Concentrated citrus reiculata Blanco juice and preparation method thereof
By combining low-temperature enzyme preparations and acid-modified clarifiers, the problems of low juice yield and low clarification efficiency in concentrated Wogan juice were solved, efficient juice extraction and clarification were achieved, the product stability and flavor retention were improved, the shelf life was extended, and the quality of the juice was improved.
Patent Information
- Application Number
- CN202510807073.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-17
- Publication Date
- 2025-09-16
AI Technical Summary
The existing concentrated mandarin orange juice preparation process has low juice yield, serious loss of nutrients and flavor substances, low clarification efficiency and unstable juice quality, which is prone to sluggish sales, especially during peak seasons.
The juice is clarified by using a new low-temperature enzyme preparation to assist low-temperature pressing combined with acid modification and a clarifier combining multiple flocculants, including the preparation of low-temperature enzyme preparations and a mixed clarifier of tannic acid, chitosan, and bentonite, to improve the juice yield and clarification efficiency and prevent the loss of nutrients and flavor substances.
The juice yield and clarification efficiency of concentrated Wogan juice have been improved, the product's light transmittance has been increased, the color has been bright, and the stability has been high. The shelf life has been extended to 9 months at room temperature and to 12 months under refrigeration, with less flavor loss and significantly improved quality.
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of fruit juice beverage preparation, in particular to concentrated mandarin orange juice and a preparation method thereof. Background Art
[0002] The Wogan fruit is tender, juicy, and richly sweet, making it a popular choice among consumers. In recent years, it has become a popular late-ripening citrus variety in my country. However, the Wogan fruit ripens relatively concentratedly, primarily between January and March each year, making it prone to sluggish sales during peak periods. With an edible rate of approximately 75% and a juice yield of around 60%, the Wogan fruit is a high-quality raw material suitable for juice processing. To alleviate the pressure of fresh sales and increase its economic value, research is underway to process the fruit into juice. Concentrated Wogan juice is one of the most popular Wogan beverages.
[0003] In the prior art, the preparation process of concentrated mandarin orange juice includes washing, squeezing, clarifying, concentrating and sterilizing mandarin oranges. The prior process has the following technical problems:
[0004] 1. The traditional juicing method is mainly used for squeezing, that is, directly putting the mandarin oranges into the juicer for squeezing. However, this method not only has a low juice yield, but also generates heat during the squeezing process, which leads to the loss of nutrients and flavor substances, dull color, and large quality fluctuations. Regarding the problem of quality reduction caused by squeezing heat, low-temperature cold pressing combined with enzymatic hydrolysis is currently used to solve it. However, since the enzyme is less active under low temperature conditions, the juice yield of the low-temperature squeezing method is difficult to improve.
[0005] Second, current clarification methods primarily use clarifiers such as chitosan, gelatin, and diatomaceous earth to adsorb and precipitate impurities such as polyphenols, proteins, and pectin in juice. However, the adsorption efficiency of some clarifiers is easily affected by environmental factors such as temperature and pH. For example, chitosan has poor adsorption at higher pH levels, resulting in lower clarification efficiency. Furthermore, improper use of some clarifiers can remove nutrients from the juice, reducing juice quality.
