CN112106904B - Processing method of fresh squeezed pear juice - Google Patents
Processing method of fresh squeezed pear juice Download PDFInfo
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- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
- A23L—FOODS, FOODSTUFFS, OR NON-ALCOHOLIC BEVERAGES, NOT COVERED BY SUBCLASSES A21D OR A23B-A23J; THEIR PREPARATION OR TREATMENT, e.g. COOKING, MODIFICATION OF NUTRITIVE QUALITIES, PHYSICAL TREATMENT; PRESERVATION OF FOODS OR FOODSTUFFS, IN GENERAL
- A23L2/00—Non-alcoholic beverages; Dry compositions or concentrates therefor; Their preparation
- A23L2/02—Non-alcoholic beverages; Dry compositions or concentrates therefor; Their preparation containing fruit or vegetable juices
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- A—HUMAN NECESSITIES
- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
- A23V—INDEXING SCHEME RELATING TO FOODS, FOODSTUFFS OR NON-ALCOHOLIC BEVERAGES AND LACTIC OR PROPIONIC ACID BACTERIA USED IN FOODSTUFFS OR FOOD PREPARATION
- A23V2002/00—Food compositions, function of food ingredients or processes for food or foodstuffs
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Abstract
The processing method of the fresh pear juice is characterized by comprising the following steps: (1) raw material selection and pretreatment: selecting fresh pear fruits, peeling and removing kernels; (2) juicing: juicing and filtering the pears treated in the step (1) to obtain pear juice; (3) primary pH value adjustment: adjusting the pH value of the pear juice obtained in the step (2) to 6.0-8.5; (4) ultrahigh pressure treatment: performing ultrahigh pressure treatment on the pear juice obtained in the step (3) within the pressure range of 300-600MPa for 5-15 min; (5) standing: standing the pear juice obtained in the step (4) at room temperature until the color of the pear juice is stable; (6) adjusting the pH value for the second time: adjusting the pH value of the pear juice obtained in the step (5) to be below 4.5; (7) and (3) cold sterilization: and (5) performing ultra-high pressure sterilization treatment on the pear juice obtained in the step (6) to obtain a fresh pear juice finished product. The processing method of the freshly squeezed pear juice can process the freshly squeezed raw pear juice which is stable in color and luster and free of cooking smell.
Description
Technical Field
The invention relates to the technical field of food and beverage, in particular to a processing method of fresh pear juice.
Background
In recent years, with the enhancement of health consciousness of people, the concepts of green, health and safety are gradually deepened into the mind, and the requirement on the internal quality is higher and higher. The healthy and delicious fruit juice beverage is a main reason for attracting consumers. The freshly squeezed juice has original taste and flavor and pure nature, and is the greatest selling point and core competitiveness. Because the fresh pear juice is easily polluted by microorganisms, the shelf life is extremely short, the optimal drinking period is only 30min, and the limitation causes the fresh pear juice to basically stay in the production mode of being squeezed and sold at the present time, the industrial development is seriously hindered, and the production scale is greatly limited.
The shelf life of the traditional pear juice is prolonged by adopting heat sterilization (such as pasteurization or ultrahigh temperature instantaneous sterilization). Because the pear juice is extremely sensitive to heat, the heat sterilization enables the raw pear juice to be changed into the cooked pear juice, the flavor is changed, and the efficacy is completely different. The raw pear juice and the cooked pear juice have different efficacies, the raw pear juice can promote the production of body fluid to quench thirst and relieve the sore throat, and the cooked pear juice can nourish yin, moisten lung, eliminate phlegm and relieve cough. Therefore, the traditional hot processing mode can only produce cooked pear juice, and the processing of raw pear juice has huge market gaps.
The ultra-high pressure technology is a non-thermal processing technology, and refers to a pressure treatment of 100-1000MPa under room temperature or mild heating condition to achieve the purpose of sterilization. The method has the advantages of no drastic temperature change in the sterilization process, no damage to covalent bonds, little influence on small molecular substances, complete retention of nutritional ingredients in the raw materials, no curing phenomenon after treatment, and retention of original flavor quality and fresh characteristics. The research and application of the ultrahigh pressure technology can effectively solve the technical bottleneck that the hot processing of the fruit juice can not break through, really realize the cold sterilization and cold processing of the fruit juice, avoid the generation of cooking flavor in the hot processing process of the pear juice, and is a technical cold revolution. Although the original flavor, efficacy and nutrition of the pear juice can be retained to the maximum extent by ultrahigh pressure treatment, and the possibility is provided for processing the raw pear juice, enzymatic browning caused by polyphenol oxidase is very easy to occur in the processing process of the pear, so that the fresh pear juice turns red, the color of the fresh pear juice is influenced, the polyphenol oxidase is a pressure-resistant enzyme, the maximum pressure of common production type ultrahigh pressure equipment is 600MPa, the polyphenol oxidase cannot be completely passivated even under the pressure, and even the activating effect is achieved, and the browning of the pear juice is accelerated.
