Production process for preventing oxidation of apple juice

Abstract

The invention discloses an anti-oxidation production process of apple juice, which comprises the following steps: carrying out whole-process control such as cleaning, crushing, squeezing, storing and sterilizing on apples in a low-temperature environment so as to inhibit oxidation reaction and bacterium breeding; in the cleaning process, ozone water and RO water are adopted for fine cleaning, so that the cleaning and sterilizing effects of the apples are ensured; apples are crushed and oxygen is isolated through the crushing adsorption machine with a parallel blade structure; the totally-closed squeezing cavity is adopted for squeezing, and fruit juice oxidation is reduced; in the whole production process, air is isolated through nitrogen protection, and oxidation is delayed; the fruit juice is conveyed to a low-temperature storage tank and sterilized by adopting an HPP ultrahigh-pressure cold sterilization technology, so that the freshness, the taste and the flavor of the fruit juice are ensured; finally, the quality of the juice is preserved through cold-chain transportation; the invention solves the problem of oxidation discoloration of the apple juice caused by oxidase reaction in the existing juice production process, provides an effective anti-oxidation technology, and ensures the quality and stability of the apple juice.

Description

Technical Field

[0001] The invention relates to the technical field of fruit processing, in particular to a production process for anti-oxidation of apple juice. Background Art

[0002] When we eat apples, we find that they are very easy to be oxidized. After being cut, the cut surface turns brown soon. The main reason for this is that there is oxidase in the apple. When the oxidase meets the air, the iron in the flesh will be oxidized and discolored under the catalysis of the enzyme. Therefore, as long as it is exposed to air, the cut surface of the apple will change color.

[0003] In large-scale industrial production, the original traditional process is to wash the apples first, then crush them, and then use a screw press or a belt press to squeeze the apple pulp. During the production process, because the apples are in contact with oxygen during crushing, the apples begin to change color during the crushing process, and then they are transported to the screw press or the belt press by the screw pump. Since the screw press and the belt press are both open structures, the apples will be oxidized very quickly, causing the juice to turn dark brown after coming out of these two presses.

[0004] For apple juice, how to prevent oxidation is also a problem that juice processing plants have been discussing and trying to improve for many years, but due to insufficient technology and equipment, the problem of anti-oxidation has not been solved. Through the development and research of juice processing equipment over the years, our company found that the oxidation of juice is related to many aspects, so we set up a special R&D team to study the oxidation of juice to solve the above problems. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the existing defects and provide a production process for anti-oxidation of apple juice. Through the implementation of this process, the color of apple juice is brighter and clearer, the flavor is well maintained, and the nutrients are more completely retained, providing consumers with higher quality juice products, and also providing a new production model for the juice industry, promoting the advancement of juice processing technology, and can effectively solve the problems in the background technology.

