pomegranate pulp.

[0058] S4, cold pressing and standing aging: the mixed pomegranate pulp is cold pressed at a pressure of 1.2 MPa, and after pressing, it is filtered through a 150-mesh screen to obtain primary pomegranate juice and filter residue. The primary pomegranate juice is aged at 6℃ for 18 h.

[0059] S5, filter residue extraction and astringency removal treatment: the obtained filter residue is added with pure water at a mass ratio of 1:8, and the solution pH is adjusted to 3.5 using citric acid. Intermittent ultrasonic assisted extraction is used: ultrasonic power 450 W, temperature 60℃, total time 20 min, work / intermittent time ratio 2:1, single ultrasonic working time 3 s.

[0060] After extraction, solid-liquid separation is performed to obtain secondary extract.

[0061] β-cyclodextrin with a mass of 1.0% is added to the secondary extract, and stirring and dissolution are performed for astringency removal treatment.

[0062] S6, mixing and microfiltration: the primary pomegranate juice obtained in S4 is mixed with the secondary extract after astringency removal obtained in S5. The mixed juice is micro-filtered through a ceramic membrane with a pore size of 0.2 μm, and the operation temperature is controlled at 20℃ to obtain clear pomegranate juice.

[0063] S7, concentrate back-blending and non-thermal sterilization: the secondary extract obtained in S5 was concentrated under vacuum at 55°C and -0.09 MPa to a soluble solids content of 45 °Brix.

[0064] Before the PEF treatment, the clarified pomegranate juice was back-blended with 10% of the above concentrate by mass.

[0065] The PEF treatment was performed immediately afterwards: electric field strength 30 kV / cm, treatment time 80 μβ.

[0066] Immediately after the PEF treatment, the UHP treatment was performed within a time interval of no more than 60 s: pressure 500 MPa, pressure holding time 4 min, temperature maintained at 22°C.

[0067] S8, aseptic filling: the pomegranate juice after the UHP sterilization was filled in a sterile environment to obtain the final pomegranate juice product.

[0068] <Testing indexes and methods> After the preparation, the two groups of final pomegranate juice products were tested for the following indexes: Juice yield: calculated according to the formula (total mass of the final product pomegranate juice / initial mass of fresh pomegranate fruit) x 100%.

[0069] Soluble solids content: determined using a digital refractometer (model: PAL-1, ATAGO, Japan) at 20°C, unit °Brix.

[0070] Turbidity: determined using a turbidimeter (model: 2100N, HACH, USA), unit NTU.

[0071] Total phenol content: Folin-Ciocalteu method was used. Gallic acid was used as the standard, and the absorbance was determined at 765 nm. The result was expressed as mg gallic acid equivalent (GAE) / 100 mL.

[0072] Analysis of volatile flavor substances: headspace-solid phase microextraction and gas chromatography-mass spectrometry (HS-SPME-GC-MS) method.

[0073] Chromatographic column: DB-WAX (60 m x 0.25 mm x 0.25 μm); Temperature program: 40°C for 3 min, increased to 230°C at 5°C / min, and maintained for 5 min; Mass spectrometry conditions: electron impact ion source (EI), ion source temperature 230°C, electron energy 70 eV, scan range m / z 35-350. The result was expressed as the peak area (x 10 6 ) of each flavor substance.

[0074] The experiment was repeated three times, and the results were averaged and recorded in the following table.

[0075] Table 1 Comparison of key indicators of pomegranate juice between Example 1 and Comparative Example 1 and Comparative Example 2 Table 2 Comparison of peak areas of some key volatile flavor substances of pomegranate juice between Example 1 and Comparative Example 1 (x 10 6 ) By comparing the experimental results of Example 1 and Comparative Example 1, it can be seen that under the same process conditions, the juice yield, soluble solids content and total phenol content of Example 1 using a complex enzyme preparation containing β-glucosidase and xylanase and performing two-step enzymolysis are higher than those of Comparative Example 1 without using the above two enzymes. The turbidity of the product of Example 1 is lower than that of Comparative Example 1, indicating that the clarity is better. In terms of volatile flavor substances, the peak area of typical floral and fruity flavor substances (such as a-terpineol and linalool) in Example 1 is significantly higher than that in Comparative Example 1.

