Blueberry and lemon lactobacillus fermented beverage and preparation method thereof

Abstract

The invention belongs to the field of beverages, and particularly relates to a blueberry and lemon lactobacillus fermented beverage and a preparation method thereof. The blueberry and lemon lactobacillus fermented beverage is prepared by raw material pretreatment, quick freezing, microwave thawing, pulping, ultrahigh-pressure non-thermal sterilization, fermentation, secondary ultrahigh-pressure non-thermal sterilization and blending. The lemons and the blueberries are selectively matched, the sour pH of the lemons can strengthen the stability of anthocyanin of the blueberries, during preparation of the beverage, heat sterilization is not adopted in the whole process, non-heat ultrahigh pressure sterilization is adopted, freeze thawing and microwave thawing are creatively combined to be used for a blueberry and lemon system, and the beverage has the advantages that the taste is good; the defect that unfrozen blueberry lemon juice is easy to lose is avoided, and lactobacillus plantarum and lactobacillus rhamnosus suitable for combined fermentation of blueberries and lemons are screened out.

Description

Technical Field

[0001] The invention belongs to the field of beverages, and particularly relates to a blueberry lemon lactic acid bacteria fermented beverage and a preparation method thereof. Background Art

[0002] Blueberry is an evergreen shrub belonging to the genus Vaccinium of the family Ericaceae. It has high nutritional value and health functions, and is rich in nutrition and sweet and sour. Blueberries contain a large amount of unsaturated fatty acids, organic acids, proteins, minerals and trace elements, and a full range of vitamins with rich content, especially vitamin B and vitamin K. In addition, blueberries contain anthocyanins, anthocyanidins, β-carotene and other substances that have antioxidant and self-immunity enhancing effects. The content of anthocyanins in blueberry fruits is the highest among all fruits and vegetables. Therefore, blueberries have broad development prospects and utilization value.

[0003] Fresh blueberries are difficult to preserve at room temperature and need to be refrigerated to extend their shelf life, but they can only be preserved for about 10 days. Drying blueberries to make preserved fruits, etc., will greatly reduce the content of active ingredients such as anthocyanins in blueberries due to heat treatment. Literature research reports that anthocyanins are more stable under relatively low pH conditions. Therefore, in recent years, blueberries have been fermented with lactic acid bacteria to reduce the pH of beverages through fermentation and improve the stability of blueberry anthocyanins.

[0004] Lemon is a plant of the genus Citrus in the Rutaceae family. Lemon is rich in organic acids such as niacin and citric acid, so it is known as the "citric acid warehouse". The acidity of lemon itself is extremely strong, and the pH value can be as low as 2.5. Therefore, the low pH property of lemon can further stabilize the anthocyanins in blueberries.

