Fruit juice processing method adopting gradient high-pressure CO2 pretreatment in cooperation with multistage HPP

Abstract

The invention relates to a fruit juice processing method through cooperation of gradient high-pressure CO2 pretreatment and multistage HPP, and belongs to the field of food processing. The method comprises the following steps: (1) carrying out gradient high-pressure CO2 pretreatment on fresh fruit juice: stage 1: treating for 1-2 minutes under the conditions that the pressure is 8-10 MPa and the CO2 concentration is 100%; stage 2: treating for 2-3 minutes under the conditions that the pressure is 15-18 MPa and the CO2 concentration is 60%; stage 3, treating for 1 to 1.5 minutes under the conditions that the pressure is 25 to 28 MPa and the CO2 concentration is 30 percent; (2) performing multi-stage gradient HPP treatment on the fruit juice subjected to gradient high-pressure CO2 pretreatment under the condition that the temperature of pressure transmission medium water is 5 DEG C; and (3) performing negative pressure filling on the fruit juice subjected to the multi-stage gradient HPP treatment. According to the method, through pressure-concentration double gradients, the enzyme residue activity is remarkably reduced, and the browning phenomenon after fruit juice storage is effectively restrained; in addition, through multi-stage gradient HPP, the treatment time is shortened, and more nutritional ingredients (anthocyanin and VC) can be reserved.

Description

Technical Field

[0001] This application relates to the field of food processing, and in particular to a juice processing method using gradient high-pressure CO2 pretreatment in conjunction with multi-stage HPP. Background Technology

[0002] In recent years, nutritious and healthy fruit juices have gradually become the mainstream in the beverage market. More and more consumers are seeking diversified and high-quality consumption methods and lifestyles, which has driven the sales of high-end fruit juices and related beverages to rise steadily.

[0003] Currently, there are three main juice pressing and sterilization processes: FC, NFC, and HPP. FC (Frequency From Concentrate) juice refers to a product obtained by adding an equal amount of water to concentrated juice to compensate for the natural water lost during concentration. One advantage of concentrated juice is its long shelf life. However, its disadvantages include the evaporation of many water-soluble flavor compounds during concentration and the alteration of flavor due to the high temperatures during sterilization. NFC, short for Not From Concentrate, refers to juice made by directly pasteurizing fruit after juicing and processing it at low temperatures. HPP juice relies on the application of HPP (High Pressure Processed) ultra-high pressure sterilization technology. This involves placing bottled fresh juice into a sealed container, using water as a medium, and applying ultra-high pressure (400-600 MPa) to kill most bacteria, molds, and yeasts. Because this method does not destroy the nutrients and flavor of the juice like high-temperature sterilization, it preserves the original freshness of the taste and retains most vitamins and minerals intact. Currently, HPP ultra-high pressure technology has been applied to the processing of various fruit and vegetable juices.

[0004] However, the existing technology for preparing fruit juice using HPP (high pressure processing) has the following problems: 1. Traditional 600MPa HPP treatment cannot completely inactivate polyphenol oxidase (PPO), with residual activity >15%, and the browning index ΔE >5.0 after 60 days of storage, resulting in a serious decline in sensory quality; 2. HPP high pressure destroys the pectin structure, and due to the instantaneous high pressure breaking down the cell wall and releasing oxidase, the anthocyanin content of blueberries decreases by 12% after 600MPa / 120s treatment.

[0005] The pursuit of eliminating enzyme activity and reducing nutrient loss in fruit juice during processing has always been a goal of those skilled in the art. Summary of the Invention

[0006] To address or partially address the problems existing in related technologies, this application provides a juice processing method that combines gradient high-pressure CO2 pretreatment with multi-stage HPP. Through the dual gradient of pressure and concentration, the residual enzyme activity is significantly reduced, effectively inhibiting the browning phenomenon of juice after storage. At the same time, the multi-stage gradient HPP shortens the processing time and can retain more nutrients (anthocyanins, vitamin C).