[0076] The experimental data show that the complex enzyme preparation formula containing β-glucosidase and xylanase and the two-step enzymolysis process have a positive technical effect on improving the juice yield of pomegranate juice, enriching functional ingredients (total phenols), enhancing the intensity of typical flavors and improving the clarity of the product.

[0077] By comparing the experimental results of Example 1 and Comparative Example 2, it can be seen that under the same process conditions, the juice yield, soluble solids content and total phenol content of Example 1 subjected to pulsed electric field (PEF) treatment are higher than those of Comparative Example 2 without PEF treatment. At the same time, the turbidity of the product of Example 1 is significantly lower than that of Comparative Example 2, indicating that the clarity is better. The experimental data show that the pulsed electric field (PEF) treatment step performed before cold pressing has a positive technical effect on significantly improving the juice yield of pomegranate juice, enriching soluble solids and total phenols and other inclusions, and improving the clarity of the product.

[0078] <Comparative Example 3> Preparation steps: Except that step S5 does not use citric acid to adjust pH, the rest of the process flow, equipment and operating parameters are exactly the same as Example 1. Among them, S5, residue extraction and astringency removal treatment: the obtained residue is added to pure water according to its mass ratio of 1:8. <Testing indicators and methods> During the preparation process, the secondary extract obtained in S5 is detected; after the preparation is completed, the two groups of pomegranate juice final products are detected: Total phenolic content of the secondary extract: measured by Folin-Ciocalteu method, the result was expressed as mg gallic acid equivalent (GAE) per 100 mL.

[0079] Color of the secondary extract: measured by colorimeter (model: CR-400, Konica Minolta, Japan), expressed as L* value, a* value and b* value, and calculated the chroma value C* = (a*2 + b*2)1 / 2. .

[0080] Turbidity of the final product: measured by turbidimeter (model: 2100N, HACH, USA), unit: NTU.

[0081] The experiment was repeated three times, and the average value was taken as the result, which was recorded in the following table.

[0082] Table 3 Comparison of key indicators of secondary extract and final product of Example 1 and Comparative Example 3 From the comparison of the experimental results of Example 1 and Comparative Example 3, it can be seen that in step S5, the total phenolic content and the chroma value C* of the secondary extract obtained by adjusting the pH to 3.5 in Example 1 are higher than those of Comparative Example 3 without pH adjustment. This shows that an acidic environment is conducive to extracting more polyphenols from pomegranate filter residue, and these substances are also the main components of the typical red color of the extract. In terms of the final product, the turbidity of the pomegranate juice of Example 1 using secondary extract with high polyphenol content is lower than that of Comparative Example 3, indicating that it has better clarity. This may be due to the interaction between polyphenols and macromolecular substances such as proteins, which promotes the removal of impurities during the subsequent microfiltration process. The experimental data shows that adjusting the pH of the extraction system to 3.0-4.0 in step S5 using citric acid has a positive technical effect on the efficient extraction of polyphenolic functional ingredients from filter residue, the enrichment of typical color, and the improvement of the clarity of the final product.

[0083] <Comparative Example 4> Preparation steps: except for omitting PEF treatment in step S7 and only performing HPP sterilization, the rest of the process flow, equipment and operating parameters are exactly the same as Example 1.

[0084] Among them, S7, concentrate back addition and single non-thermal sterilization: the secondary extract obtained in S5 was vacuum concentrated to a soluble solid content of 45°Brix at 55℃ and -0.09MPa. Before sterilization, 10% of the above concentrate was added back to the clarified pomegranate juice by mass. (This comparative example omits the pulse electric field (PEF) treatment in step S7, and directly proceeds to the subsequent ultra-high pressure (HPP) treatment.) The clarified pomegranate juice after adding back the concentrate was subjected to ultra-high pressure treatment: pressure 500MPa, pressure holding time 4min, temperature maintained at 22℃.

[0085] <Detection index and method> After preparation, the following indicators of the two groups of pomegranate juice final products were detected: Total bacterial count: Refer to GB 4789.2-2016 “National food safety standard Food microbiological examination Determination of total bacterial count” for detection.

[0086] Anthocyanin retention rate: pH differential method was used. The anthocyanin content of pomegranate juice before and after sterilization was determined, and the retention rate was calculated according to the formula (anthocyanin content after sterilization / anthocyanin content before sterilization) x 100%.