[0005] After searching, it is found that there are beverages prepared by fermenting blueberries or lemons with lactic acid bacteria in the prior art, such as CN107373230A, a lemon oligosaccharide lactic acid bacteria beverage, which discloses mixing fermented milk with raw materials such as lemon juice for fermentation; CN 116569999A, a blueberry juice fermentation method, which discloses mixing blueberries with Bifidobacterium lactis JYBR-190CGMCC No. 18092, Lactobacillus plantarum JYLP-326CGMCC No. 18038, and Lactococcus lactis JYLL-60CGMCC No. 2335 for fermentation; CN117617424A, a blueberry juice fermentation method, which discloses mixing blueberries with Bifidobacterium lactis JYBR-190CGMCC No. 18092, Lactobacillus plantarum JYLP-326CGMCC No. 18038, and Lactococcus lactis JYLL-60CGMCC No. 2335 for fermentation; A A blueberry lactic acid bacteria fermented beverage rich in antioxidant activity, disclosing the fermentation of blueberries by a combination of lactic acid bacteria, Lactobacillus rhamnosus and Lactobacillus fermentation; CN104305465A A method for preparing lactic acid bacteria fermented blueberry juice, disclosing the fermentation of blueberries by a combination of 20% bifidobacterium, 20% Lactobacillus bulgaricus, 15% Streptococcus thermophilus, 15% Lactobacillus acidophilus, 10% Lactobacillus casei, and 10% Lactobacillus rhamnosus; CN110236046A A high-active lactic acid bacteria fermented blueberry pomace beverage and a preparation method thereof, disclosing the fermentation of blueberry pomace by Lactobacillus rhamnosus LGG and Lactobacillus plantarum PL-1; Document 1 (“Optimization of blueberry raw material lactic acid bacteria fermentation process by response surface methodology”, Hu Nan, et al., Food Science and Technology, 2021) discloses the use of lactic acid bacteria TUST-L 4, TUST-L 26 and TUST-L27 fermented blueberries; Document 2 ("Fermentation Characteristics of Lactic Acid Bacteria in Blueberry Juice", Wu Wanlin, et al., Modern Food Science and Technology, Vol. 36, No. 3, 2020) discloses the effects of Lactobacillus casei, Lactobacillus bulgaricus, Lactobacillus plantarum and Lactobacillus acidophilus on the fermentation of blueberry juice; Document 3 ("Optimization of Blueberry Juice Fermentation Process and Analysis of Volatile Flavor Substances", Huang Kexia, China Brewing, 2021) discloses the use of brewer's yeast and lactic acid bacteria in a staged fermentation process to prepare fermented blueberry juice.

[0006] It can be seen that although there are blueberry lactic acid bacteria fermented beverages or lemon lactic acid bacteria fermented beverages in the prior art, there are few studies on the combination of blueberry and lemon to prepare lactic acid bacteria fermented beverages. The prior art has not studied the influence of different lactic acid bacteria on the combined fermentation of blueberry and lemon. The only combination of Lactobacillus plantarum and Lactobacillus rhamnosus is targeted at blueberry pomace, and specific strains of Lactobacillus plantarum and Lactobacillus rhamnosus are required. The present invention starts from the defects of existing blueberry lactic acid bacteria fermentation such as heat sterilization or low content of blueberry anthocyanins, and selectively uses lemon and blueberry for matching. The acidic pH of lemon can enhance the stability of blueberry anthocyanins, and when preparing lactic acid bacteria fermented beverages, heat sterilization is not used throughout the process, but non-thermal ultra-high pressure sterilization is used. Before preparing the beverage, blueberries and lemons are subjected to freeze-thaw treatment to destroy their cell structures and facilitate the outflow of juice; for the combination of blueberries and lemons, starting from the existing common blueberry fermented lactic acid bacteria, the influence of different lactic acid bacteria on the blueberry lemon fermented beverage is studied, and plant lactobacillus and rhamnosus lactobacillus suitable for the combined fermentation of blueberries and lemons are screened out. The blueberry lemon lactic acid bacteria fermented beverage of the invention has strong industrial application prospects. Summary of the invention

[0007] On one hand, the present invention provides a method for preparing a blueberry lemon lactic acid bacteria fermented beverage, which selectively uses lemon and blueberry for combination, and the lower pH of lemon can enhance the stability of blueberry anthocyanin, and non-thermal ultra-high pressure sterilization is used instead of thermal sterilization. Before preparing the beverage, the blueberry and lemon are subjected to freeze-thaw treatment to destroy their cell structure and facilitate the outflow of juice, and microwave thawing can be performed in a short time to avoid the defect that the blueberry lemon juice is easily lost when thawed for a long time at room temperature; plant lactobacillus and rhamnosus lactobacillus suitable for the combined fermentation of blueberry and lemon are screened.

