Method for preparing blueberry juice through ultrahigh pressure pretreatment and lactobacillus plantarum fermentation

Abstract

The invention relates to the field of lactobacillus plantarum fermented blueberry juice, and particularly provides a preparation method of lactobacillus plantarum fermented blueberry juice through ultrahigh pressure pretreatment. The method comprises the following steps: selecting fresh blueberries without insect pests and mildew, cleaning, pulping, carrying out enzymolysis, filtering and other pretreatment steps, carrying out pretreatment sterilization on blueberry juice by using an ultrahigh pressure technology, adjusting the initial pH value of a system, and adding plant lactic acid bacteria for fermentation. The obtained fermented blueberry juice has relatively high nutritional value and health-care value, and the flavor quality of the fermented blueberry juice is effectively improved. According to the method, ultrahigh-pressure treatment is used for replacing traditional pasteurization, damage of high temperature to the sensory quality and nutritional value of the blueberry juice is avoided, meanwhile, an exogenous nutritional agent is added to stimulate the number of viable bacteria in the blueberry juice, and lactic acid bacteria in the blueberry juice reach a high level.

Description

Technical Field

[0001] The invention relates to the field of plant lactobacillus fermented blueberry juice, and in particular to a method for preparing plant lactobacillus fermented blueberry juice through ultrahigh pressure pretreatment. Background Art

[0002] Blueberry, also known as lingonberry, blueberry, belongs to the genus Vaccinium of the Ericaceae family. Blueberry fruit is small, with a blue-black skin, bright color, delicate flesh, sweet and sour taste. Blueberry contains a variety of bioactive ingredients, such as polysaccharides, vitamins, anthocyanins, polyphenols, flavonoids, catechins, etc. The various bioactive ingredients give blueberry the functions of anti-oxidation, anti-tumor, prevention of Alzheimer's disease, relief of visual fatigue, anti-inflammatory, anti-aging, and regulation of the body's immunity.

[0003] Since fresh fruits have a short storage period and are easily contaminated by microorganisms during storage, causing them to rot, in addition to being eaten fresh, fruits are often made into juice, preserved fruits, canned fruits, jams and other products. Fermentation is the most common processing method, often using microorganisms such as lactic acid bacteria and yeast on the surface of fruits and vegetables. Or fermentation with the aid of lactic acid bacteria can produce fermented fruit juice, fermented fruit and vegetable juice, etc. Substances such as aldehydes and ketones produced by microbial metabolism give the product unique sensory qualities, while improving the antioxidant properties of fruits and vegetables and enriching the functionality of fermented fruits and vegetables.

[0004] Lactic acid bacteria, as a Gram-positive bacteria, can form lactic acid by breaking down sugars. Studies have found that the enzymes secreted by lactic acid bacteria during the fermentation process can change the chemical structure of substances and produce various metabolites (biotransformation) that promote health. In addition, some lactic acid bacteria fermentation has shown a positive effect on the conversion of polyphenol compounds in fruits and vegetables and the bioavailability of antioxidant activity.

[0005] In the process of making fermented juice, the sterilization method before fermentation is the main factor affecting the flavor quality of fermented juice. During the juice preparation process, the microorganisms carried in the peel are easily mixed into the juice, which may cause microbial contamination of the juice. Therefore, sterilization is required before preparing the fermented juice. Traditionally, the juice is pasteurized by heat treatment before microbial fermentation, but due to the high temperature, it will cause loss of nutrition, color and flavor. Ultra-high pressure treatment is a non-thermal sterilization technology that inactivates corrupt and pathogenic microorganisms while hardly affecting the sensory quality and nutritional value of the juice. It has been reported in the literature that ultra-high pressure treatment can retain volatile flavor substances and maintain physical and chemical properties. Therefore, it is of great significance to use ultra-high pressure treatment instead of traditional pasteurization to innovate and upgrade the processing technology of preparing fermented blueberry juice and improve the stability and nutritional and health value of blueberry juice. Summary of the invention

[0006] In view of this, the present invention aims to propose a method for preparing ultra-high pressure pre-treated plant lactobacillus fermented blueberry juice, which uses blueberry as fermentation raw material, pre-treats blueberry, adds pectinase to destroy the cell wall of the fruit, accelerates the dissolution of juice, allows the content to quickly enter the solvent, and uses gauze for filtering. The filtered raw pulp is sterilized by ultra-high pressure pre-treatment, the initial pH value of the system is adjusted, and plant lactobacillus is added for fermentation. The obtained fermented blueberry juice has high nutritional value and health value, and effectively improves the flavor quality of the fermented blueberry juice.