The prior art mainly adopts a method of heating enzyme deactivation and combining an anti-browning agent to inhibit browning. As mentioned above, pear juice is extremely sensitive to heat, even if microwave or steam enzyme deactivation is carried out for a short time, cooking flavor is generated to a greater or lesser extent, and meanwhile, raw pear juice is converted into cooked pear juice, and the flavor efficacy of the raw pear juice is lost. Therefore, the processing of the fresh pear juice adopts the mode of combining ultrahigh pressure with the anti-browning agent, but has the following problems: (1) The ultra-high pressure treatment is not thorough, and even polyphenol oxidase can be activated, so that the browning of pear juice is accelerated, and the application of the pear juice is limited; (2) And (2) the anti-browning agent is used for processing synergistically, the anti-browning agent only inhibits polyphenol oxidase so as to delay the browning phenomenon in the shelf life, enzymatic browning cannot be stopped, and the polyphenol oxidase in the fresh squeezed pear juice can still catalyze phenolic substances to generate browning along with the prolonging of the shelf life time, so that the color of the fresh squeezed pear juice is gradually deepened, and the color stability of the fresh squeezed pear juice in the shelf life is seriously influenced.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a processing method of fresh pear juice aiming at the technical current situation, the fresh pear juice with stable luster and no cooking flavor can be processed, and the original flavor, efficacy and nutrition of the fresh pear juice are retained to the maximum extent.
The technical scheme adopted by the invention for solving the technical problems is as follows: the processing method of the fresh pear juice is characterized by comprising the following steps:
(1) raw material selection and pretreatment: selecting fresh pear fruits, peeling and removing kernels;
(2) juicing: juicing and filtering the pears treated in the step (1) to obtain pear juice;
(3) primary pH value adjustment: adjusting the pH value of the pear juice obtained in the step (2) to 6.0-8.5;
(4) ultrahigh pressure treatment: performing ultrahigh pressure treatment on the pear juice obtained in the step (3), wherein the pressure range is 300-600MPa, and the treatment time is 5-15 min;
(5) standing: standing the pear juice obtained in the step (4) at room temperature until the color of the pear juice is stable;
(6) adjusting the pH value for the second time: adjusting the pH value of the pear juice obtained in the step (5) to be below 4.5;
(7) and (3) cold sterilization: and (5) performing ultra-high pressure sterilization treatment on the pear juice obtained in the step (6) to obtain a fresh pear juice finished product.
The pear juice obtained in the step (2) is light white, nearly colorless, clear and transparent, and the pH value range is about 5.2-5.8. Due to browning caused by polyphenol oxidase, the color of the fresh pear juice turns red and is unstable in the shelf life. The method has the advantages that the affinity between polyphenol oxidase and substrate phenolic substances can be improved by processing the fresh squeezed pear juice at ultrahigh pressure (300-600 MPa), the browning of the fresh squeezed pear juice is accelerated, and the browning speed is faster along with higher pressure. Through previous researches of the applicant, two polyphenol oxidases of PPO1 and PPO2 exist in fresh pear juice, and when the pH value is lower than 5.5, PPO1 catalyzes a substrate phenolic substance to generate red browning, and when the pH value ranges from 6.0 to 8.5, PPO2 catalyzes the phenolic substance to generate yellow browning. In contrast, the yellow brown stain of the fresh pear juice is similar to the color of the commercial cooked pear juice, and is more easily accepted by consumers. Based on the ultrahigh-pressure enzyme activation effect and the catalytic enzymatic browning mechanism under the acidic and alkaline conditions, the PPO2 is activated by adjusting the pH value and processing the pear juice under the ultrahigh pressure, so that the yellow browning reaction of the pear juice is accelerated, the red browning of the pear juice is avoided, and the color change of the pear juice is more acceptable to consumers. The process is carried out at room temperature, without heating the pear juice, which in the present invention is generally 20-35 ℃. As the limited substrate phenolic substances in the pear juice are consumed by the full reaction of the PPO2 and the substrate phenolic substances in the standing process, even if PPO1 remains in the pear juice, red browning cannot be generated to cause the color change of the pear juice, so that the pear juice finally presents stable light yellow. And regulating the pH value of the pear juice to be below 4.5 for inhibiting the germination of spores, and performing cold sterilization by adopting an ultrahigh pressure technology.