[0007] This application discloses a juice processing method using gradient high-pressure CO2 pretreatment in conjunction with multi-stage HPP, comprising the following steps: (1) Pre-treat fresh juice with gradient high-pressure CO2: Phase 1: Treat for 1-2 minutes under conditions of 8-10 MPa pressure and 100% CO2 concentration; Phase 2: Treat for 2-3 minutes at a pressure of 15-18 MPa and a CO2 concentration of 60%; Phase 3: Treat for 1-1.5 min at a pressure of 25-28 MPa and a CO2 concentration of 30%; (2) The juice that has undergone gradient high-pressure CO2 pretreatment is subjected to multi-stage gradient HPP treatment at a water temperature of 5°C in the pressure transmission medium: Phase 1: Treat at 200 MPa for 25-30 seconds; Phase 2: Treatment at 400 MPa for 20-25 seconds; Stage 3: Treatment at 600MPa for 10-15 seconds; (3) Negative pressure filling of juice after multi-level gradient HPP treatment.

[0008] Furthermore, the CO2 concentrations corresponding to stages 2 and 3 in step (1) are achieved through nitrogen dilution. Nitrogen dilution enhances CO2 mass transfer efficiency and increases the dissolved CO2 concentration, while also preventing protein denaturation and precipitation caused by an overly acidic environment (pH < 3.5). Additionally, dissolved CO2 chelates the CaO of PME. 2+ The optimal pH for the active site is 4.0.

[0009] Furthermore, the gradient high-pressure CO2 pretreatment in step (1) specifically includes: Phase 1: Treat for 2 min at a pressure of 8-10 MPa and a CO2 concentration of 100%; Phase 2: Treat for 2 min at a pressure of 15-18 MPa and a CO2 concentration of 60%; Phase 3: Treat for 1 min at a pressure of 25-28 MPa and a CO2 concentration of 30%; Furthermore, the multi-level gradient HPP processing in step (3): Phase 1: Treatment at 200 MPa for 30 seconds; Phase 2: Treatment at 400 MPa for 20 seconds; Phase 3: Process at 600MPa for 15 seconds.

[0010] This application also provides a fruit juice product prepared by any of the methods described above.

[0011] The beneficial effects of this application are: 1. This application is the first to propose a dual-gradient pressure-CO2 concentration process for fruit juice, in which high concentrations of CO2 form H2CO3, which acts as a protonator for PPO (His). + The residues act, while medium pressure promotes CO2 dissolution and chelates the Ca2+ of pectinase (PME). 2+ The cofactors work in conjunction with physical membrane disruption under high pressure, while residual CO2 interferes with microbial metabolism. This application uses a dual gradient of pressure and CO2 concentration to significantly reduce residual enzyme activity, effectively inhibiting browning after fruit juice storage, and ultimately achieving the technical effect of enzyme activity eradication (PPO < 0.5%). At the same time, the multi-level gradient HPP shortens the treatment time and retains more nutrients (anthocyanins, vitamin C).

[0012] 2. This application is particularly applicable to high-end functional beverages such as high-anthocyanin blueberry juice or compound fruit juice. Detailed Implementation

[0013] The embodiments of this application will now be described in more detail with reference to the examples. While embodiments of this application are shown in the examples, it should be understood that this application can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to make this application more thorough and complete, and to fully convey the scope of this application to those skilled in the art. Example 1

[0014] The fruit juice processing method in this embodiment includes the following steps: (1) Take freshly pressed blueberry juice and apple juice, with a mass ratio of blueberry juice to apple juice of 6:4, and mix them well; (2) The mixed juice was subjected to gradient high-pressure CO2 pretreatment: Phase 1: Treat for 2 min at a pressure of 10 MPa and a CO2 concentration of 100%; After stage 1 treatment, the PPO content in the juice was found to be 99.1% inactivated. Phase 2: Treat for 2 min at a pressure of 18 MPa and a CO2 concentration of 60%; After stage 2 treatment, the PME activity in the juice decreased to 3.2%. Phase 3: Treat for 1 min at a pressure of 25 MPa and a CO2 concentration of 30%; After stage 3 treatment, the total bacterial count in the juice was <5 CFU / mL; (3) The juice after gradient high pressure CO2 pretreatment is subjected to multi-stage HPP: the water temperature of the pressure transmission medium is 5℃, 200MPa×30s → 400MPa×20s → 600MPa×10s; where 200MPa×30s refers to treatment at 200MPa pressure for 30s, and the rest are similar.