[0007] In order to achieve the above object, this experimental invention is achieved as follows:

[0008] A method for preparing blueberry juice fermented by ultrahigh pressure pre-treatment of plant lactobacillus comprises the following steps:

[0009] (1) Raw material cleaning: Select fresh blueberries that are free of insect pests and mildew, clean the dirt on the surface with distilled water, and drain the surface water after cleaning;

[0010] (2) Pulping and enzymolysis: The washed blueberries are mixed with water in a certain solid-liquid ratio, and then pulped using a pulper to obtain blueberry pulp, which is then poured out for later use; a certain proportion of pectinase is added to the blueberry pulp for enzymolysis; after the enzymolysis is completed, the blueberry pulp is filtered using gauze;

[0011] (3) pH adjustment: adding a certain amount of oligofructose to the blueberry pulp after enzymatic filtration, and then adding sodium carbonate to adjust the initial pH;

[0012] (4) Ultrahigh pressure treatment: The blueberry pulp after pH adjustment is vacuum packed in a plastic bag and then subjected to ultrahigh pressure treatment;

[0013] (5) Flavor preparation: Under aseptic conditions, a certain amount of glucose and milk powder is added to the blueberry pulp as an additional nutrient source and to increase the flavor;

[0014] (6) Inoculation and fermentation: Inoculate plant lactic acid bacteria into blueberry pulp for fermentation, and obtain the finished product after the fermentation is completed.

[0015] Furthermore, the liquid ratio of blueberry to water in step (2) is 1:4-1:6 (g:mL).

[0016] Furthermore, the amount of pectinase added in step (2) is 0.03-0.05%.

[0017] Furthermore, in step (2), the filtration process is performed using 8 layers of gauze.

[0018] Furthermore, in step (3), the amount of oligofructose added is such that the soluble solids in the fermentation broth is measured to be 14-16° Brix using a digital saccharimeter.

[0019] Furthermore, in step (3), sodium carbonate is added to adjust the initial pH of the blueberry pulp after enzymatic hydrolysis and filtration to 5.5.

[0020] Furthermore, the ultrahigh pressure treatment conditions in step (4) are 200-400 MPa and the pressure is maintained for 15 minutes.

[0021] Furthermore, the amount of the added nutrient in step (5) is 5% glucose and 10% milk powder.

[0022] Furthermore, in step (6), the plant lactic acid bacteria were first activated with 10 mL of glucose aqueous solution for 20 min, so that the concentration of the activated bacteria reached 60 × 10 7 (CFU / mL), the inoculum size was 0.06%.

[0023] Furthermore, the fermentation condition of step (6) is to place the mixture in a 37°C constant temperature incubator for anaerobic fermentation for 36 hours.

[0024] Compared with the prior art, the present invention has the following advantages and effects:

[0025] (1) In the present invention, blueberry juice is fermented by plant lactic acid bacteria. Substances such as aldehydes and ketones produced by microbial metabolism can give the blueberry juice unique sensory qualities, while also improving the antioxidant properties of the blueberry juice, enriching the functionality of the fermented blueberry juice, and extending the shelf life of the blueberry juice.

[0026] (2) The present invention uses ultra-high pressure pre-treatment sterilization to replace traditional pasteurization. Pasteurization will cause loss of nutrition, color and flavor due to excessively high temperature. Ultra-high pressure treatment is a non-thermal sterilization technology that inactivates spoilage and pathogenic microorganisms while hardly affecting the sensory quality and nutritional value of blueberry juice.

[0027] (3) Adding exogenous nutrients can stimulate the number of live bacteria in blueberry juice, so that the lactic acid bacteria in blueberry juice reaches a higher level. A high number of live bacteria can ensure that most lactic acid bacteria enter the human intestine to the greatest extent possible, thereby playing the role of beneficial bacteria.