[0006] To achieve the above object, the present invention provides the following technical solution: a production process for anti-oxidation of apple juice, the production process comprising the following steps: Step 1: Environmental control: The entire process of washing, crushing, pressing, storing and sterilizing apples is controlled in a low temperature environment of 4-5°C to inhibit oxidation reactions and bacterial growth; Step 2: Cleaning process: pre-washing, using clean water to remove dust, sand and impurities on the surface of the apples; ozone water sterilization cleaning, soaking the apples in ozone water that continuously flows with ozone for sterilization, controlling the concentration, temperature and treatment time of the ozone water to ensure the sterilization effect; RO water fine washing, using RO water to wash the apples. RO water is reverse osmosis water, and RO water is not recycled to ensure cleanliness and hygiene; Step 3: Air drying: After the apples are cleaned in step 2, the surface of the apples is air dried using an air drying device to prevent raw water from being brought into the subsequent processing steps; Step 4: crushing, the air-dried apples in step 3 are sent to an apple crushing adsorption machine for crushing. The apple crushing adsorption machine includes: a parallel blade structure for making a number of cracks on the surface of the apples without separating the apples as a whole, thereby reducing the contact between the apples and oxygen; the apples after the cracks are crushed and transported in an environment isolated from oxygen; Step 5: Squeezing: The crushed apples are sent into a fully enclosed squeezing chamber for squeezing. The squeezing chamber is characterized by a detachable outer shield for easy cleaning. During the squeezing process, the juice flows out from the periphery of the sieve cylinder, and the pomace is discharged from the tail of the sieve cylinder. The entire process is isolated from the outside air to avoid oxidation. Step 6: Nitrogen protection. During the entire process of steps 4 and 5, nitrogen isolation protection is used. Oxygen is isolated from the juice through a nitrogen shielding process to ensure that the juice is completely isolated from oxygen and reduce oxidation. Step 7: Transportation and storage step, using a negative pressure diaphragm pump to extract the squeezed juice from the fully enclosed squeezing chamber and transport it to a low-temperature storage tank. During the juice transportation process, the juice is always isolated from the air, and the temperature in the storage tank is kept below 4°C, further delaying the oxidation process of the juice; Step 8: Sterilization: After the juice is sent to the low-temperature storage tank, the HPP ultra-high pressure cold sterilization technology is used to sterilize the juice. The sterilization process is as follows: a high pressure of 600MPa is applied to the juice in a low-temperature environment to kill microorganisms; The sterilization process avoids the damage to flavor and taste caused by high temperature sterilization, ensuring that the taste, flavor and color of the juice are consistent with freshly squeezed juice; Step 9: Cold chain transportation. The juice that has undergone HPP ultra-high pressure cold sterilization is stored and transported via cold chain transportation to ensure that the freshness, taste and quality of the juice remain unchanged.

[0007] Furthermore, in the ozone water sterilization cleaning process in the cleaning process, the concentration of ozone water is 0.5~1.55mg / L.

[0008] Furthermore, during the ozone water sterilization cleaning process, the temperature of the ozone water is maintained between 5 and 15°C. Furthermore, in the crushing step, the blades are arranged in a parallel blade structure, and the spacing between the blades is 2 to 5 mm.

[0009] Furthermore, a nitrogen protection device is provided inside the apple crushing adsorption machine, and the nitrogen flow rate is 1~2L / min per minute, which is used to isolate the outside air from contacting the apples.

[0010] Furthermore, the pressing chamber is a fully enclosed structure, and the pressing chamber is squeezed by negative pressure. A detachable protective cover is provided on the periphery of the pressing chamber to facilitate subsequent cleaning and maintenance.

[0011] Furthermore, HPP ultra-high pressure cold sterilization technology is used for sterilization, with an ultra-high pressure of 600 MPa and a sterilization time of 3 to 5 minutes to ensure that the microorganisms in the juice are effectively killed.

[0012] Furthermore, the temperature of the warm storage tank is controlled below 4°C, and a temperature control device is provided in the storage tank to maintain a stable temperature during storage.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. The anti-oxidation production process of apple juice of the present invention combines a number of advanced technologies such as low temperature environment, ozone water sterilization, nitrogen protection, ultra-high pressure cold sterilization, etc., and effectively reduces the occurrence of oxidation reaction through fine control of the entire process of juice production, thereby improving the quality and flavor of the juice; specifically, the use of low temperature 4-5°C treatment, ozone water cleaning, nitrogen protection pressing and HPP cold sterilization not only maintains the freshness and taste of the apple juice, but also improves the nutrient retention, flavor, taste and food safety of the juice, and has significant economic and social benefits.

[0014] 2. The present invention effectively reduces the contact between apple juice and air, thereby significantly reducing the activity of oxidase and slowing down the occurrence of oxidation reaction. This not only maintains the original color of the juice, but also significantly improves the flavor and taste of the juice, avoiding the dark brown juice and deterioration common in traditional processes.