[0008] The first aspect of the present invention provides a method for preparing a blueberry lemon lactic acid bacteria fermented beverage, comprising the following steps: (1) Raw material pretreatment: Select fresh, non-rotten blueberries and lemons, wash them with clean water, peel the lemons and set aside; (2) Quick freezing: Quickly freeze the pretreated blueberries and lemons at -30 to -45°C; (3) Microwave thawing, pulping, and ultra-high pressure sterilization: The quick-frozen blueberries and lemons are thawed by microwaves at a microwave thawing temperature of 35-48°C, a microwave thawing power of 350-450W, and a microwave thawing time of 5-10 min. The blueberries and lemons are mixed in a mass ratio of 1-3:1-3, added to a pulper for pulping, and then pulped with a colloid mill. The concentration of the pulp is adjusted to 25-40%, and sucrose is added to account for 2.5-3.5% of the adjusted pulp mass. The mixture is placed in a 550-650MPa ultra-high pressure sterilizer for ultra-high pressure sterilization rather than thermal sterilization. The ultra-high pressure sterilization time is 5-10 min. (4) fermentation: inoculating the fruit pulp obtained in step (3) with a mixture of Lactobacillus plantarum and Lactobacillus rhamnosus at a mass ratio of 0.5-1% of the fruit pulp, wherein the mass ratio of Lactobacillus plantarum to Lactobacillus rhamnosus is 1-1.5:1-1.5, and fermenting the inoculated fruit pulp at a constant temperature of 37° C. for 36-50 hours; (5) Ultra-high pressure non-thermal sterilization: Place the fermented pulp in a 550-650MPa ultra-high pressure sterilizer for ultra-high pressure non-thermal sterilization. The ultra-high pressure sterilization time is 5-10 minutes. (6) Preparation: The ultra-high pressure non-thermal sterilization beverage is prepared to obtain a blueberry lemon lactic acid bacteria fermented beverage.

[0009] Preferably, the quick freezing temperature in step (2) is -35°C.

[0010] Preferably, the microwave thawing parameters in step (3) are: microwave thawing temperature is 45° C., microwave thawing power is 400 W, and microwave thawing time is 10 min.

[0011] Preferably, in step (3), blueberries and lemons are mixed in a mass ratio of 3:2.

[0012] Preferably, the concentration of the fruit pulp is adjusted to 30% in step (3).

[0013] Preferably, in step (3), 3% of the weight of the adjusted pulp is added with sucrose.

[0014] Preferably, in step (4), a mixture of Lactobacillus plantarum and Lactobacillus rhamnosus is inoculated at 0.8% of the mass of the fruit pulp, wherein the mass ratio of Lactobacillus plantarum to Lactobacillus rhamnosus is 1.5:1.

[0015] Preferably, the inoculated pulp in step (4) is fermented at a constant temperature of 37° C. for 48 hours.

[0016] Preferably, the ultrahigh pressure non-thermal sterilization parameters in step (3) and step (5) are: ultrahigh pressure pressure of 600 MPa, and ultrahigh pressure sterilization time of 10 min.

[0017] The blueberry lemon lactic acid bacteria fermented beverage is prepared by any of the methods described above.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention selectively uses lemon and blueberry as a combination. The lower pH of lemon can enhance the stability of blueberry anthocyanins.

[0019] (2) In view of the fact that blueberry anthocyanins are unstable to heat, the present invention does not use thermal sterilization during the entire process of beverage preparation, but instead uses non-thermal ultra-high pressure sterilization.

[0020] (3) The present invention creatively combines freeze-thaw and microwave thawing for a blueberry and lemon system. The freeze-thaw treatment of blueberries and lemons can destroy their cell structures, facilitating the outflow of juice. The subsequent microwave thawing can thaw the blueberries and lemons in a short time, thus avoiding the defect of easy loss of juice from long-term thawing at room temperature.

[0021] (4) The present invention starts from the lactic acid bacteria commonly used in fermentation of blueberry, such as Bifidobacterium lactis, Bifidobacterium adolescentis, Lactobacillus acidophilus, Lactobacillus plantarum, Lactobacillus bulgaricus, Lactobacillus paracasei, Lactococcus lactis, Lactobacillus rhamnosus, and Lactobacillus casei, and screens out Lactobacillus plantarum and Lactobacillus rhamnosus that are suitable for the combined fermentation of blueberry and lemon.