[0028] (4) The present invention only uses oligofructose and glucose as flavoring agents, which ensures that the product is green and healthy and is suitable for a wide range of people. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0030] Example 1

[0031] A method for preparing blueberry juice fermented by ultrahigh pressure pre-treatment of plant lactobacillus comprises the following steps:

[0032] (1) Raw material cleaning: Select fresh blueberries that are free of insects and mold. Use distilled water to clean the dirt on the surface. After cleaning, drain the surface water.

[0033] (2) Pulping and enzymatic hydrolysis: The washed blueberries were mixed with water at a solid-liquid ratio of 1:4 (g:mL), and then pulped using a pulper to obtain blueberry pulp, which was then poured out for later use; 0.05% pectinase was added to the blueberry pulp for enzymatic hydrolysis (45°C water bath for 2h); after the enzymatic hydrolysis was completed, the blueberry pulp was filtered using 8 layers of gauze.

[0034] (3) pH adjustment: Fructooligosaccharides were added to the blueberry pulp after enzymatic filtration, and then sodium carbonate was added to adjust the initial pH to 5.5. The soluble solids of the fermentation broth were measured using a digital saccharimeter and found to be 16° Brix.

[0035] (4) Ultrahigh pressure treatment: The blueberry pulp after pH adjustment was vacuum packed in a plastic bag and then subjected to ultrahigh pressure treatment at 300 MPa for 15 min.

[0036] (5) Flavor preparation: Under aseptic conditions, 5% glucose and 10% milk powder are added to the blueberry pulp as an external nutrient source and to increase the flavor.

[0037] (6) Inoculation and fermentation: Plant lactic acid bacteria were inoculated into blueberry pulp for fermentation. The plant lactic acid bacteria were first activated with 10 mL of glucose aqueous solution for 20 min so that the concentration of the activated bacteria reached 60 × 10 7 (CFU / mL), the inoculation amount was 0.06%, and the fermentation conditions were anaerobic fermentation at 37°C for 36 hours, and the finished product was obtained after the fermentation was completed.

[0038] Example 2

[0039] A method for preparing blueberry juice fermented by ultrahigh pressure pre-treatment of plant lactobacillus comprises the following steps:

[0040] (1) Raw material cleaning: Select fresh blueberries that are free of insects and mold. Use distilled water to clean the dirt on the surface. After cleaning, drain the surface water.

[0041] (2) Pulping and enzymatic hydrolysis: The washed blueberries were mixed with water at a solid-liquid ratio of 1:5 (g:mL), and then pulped using a pulper to obtain blueberry pulp, which was then poured out for later use; 0.05% pectinase was added to the blueberry pulp for enzymatic hydrolysis (45°C water bath for 2h); after the enzymatic hydrolysis was completed, the blueberry pulp was filtered using 8 layers of gauze.

[0042] (3) pH adjustment: Fructooligosaccharides were added to the blueberry pulp after enzymatic filtration, and then sodium carbonate was added to adjust the initial pH to 5.5. The soluble solids of the fermentation broth were measured using a digital saccharimeter and found to be 16° Brix.

[0043] (4) Ultrahigh pressure treatment: The blueberry pulp after pH adjustment was vacuum packed in a plastic bag and then subjected to ultrahigh pressure treatment at 300 MPa for 15 min.

[0044] (5) Flavor preparation: Under aseptic conditions, 5% glucose and 10% milk powder are added to the blueberry pulp as an external nutrient source and to increase the flavor.

[0045] (6) Inoculation and fermentation: Plant lactic acid bacteria were inoculated into blueberry pulp for fermentation. The plant lactic acid bacteria were first activated with 10 mL of glucose aqueous solution for 20 min so that the concentration of the activated bacteria reached 60 × 10 7 (CFU / mL), the inoculation amount was 0.06%, and the fermentation conditions were anaerobic fermentation at 37°C for 36 hours, and the finished product was obtained after the fermentation was completed.

[0046] Example 3

[0047] A method for preparing blueberry juice fermented by ultrahigh pressure pre-treatment of plant lactobacillus comprises the following steps:

[0048] (1) Raw material cleaning: Select fresh blueberries that are free of insects and mold. Use distilled water to clean the dirt on the surface. After cleaning, drain the surface water.