[0015] 3. By introducing a process that specifically creates several cracks on the surface of the apple without separating the apple as a whole, and cooperating with a nitrogen protection device, the contact between apples and air is greatly reduced during the crushing and pressing process, further avoiding oxidation problems caused by air contact. The entire production process uses a closed environment and negative pressure oxygen isolation technology to ensure that apples are always kept in a low-oxygen environment throughout the production process, eliminating oxidation at the source. DETAILED DESCRIPTION

[0016] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicating directions or positional relationships are based on the directions or positional relationships shown, and are only for the convenience of describing the present invention, and do not indicate or imply that the devices or elements referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention; Example

[0017] The present invention provides a technical solution: a production process for anti-oxidation of apple juice, comprising the following steps: 1. Choose fresh, undamaged apples. The variety of apples is not limited, but they must meet production requirements. Make sure there is no sand or impurities on the surface of the apples, and try to minimize storage time after picking. Second, the first wash: put the apples into a clean water pool for pre-washing to remove surface dust, sand and other impurities; Second pass: transfer the apples into the ozone water pool and sterilize them with ozone water; control the concentration of ozone water at 0.5~1.55mg / L, and ensure that the apples are immersed in ozone water for 3-5 minutes; continue to deliver ozone to maintain the concentration; The third time: Use RO water for fine washing. RO water is reverse osmosis water, which removes residual ozone and other impurities on the surface of the apples to ensure that the fruit surface is clean and free of bacteria; 3. The washed apples are air-dried by the air-drying device installed on the elevator to ensure that there is no moisture left on the surface of the apples to prevent moisture from being brought into the subsequent crushing process; Fourth, the apples enter a special crushing adsorption machine, which is equipped with multiple sets of parallel blades on both sides to split the apples; each apple is cut with several cracks, but the middle of the flesh remains connected to reduce contact with oxygen; The split apples enter the screw conveying pump, and the crushing device in the pump further crushes the split apples into pulp; 5. The crushed apple pulp enters the fully enclosed pressing chamber; a detachable protective cover is provided outside the pressing chamber for easy cleaning; nitrogen protection is used during the pressing process, and the entire pressing process is carried out in a nitrogen-isolated environment to prevent oxygen from contacting the juice and reduce oxidation; the juice flows out through the outer shell of the sieve cylinder, and the pomace is discharged through the tail of the sieve cylinder; 6. The squeezed juice is extracted through the connected diaphragm pump; the diaphragm pump uses the negative pressure principle to extract the juice from the squeezing chamber; the juice is transported to the low-temperature storage tank through the diaphragm pump to ensure that the juice is completely isolated from the air and reduce the risk of oxidation; 7. After the juice enters the low-temperature storage tank, it is transported to the filling machine by a rotor pump; the temperature of the storage tank is maintained at 4~5℃; the juice is transported to the HPP ultra-high pressure sterilization equipment through the rotor pump; under the high pressure of 600MPa, the microorganisms in the juice are effectively killed, while maintaining the original flavor and nutritional components of the juice; 8. The juice after HPP treatment is aseptically filled through the filling machine; the filling environment is kept at a low temperature to avoid any microbial contamination; after the juice is filled, it is immediately sealed and packaged to ensure that the juice is not contaminated by the outside world and enters the circulation link.

[0018] The final apple juice obtained has bright color and fresh taste, retains the natural aroma and nutrients of apples, and the juice will not oxidize and discolor, and has a long shelf life. The juice processed by this process has excellent flavor, is rich in vitamins, minerals and other nutrients, and meets food safety requirements.

[0019] Example 2: Optimization of the production process of anti-oxidation of apple juice 1. Select specific high-sugar apple varieties with higher juice yield and better flavor; try to control the transportation time of all apples after picking to maintain the freshness of the fruit; 2. After pre-washing, the apples are disinfected in an ozone pool with an ozone concentration of 1.55 mg / L or above for 5 minutes to better remove surface microorganisms. RO water is used in the fine washing process to ensure that the water quality of each batch of fruit meets the hygiene standards after washing. 3. The wind speed and temperature of the air drying device are optimized to ensure a uniform air drying process and avoid moisture residue on the surface of the apples; this can effectively prevent the influence of moisture on the crushing process; 4. The crushing adsorption machine evenly splits the apples to further reduce the possibility of oxidation; during the crushing process, the gas circulation device is used to further reduce air contact; 5. The entire pressing chamber is protected by nitrogen, and when entering the pressing chamber, the nitrogen flow and concentration are strictly controlled to ensure that the apples are completely isolated from oxygen; the squeezed juice directly enters the anaerobic delivery channel; 6. The juice is extracted by a diaphragm pump and transported to the cooling tank to ensure that the juice is not contaminated by air in a low temperature environment; 7. Use HPP technology to sterilize the juice, ensuring that microorganisms are completely killed while maintaining nutrition; the juice is then filled through a fully closed system to avoid any external contamination; 8. After the juice is filled, it is packaged under aseptic conditions and packaged in PET bottles or glass bottles to ensure the safety and hygiene of the product quality during the circulation process.