[0015] (4) Negative pressure filling: Filling under the conditions of 0.5 atm negative pressure, 4℃, and 0.3 ppm residual oxygen.

[0016] Fruit juice products stored at 4℃ for 90 days were tested. The results showed that after 90 days, the anthocyanin retention rate was 99.5%, the vitamin C retention rate was 99.2%, ΔE=1.2, the PPO residual activity was 0.5%, and the PME activity was 2.7%. Example 2

[0017] The fruit juice processing method in this embodiment includes the following steps: (1) Take freshly pressed blueberry juice and blackcurrant juice, with a mass ratio of 7:3, and mix them well; (2) The mixed juice was subjected to gradient high-pressure CO2 pretreatment: Phase 1: Treat for 1 min at a pressure of 10 MPa and a CO2 concentration of 100%; After stage 1 treatment, 99.0% of the PPO in the juice was found to be inactivated. Phase 2: Treat for 3 min at a pressure of 18 MPa and a CO2 concentration of 60%; After stage 2 treatment, the PME activity in the juice decreased to 3.1%. Phase 3: Treat for 1.5 min at a pressure of 25 MPa and a CO2 concentration of 30%; After stage 3 treatment, the total bacterial count in the juice was <5 CFU / mL; (3) The juice after gradient high pressure CO2 pretreatment is subjected to multi-stage HPP: the water temperature of the pressure transmission medium is 5℃, 200MPa×25s → 400MPa×25s → 600MPa×10s; (4) Negative pressure filling: Filling under the conditions of 0.5 atm negative pressure, 4℃, and 0.4 ppm residual oxygen.

[0018] Fruit juice products stored at 4℃ for 90 days were tested. The results showed that after 90 days, the anthocyanin retention rate was 99.4% (358 mg / L before treatment and 356 mg / L after treatment), the vitamin C retention rate was 92.8%, ΔE=1.6, the residual activity of PPO was 0.4%, and the activity of PME was 2.4%. Example 3

[0019] The fruit juice processing method in this embodiment includes the following steps: (1) Take freshly pressed navel orange juice and grapefruit juice, with a mass ratio of navel orange juice to grapefruit juice of 8:2, and mix them well; (2) The mixed juice was subjected to gradient high-pressure CO2 pretreatment: Phase 1: Treat for 2 min at a pressure of 10 MPa and a CO2 concentration of 100%; Phase 2: Treat for 2 min at a pressure of 18 MPa and a CO2 concentration of 60%; Phase 3: Treat for 1 min at a pressure of 25 MPa and a CO2 concentration of 30%; (3) The juice after gradient high pressure CO2 pretreatment is subjected to multi-stage HPP: the water temperature of the pressure transmission medium is 5℃, 200MPa×25s → 400MPa×20s → 600MPa×15s; (4) Negative pressure filling: 0.5 atm negative pressure, 4℃, residual oxygen 0.2 ppm.

[0020] Fruit juice products stored at 4℃ for 90 days were tested. The results showed that after 90 days, the VC retention rate was 99.1%, ΔE=1.4, PPO residual activity was 0.4%, and PME activity was 2.5%.