[0006] In summary, the present invention aims to provide a concentrated mandarin orange juice and a preparation method thereof to solve the above problems. Summary of the Invention
[0007] To address the above shortcomings, the present invention provides concentrated Wogan juice and a preparation method thereof. By using a novel low-temperature enzyme preparation to assist in low-temperature pressing and a clarifier prepared by combining acid modification and multiple flocculants for clarification, the juice yield and clarification efficiency of the concentrated Wogan juice are increased, effectively preventing the loss of nutrients and flavor substances in the Wogan juice, and improving product quality. The specific technical solution is as follows:
[0008] A method for preparing concentrated Wogan juice comprises the following steps:
[0009] (1) Raw material preparation: Select mature and healthy mandarin oranges, pick them, peel them, wash them, and pre-cool them at 1-7°C for 10-20 hours for later use;
[0010] (2) Juicing: Place the pre-cooled mandarin oranges and the low-temperature enzyme preparation into a juicer and perform low-temperature squeezing at 10-15°C to obtain mandarin orange juice;
[0011] The preparation method of the low-temperature enzyme preparation comprises: taking Bacillus subtilis acclimated at 10-15°C as a fermentation strain, fermenting in a culture medium containing 60-80 mg / L orange peel powder, under the following fermentation conditions: inoculation amount 8-10%, temperature 10-15°C, oxygen flow rate 2-4 L / min, fermentation time 2-3 days, and sterilizing the obtained fermentation broth by centrifugation, ultrafiltration concentration, and freeze drying to obtain the low-temperature enzyme preparation;
[0012] (3) Clarification and filtration: adding tannic acid-chitosan-bentonite clarifier to the Wogan juice, mixing and stirring evenly, standing for clarification, and filtering the upper layer to obtain Wogan juice;
[0013] (4) Concentrating: vacuum concentrating the mandarin orange juice until the soluble solids are 50-55° Brix;
[0014] (5) Sterilization: The concentrated Wogan juice is sterilized by ultra-high pressure and then bottled to obtain the concentrated Wogan juice.
[0015] Furthermore, in step (2), the amount of the low-temperature enzyme preparation added is 3-5% of the weight of the mandarin orange.
[0016] Furthermore, in step (2), the preparation method of the fermentation strain is as follows: inoculating Bacillus subtilis at an inoculum size of 5-10% into a culture medium containing 30-40 mg / L orange peel powder, and culturing at 18-20°C on a shaking table for 3-5 days to obtain a first bacterial liquid; inoculating the first bacterial liquid at an inoculum size of 10-15% into a culture medium containing 50-55 mg / L orange peel powder, and culturing at 15-17°C on a shaking table for 3-5 days to obtain a second bacterial liquid; and inoculating the second bacterial liquid at an inoculum size of 10-15%. 10-15% of the inoculum is inoculated into a culture medium containing 56-60 mg / L tangerine peel powder, and cultured in a shaker at 10-15° C. for 3-5 days to obtain a third bacterial liquid; the third bacterial liquid is used to spread on a plate, and the culture dish is placed in a constant temperature incubator at 10-15° C. and cultured for 3-5 days, and Bacillus subtilis colonies that can maintain growth are picked and transferred to a culture medium containing 56-60 mg / L tangerine peel powder and cultured at 10-15° C. for 2-3 days to obtain the fermentation strain.
[0017] Furthermore, the culture medium formula is: yeast powder 5-10g / L, peptone 3-6g / L, calcium chloride 0.5-1g / L, ferric chloride 0.1-0.4g / L, magnesium sulfate heptahydrate 0.2-0.5g / L, potassium dihydrogen phosphate 0.3-0.8g / L, and the balance is water; the culture medium is sterilized at high temperature at 121°C for 20-30min before use.
[0018] Furthermore, in step (3), the mass ratio of the Wogan orange juice to the tannic acid-chitosan-bentonite clarifier is 1:(0.2-0.8).
[0019] Furthermore, in step (3), the preparation method of the tannic acid-chitosan-bentonite clarifier is:
[0020] S1. Mix tannic acid and acetic acid solution with a mass concentration of 0.5-1.5% in a mass volume ratio of 1 g: (30-40) mL, and stir to obtain a tannic acid solution;
[0021] S2. Mix chitosan and acetic acid solution with a mass concentration of 2-3% at a mass volume ratio of 1 g: (60-80) mL, and stir to obtain a chitosan solution;
[0022] S3, mixing bentonite and water in a mass ratio of 1: (20-30), stirring for 3-4 hours to obtain a bentonite solution;
[0023] S4. The tannic acid solution, chitosan solution and bentonite solution are mixed in a mass ratio of (2-6): (7-12): 1, stirred at 30-50° C. and 1000-2000 r / min for 3-4 h, allowed to stand overnight, dried at 50-60° C., and ground into powder to obtain the tannic acid-chitosan-bentonite clarifier.
[0024] Furthermore, in step (4), the vacuum degree of the vacuum concentration is 0.08-0.095 MPa.