[0020] The apple juice processed by this optimized process has a fresher flavor, brighter color, and a significantly extended shelf life, making it suitable for long-term storage and large-scale production. Example

[0021] Further analysis of anti-oxidation of apple juice First, the requirements for the surrounding environment; since oxidation is easier at higher temperatures, high-end juice processing workshops require low-temperature processing, and the optimal temperature is 4~5℃; in a low-temperature environment, bacteria are not easy to breed and the rate of oxidation will slow down.

[0022] Second, the requirements for cleaning. The original plan was to wash with clean water and then process it after it was clean. In the new process, we require at least three washes. The first wash is a pre-wash to clean off dust, sand and other impurities on the surface. The second is a sterilization wash. A certain amount of ozone is added to the cleaning water and the ozone is continuously delivered to the apples so that they are washed in an ozone pool of a certain concentration for a certain period of time. At this time, the bacteria on the surface can be killed. The third wash is a fine wash. The water used for cleaning is RO water, and it is required not to be recycled.

[0023] Third, add an air-drying device to the elevator. The main purpose of air-drying is to prevent raw water from being brought into the subsequent crushing process.

[0024] Fourth, use a special apple crushing adsorption machine; after the apples enter the crushing adsorption machine, there are many parallel blades on both sides of the adsorption machine, which cut several cracks on both sides of the apples but ensure that the middle of the apples are connected. In this way, the cracks are basically not in contact with oxygen, and the subsequent crushing reduces a lot of pressure; the cracked apples enter the conveying pump driven by the screw below, which is equipped with a crushing device inside. The crushing device breaks the apples that were originally cut but not split, and then conveys them out through the spiral and the rotor stator.

[0025] The crushed apples enter a pressing chamber, which is a fully enclosed pressing chamber. The outer protective cover of the pressing chamber can be easily removed for later cleaning. After the apples enter the pressing chamber, the pressing begins. During the pressing, the juice flows out from the outside of the sieve cylinder, and the pomace is discharged through the tail of the sieve cylinder. After the juice remains, a diaphragm pump is connected to the front end. The diaphragm pump uses the principle of negative pressure to extract the juice, and then transports it to the low-temperature storage tank.

[0026] When the apples enter the crushing process, the entire device begins to use nitrogen protection to isolate the air in the cavity; then after it is crushed and enters the pressing cavity, it is a completely negative pressure and oxygen-isolated environment, so the apples cannot come into contact with oxygen, including after they come out of the diaphragm pump, they are also completely isolated from the air.

[0027] After the juice enters the low-temperature tank, it is transported to the filling machine by a rotor pump, and then quickly enters the HPP ultra-high pressure sterilization equipment. Originally, most of the juice was sterilized by heat sterilization. Due to the high temperature, the flavor and taste of the juice changed greatly during the sterilization. The HPP ultra-high pressure cold sterilization technology uses a pressure of 600MPa to kill microorganisms, mainly by destroying cell membranes, inhibiting enzyme activity and affecting the replication of genetic materials such as DNA. In addition, the sterilization step is carried out at low temperature. Due to the low temperature, compared with heat sterilization, it can simultaneously ensure that the sterilization effect is better and the time is shorter. Under the same sterilization effect, the quality of the food can be better maintained, so that the taste of the juice can be better guaranteed like freshly squeezed juice. And the HPP sterilization technology can not only kill microorganisms, but also improve the texture and nutritional content of food.

[0028] After the ultra-high pressure equipment completes sterilization, the fruit juice is transported and stored using cold chain transportation; the sterilized juice processed by the ultra-high pressure equipment can completely reach the level of freshly squeezed juice, and the color, flavor and taste remain unchanged.