As an improvement, the denucleation in step (1) comprises the removal of the stone cell region of the pear fruit and the carpopodium of the fruit seed. Because the activity of polyphenol oxidase in the stone cell area of the pear fruit is far higher than that of pulp, browning is easier to occur, and thus, the browning degree in the crushing process can be reduced.
As an improvement, a juice extractor is adopted in the step (2) to extract juice and collect the juice, and then the juice is filtered by diatomite to obtain clarified pear juice.
As a modification, the substance for adjusting the pH value in the step (3) is at least one of sodium citrate, sodium bicarbonate, sodium pyrophosphate and sodium tripolyphosphate.
As a modification, the pH value in the step (3) is in the range of 6.5 to 7.5. More preferably, the pH in step (3) is in the range of 6.8 to 7.2.
As an improvement, the step (4) also comprises the addition of neutral protease accounting for 0.1-0.3% of the weight of the pear juice, so that the standing time in the step (5) can be shortened to 2-6h. The addition of the neutral protease can degrade part of polyphenol oxidase in the pear juice, thereby shortening the standing time; when no neutral protease is added, the standing time in the step (5) is more than 8h, and the neutral protease accounting for 0.3 percent of the weight of the pear juice is added, so that the standing time in the step (5) can be shortened to 2h.
As an improvement, the pressure range in the step (4) is 400-500MPa, and the treatment time is 5-10 min.
In the improvement, in the step (6), the pH value is adjusted by using an organic acid, and the organic acid is at least one of citric acid, malic acid and tartaric acid.
As a modification, the pH value in the step (6) is in the range of 4.0 to 4.5. More preferably, the pH in step (6) is in the range of 4.2 to 4.5. When the pH value is acidic, the activity of neutral protease can be inhibited, and the residual activity of PPO2 can be inhibited.
As an improvement, the sterilization treatment in the step (7) is to treat the pear juice for 5-15 min by adopting the pressure of 500-800 MPa. More preferably, the sterilization treatment in the step (7) is to treat the pear juice for 5 to 15min by adopting the pressure of 500 to 600 MPa.
Compared with the prior art, the invention has the advantages that: the processing process is not heated, the curing phenomenon of the fresh raw pear juice cannot be caused, the cooking flavor is avoided, the flavor and the nutrition of the fresh raw pear juice can be reserved to the maximum extent, the energy consumption is reduced, and the production cost is saved; the color stability in shelf life is good; the ultrahigh pressure sterilization is combined with the pH value adjustment to be acidic, so that the mould, yeast and bacteria can be killed, the spore germination can be inhibited, and the drinking safety of the fresh pear juice is higher.
Drawings
FIG. 1 is a flow chart of the process of fresh pear juice according to example 1 of the present invention;
FIG. 2 is a graph showing the effect of pH on polyphenol oxidase activity in fresh pressed pear juice according to example 3 of the present invention.
Detailed Description
The invention is described in further detail below with reference to the accompanying examples.
Example 1
The fresh pear juice of the embodiment is processed according to the following steps:
(1) fresh, eight-ripe, moderate-size and disease-free green-coronal pears are taken as experimental raw materials, and peeled by a peeler; then, an enucleator stone cell area with the diameter of 2cm is used together with the fruit stem of the fruit seed;
(2) juicing: and (2) cleaning the pears treated in the step (1), cutting into blocks, juicing by using a juice machine to remove pomace, and filtering the collected juice by using diatomite to remove suspended matters to obtain the nearly colorless and transparent clear pear juice.
(3) Primary pH value adjustment: and (3) adjusting the pH value of the clarified pear juice (initial pH value is 5.5) obtained in the step (2) to 7.0 by adopting sodium citrate.
(4) Ultrahigh pressure treatment: and (4) filling the pear juice obtained in the step (3) into a plastic bottle, and treating for 5min by adopting the pressure of 500 MPa.
(5) Carrying out enzymolysis by neutral protease: and (4) adding neutral protease powder accounting for 0.2% of the weight of the pear juice into the pear juice obtained in the step (4) for enzymolysis for 1h.