[0087] The experiment was repeated three times, and the average value was taken as the result, which was recorded in the following table.

[0088] Table 4 Comparison of sterilization effect and ingredient retention of pomegranate juice between Example 1 and Comparative Example 4 By comparing the experimental results of Example 1 and Comparative Example 4, it can be seen that in step S7, the product of Example 1 using PEF+HPP combined sterilization has lower total bacterial count than Comparative Example 4 using only HPP single sterilization, achieving a more optimal commercial sterile level. The anthocyanin retention rate of Example 1 product is higher than that of Comparative Example 4, indicating that PEF as a pretreatment may weaken the pressure resistance of microbial cells through transient electroporation, allowing the subsequent HPP treatment to achieve the same or even better sterilization effect under relatively mild conditions, thereby better protecting pressure-sensitive active ingredients such as anthocyanins. The experimental data show that the combined sterilization strategy of pulsed electric field (PEF) and high pressure processing (HPP) used in step S7 has a synergistic effect in improving the microbial safety of the final product and better retaining heat-sensitive active ingredients compared to single HPP sterilization.

[0089] <Comparative Example 5> Preparation steps: steps S1 to S6 are exactly the same as Example 1, wherein, S7, non-thermal sterilization: the clarified pomegranate juice obtained in S6 is directly subjected to pulsed electric field treatment: electric field strength 30 kV / cm, treatment time 80 μs. After pulsed electric field treatment, within an interval not exceeding 60 s, high pressure treatment is immediately carried out: pressure 500 MPa, holding time 4 min, temperature maintained at 22°C. (Note: the “concentrate back addition” step of Example 1 is omitted in Comparative Example 5, i.e. no concentrate is prepared and no any substance is added back to the clarified pomegranate juice.) S8, aseptic filling: the pomegranate juice after high pressure sterilization is filled in a sterile environment, and the pomegranate juice final product is obtained.

[0090] <Detection index and method> The following indicators were detected for the pomegranate juice end product of Example 1 and Comparative Example 5, focusing on evaluating the retention rate of active ingredients and oxidative stability: Anthocyanin retention rate: pH differential method was used. The anthocyanin content was measured immediately after sterilization (0 days) and after 30 days of storage, and the retention rate was calculated according to the formula (anthocyanin content after storage / anthocyanin content immediately after sterilization) x 100%. Total phenol content. Color change (ΔE) value): The color difference meter (model: CR-400, Konica Minolta, Japan) was used to measure the value, and the color change after 30 days of storage was calculated according to the formula The smaller the value, the more stable the color. Total bacterial count.

[0091] All experiments were repeated three times, and the results were averaged.

[0092] Table 5 Comparison of key indicators of pomegranate juice between Example 1 and Comparative Example 5 There was little difference in anthocyanin retention rate and total phenol content between Example 1 and Comparative Example 5 immediately after sterilization, indicating that the addition of concentrate had little effect on the initial ingredients.

[0093] After 30 days of storage, the anthocyanin retention rate of Example 1 (95.2%) was significantly higher than that of Comparative Example 5 (88.3%), and the total phenol content also decreased less (Example 1 decreased by 2.3%, and Comparative Example 5 decreased by 12.3%). The value (2.1) of Example 1 was significantly lower than that of Comparative Example 5 (4.5), indicating that the addition of concentrate effectively inhibited the color change and improved the color stability. The total bacterial count was less than 10 CFU / mL, indicating that the sterilization effect was not affected by the addition of concentrate.

[0094] <Comparative Example 6> Preparation steps: Steps S1 to S4 (except for standing and aging), S5 to S8 are exactly the same as Example 1: S4, cold pressing (omit standing and aging): The mixed pomegranate pulp was cold pressed at a pressure of 1.2 MPa, and the pressed juice was filtered through a 150-mesh screen to obtain primary pomegranate juice and filter residue. (This comparative example omitted the step of "standing and aging the primary pomegranate juice at 6°C for 18h" in Example 1, and the primary pomegranate juice obtained after pressing and filtering was directly used in the subsequent S6 step.) <Testing indicators and methods> The following indicators were detected for the pomegranate juice preparation process and end product of Example 1 and Comparative Example 6: Microfiltration membrane flux decline rate: During the ceramic membrane microfiltration process in S6 step, the initial membrane flux (J0, L / (m 2 ​·h)) and the membrane flux at the end of filtration (J1), according to the formula The membrane flux decline rate is calculated to characterize the degree of membrane fouling.