[0049] (2) Pulping and enzymatic hydrolysis: The washed blueberries were mixed with water at a solid-liquid ratio of 1:6 (g:mL), and then pulped using a pulper to obtain blueberry pulp, which was then poured out for later use; 0.05% pectinase was added to the blueberry pulp for enzymatic hydrolysis (45°C water bath for 2h); after the enzymatic hydrolysis was completed, the blueberry pulp was filtered using 8 layers of gauze.

[0050] (3) pH adjustment: Fructooligosaccharides were added to the blueberry pulp after enzymatic filtration, and then sodium carbonate was added to adjust the initial pH to 5.5. The soluble solids of the fermentation broth were measured using a digital saccharimeter and found to be 16° Brix.

[0051] (4) Ultrahigh pressure treatment: The blueberry pulp after pH adjustment was vacuum packed in a plastic bag and then subjected to ultrahigh pressure treatment at 300 MPa for 15 min.

[0052] (5) Flavor preparation: Under aseptic conditions, 5% glucose and 10% milk powder are added to the blueberry pulp as an external nutrient source and to increase the flavor.

[0053] (6) Inoculation and fermentation: Plant lactic acid bacteria were inoculated into blueberry pulp for fermentation. The plant lactic acid bacteria were first activated with 10 mL of glucose aqueous solution for 20 min so that the concentration of the activated bacteria reached 60 × 10 7 (CFU / mL), the inoculation amount was 0.06%, and the fermentation conditions were anaerobic fermentation at 37°C for 36 hours, and the finished product was obtained after the fermentation was completed.

[0054] Example 4

[0055] A method for preparing blueberry juice fermented by ultrahigh pressure pre-treatment of plant lactobacillus comprises the following steps:

[0056] (1) Raw material cleaning: Select fresh blueberries that are free of insects and mold. Use distilled water to clean the dirt on the surface. After cleaning, drain the surface water.

[0057] (2) Pulping and enzymatic hydrolysis: The washed blueberries were mixed with water at a solid-liquid ratio of 1:5 (g:mL), and then pulped using a pulper to obtain blueberry pulp, which was then poured out for later use; 0.03% pectinase was added to the blueberry pulp for enzymatic hydrolysis (45°C water bath for 2h); after the enzymatic hydrolysis was completed, the blueberry pulp was filtered using 8 layers of gauze.

[0058] (3) pH adjustment: Fructooligosaccharides were added to the blueberry pulp after enzymatic filtration, and then sodium carbonate was added to adjust the initial pH to 5.5. The soluble solids of the fermentation broth were measured using a digital saccharimeter and found to be 16° Brix.

[0059] (4) Ultrahigh pressure treatment: The blueberry pulp after pH adjustment was vacuum packed in a plastic bag and then subjected to ultrahigh pressure treatment at 300 MPa for 15 min.

[0060] (5) Flavor preparation: Under aseptic conditions, 5% glucose and 10% milk powder are added to the blueberry pulp as an external nutrient source and to increase the flavor.

[0061] (6) Inoculation and fermentation: Plant lactic acid bacteria were inoculated into blueberry pulp for fermentation. The plant lactic acid bacteria were first activated with 10 mL of glucose aqueous solution for 20 min so that the concentration of the activated bacteria reached 60 × 10 7 (CFU / mL), the inoculation amount was 0.06%, and the fermentation conditions were anaerobic fermentation at 37°C for 36 hours, and the finished product was obtained after the fermentation was completed.

[0062] Example 5

[0063] A method for preparing blueberry juice fermented by ultrahigh pressure pre-treatment of plant lactobacillus comprises the following steps:

[0064] (1) Raw material cleaning: Select fresh blueberries that are free of insects and mold. Use distilled water to clean the dirt on the surface. After cleaning, drain the surface water.

[0065] (2) Pulping and enzymatic hydrolysis: The washed blueberries were mixed with water at a solid-liquid ratio of 1:5 (g:mL), and then pulped using a pulper to obtain blueberry pulp, which was then poured out for later use; 0.04% pectinase was added to the blueberry pulp for enzymatic hydrolysis (45°C water bath for 2h); after the enzymatic hydrolysis was completed, the blueberry pulp was filtered using 8 layers of gauze.