(6) Standing: and (6) standing the pear juice obtained in the step (5) at the temperature of 20-35 ℃ for 4-6 h until the pear juice is stable and light yellow in color.
(7) Adjusting the pH value for the second time: and (5) adjusting the pH value of the pear juice obtained in the step (6) to 4.3 by using citric acid.
(8) And (3) cold sterilization: and (4) treating the pear juice obtained in the step (7) for 10min under the pressure of 550MPa to obtain the fresh squeezed pear juice.
The specific processing flow chart is shown in figure 1.
Comparative example 1
Vc is a common browning inhibitor, can be added into the fresh pear juice to well keep the fresh color of the fresh pear juice, and is suitable for short-term pear juice sale. In comparative example 1, the browning of the fresh pear juice was suppressed by adding different amounts of Vc to the fresh pear juice, and compared with the change in color of the fresh pear juice during the shelf life in example 1 of the present invention.
Preparation method of comparative example 1: fresh, medium-ripened and disease-free Cuiguan pears are used as experimental raw materials, peeled and cored, and juice is squeezed by a juice machine to remove fruit residues, and the juice is filtered by diatomite. Adding Vc 0.1%, 0.2% and 0.3% of the pear juice respectively, and treating with 550MPa pressure for 10min.
The comparison results are shown in table 1:
TABLE 1 changes of shelf-life color of fresh pear juice by different processing methods
As shown in table 1, the fresh pear juice obtained in example 1 was light yellow in color and stable in color during the shelf life. In the comparative example 1, the Vc is added to inhibit the browning of the pear juice, and the control group with the addition amount of 0.2 percent and 0.3 percent of the Vc can obviously inhibit enzymatic browning and keep the fruit juice light white; however, the color of the pear juice is changed due to browning phenomenon along with the prolonging of the shelf life, the color of the pear juice is gradually changed from light white to light red, then is dark red, the color is unstable, the commodity of the freshly-squeezed pear juice is influenced, and the single use amount of Vc is large, such as the Vc addition amount of 300ml per bottle, 0.3 percent of Vc is added, the Vc content is 900mg, and the Vc content is far more than the recommended intake of an adult of 100mg/d (the relevant standard refers to WS/T578.5-2018).
Example 2: influence of ultrahigh pressure treatment on pear juice browning
Fresh, medium-ripened and disease-free Cuiguan pears are used as experimental raw materials, peeled by a peeler, and stoned cell areas are removed by a stoner with the diameter of 2 cm. Squeezing juice with a juice machine, removing fruit residues, and filtering the juice with diatomite to remove suspended matters. And (3) carrying out plastic bottle splitting filling on the obtained pear juice, treating the experiment group (HPP) for 5min under the pressure of 500MPa, and not carrying out ultrahigh pressure treatment on the control group (CK). The color difference was then determined for the test (HPP) and Control (CK) samples at 6h intervals.
The color difference testing method comprises the following steps: a15 ml sample was placed in a sample dish (CM-A128), and values of L, a, b were measured by a color difference meter (measurement mode: reflectance measurement, measurement caliber: 30 mm), and then the color difference value was calculated according to the following formula:
in the formula, L0 *、a0 *0、b0 *Is the initial color difference value.
The results are shown in table 2:
TABLE 2 influence of ultra-high pressure treatment on the color difference and color change of fresh pear juice in shelf life
As shown in table 2, after 24 hours of shelf life, the pear juice in the control group (CK) was slowly browned, the color change of the pear juice was still not obvious, and the color difference Δ E was only 0.56, which is smaller than the color difference (1.5) recognized by human eyes. After 24h shelf life, the color of the pears in the experimental group (HPP) changed from pale white to pale red, followed by dark red, with a rapid decrease in L and a rapid increase in Δ E. When the shelf life is 6 hours, the delta E of the pear juice in the experimental group (HPP) reaches 1.61, and the color difference value which can be obviously identified by naked eyes is achieved; after the shelf life is 12 hours, the color change of the pear juice tends to be slow, but the delta E still gradually rises. In conclusion, the browning speed of the freshly squeezed green-coronal pear juice is relatively slow, but the browning speed of the freshly squeezed green-coronal pear juice is accelerated after the ultrahigh-pressure treatment.