[0095] Total microfiltration time: Record the total time (min) required to complete the microfiltration of all the mixed juices in step S6.

[0096] Turbidity of the final product.

[0097] Storage stability (turbidity change): After storing the final product at 4°C in the dark for 30 days, the turbidity was measured again, and the turbidity change was calculated. ).

[0098] All experiments were repeated three times, and the results were averaged.

[0099] Table 6 Comparison of preparation process and key indicators of final product between Example 1 and Comparative Example 6 The membrane flux reduction rate of Comparative Example 6 (without static aging) (23.7%) was significantly higher than that of Example 1 (10.2%), and the total filtration time (68 min) was significantly longer than that of Example 1 (45 min). This indicates that omitting the static aging step resulted in unstable colloids, microparticles, and other substances in the juice failing to fully flocculate and settle, leading to faster and more severe contamination of the ceramic membrane during microfiltration, thus reducing filtration efficiency. The initial turbidity of the final product obtained in Comparative Example 6 (3.9 NTU) was higher than that in Example 1 (2.5 NTU). After 30 days of storage, the turbidity change of Comparative Example 6 ( =1.7) is much larger than Example 1 ( =0.3), indicating that products that have not been allowed to stand and age are more prone to precipitation or turbidity during storage and have poor stability.

[0100] Comparing the experimental results of Example 1 and Comparative Example 6, it can be seen that the static aging step following cold pressing in step S4 has a significant and positive technical effect on reducing membrane fouling in subsequent ceramic membrane microfiltration, improving filtration efficiency, enhancing the initial clarity of the final product, and strengthening its storage stability. This step, through a controllable low-temperature delayed process, promotes the natural flocculation and sedimentation of unstable substances in the juice.

[0101] <Comparative Example 7> Preparation steps: Steps S1 to S5 (except for the deastringency treatment) and S6 to S8 are exactly the same as in Example 1: S5, residue extraction (omit astringency removal): the residue was added with pure water at a mass ratio of 1:8, and the pH of the solution was adjusted to 3.5 using citric acid. The solution was extracted using intermittent ultrasonic assistance: ultrasonic power 450 W, temperature 60 °C, total time 20 min, work / interval time ratio 2:1, and single ultrasonic working time 3 s. After extraction, solid-liquid separation was performed to obtain the secondary extract. (The step of "adding 1.0% of β-cyclodextrin by mass to the secondary extract, stirring to dissolve, and removing astringency" in Example 1 was omitted in this comparative example, and the secondary extract was directly used in the subsequent S6 step.) <Testing index and method> The secondary extract of Example 1 and Comparative Example 7 and the final product of pomegranate juice were tested for the following indexes: Secondary extract tannin content: determined by the Folin-Denis method, and the result was expressed in mg gallic acid equivalent (GAE) / 100 mL.

[0102] Final product total phenol content: determined by the Folin-Ciocalteu method, and the result was expressed in mg GAE / 100 mL.

[0103] Final product astringency value (instrument method): determined by an astringency sensory analyzer (model: TS-5000Z, INSENT, Japan), and expressed in astringency response intensity value (unit: standard astringency unit, SSU). The instrument simulates the response of human taste cells to astringent substances, providing objective and quantitative astringency evaluation.

[0104] Final product sensory evaluation: trained sensory evaluators (not less than 10 people) evaluated the astringency intensity of the final product using a 0-5 point scale method (0 points: no astringency; 5 points: extremely strong astringency).

[0105] All chemical and instrument analysis experiments were repeated three times, and the average value was taken.