[0066] (3) pH adjustment: Fructooligosaccharides were added to the blueberry pulp after enzymatic filtration, and then sodium carbonate was added to adjust the initial pH to 5.5. The soluble solids of the fermentation broth were measured using a digital saccharimeter and found to be 16° Brix.

[0067] (4) Ultrahigh pressure treatment: The blueberry pulp after pH adjustment was vacuum packed in a plastic bag and then subjected to ultrahigh pressure treatment at 300 MPa for 15 min.

[0068] (5) Flavor preparation: Under aseptic conditions, 5% glucose and 10% milk powder are added to the blueberry pulp as an external nutrient source and to increase the flavor.

[0069] (6) Inoculation and fermentation: Plant lactic acid bacteria were inoculated into blueberry pulp for fermentation. The plant lactic acid bacteria were first activated with 10 mL of glucose aqueous solution for 20 min so that the concentration of the activated bacteria reached 60 × 10 7 (CFU / mL), the inoculation amount was 0.06%, and the fermentation conditions were anaerobic fermentation at 37°C for 36 hours, and the finished product was obtained after the fermentation was completed.

[0070] Example 6

[0071] A method for preparing blueberry juice fermented by ultrahigh pressure pre-treatment of plant lactobacillus comprises the following steps:

[0072] (1) Raw material cleaning: Select fresh blueberries that are free of insects and mold. Use distilled water to clean the dirt on the surface. After cleaning, drain the surface water.

[0073] (2) Pulping and enzymatic hydrolysis: The washed blueberries were mixed with water at a solid-liquid ratio of 1:5 (g:mL), and then pulped using a pulper to obtain blueberry pulp, which was then poured out for later use; 0.05% pectinase was added to the blueberry pulp for enzymatic hydrolysis (45°C water bath for 2h); after the enzymatic hydrolysis was completed, the blueberry pulp was filtered using 8 layers of gauze.

[0074] (3) pH adjustment: Fructooligosaccharides were added to the blueberry pulp after enzymatic filtration, and then sodium carbonate was added to adjust the initial pH to 5.5. The soluble solids of the fermentation broth were measured using a digital saccharimeter and found to be 14° Brix.

[0075] (4) Ultrahigh pressure treatment: The blueberry pulp after pH adjustment was vacuum packed in a plastic bag and then subjected to ultrahigh pressure treatment at 300 MPa for 15 min.

[0076] (5) Flavor preparation: Under aseptic conditions, 5% glucose and 10% milk powder are added to the blueberry pulp as an external nutrient source and to increase the flavor.

[0077] (6) Inoculation and fermentation: Plant lactic acid bacteria were inoculated into blueberry pulp for fermentation. The plant lactic acid bacteria were first activated with 10 mL of glucose aqueous solution for 20 min so that the concentration of the activated bacteria reached 60 × 10 7 (CFU / mL), the inoculation amount was 0.06%, and the fermentation conditions were anaerobic fermentation at 37°C for 36 hours, and the finished product was obtained after the fermentation was completed.

[0078] Example 7

[0079] A method for preparing blueberry juice fermented by ultrahigh pressure pre-treatment of plant lactobacillus comprises the following steps:

[0080] (1) Raw material cleaning: Select fresh blueberries that are free of insects and mold. Use distilled water to clean the dirt on the surface. After cleaning, drain the surface water.

[0081] (2) Pulping and enzymatic hydrolysis: The washed blueberries were mixed with water at a solid-liquid ratio of 1:5 (g:mL), and then pulped using a pulper to obtain blueberry pulp, which was then poured out for later use; 0.05% pectinase was added to the blueberry pulp for enzymatic hydrolysis (45°C water bath for 2h); after the enzymatic hydrolysis was completed, the blueberry pulp was filtered using 8 layers of gauze.

[0082] (3) pH adjustment: Fructooligosaccharides were added to the blueberry pulp after enzymatic filtration, and then sodium carbonate was added to adjust the initial pH to 5.5. The soluble solids of the fermentation broth were measured using a digital saccharimeter to be 15° Brix.

[0083] (4) Ultrahigh pressure treatment: The blueberry pulp after pH adjustment was vacuum packed in a plastic bag and then subjected to ultrahigh pressure treatment at 300 MPa for 15 min.

[0084] (5) Flavor preparation: Under aseptic conditions, 5% glucose and 10% milk powder are added to the blueberry pulp as an external nutrient source and to increase the flavor.