[0025] Furthermore, in step (5), the ultrahigh pressure sterilization pressure is 500-600 MPa and the time is 5-10 min.
[0026] The orange peel powder is obtained by crushing orange peel with a water content of 5-10%.
[0027] Compared with the prior art, the present invention has the following beneficial effects:
[0028] 1. The present invention uses a new low-temperature enzyme preparation to assist low-temperature squeezing, and uses a clarifier prepared by combining acid modification and multiple flocculants for clarification, thereby improving the juice yield and clarification efficiency of concentrated Wogan juice, effectively preventing the loss of nutrients and flavor substances in the Wogan juice, and improving product quality. The Wogan juice yield using the squeezing method of the present invention is 85-95%, which is 15-25% higher than the traditional squeezing method; using the clarifier and clarification method of the present invention for clarification, the product transmittance can be as high as 90% or more, which is about 20% higher than the conventional clarifier, and the color is bright and the product is highly stable. The shelf life at room temperature can be extended from the original 3-6 months to 6-9 months, and from 6-9 months to 9-12 months under refrigerated conditions. At the same time, the product of the present invention has little flavor loss, and there is no flavor deterioration or darkening of color.
[0029] 2. The low-temperature enzyme preparation of the present invention is prepared by fermenting Bacillus subtilis after low-temperature acclimation at 10-15°C. Its enzyme activity is still high at lower temperatures, and it can be efficiently enzymatically hydrolyzed under cold pressing conditions, thereby improving the juice yield.
[0030] 3. The clarifier of the present invention is prepared by acid-modified tannic acid, chitosan and bentonite, which improves the adsorption and precipitation of pectin, protein and polyphenols, and improves the quality of Wogan concentrated juice.
[0031] 4. The Wogan raw material of the present invention can reduce the loss of juice flavor by precooling at 1-7°C and low-temperature pressing at 10-15°C, thereby preventing flavor deterioration and browning. DETAILED DESCRIPTION
[0032] The specific embodiments of the present invention are described in detail below, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.
[0033] The Bacillus subtilis involved in the following was purchased from the China General Microbiological Culture Collection Center with the collection number CGMCC 1.3358.
[0034] Example 1
[0035] A method for preparing concentrated Wogan juice comprises the following steps:
[0036] (1) Raw material preparation: Select mature and healthy mandarin orange fruits, pick them, peel them, wash them, and pre-cool them at 4°C for 10 hours for later use.
[0037] (2) Juicing: Place the pre-cooled mandarin oranges and the low-temperature enzyme preparation into a juicer, wherein the amount of the low-temperature enzyme preparation added is 3% of the weight of the mandarin oranges, and perform low-temperature squeezing at 10° C. to obtain mandarin orange juice;
[0038] The preparation method of the low-temperature enzyme preparation comprises: taking Bacillus subtilis acclimated at 10°C as a fermentation strain, fermenting in a culture medium containing 60 mg / L orange peel powder, under the following conditions: inoculation amount 8%, temperature 10°C, oxygen flow rate 2 L / min, fermentation time 3 days, and sterilizing the obtained fermentation broth by centrifugation, ultrafiltration concentration, and freeze-drying to obtain the low-temperature enzyme preparation;
[0039] The preparation method of the fermentation strain comprises the following steps: inoculating Bacillus subtilis at an inoculum size of 5% into a culture medium containing 30 mg / L tangerine peel powder, and culturing the culture medium on a shaking platform at 18° C. for 3 days to obtain a first bacterial liquid; inoculating the first bacterial liquid at an inoculum size of 10% into a culture medium containing 50 mg / L tangerine peel powder, and culturing the culture medium on a shaking platform at 15° C. for 3 days to obtain a second bacterial liquid; inoculating the second bacterial liquid at an inoculum size of 10% into a culture medium containing 56 mg / L tangerine peel powder, and culturing the culture medium on a shaking platform at 10° C. for 3 days to obtain a third bacterial liquid; using the third bacterial liquid for plate coating, placing the culture dish in a constant temperature incubator at 10° C. for culturing for 3 days, picking Bacillus subtilis colonies that can maintain growth, transferring them to a culture medium containing 56 mg / L tangerine peel powder, and culturing them at 10° C. for 2 days to obtain the fermentation strain.