[0021] Comparative Example 1 The fruit juice processing method in Comparative Example 1 differs from that in Example 1 in that it uses conventional HPP for processing, and the steps are as follows: (1) Take freshly pressed blueberry juice and apple juice, with a mass ratio of blueberry juice to apple juice of 6:4, and mix them well; (2) The mixed juice is subjected to HPP treatment: the obtained juice is treated for 60s under the conditions of water temperature of 5℃ and pressure of 600MPa in the pressure transmission medium. (3) Negative pressure filling: Filling under the conditions of 0.5 atm negative pressure, 4℃, and 0.3 ppm residual oxygen.

[0022] Fruit juice products stored at 4℃ for 90 days were tested. The results showed that after 90 days, the anthocyanin retention rate was 88%, the vitamin C retention rate was 87.5%, ΔE=6.2, the PPO residual activity was 15.2%, and the PME activity was 18.7%.

[0023] Comparative Example 2 The fruit juice processing method in Comparative Example 2 differs from that in the embodiment in that it uses a single CO2 and conventional HPP for processing. The steps are as follows: (1) Take freshly pressed blueberry juice and apple juice, with a mass ratio of blueberry juice to apple juice of 6:4, and mix them well; (2) The mixed juice was treated for 5.5 min under a pressure of 18 MPa and a CO2 concentration of 100%; (3) The processed juice is subjected to HPP treatment: the obtained juice is treated for 60s under the conditions of water temperature of 5℃ and pressure of 600MPa in the pressure transmission medium. (4) Negative pressure filling: Filling under the conditions of 0.5 atm negative pressure, 4℃, and 0.3 ppm residual oxygen.

[0024] Fruit juice products stored at 4℃ for 90 days were tested. The results showed that after 90 days, the anthocyanin retention rate was 85.6%, the vitamin C retention rate was 88.4%, ΔE=3.7, the PPO residual activity was 8.1%, and the PME activity was 12.3%.

[0025] As can be seen from the examples and comparative examples, the dual gradient of pressure and CO2 concentration in this application significantly reduces enzyme residual activity and effectively inhibits browning after fruit juice storage; the multi-level gradient HPP method shortens the processing time and can retain more nutrients (anthocyanins, vitamin C).

[0026] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for processing fruit juice using gradient high-pressure CO2 pretreatment combined with multi-stage HPP, characterized in that, Includes the following steps: (1) Pre-treat fresh juice with gradient high-pressure CO2: Phase 1: Treat for 1-2 minutes under conditions of 8-10 MPa pressure and 100% CO2 concentration; Phase 2: Treat for 2-3 minutes at a pressure of 15-18 MPa and a CO2 concentration of 60%; Phase 3: Treat for 1-1.5 min at a pressure of 25-28 MPa and a CO2 concentration of 30%; (2) The juice that has undergone gradient high-pressure CO2 pretreatment is subjected to multi-stage gradient HPP treatment at a water temperature of 5°C in the pressure transmission medium: Phase 1: Treat at 200 MPa for 25-30 seconds; Phase 2: Treatment at 400 MPa for 20-25 seconds; Stage 3: Treatment at 600MPa for 10-15 seconds; (3) Negative pressure filling of juice after multi-level gradient HPP treatment.

2. The fruit juice processing method according to claim 1, characterized in that, The CO2 concentrations corresponding to stages 2 and 3 in step (1) are achieved by nitrogen dilution.

3. The juice processing method according to claim 1, characterized in that, The gradient high-pressure CO2 pretreatment in step (1) specifically involves: Phase 1: Treat for 2 min at a pressure of 8-10 MPa and a CO2 concentration of 100%; Phase 2: Treat for 2 min at a pressure of 15-18 MPa and a CO2 concentration of 60%; Phase 3: Treat for 1 min at a pressure of 25-28 MPa and a CO2 concentration of 30%.

4. The juice processing method according to claim 1, characterized in that, The multi-level gradient HPP processing in step (3): Phase 1: Treatment at 200 MPa for 30 seconds; Phase 2: Treatment at 400 MPa for 20 seconds; Phase 3: Process at 600MPa for 15 seconds.

5. A fruit juice product, characterized in that, Prepared by the method described in any one of claims 1-4.