Example 3: influence of pH value on color of fresh pear juice
Fresh, medium-ripened and disease-free Cuiguan pears are used as experimental raw materials, peeled by a peeler, and stoned cell areas are removed by a stoner with the diameter of 2 cm. Squeezing juice with a juice machine, removing fruit residues, and filtering the juice with diatomite to remove suspended matters. And (3) carrying out plastic bottle splitting filling on the obtained pear juice, treating the experiment group (HPP) for 5min under the pressure of 500MPa, and not carrying out ultrahigh pressure treatment on the control group (CK). The PPO activity of the test group (HPP) and the control group (CK) at different pH values were then measured, respectively, and the color of the pear juice after standing at room temperature (30 ℃) for 24 hours at different pH values was observed.
The PPO activity of the test group (HPP) and the control group (CK) at different pH values is shown in FIG. 2, and the PPO activity of the test group (HPP) is higher than that of the control group (CK) at any pH value. The optimum reaction pH values of PPO of the experimental group (HPP) are two 5.0 and 7.0, the corresponding enzymes are PPO1 and PPO2 respectively, but the optimum pH value of the control group (CK) is only 5.0, and the peak with the pH value of 7.0 is not obvious. The activity of PPO1 before the ultrahigh pressure treatment is 6.5U/mL, the activity after the treatment is 14.1U/mL, and the activity is increased by 2.17 times; the activity of PPO2 before ultrahigh pressure treatment is 2.6U/mL, and the activity after ultrahigh pressure treatment is 25.5U/mL, which is increased by 9.8 times. In conclusion, the ultrahigh pressure treatment enables the low-activity and even inactive PPO to show high catalytic activity, namely activation effect.
The color conditions of the fresh pear juice after 24 hours of shelf life under different pH values are as follows:
TABLE 3 change of color after 24h of fresh pear juice at different pH values
| pH value | CK | HPP |
| 3.5 | Light red | Dark red |
| 4.0 | Light red | Dark red |
| 4.5 | Light red | Dark red |
| 5.0 | Light red | Dark red |
| 5.5 | Light white | Dark red |
| 6.0 | Light white | Light yellow |
| 7.0 | Light white | Light yellow |
| 7.5 | Light white | Light yellow |
| 8.0 | Light white | Light yellow |
| 8.5 | Light white | Light yellow |
As shown in table 3, after 24 hours of shelf life, the color of the fresh pear juice with pH value lower than 5.0 in the control group (CK) was light red, while the color of the fresh pear juice with pH value higher than 5.5 remained light white, so that it was found that the fresh pear juice without ultra-high pressure treatment was more prone to browning under acidic conditions. After 24h of shelf life, the fresh pear juice with pH value lower than 5.5 in the experimental group (HPP) is dark red, and the fresh pear juice with pH value higher than 6.0 is light yellow. In conclusion, the PPO activity can be activated by ultrahigh pressure treatment, and the pear juice browning is accelerated; when the pH value is lower than 5.5, the ultrahigh pressure treatment mainly catalyzes the pear juice to generate red browning, and when the pH value is higher than 6.0, the ultrahigh pressure treatment mainly catalyzes the pear juice to generate yellow browning.
Example 4: influence of standing time on color of fresh squeezed pear juice
Fresh, medium-ripened and disease-free green-crown pears are used as experimental raw materials, peeled and cored, and juice is squeezed by a juice machine to remove fruit residues, and the juice is filtered by diatomite. Adjusting pH value of the obtained pear juice to 7.0 with sodium citrate, bottling with plastic bottle, and treating under 500MPa for 5min. Standing the obtained pear juice at room temperature (30 deg.C) for 0, 2, 4, 6, 8, 10, and 12h respectively, adjusting pH to 4.3, and treating under 550MPa for 10min. The color of the fresh pear juice after 24 hours of shelf life is observed in different standing times, and the results are as follows:
TABLE 4 influence of the standing time on the color of ultrahigh-pressure freshly squeezed pear juice after 24h
| Standing time | Color |
| 0h | Dark red |
| 2h | Dark red |
| 4h | Light red |
| 6h | Light red |
| 8h | Light yellow |
| 10h | Light yellow |
| 12h | Light yellow |
As shown in table 4, when the standing time is 0-6h, the color of the fresh pear juice is dark red or light red after 24h of shelf life, because the standing time is short, the yellow browning of the fresh pear juice in a neutral environment is incomplete, the pH value is adjusted to be acidic, and the pear juice still has red browning; when the standing time is 8-10h, the color of the fresh pear juice is changed into light yellow. Therefore, with the prolonging of the standing time, the higher the yellow browning degree of the fresh pear juice in a neutral environment, and after the yellow browning degree of the fresh pear juice reaches a certain degree, the color of the fresh pear juice is stable and light yellow and does not change to dark red any more.