[0029] Fresh-cut fruit processing technology Apples → wash with tap water → soak in 200 mg sodium hypochlorite for 5 min → peel, core and cut → sterilize → drain and package → store at 5°C. Note: knives, containers, gloves, cutting boards, etc. must be soaked in 200 mg sodium hypochlorite solution and tested by ATP fluorescence detector with a reading of 0 RLU; the operating environment must be irradiated with ultraviolet light for 1 hour.

[0030] Study on the process parameters of ozone water sterilization, preparation of ozone water, ozone generator uses air as raw material, generates ozone gas by corona discharge, the equipment is preheated for 15 minutes before use, the generated ozone gas is passed into 5L ultrapure water, and the ozone gas is fully dissolved; ozone water with different concentrations is prepared by different ventilation times, and after preparation, the concentration of ozone water is immediately measured and used.

[0031] Ozone water concentration screening Ozone water was set at 15 ℃ with three mass concentration gradients of 0.50, 1.00 and 1.55 mg / L to sterilize fresh-cut apples for 5 min. The samples without sterilization were used as controls.

[0032] Ozone water temperature screening The temperature of ozone water with a mass concentration of 1.00 mg / ml was set at 5℃, 10℃, 15℃ and 20℃, respectively, to sterilize fresh-cut apples for 5 minutes, and the unsterilized samples were used as controls. The total colony counts were carried out on the 3rd, 5th, 7th and 9th days of storage, and quality indicators were measured regularly.

[0033] Index determination method The ozone water concentration is measured using a D0Z30 ozone tester and the unit is mg.

[0034] For the total colony count determination, weigh 25 g of sample and place it in a 225 mL sterile cup of physiological saline, stir magnetically for 10 min to prepare a 1:10 g / mL sample solution; draw 1 mL of the 1:10 g / mL sample solution and inject it into a sterile test tube containing 9 mL of diluent along the tube wall, mix evenly to prepare a 1:100 g / mL sample solution, and so on, prepare a 10-fold serial dilution sample solution; use a sterile pipette to draw 1 mL of the sample solution of appropriate dilution onto the total colony count test piece, make 2 test pieces for each dilution, and take 1 mL of blank dilution solution on two test pieces as a blank control; place the test piece in a 36°C incubator for 48 h; the colonies on the total colony count test piece will appear red, and the number of colonies and the corresponding dilution factor will be recorded; the unit of the total colony count is lgCFU / g.

[0035] Quality index determination The hardness was measured using a FT327 hardness tester with a probe diameter of 8mm. The soluble solids content was measured using a PAL-1 refractometer. The weight loss rate was measured using a weighing method. The color difference index L* value was measured using a CR-400 colorimeter. The L** value represents the lightness or darkness of fresh-cut fruits. The lower the value from 0 to 100, the more severe the browning.

[0036] Data analysis methods All experimental data were statistically analyzed and plotted using Excel 2003 software, and significance analysis was performed using SPSS 17.0 software. The total number of colonies was counted on the 5th, 7th, and 9th days, and quality indicators were measured regularly.

[0037] Ozone water treatment time screening Fresh-cut apples were treated with 1.00 mg ozone water at 15°C for 2, 5 and 10 min respectively. Unsterilized samples were used as controls, and each treatment was replicated three times. The total colony counts were performed on the 3rd, 5th, 7th and 9th days of storage, and quality indicators were measured regularly.

[0038] Effects of ozone water concentration on total colony count and quality of fresh-cut apples During storage, the total colony count of fresh-cut apples increased rapidly with the extension of storage time; ozone water treatment had a significant killing effect on microorganisms, and the higher the concentration of ozone water, the better the sterilization effect; after 9 days of storage, the total colony counts of fresh-cut apples treated with ozone water at mass concentrations of 0.50, 1.00 and 1.55 mg / L were 3.44, 2.56 and 1.98IS CFU / g, which were 13.9%, 1.7% and 0.5% of the control group (4.331gCFU / g), respectively; the results showed that the sterilization effect of fresh-cut apples treated with ozone water at a mass concentration of more than 1.00 mg / L was significant.