[0040] The culture medium formula is: 5 g / L yeast powder, 3 g / L peptone, 0.5 g / L calcium chloride, 0.1 g / L ferric chloride, 0.2 g / L magnesium sulfate heptahydrate, 0.3 g / L potassium dihydrogen phosphate, and the balance is water; the culture medium is sterilized at high temperature at 121° C. for 20 minutes before use.
[0041] The orange peel powder is obtained by crushing orange peel with a water content of 5%.
[0042] (3) Clarification and filtration: Add tannic acid-chitosan-bentonite clarifier to the Wogan juice, wherein the mass ratio of the Wogan juice to the tannic acid-chitosan-bentonite clarifier is 1:0.2, mix and stir evenly, let stand to clarify, take the upper layer liquid and filter to obtain Wogan juice.
[0043] The preparation method of the tannic acid-chitosan-bentonite clarifier is:
[0044] S1. Mix tannic acid and 0.5% acetic acid solution in a mass volume ratio of 1 g:30 mL, and stir to obtain a tannic acid solution;
[0045] S2. Mix chitosan and 2% acetic acid solution in a mass volume ratio of 1 g:60 mL, and stir to obtain a chitosan solution;
[0046] S3, mixing bentonite and water in a mass ratio of 1:20, stirring for 3 hours to obtain a bentonite solution;
[0047] S4. The tannic acid solution, chitosan solution, and bentonite solution were mixed in a mass ratio of 2:7:1, stirred at 30° C. and 1000 rpm for 3 h, allowed to stand overnight, dried at 50° C., and ground into powder to obtain the tannic acid-chitosan-bentonite clarifier.
[0048] (4) Concentration: The mandarin orange juice is vacuum concentrated until the soluble solids are 50° Brix; the vacuum degree of vacuum concentration is 0.08 MPa.
[0049] (5) Sterilization: The concentrated Wogan juice is sterilized by ultra-high pressure at a pressure of 500 MPa for 5 minutes, and then filled to obtain the concentrated Wogan juice.
[0050] Example 2
[0051] A method for preparing concentrated Wogan juice comprises the following steps:
[0052] (1) Raw material preparation: Select mature and healthy mandarin oranges, pick them, peel them, wash them, and pre-cool them at 4°C for 20 hours for later use.
[0053] (2) Juicing: Place the pre-cooled mandarin oranges and the low-temperature enzyme preparation into a juicer, wherein the amount of the low-temperature enzyme preparation added is 5% of the weight of the mandarin oranges, and perform low-temperature squeezing at 15° C. to obtain mandarin orange juice;
[0054] The preparation method of the low-temperature enzyme preparation comprises: taking Bacillus subtilis acclimated at 15°C as a fermentation strain, fermenting in a culture medium containing 80 mg / L orange peel powder, under the following fermentation conditions: inoculation amount 10%, temperature 15°C, oxygen flow rate 4 L / min, fermentation time 3 days, and sterilizing the obtained fermentation broth by centrifugation, ultrafiltration concentration, and freeze-drying to obtain the low-temperature enzyme preparation;
[0055] The preparation method of the fermentation strain comprises the following steps: inoculating Bacillus subtilis at an inoculum size of 10% into a culture medium containing 40 mg / L tangerine peel powder, and culturing the culture at 20° C. on a shaking platform for 5 days to obtain a first bacterial liquid; inoculating the first bacterial liquid at an inoculum size of 15% into a culture medium containing 55 mg / L tangerine peel powder, and culturing the culture at 17° C. on a shaking platform for 5 days to obtain a second bacterial liquid; inoculating the second bacterial liquid at an inoculum size of 15% into a culture medium containing 60 mg / L tangerine peel powder, and culturing the culture at 15° C. on a shaking platform for 5 days to obtain a third bacterial liquid; using the third bacterial liquid for plate coating, placing the culture dish in a constant temperature incubator at 15° C. for culturing for 5 days, picking Bacillus subtilis colonies that can maintain growth, transferring them to a culture medium containing 60 mg / L tangerine peel powder, and culturing at 15° C. for 3 days to obtain the fermentation strain.