[0085] (6) Inoculation and fermentation: Plant lactic acid bacteria were inoculated into blueberry pulp for fermentation. The plant lactic acid bacteria were first activated with 10 mL of glucose aqueous solution for 20 min so that the concentration of the activated bacteria reached 60 × 10 7 (CFU / mL), the inoculation amount was 0.06%, and the fermentation conditions were anaerobic fermentation at 37°C for 36 hours, and the finished product was obtained after the fermentation was completed.

[0086] Example 8

[0087] A method for preparing blueberry juice fermented by ultrahigh pressure pre-treatment of plant lactobacillus comprises the following steps:

[0088] (1) Raw material cleaning: Select fresh blueberries that are free of insects and mold. Use distilled water to clean the dirt on the surface. After cleaning, drain the surface water.

[0089] (2) Pulping and enzymatic hydrolysis: The washed blueberries were mixed with water at a solid-liquid ratio of 1:5 (g:mL), and then pulped using a pulper to obtain blueberry pulp, which was then poured out for later use; 0.05% pectinase was added to the blueberry pulp for enzymatic hydrolysis (45°C water bath for 2h); after the enzymatic hydrolysis was completed, the blueberry pulp was filtered using 8 layers of gauze.

[0090] (3) pH adjustment: Fructooligosaccharides were added to the blueberry pulp after enzymatic filtration, and then sodium carbonate was added to adjust the initial pH to 5.5. The soluble solids of the fermentation broth were measured using a digital saccharimeter and found to be 16° Brix.

[0091] (4) Ultrahigh pressure treatment: The blueberry pulp after pH adjustment was vacuum packed in a plastic bag and then subjected to ultrahigh pressure treatment at 200 MPa for 15 min.

[0092] (5) Flavor preparation: Under aseptic conditions, 5% glucose and 10% milk powder are added to the blueberry pulp as an external nutrient source and to increase the flavor.

[0093] (6) Inoculation and fermentation: Plant lactic acid bacteria were inoculated into blueberry pulp for fermentation. The plant lactic acid bacteria were first activated with 10 mL of glucose aqueous solution for 20 min so that the concentration of the activated bacteria reached 60 × 10 7 (CFU / mL), the inoculation amount was 0.06%, and the fermentation conditions were anaerobic fermentation at 37°C for 36 hours, and the finished product was obtained after the fermentation was completed.

[0094] Example 9

[0095] A method for preparing blueberry juice fermented by ultrahigh pressure pre-treatment of plant lactobacillus comprises the following steps:

[0096] (1) Raw material cleaning: Select fresh blueberries that are free of insects and mold. Use distilled water to clean the dirt on the surface. After cleaning, drain the surface water.

[0097] (2) Pulping and enzymatic hydrolysis: The washed blueberries were mixed with water at a solid-liquid ratio of 1:5 (g:mL), and then pulped using a pulper to obtain blueberry pulp, which was then poured out for later use; 0.05% pectinase was added to the blueberry pulp for enzymatic hydrolysis (45°C water bath for 2h); after the enzymatic hydrolysis was completed, the blueberry pulp was filtered using 8 layers of gauze.

[0098] (3) pH adjustment: Fructooligosaccharides were added to the blueberry pulp after enzymatic filtration, and then sodium carbonate was added to adjust the initial pH to 5.5. The soluble solids of the fermentation broth were measured using a digital saccharimeter and found to be 16° Brix.

[0099] (4) Ultrahigh pressure treatment: The blueberry pulp after pH adjustment was vacuum packed in a plastic bag and then subjected to ultrahigh pressure treatment at 400 MPa for 15 min.

[0100] (5) Flavor preparation: Under aseptic conditions, 5% glucose and 10% milk powder are added to the blueberry pulp as an external nutrient source and to increase the flavor.

[0101] (6) Inoculation and fermentation: Plant lactic acid bacteria were inoculated into blueberry pulp for fermentation. The plant lactic acid bacteria were first activated with 10 mL of glucose aqueous solution for 20 min so that the concentration of the activated bacteria reached 60 × 10 7 (CFU / mL), the inoculation amount was 0.06%, and the fermentation conditions were anaerobic fermentation at 37°C for 36 hours, and the finished product was obtained after the fermentation was completed.