[0039] Ozone water has a significant killing effect on microorganisms on the surface of fresh-cut apples, and the higher the concentration of ozone water, the longer the treatment time, and the lower the temperature, the more obvious the sterilization effect; at the same time, ozone water sterilization can inhibit the browning of fresh-cut apples and the decrease in hardness, soluble solids and ascorbic acid content, and reduce the weight loss rate; the results showed that fresh-cut apples treated with 1.00mmg / L15℃ ozone water for 5 min had a good sterilization effect and a good effect on maintaining the quality of fresh-cut fruits.

[0040] The basic principles, main features and advantages of the present invention are shown and described above. Without departing from the spirit and scope of the present invention, the present invention may also be subject to various changes and improvements, which all fall within the scope of the present invention to be protected.

Claims

1. A production process for anti-oxidation of apple juice, characterized in that: The production process includes the following steps: Step 1: Environmental control: Full control of the apple washing, crushing, squeezing, storage and sterilization process in a low temperature environment of 4-5°C; Step 2: Cleaning process: pre-washing, using clean water to remove dust, sand and impurities on the surface of the apples; ozone water sterilization cleaning, soaking the apples in ozone water that continuously flows with ozone for sterilization; RO water polishing, using RO water to clean the apples, and the RO water is not recycled; Step 3: air drying: after the apples are cleaned in step 2, the surface of the apples is air dried using an air drying device; Step 4: crushing, the air-dried apples in step 3 are sent to an apple crushing adsorption machine for crushing. The apple crushing adsorption machine includes: a parallel blade structure for making a number of cracks on the surface of the apples without separating the apples as a whole, thereby reducing the contact between the apples and oxygen; the apples after the cracks are crushed and transported in an environment isolated from oxygen; Step 5: Squeezing: The crushed apples are sent into a fully enclosed squeezing chamber for squeezing. During the squeezing process, the juice flows out from the periphery of the sieve cylinder, and the pomace is discharged from the tail of the sieve cylinder. The entire process is isolated from the outside air to avoid oxidation. Step 6: Nitrogen protection: In the entire process of steps 4 and 5, nitrogen isolation protection is adopted to isolate oxygen from the outside through the nitrogen shielding process; Step 7: Transportation and storage step, using a negative pressure diaphragm pump to extract the squeezed juice from the fully enclosed squeezing chamber and transport it to a low-temperature storage tank. During the juice transportation process, the juice is always isolated from the air, and the temperature in the storage tank is kept below 4°C, further delaying the oxidation process of the juice; Step 8: Sterilization: After the juice is sent to the low-temperature storage tank, the HPP ultra-high pressure cold sterilization technology is used to sterilize the juice. The sterilization process is as follows: a high pressure of 600MPa is applied to the juice in a low-temperature environment to kill microorganisms; Step nine: Cold chain transportation. The juice that has undergone HPP ultra-high pressure cold sterilization is stored and transported via cold chain transportation.

2. The production process for anti-oxidation of apple juice according to claim 1, characterized in that: In the ozone water sterilization cleaning process in the cleaning process, the concentration of ozone water is 0.5~1.55mg / L.

3. The production process for anti-oxidation of apple juice according to claim 1, characterized in that: During the ozone water sterilization cleaning process in the cleaning process, the temperature of the ozone water is maintained between 5 and 15°C.

4. The production process for anti-oxidation of apple juice according to claim 1, characterized in that: In the crushing step, the blades are arranged in a parallel blade structure, and the spacing between the blades is 2~5mm.

5. The production process for anti-oxidation of apple juice according to claim 1, characterized in that: The apple crushing adsorption machine is equipped with a nitrogen protection device inside, with a nitrogen flow rate of 1~2L / min, which is used to isolate the outside air from contacting the apples.

6. The production process for anti-oxidation of apple juice according to claim 1, characterized in that: The pressing chamber is a fully enclosed structure, and the pressing chamber is squeezed by negative pressure. A detachable protective cover is provided on the periphery of the pressing chamber.

7. The production process for anti-oxidation of apple juice according to claim 1, characterized in that: Sterilization adopts HPP ultra-high pressure cold sterilization technology, the ultra-high pressure is 600 MPa, and the sterilization time is 3 to 5 minutes.

8. The production process for anti-oxidation of apple juice according to claim 1, characterized in that: The temperature of the warm storage tank is controlled below 4°C, and a temperature control device is installed inside the storage tank to keep the temperature stable during storage.