[0056] The culture medium formula is: 10 g / L yeast powder, 6 g / L peptone, 1 g / L calcium chloride, 0.4 g / L ferric chloride, 0.5 g / L magnesium sulfate heptahydrate, 0.8 g / L potassium dihydrogen phosphate, and the balance is water; the culture medium is sterilized at high temperature at 121° C. for 30 minutes before use.
[0057] The orange peel powder is obtained by crushing orange peel with a water content of 10%.
[0058] (3) Clarification and filtration: Add tannic acid-chitosan-bentonite clarifier to the Wogan juice, wherein the mass ratio of the Wogan juice to the tannic acid-chitosan-bentonite clarifier is 1:0.8, mix and stir evenly, let stand to clarify, take the upper layer of liquid and filter to obtain Wogan juice.
[0059] The preparation method of the tannic acid-chitosan-bentonite clarifier is:
[0060] S1. Mix tannic acid and 1.5% acetic acid solution in a mass volume ratio of 1 g:40 mL, and stir to obtain a tannic acid solution;
[0061] S2. Mix chitosan and 3% acetic acid solution in a mass volume ratio of 1 g:80 mL, and stir to obtain a chitosan solution;
[0062] S3, mixing bentonite and water in a mass ratio of 1:30, stirring for 4 hours to obtain a bentonite solution;
[0063] S4. The tannic acid solution, chitosan solution, and bentonite solution were mixed in a mass ratio of 6:12:1, stirred at 50° C. and 2000 rpm for 4 h, allowed to stand overnight, dried at 60° C., and ground into powder to obtain the tannic acid-chitosan-bentonite clarifier.
[0064] (4) Concentration: The mandarin orange juice is vacuum concentrated until the soluble solids are 55° Brix; the vacuum degree of vacuum concentration is 0.095 MPa.
[0065] (5) Sterilization: The concentrated mandarin orange juice is sterilized by ultra-high pressure at a pressure of 600 MPa for 10 min, and then filled to obtain the concentrated mandarin orange juice.
[0066] Example 3
[0067] A method for preparing concentrated Wogan juice comprises the following steps:
[0068] (1) Raw material preparation: Select mature and healthy mandarin orange fruits, pick them, peel them, wash them, and pre-cool them at 4°C for 15 hours for later use.
[0069] (2) Juicing: Place the pre-cooled mandarin oranges and the low-temperature enzyme preparation into a juicer, wherein the amount of the low-temperature enzyme preparation added is 4% of the weight of the mandarin oranges, and perform low-temperature squeezing at 12° C. to obtain mandarin orange juice;
[0070] The preparation method of the low-temperature enzyme preparation comprises: taking Bacillus subtilis CGMCC1.3358 acclimated at 12°C as a fermentation strain, fermenting in a culture medium containing 70 mg / L orange peel powder, under the following fermentation conditions: inoculation amount 9%, temperature 12°C, oxygen flow rate 3.5 L / min, fermentation time 3 days, and sterilizing the obtained fermentation broth by centrifugation, ultrafiltration concentration, and freeze-drying to obtain the low-temperature enzyme preparation;
[0071] The preparation method of the fermentation strain comprises the following steps: inoculating Bacillus subtilis at an inoculum size of 6% into a culture medium containing 33 mg / L tangerine peel powder, and culturing the culture medium on a shaking platform at 19° C. for 4 days to obtain a first bacterial liquid; inoculating the first bacterial liquid at an inoculum size of 12% into a culture medium containing 52 mg / L tangerine peel powder, and culturing the culture medium on a shaking platform at 16° C. for 4 days to obtain a second bacterial liquid; inoculating the second bacterial liquid at an inoculum size of 12% into a culture medium containing 58 mg / L tangerine peel powder, and culturing the culture medium on a shaking platform at 12° C. for 4 days to obtain a third bacterial liquid; using the third bacterial liquid for plate coating, placing the culture dish in a constant temperature incubator at 12° C. for culturing for 4 days, picking Bacillus subtilis colonies that can maintain growth, transferring them to a culture medium containing 58 mg / L tangerine peel powder, and culturing them at 12° C. for 3 days to obtain the fermentation strain.