[0102] The fermented blueberry juice prepared in Example 1-9 was randomly distributed to 50 people for tasting, and the testers gave sensory ratings on the product, as shown in Table 1.

[0103] Table 1 Taste and color evaluation

[0104]

[0105]

[0106] The fermented blueberry juices prepared in Examples 1-9 were subjected to antioxidant tests, including the DPPH and ABTS free radical scavenging abilities, and the number of viable bacteria in the fermented blueberry juices was measured. The test results are shown in Table 2.

[0107] Table 2 DPPH and ABTS free radical scavenging rate and viable bacterial count

[0108]

Claims

1. A method for preparing blueberry juice fermented by ultrahigh pressure pretreatment of plant lactobacillus, characterized in that: The following steps are involved: (1) Raw material cleaning: Select fresh blueberries that are free of insect pests and mildew, clean the dirt on the surface with distilled water, and drain the surface water after cleaning; (2) Pulping and enzymolysis: The washed blueberries are mixed with water in a certain solid-liquid ratio, and then pulped using a pulper to obtain blueberry pulp, which is then poured out for later use; a certain proportion of pectinase is added to the blueberry pulp for enzymolysis; after the enzymolysis is completed, the blueberry pulp is filtered using gauze; (3) pH adjustment: adding a certain amount of oligofructose to the blueberry pulp after enzymatic filtration, and then adding sodium carbonate to adjust the initial pH; (4) Ultrahigh pressure treatment: The blueberry pulp after pH adjustment is vacuum packed in a plastic bag and then subjected to ultrahigh pressure treatment; (5) Flavor preparation: Under aseptic conditions, a certain amount of glucose and milk powder is added to the blueberry pulp as an additional nutrient source and to increase the flavor; (6) Inoculation and fermentation: Inoculate plant lactic acid bacteria into blueberry pulp for fermentation, and obtain the finished product after the fermentation is completed.

2. The method for preparing blueberry juice fermented by ultrahigh pressure pretreatment of lactobacillus plantarum according to claim 1, characterized in that: The solid-liquid ratio of blueberry to water in step (2) is 1:4-1:6 (g:mL).

3. The method for preparing blueberry juice fermented by ultrahigh pressure pretreatment of lactobacillus plantarum according to claim 1, characterized in that: The amount of pectinase added in step (2) is 0.03-0.05%.

4. The method for preparing blueberry juice fermented by ultrahigh pressure pretreatment of lactobacillus plantarum according to claim 1, characterized in that: In the step (2), 8 layers of gauze are used for filtering.

5. The method for preparing blueberry juice fermented by ultrahigh pressure pretreatment of lactobacillus plantarum according to claim 1, characterized in that: The amount of oligofructose added in step (3) is such that the soluble solids in the fermentation broth measured by a digital saccharimeter is 14-16° Brix.

6. The method for preparing blueberry juice fermented by ultrahigh pressure pretreatment of Lactobacillus plantarum according to claim 1, characterized in that: In the step (3), sodium carbonate is added to adjust the initial pH of the blueberry pulp after enzymatic hydrolysis and filtration to 5.

5.

7. The method for preparing blueberry juice fermented by ultrahigh pressure pretreatment of lactobacillus plantarum according to claim 1, characterized in that: The ultra-high pressure treatment conditions in step (4) are 200-400 MPa and pressure maintenance for 15 minutes.

8. The method for preparing blueberry juice fermented by ultrahigh pressure pretreatment of lactobacillus plantarum according to claim 1, characterized in that: The amount of the added nutrient in step (5) is 5% glucose and 10% milk powder.

9. The method for preparing blueberry juice fermented by ultrahigh pressure pretreatment of Lactobacillus plantarum according to claim 1, characterized in that: In step (6), the plant lactic acid bacteria are first activated with 10 mL of glucose aqueous solution for 20 min, so that the concentration of the activated bacteria reaches 60×10 7 (CFU / mL), the inoculum size was 0.06%.

10. The method for preparing blueberry juice fermented by ultrahigh pressure pre-treatment of lactobacillus plantarum according to claim 1, characterized in that: The fermentation condition of step (6) is to place the mixture in a 37°C constant temperature incubator for anaerobic fermentation for 36 hours.

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