Example 5: influence of addition amount of neutral protease on color of fresh pear juice
Fresh, medium-ripened and disease-free green-crown pears are used as experimental raw materials, peeled and cored, and juice is squeezed by a juice machine to remove fruit residues, and the juice is filtered by diatomite. Adjusting pH value of the obtained pear juice to 7.0 with sodium citrate, bottling with plastic bottle, treating under 500MPa for 5min, and adding neutral protease powder 0.1%, 0.2%, and 0.3% of the pear juice. Standing the obtained pear juice at room temperature (30 deg.C) for 0, 2, 4, 6, 8, 10, and 12h respectively, adjusting pH to 4.3, and treating under 550MPa for 10min. The influence of the standing time and the addition amount of the neutral protease on the color of the fresh pear juice after 24 hours of shelf life is observed, and the results are shown in the following table:
TABLE 5 influence of neutral protease concentration on color of ultrahigh-pressure fresh pear juice after 24h
As shown in table 5, 0.1%, 0.2%, and 0.3% of neutral protease powder was added to the fresh pear juice, and the standing time for the fresh pear juice to be stable in color and light yellow after 24 hours of shelf life was 6 hours, 4 hours, and 2 hours, respectively, which significantly shortened the standing time required for the fresh pear juice to be stable in color and light yellow after 24 hours of shelf life, compared to the standing time for the fresh pear juice without neutral protease in example 4, which was 8 hours corresponding to the fresh pear juice without neutral protease added. Therefore, the addition of the neutral protease after the pH value is adjusted for the first time can effectively shorten the standing time required for the color of the fresh pear juice to be changed into stable light yellow, and the processing time of the fresh pear juice can be saved by adding the neutral protease after the pH value is adjusted for the first time; and with the increase of the addition amount of the neutral protease, the shorter the standing time required for the color of the fresh pear juice to be converted into stable light yellow.
Claims (9)
1. The processing method of the fresh pear juice is characterized by comprising the following steps:
(1) Raw material selection and pretreatment: selecting fresh pear fruits, peeling and removing kernels;
(2) Juicing: juicing and filtering the pears treated in the step (1) to obtain pear juice;
(3) Primary pH value adjustment: adjusting the pH value of the pear juice obtained in the step (2) to 6.0-8.5;
(4) Ultrahigh pressure treatment: will be described in detail
The obtained pear juice is processed under ultrahigh pressure, the pressure range is 500MPa, and the processing time is 5-15min;
(5) Standing: standing the pear juice obtained in the step (4) at room temperature until the color of the pear juice is stable;
(6) Adjusting the pH value for the second time: adjusting the pH value of the pear juice obtained in the step (5) to be below 4.5;
(7) And (3) cold sterilization: and (4) performing ultrahigh pressure sterilization treatment on the pear juice obtained in the step (6) to obtain a fresh pear juice finished product.
2. The method of claim 1, wherein the removing of the stone in step (1) comprises removing the stone cell region and the seed stalk of the pear fruit.
3. The method for processing freshly squeezed pear juice according to claim 1, wherein in the step (2), a juice extractor is used for extracting juice to collect the raw juice, and the raw juice is filtered by diatomite to obtain the clarified pear juice.
4. The method for processing fresh pear juice according to claim 1, wherein the substance for adjusting pH in step (3) is at least one of sodium citrate, sodium bicarbonate, sodium pyrophosphate and sodium tripolyphosphate.
5. The process for preparing fresh pear juice according to claim 1 or 4, wherein the pH value in step (3) is in the range of 6.5-7.5.
6. The processing method of fresh pear juice according to claim 5, wherein the step (4) further comprises adding neutral protease in an amount of 0.1-0.3% by weight of the pear juice
The standing time in (1) is shortened to 2-6h.
7. The method for processing fresh pear juice according to claim 1, wherein the organic acid is used for adjusting the pH value in step (6), and the organic acid is at least one of citric acid, malic acid and tartaric acid.
8. The process for preparing fresh pear juice according to claim 1 or 7, wherein the pH value in step (6) is in the range of 4.0-4.5.
9. The method for processing freshly squeezed pear juice according to claim 1, wherein the sterilization treatment in the step (7) is treatment of the pear juice under a pressure of 500 to 800MPa for 5 to 15min.
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