[0072] The culture medium formula is: yeast powder 8g / L, peptone 5g / L, calcium chloride 0.9g / L, ferric chloride 0.4g / L, magnesium sulfate heptahydrate 0.3g / L, potassium dihydrogen phosphate 0.5g / L, and the balance is water; the culture medium is sterilized at high temperature at 121°C for 25 minutes before use.
[0073] The orange peel powder is obtained by crushing orange peel with a water content of 8%.
[0074] (3) Clarification and filtration: Add tannic acid-chitosan-bentonite clarifier to the Wogan juice, wherein the mass ratio of the Wogan juice to the tannic acid-chitosan-bentonite clarifier is 1:0.7, mix and stir evenly, let stand to clarify, take the upper liquid and filter to obtain Wogan juice.
[0075] The preparation method of the tannic acid-chitosan-bentonite clarifier is:
[0076] S1. Mix tannic acid and 1% acetic acid solution in a mass volume ratio of 1 g:35 mL, and stir to obtain a tannic acid solution;
[0077] S2. Mix chitosan and 2.5% acetic acid solution in a mass volume ratio of 1 g:70 mL, and stir to obtain a chitosan solution;
[0078] S3, mixing bentonite and water in a mass ratio of 1:25, stirring for 4 hours to obtain a bentonite solution;
[0079] S4. The tannic acid solution, chitosan solution, and bentonite solution were mixed in a mass ratio of 4:11:1, stirred at 40° C. and 1500 rpm for 4 h, allowed to stand overnight, dried at 55° C., and ground into powder to obtain the tannic acid-chitosan-bentonite clarifier.
[0080] (4) Concentration: The mandarin orange juice is vacuum concentrated until the soluble solids are 55° Brix; the vacuum degree of vacuum concentration is 0.09 MPa.
[0081] (5) Sterilization: The concentrated Wogan juice is sterilized under ultrahigh pressure at a pressure of 550 MPa for 7 minutes, and then filled to obtain the concentrated Wogan juice.
[0082] Comparative Example 1: Traditional squeezing method, i.e. directly putting the mandarin oranges into a juicer for squeezing at room temperature without enzyme-assisted squeezing.
[0083] Comparative Example 2: Low-temperature squeezing method, i.e. directly putting the mandarin oranges into a juicer and squeezing them at 10-15°C without enzyme-assisted squeezing.
[0084] Comparative Example 3: In step (2), the low-temperature enzyme preparation was replaced with pectinase, that is, pectinase-assisted low-temperature pressing was used for juice extraction. Other preparation methods were the same as those in Example 1.
[0085] The juice yield of Examples 1 to 3 and Comparative Examples 1 to 3 was tested. The mandarin oranges used in each group were all picked from the same batch of fruit trees. Juice yield = (total weight of mandarin oranges - weight of pomace after squeezing) / total weight of mandarin oranges × 100%. The results are shown in Table 1:
[0086] Table 1 Comparison of juice yield in each group
[0087] Group Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Juice yield (%) 85 90 95 58.8 56.4 56.9
[0088] Table 1 shows that the juice yield of the mandarin oranges using the squeezing method of the present invention is 85-95%, which is 15-25% higher than that of the traditional squeezing method. Furthermore, a comparison of the data from Example 1, Comparative Examples 2, and 3 shows that the pectinase-assisted low-temperature squeezing method does not significantly improve the juice yield, indicating that the pectinase has low enzymatic activity at low temperatures and its effect is not significant. However, the low-temperature enzyme preparation of the present invention maintains high enzymatic activity at low temperatures, allowing efficient enzymatic hydrolysis under cold pressing conditions to improve the juice yield.