[0022] (5) At the same inoculation rate, the combination of Lactobacillus plantarum and Lactobacillus rhamnosus can significantly increase the content of total acid, total phenols, total anthocyanins and DPPH scavenging rate in the blueberry lemon beverage system. The possible reason is that there is a certain synergistic effect between Lactobacillus plantarum and Lactobacillus rhamnosus. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Different batches of blueberry lemon lactic acid bacteria fermented beverages prepared in Example 3. DETAILED DESCRIPTION

[0024] The specific implementation of the present invention is described below with reference to the accompanying drawings. The experimental methods used in the implementation examples are all conventional methods unless otherwise specified; the materials and reagents used are all commercially available unless otherwise specified.

[0025] Example 1 Effects of different lactic acid bacteria on blueberry lemon lactic acid bacteria fermented beverage.

[0026] Lactic acid bacteria commonly used in fermentation of blueberry and other fruits and vegetables were selected as the strains for blueberry lemon fermentation: Bifidobacterium lactis, Bifidobacterium adolescentis, Lactobacillus acidophilus, Lactobacillus plantarum, Lactobacillus bulgaricus, Lactobacillus paracasei, Lactococcus lactis, Lactobacillus rhamnosus and Lactobacillus casei. The effects of different fermentation strains on the total acidity, total anthocyanins, total phenols and DPPH clearance rate of blueberry lemon fermented beverage were studied.

[0027] The total acid content was determined according to GB / T 12456-2008 Determination of total acid in food.

[0028] The determination method of total anthocyanins, total polyphenols, and DPPH scavenging rate adopts the method described in Sections 1.7.4-1.7.6 of the literature ("Fermentation Characteristics of Lactic Acid Bacteria in Blueberry Juice", Wu Wanlin, et al., Modern Food Science and Technology, Vol. 36, No. 3, 2020).

[0029] The preparation method of the blueberry lemon lactic acid bacteria fermented beverage specifically comprises: (1) Raw material pretreatment: Select fresh, non-rotten blueberries and lemons, wash them with clean water, peel the lemons and set aside; (2) Quick freezing: the pretreated blueberries and lemons are quick frozen at -35°C; (3) Microwave thawing and grinding: The quick-frozen blueberries and lemons were thawed by microwave at a microwave thawing temperature of 45°C, a microwave thawing power of 400 W, and a microwave thawing time of 10 min. The blueberries and lemons were mixed in a mass ratio of 3:2, added to a pulper for pulping, and then ground with a colloid mill. The concentration of the pulp was adjusted to 30%, and 3% of the mass of the adjusted pulp was added with sucrose. The mixture was placed in a 600MPa ultra-high pressure sterilizer for ultra-high pressure sterilization rather than thermal sterilization. The ultra-high pressure sterilization time was 8 min. (4) Fermentation: Divide the fruit pulp obtained in step (3) into 9 equal portions, inoculate each portion of the fruit pulp with 0.8% by weight of the fruit pulp of Bifidobacterium lactis, Bifidobacterium adolescentis, Lactobacillus acidophilus, Lactobacillus plantarum, Lactobacillus bulgaricus, Lactobacillus paracasei, Lactococcus lactis, Lactobacillus rhamnosus, and Lactobacillus casei, respectively, and ferment the inoculated fruit pulp at a constant temperature of 37° C. for 48 hours; (5) Ultra-high pressure non-thermal sterilization: The fermented fruit pulp is placed in a 600MPa ultra-high pressure sterilizer for ultra-high pressure non-thermal sterilization. The ultra-high pressure sterilization time is 10 minutes. (6) Preparation: The ultra-high pressure non-thermal sterilization beverage is prepared separately, such as optionally adding stabilizers, sweeteners, etc., to obtain a blueberry lemon lactic acid bacteria fermented beverage.