[0106] Table 7 Comparison of key indexes of secondary extract and final product of Example 1 and Comparative Example 7 The tannin content of the secondary extract of Comparative Example 7 (352.4 mg GAE / 100 mL) was significantly higher than that of Example 1 (185.6 mg GAE / 100 mL), which proved that the de-astringency treatment with β-cyclodextrin effectively reduced the content of key substances causing astringency. The total phenol content of the final product of Comparative Example 7 (315.8 mg GAE / 100 mL) was slightly higher than that of Example 1 (285.6 mg GAE / 100 mL), which indicated that the de-astringency treatment had little effect on the absolute content of total polyphenols while reducing astringency, mainly selectively acting on part of the hydrophobic astringent polyphenols (such as part of the tannins), which was consistent with the mechanism of action of β-cyclodextrin. The instrumental astringency value (8.9 SSU) and the sensory astringency intensity score (3.8 points) of the final product of Comparative Example 7 were both significantly higher than those of Example 1 (4.2 SSU, 1.5 points). This clearly showed that the final product without de-astringency treatment had a strong astringent taste, which was beyond the acceptable range of most consumers, while the product with de-astringency treatment had significantly reduced astringency and better palatability.

[0107] From the experimental results of Example 1 and Comparative Example 7, it can be seen that the β-cyclodextrin de-astringency treatment of the secondary extract in step S5 has a significant and positive technical effect on selectively reducing the astringency of the final product, significantly improving the sensory palatability, while basically maintaining the high total phenol content of the final product. This step precisely solves the contradiction between the high nutritional value and good palatability in the utilization of pomegranate whole fruit.

[0108] <Example 2> Application of pomegranate juice in functional beverages: The pomegranate juice prepared in Example 1 based on the utilization of whole fruit is used as the core raw material and basic ingredients to prepare a high-antioxidant functional pomegranate beverage.

[0109] Formulation (based on 1000 kg of final product): 400 kg of pomegranate juice prepared in Example 1; 80 kg of high fructose syrup (F55); 20 kg of erythritol; 2 kg of food-grade citric acid (for adjusting and coordinating the sweet-sour ratio); 0.5 kg of pomegranate essence (natural); 0.3 kg of potassium sorbate (preservative); and pure water: make up to 1000 kg.

[0110] Preparation process: 1. Sugar melting and dissolution: In the sugar melting tank, add part of the pure water and heat to 70-75°C. Under stirring conditions, add high fructose syrup and erythritol in sequence and stir until completely dissolved.

[0111] 2. Mixing: Cool the sugar solution to below 30°C, and mix with the pomegranate juice prepared in Example 1, citric acid, pomegranate essence, potassium sorbate (previously dissolved with a small amount of water), and the remaining pure water in the ingredient tank.

[0112] 3. Volume and homogenization: the mixed liquid is made up to 1000 kg, and after stirring evenly, it is treated by high-pressure homogenizer under 20 MPa pressure.

[0113] 4. Filling and sterilization: the homogenized liquid is filled into heat-resistant PET bottles, and water bath pasteurization (85℃, 15-20 min) is adopted.

[0114] 5. Cooling and inspection: after sterilization, it is quickly cooled to room temperature, and after inspection, high-antioxidant functional pomegranate beverage is obtained.

[0115] Product properties: total phenol content: ≥100 mg GAE / 100 mL (based on beverage).

[0116] Anthocyanin content: ≥15 mg / 100 mL (based on beverage).

[0117] Sensory quality: it has typical pomegranate flavor, red color, coordinated taste, and moderate astringency.

[0118] Stability: after 6 months of storage at room temperature, there is no obvious precipitation, and the retention rate of color and active ingredients is stable.

[0119] <Example 3> Application of pomegranate juice in health products (capsules): the pomegranate juice based on whole fruit obtained in Example 1 is spray dried to powder, which is used to prepare pomegranate polyphenol capsules.

[0120] Preparation of pomegranate juice powder: Auxiliary materials: malt dextrin (carrier, added amount is 30% of the mass of soluble solids in pomegranate juice).

[0121] Process: the pomegranate juice obtained in Example 1 is mixed with malt dextrin, and spray dried. The inlet air temperature is 170-180℃, the outlet air temperature is 80-85℃, and the material flow is adjusted according to the equipment model to obtain pomegranate juice powder.

[0122] Powder properties: moisture content ≤5%, total phenol content ≥25% (based on dry basis).

[0123] Capsule formula (per capsule content, capsule size 0): Pomegranate juice powder: 350 mg; microcrystalline cellulose: 98 mg; magnesium stearate: 2 mg.

[0124] Preparation process: 1. Mixing: the pomegranate juice powder, microcrystalline cellulose, and magnesium stearate are placed in a mixer and mixed evenly.