[0089] Comparative Example 4: This comparative example uses chitosan-bentonite clarifier for clarification, and the other methods are the same as those in Example 3; the preparation method of the chitosan-bentonite clarifier is:
[0090] S1. Mix chitosan and 2.5% acetic acid solution in a mass volume ratio of 1 g:70 mL, and stir to obtain a chitosan solution;
[0091] S2. Mix bentonite and water in a mass ratio of 1:25 and stir for 4 h to obtain a bentonite solution;
[0092] S3. Mix the chitosan solution and the bentonite solution in a mass ratio of 11:1, stir at 40° C. and 1500 r / min for 4 h, let stand overnight, dry at 55° C., and grind into powder to obtain the chitosan-bentonite clarifier.
[0093] Comparative Example 5: This comparative example uses tannic acid-bentonite clarifier for clarification, and the other methods are the same as those in Example 3; the preparation method of tannic acid-bentonite clarifier is:
[0094] The preparation method of the tannic acid-bentonite clarifier is:
[0095] S1. Mix tannic acid and 1% acetic acid solution in a mass volume ratio of 1 g:35 mL, and stir to obtain a tannic acid solution;
[0096] S2. Mix bentonite and water in a mass ratio of 1:25 and stir for 4 h to obtain a bentonite solution;
[0097] S3. Mix the tannic acid solution and the bentonite solution in a mass ratio of 4:1, stir at 40° C. and 1500 r / min for 4 h, let stand overnight, dry at 55° C., and grind into powder to obtain the tannic acid-bentonite clarifier.
[0098] Comparative Example 6: This comparative example uses a conventional clarifier, i.e., chitosan and bentonite are directly mixed as a clarifier for clarification. The mass ratio of Wogan juice, chitosan, and bentonite is 1:0.3:0.6. Other methods are the same as those in Example 3, i.e., no acid modification is performed.
[0099] The transmittance and ascorbic acid content of the products prepared in Examples 1 to 3 and Comparative Examples 4 to 6 were tested, and the products that were not clarified were used as blank groups. The transmittance was measured using a spectrophotometer, and the ascorbic acid content was measured using the 2,6-dichloroindophenol titration method. The shelf life at room temperature and the refrigerated shelf life (refrigerated at about 4°C) of each group were tested. The mandarin oranges used in each group were all picked from the same batch of fruit trees. The results are shown in Table 2:
[0100] Table 2 Clarification and ascorbic acid content of each group
[0101]
[0102] Table 2 shows that the present invention utilizes a clarifier combining acid modification and multiple flocculants to produce a clarifier with a light transmittance exceeding 90%, a 20% increase compared to conventional clarifiers. This improves the efficiency of clarification of concentrated Wogan juice and prevents the loss of nutrients and flavors, such as ascorbic acid, thereby enhancing product quality. Furthermore, the Wogan juice produced using the present invention is highly stable, with a shelf life of up to 9 months at room temperature and 12 months in a refrigerated environment. Furthermore, the juice exhibits no flavor deterioration or browning during storage, resulting in a high-quality product.
[0103] The foregoing descriptions of specific exemplary embodiments of the present invention are for purposes of illustration and description. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many variations and modifications are possible in light of the foregoing teachings. The exemplary embodiments have been selected and described for the purpose of explaining the specific principles of the invention and their practical application, thereby enabling those skilled in the art to realize and utilize a variety of exemplary embodiments of the invention and various options and modifications. The scope of the invention is intended to be defined by the claims and their equivalents.
Claims
1. A method for preparing concentrated mandarin orange juice, characterized in that: The following steps are involved: (1) Raw material preparation: Select mature and healthy mandarin oranges, pick them, peel them, wash them, and pre-cool them at 1-7°C for 10-20 hours for later use; (2) Juicing: Place the pre-cooled mandarin oranges and the low-temperature enzyme preparation into a juicer and perform low-temperature squeezing at 10-15°C to obtain mandarin orange juice; The preparation method of the low-temperature enzyme preparation comprises: taking Bacillus subtilis acclimated at 10-15°C as a fermentation strain, fermenting in a culture medium containing 60-80 mg / L orange peel powder, under the following fermentation conditions: inoculation amount 8-10%, temperature 10-15°C, oxygen flow rate 2-4 L / min, fermentation time 2-3 days, and sterilizing the obtained fermentation broth by centrifugation, ultrafiltration concentration, and freeze drying to obtain the low-temperature enzyme preparation; (3) Clarification and filtration: adding tannic acid-chitosan-bentonite clarifier to the Wogan juice, mixing and stirring evenly, standing for clarification, and filtering the upper layer to obtain Wogan juice; (4) Concentrating: vacuum concentrating the mandarin orange juice until the soluble solids are 50-55° Brix; (5) Sterilization: The concentrated Wogan juice is sterilized by ultra-high pressure and then bottled to obtain the concentrated Wogan juice.