[0030] According to the aforementioned measurement method, the total acid, total anthocyanin, total polyphenol content, and DPPH scavenging rate in the blueberry lemon lactic acid bacteria fermented beverage were measured, as shown in Table 1 below: Table 1

[0031] From Table 1, it can be seen that different lactic acid bacteria have different effects on total acid (g / L), total phenol (mg / L), total anthocyanin (mg / L), and DPPH clearance rate (%) in the blueberry and lemon fermentation system. Compared with Bifidobacterium lactis, Bifidobacterium adolescentis, Lactobacillus acidophilus, Lactobacillus bulgaricus, Lactobacillus paracasei, Lactococcus lactis, and Lactobacillus casei, the total acid, total phenol, and total anthocyanin content in the blueberry lemon beverage system after fermentation by Lactobacillus plantarum and Lactobacillus rhamnosus are higher, and the DPPH clearance rate is higher. For Lactobacillus plantarum and Lactobacillus rhamnosus, the total acid and total phenol content in the blueberry lemon beverage system after fermentation by Lactobacillus plantarum is higher than that of Lactobacillus rhamnosus, while the total anthocyanin and DPPH clearance rate in the blueberry lemon beverage system after fermentation by Lactobacillus rhamnosus is higher than that of Lactobacillus plantarum. Therefore, Lactobacillus plantarum and Lactobacillus rhamnosus were selected as the strains of blueberry lemon lactic acid bacteria fermented beverages.

[0032] Example 2 Effect of co-fermentation of Lactobacillus plantarum and Lactobacillus rhamnosus on blueberry lemon lactic acid bacteria fermented beverage.

[0033] The preparation method of the blueberry lemon lactic acid bacteria fermented beverage specifically comprises: (1) Raw material pretreatment: Select fresh, non-rotten blueberries and lemons, wash them with clean water, peel the lemons and set aside; (2) Quick freezing: the pretreated blueberries and lemons are quick frozen at -35°C; (3) Microwave thawing, pulping, and ultra-high pressure sterilization: The quick-frozen blueberries and lemons were thawed by microwave at a microwave thawing temperature of 45°C, a microwave thawing power of 400 W, and a microwave thawing time of 10 min. The blueberries and lemons were mixed in a mass ratio of 3:2, added to a pulper for pulping, and then pulped with a colloid mill. The concentration of the pulp was adjusted to 30%, and sucrose was added to 3% of the adjusted pulp mass. The mixture was placed in a 600 MPa ultra-high pressure sterilizer for ultra-high pressure sterilization rather than thermal sterilization. The ultra-high pressure sterilization time was 8 min. (4) Fermentation: inoculating the fruit pulp obtained in step (3) with a mixture of Lactobacillus plantarum and Lactobacillus rhamnosus at a mass ratio of 0.8% of the fruit pulp, wherein the mass ratio of Lactobacillus plantarum to Lactobacillus rhamnosus is 1.5:1, and fermenting the inoculated fruit pulp at a constant temperature of 37° C. for 48 hours; (5) Ultra-high pressure non-thermal sterilization: The fermented pulp is placed in a 600MPa ultra-high pressure sterilizer for ultra-high pressure non-thermal sterilization. The ultra-high pressure sterilization time is 10 minutes. (6) Preparation: The ultra-high pressure non-thermal sterilization beverage is prepared, such as optionally adding stabilizers, sweeteners, etc., to obtain a blueberry lemon lactic acid bacteria fermented beverage.

[0034] According to the aforementioned measurement method, the total acid, total anthocyanin, total polyphenol content, and DPPH clearance rate in the blueberry lemon lactic acid bacteria fermented beverage were measured, as shown in Table 2 below: Table 2

[0035] As can be seen from Table 2, under the same inoculation amount, the combination of Lactobacillus plantarum and Lactobacillus rhamnosus can significantly increase the content of total acid, total phenols, total anthocyanins and DPPH clearance rate in the blueberry lemon beverage system. The possible reason is that there is a certain synergistic effect between Lactobacillus plantarum and Lactobacillus rhamnosus.