[0125] 2. Capsule filling: the mixed material is filled into the hollow capsule shell using a full-automatic capsule filling machine.

[0126] 3. Polishing and packaging: polish the filled capsules to remove surface dust, and then use aluminum-plastic blister packaging, and the pomegranate polyphenol capsules are obtained.

[0127] Product characteristics: Each capsule is marked with a total phenol content of ≥90 mg / particle. The disintegration time limit meets the relevant provisions of the "People's Republic of China Pharmacopoeia".

[0128] Action and use: It can be used as a dietary supplement rich in pomegranate polyphenols, tannic acid and other antioxidant ingredients.

[0129] <Example 4> Application of pomegranate juice in food additives (natural pigment and flavor enhancer): the pomegranate juice prepared in Example 1 based on whole fruit utilization is used as a natural pigment and flavor enhancer in the preparation of yogurt.

[0130] Application product: pomegranate-flavored yogurt.

[0131] Basic yogurt formula (based on 1000 kg of final product): Fresh milk: 800 kg; white granulated sugar: 80 kg; yogurt starter: 0.5 kg; pomegranate juice prepared in Example 1: 50 kg (added after fermentation); agar: 2 kg; citrus fiber: 1 kg; pure water: make up to 1000 kg.

[0132] Preparation process: 1. Yogurt base preparation: after purification, standardization, preheating, homogenization (15-20 MPa), sterilization (95℃, 5min) of fresh milk, cooling to 42-45℃, inoculating yogurt starter, and fermenting at 42℃ to pH 4.5-4.6, the yogurt base is obtained.

[0133] 2. Pomegranate juice preparation: the pomegranate juice prepared in Example 1 is prepared.

[0134] 3. Mixing and blending: cool the fermented yogurt base to below 20℃, and slowly mix evenly with white granulated sugar, stabilizer (agar, citrus fiber, which needs to be pre-swollen and sterilized), and pomegranate juice prepared in Example 1 under stirring conditions.

[0135] 4. Homogenization and filling: the mixed liquid is subjected to secondary homogenization in a homogenizer at 10-15 MPa, and then filled.

[0136] 5. Cold storage and maturation: the filled product is subjected to cold storage and maturation at 2-6℃ for 12-24h, and the pomegranate-flavored yogurt is obtained.

[0137] Application effect: Coloring effect: The product presents natural pink to red color, which is uniform and stable, replacing part of the use of synthetic red pigment (such as carmine).

[0138] Flavor enhancement: The product is endowed with fresh and rich pomegranate characteristic flavor, reducing the amount of artificial flavor added.

[0139] Nutrition fortification: The product is additionally added with functional ingredients such as pomegranate polyphenol, improving the nutritional value.

[0140] Although the embodiments of the present application have been disclosed as above, it is not limited to the use listed in the specification and the embodiments, and can be fully applied to various fields suitable for the present application, and additional modifications can be easily realized by those skilled in the art, and therefore the present application is not limited to specific details and examples shown and described herein, without departing from the general concept defined by the claims and the equivalent scope.