2. The method for preparing concentrated mandarin orange juice according to claim 1, wherein: In step (2), the amount of the low-temperature enzyme preparation added is 3-5% of the weight of the mandarin oranges.
3. The method for preparing concentrated mandarin orange juice according to claim 1, wherein: In step (2), the preparation method of the fermentation strain is as follows: inoculating Bacillus subtilis at an inoculum of 5-10% into a culture medium containing 30-40 mg / L orange peel powder, and culturing at 18-20°C on a shaking table for 3-5 days to obtain a first bacterial liquid; inoculating the first bacterial liquid at an inoculum of 10-15% into a culture medium containing 50-55 mg / L orange peel powder, and culturing at 15-17°C on a shaking table for 3-5 days to obtain a second bacterial liquid; inoculating the second bacterial liquid at an inoculum of 10 -15% of the inoculum size is inoculated into a culture medium containing 56-60 mg / L tangerine peel powder, and cultured in a shaker at 10-15°C for 3-5 days to obtain a third bacterial liquid; the third bacterial liquid is used to spread on a plate, and the culture dish is placed in a constant temperature incubator at 10-15°C for 3-5 days. Bacillus subtilis colonies that can maintain growth are picked, transferred to a culture medium containing 56-60 mg / L tangerine peel powder, and cultured at 10-15°C for 2-3 days to obtain the fermentation strain.
4. The method for preparing concentrated mandarin orange juice according to claim 1 or 3, wherein: The culture medium formula is: yeast powder 5-10g / L, peptone 3-6g / L, calcium chloride 0.5-1g / L, ferric chloride 0.1-0.4g / L, magnesium sulfate heptahydrate 0.2-0.5g / L, potassium dihydrogen phosphate 0.3-0.8g / L, and the balance is water; the culture medium is sterilized at high temperature at 121°C for 20-30 minutes before use.
5. The method for preparing concentrated mandarin orange juice according to claim 1, wherein: In step (3), the mass ratio of the mandarin orange juice to the tannic acid-chitosan-bentonite clarifier is 1:(0.2-0.8).
6. The method for preparing concentrated mandarin orange juice according to claim 1, wherein: In step (3), the preparation method of the tannic acid-chitosan-bentonite clarifier is: S1. Mix tannic acid and acetic acid solution with a mass concentration of 0.5-1.5% in a mass volume ratio of 1 g: (30-40) mL, and stir to obtain a tannic acid solution; S2. Mix chitosan and acetic acid solution with a mass concentration of 2-3% at a mass volume ratio of 1 g: (60-80) mL, and stir to obtain a chitosan solution; S3, mixing bentonite and water in a mass ratio of 1: (20-30), stirring for 3-4 hours to obtain a bentonite solution; S4. The tannic acid solution, chitosan solution and bentonite solution are mixed in a mass ratio of (2-6): (7-12): 1, stirred at 30-50° C. and 1000-2000 r / min for 3-4 h, allowed to stand overnight, dried at 50-60° C., and ground into powder to obtain the tannic acid-chitosan-bentonite clarifier.
7. The method for preparing concentrated mandarin orange juice according to claim 1, wherein: In step (4), the vacuum degree of the vacuum concentration is 0.08-0.095 MPa.
8. The method for preparing concentrated mandarin orange juice according to claim 1, wherein: In step (5), the ultrahigh pressure sterilization pressure is 500-600 MPa and the time is 5-10 min.