[0036] Comparative Example 1: The difference from Example 2 is that room temperature thawing is used instead of microwave thawing, and the remaining steps are the same as Example 2.

[0037] Comparative Example 2: The difference from Example 2 is that high temperature instantaneous sterilization is used instead of ultrahigh pressure sterilization in step (3), and the remaining steps are the same as those in Example 2.

[0038] Comparative Example 3: The difference from Example 2 is that high temperature instantaneous sterilization is used instead of ultrahigh pressure sterilization in step (5), and the remaining steps are the same as those in Example 2.

[0039] According to the aforementioned measurement method, the total acid, total anthocyanin, total polyphenol content, and DPPH clearance rate in the blueberry lemon lactic acid bacteria fermented beverages of Comparative Examples 1-3 were measured, as shown in Table 3 below: Table 3

[0040] From Table 3, it can be seen that the contents of total acid, total phenols, total anthocyanins and DPPH clearance rate decreased when thawing at room temperature instead of microwave thawing. The possible reasons are: due to the long thawing time at room temperature, the cells of blueberries and lemons have been broken after freezing and thawing. If they are left to thaw for a long time, the juice is easy to flow out and be lost.

[0041] It can be seen from Comparative Examples 2-3 in Table 3 that high temperature sterilization can significantly reduce the content of total phenols and total anthocyanins in the blueberry lemon beverage system, thereby significantly reducing the DPPH clearance rate. The possible reason is that polyphenols such as anthocyanins in blueberries and lemons are sensitive to heat and are easily degraded at high temperatures. Example 3

[0042] The preparation method of the blueberry lemon lactic acid bacteria fermented beverage specifically comprises: (1) Raw material pretreatment: Select fresh, non-rotten blueberries and lemons, wash them with clean water, peel the lemons and set aside; (2) Quick freezing: the pretreated blueberries and lemons are quick frozen at -30°C; (3) Microwave thawing, pulping, and ultra-high pressure sterilization: The quick-frozen blueberries and lemons were thawed by microwave at a microwave thawing temperature of 35°C, a microwave thawing power of 350W, and a microwave thawing time of 12 min. The blueberries and lemons were mixed in a mass ratio of 1:1, added to a pulper for pulping, and then pulped with a colloid mill. The concentration of the pulp was adjusted to 25%, and sucrose was added to account for 2.5% of the adjusted pulp mass. The mixture was placed in a 550MPa ultra-high pressure sterilizer for ultra-high pressure sterilization rather than thermal sterilization. The ultra-high pressure sterilization time was 10 min. (4) Fermentation: inoculating the fruit pulp obtained in step (3) with a mixture of Lactobacillus plantarum and Lactobacillus rhamnosus at a mass ratio of 0.5% of the fruit pulp, wherein the mass ratio of Lactobacillus plantarum to Lactobacillus rhamnosus is 1:1, and fermenting the inoculated fruit pulp at a constant temperature of 37° C. for 36 hours; (5) Ultra-high pressure non-thermal sterilization: The fermented fruit pulp is placed in a 550MPa ultra-high pressure sterilizer for ultra-high pressure non-thermal sterilization. The ultra-high pressure sterilization time is 12 minutes. (6) Preparation: The ultra-high pressure non-thermal sterilization beverage is prepared, such as optionally adding stabilizers, sweeteners, etc., to obtain a blueberry lemon lactic acid bacteria fermented beverage. Example 4