Claims

1. A method for the preparation of pomegranate juice based on whole fruit utilization, characterized by, The application relates to a method for preparing pomegranate juice. The method comprises the following steps: S1, crushing pomegranate pulp into pomegranate pulp after washing the fresh pomegranate, wherein the pomegranate pulp contains pomegranate peel, pomegranate seeds and pomegranate pulp; S2, adding a compound enzyme preparation into the pomegranate pulp, and carrying out enzymolysis at 35-50 DEG C for 1-3 h; the compound enzyme preparation comprises the following mass percentages of enzymes: 40%-50% of pectinase, 20%-25% of cellulase, 10%-15% of hemicellulase, 8%-12% of beta-glucosidase and 5%-8% of xylanase; the adding amount of the compound enzyme preparation is 0.01%-0.05% of the mass of the pomegranate pulp; S3, treating the pomegranate pulp after enzymolysis under the conditions of an electric field intensity of 15-40 kV / cm, a pulse width of 10-100 mu s and a pulse frequency of 100-500 Hz for 100-500 mu s; S4, carrying out cold pressing on the pomegranate pulp after the pulse electric field treatment, the pressure is 0.5-2 MPa, and the pomegranate pulp after the pressing is filtered through a 100-200 mesh screen to obtain primary pomegranate juice and filter residue; S5, adding pure water into the filter residue according to the mass ratio of 1: (5-10), adjusting the pH of the solution to 3.0-4.0 by using citric acid, and carrying out ultrasonic-assisted extraction under the conditions of an ultrasonic power of 300-600 W, a temperature of 50-70 DEG C and a time of 10-30 min, and then carrying out solid-liquid separation to obtain secondary extraction liquid; S6, mixing the primary pomegranate juice obtained in the step S4 with the secondary extraction liquid obtained in the step S5, and then carrying out microfiltration on the mixed juice through a ceramic membrane with a pore size of 0.1-0.5 mu m to obtain clarified pomegranate juice; S7, carrying out pulse electric field treatment on the clarified pomegranate juice under the conditions of an electric field intensity of 25-35 kV / cm and a treatment time of 50-100 mu s, and then carrying out ultrahigh pressure treatment under the conditions of a pressure of 400-600 MPa, a pressure maintaining time of 3-5 min and a temperature of 20-25 DEG C, wherein the interval time between the pulse electric field treatment and the ultrahigh pressure treatment is not more than 60 s; 2. The method of preparation of pomegranate juice based on whole fruit utilization as claimed in claim 1, wherein, S8, filling the pomegranate juice after the ultrahigh pressure sterilization in a sterile environment to obtain the pomegranate juice.

3. The method of preparation of pomegranate juice based on whole fruit utilization as claimed in claim 1, wherein, Before the pulse electric field treatment in the step S7, the clarified pomegranate juice is added with a concentrate of the secondary extraction liquid in the step S5, and the adding amount of the concentrate is 5%-15% of the mass of the clarified pomegranate juice; the concentrate is obtained by vacuum concentration of the secondary extraction liquid under the conditions of a temperature of 50-60 DEG C and a pressure of (-0.08)-(-0.10) MPa until the soluble solid content is 40-50 DEG Brix.

4. The method of preparation of pomegranate juice based on whole fruit utilization as claimed in claim 1, wherein, The operation temperature of the ceramic membrane microfiltration in the step S6 is controlled to be 15-25 DEG C.

5. The method of preparation of pomegranate juice based on whole fruit utilization as claimed in claim 1, wherein, The ultrasonic-assisted extraction in the step S5 is carried out in an intermittent ultrasonic mode, and the ratio of the working time to the interval time is (1-3):1, and the single ultrasonic working time is not more than 5 s. The enzymolysis process in the step S2 is divided into two steps, the first step is to add 60%-70% of the total mass of the compound enzyme preparation into the pomegranate pulp, and to carry out enzymolysis under the conditions of a temperature of 38-42 DEG C and a pH of 3.5-4.0 for 40-60 min, and the second step is to add the remaining compound enzyme preparation, and to carry out enzymolysis under the conditions of a temperature of 45-50 DEG C and a pH of 4.0-4.5 for 20-40 min, and the stirring is continuously carried out at a speed of 50-150 rpm during the enzymolysis process.

6. The method of preparation of pomegranate juice based on whole fruit utilization as claimed in claim 1, wherein, Before the step S3, the enzymatic pomegranate pulp is pre-filtered through a 50-100 mesh screen, and the filtered pomegranate pulp is subjected to the step S3. The components on the screen include the peel and seeds, which are crushed by a wall-breaking machine and then mixed with the pomegranate pulp subjected to the step S3.

7. The method as claimed in claim 1, wherein the pomegranate juice is prepared using whole fruit based utilization. After the step S4, the obtained primary pomegranate juice is aged at 4-10℃ for 12-24h, and then subjected to the step S6.

8. The method as claimed in claim 1, wherein the pomegranate juice is prepared using whole fruit based utilization. In the step S5, the obtained secondary extract is subjected to a solid-liquid separation after the ultrasonic-assisted extraction, and then subjected to a de-astringency treatment before being added back. The de-astringency treatment is carried out by embedding with β-cyclodextrin, and the amount of the β-cyclodextrin added is 0.5%-1.5% of the mass of the secondary extract.

9. A pomegranate juice prepared by the method of any one of claims 1-8.

10. Use of the pomegranate juice of claim 9 in the preparation of a functional beverage, a health product or a food additive.

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