[0043] The preparation method of the blueberry lemon lactic acid bacteria fermented beverage specifically comprises: (1) Raw material pretreatment: Select fresh, non-rotten blueberries and lemons, wash them with clean water, peel the lemons and set aside; (2) Quick freezing: the pretreated blueberries and lemons are quick frozen at -45°C; (3) Microwave thawing, pulping, and ultra-high pressure sterilization: The quick-frozen blueberries and lemons were thawed by microwave at a microwave thawing temperature of 48°C, a microwave thawing power of 450W, and a microwave thawing time of 5 minutes. The blueberries and lemons were mixed in a mass ratio of 2:3, added to a pulper for pulping, and then pulped with a colloid mill. The concentration of the pulp was adjusted to 40%, and sucrose was added to account for 3.5% of the adjusted pulp mass. The mixture was placed in a 650MPa ultra-high pressure sterilizer for ultra-high pressure sterilization rather than thermal sterilization. The ultra-high pressure sterilization time was 5 minutes. (4) fermentation: inoculating the fruit pulp obtained in step (3) with a mixture of Lactobacillus plantarum and Lactobacillus rhamnosus at 1% by mass of the fruit pulp, wherein the mass ratio of Lactobacillus plantarum to Lactobacillus rhamnosus is 1:1.5, and fermenting the inoculated fruit pulp at a constant temperature of 37° C. for 50 hours; (5) Ultra-high pressure non-thermal sterilization: The fermented pulp is placed in a 650MPa ultra-high pressure sterilizer for ultra-high pressure non-thermal sterilization. The ultra-high pressure sterilization time is 5 minutes. (6) Preparation: The ultra-high pressure non-thermal sterilization beverage is prepared, such as optionally adding stabilizers, sweeteners, etc., to obtain a blueberry lemon lactic acid bacteria fermented beverage.

[0044] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. A method for preparing a blueberry lemon lactic acid bacteria fermented beverage, characterized in that: The steps include: (1) Raw material pretreatment: Select fresh, non-rotten blueberries and lemons, wash them with clean water, peel the lemons and set aside; (2) Quick freezing: Quickly freeze the pretreated blueberries and lemons at -30 to -45°C; (3) Microwave thawing, pulping, and ultra-high pressure non-thermal sterilization: The quick-frozen blueberries and lemons are thawed by microwave at a microwave thawing temperature of 35-48°C, a microwave thawing power of 350-450W, and a microwave thawing time of 5-10 min. The blueberries and lemons are mixed in a mass ratio of 1-3:1-3, added to a pulper for pulping, and then pulped with a colloid mill. Water is added to adjust the pulp concentration to 25-40%, and sucrose is added to 2.5-3.5% of the adjusted pulp mass. The mixture is placed in a 550-650MPa ultra-high pressure sterilizer for ultra-high pressure sterilization without thermal sterilization, and the ultra-high pressure sterilization time is 5-10 min. (4) fermentation: inoculating the fruit pulp obtained in step (3) with a mixture of Lactobacillus plantarum and Lactobacillus rhamnosus at a mass ratio of 0.5-1% of the fruit pulp, wherein the mass ratio of Lactobacillus plantarum to Lactobacillus rhamnosus is 1-1.5:1-1.5, and fermenting the inoculated fruit pulp at a constant temperature of 37° C. for 36-50 hours; (5) Secondary ultra-high pressure non-thermal sterilization: The fermented pulp is placed in a 550-650MPa ultra-high pressure sterilizer for secondary ultra-high pressure non-thermal sterilization. The ultra-high pressure sterilization time is 5-10 minutes. (6) Preparation: The secondary ultra-high pressure non-thermal sterilization beverage is prepared to obtain a blueberry lemon lactic acid bacteria fermented beverage.

2. The method for preparing a blueberry lemon lactic acid bacteria fermented beverage according to claim 1, characterized in that: The quick freezing temperature in step (2) is -35°C.

3. The method for preparing a blueberry lemon lactic acid bacteria fermented beverage according to claim 1, characterized in that: The parameters of microwave thawing in step (3) are: microwave thawing temperature is 45°C, microwave thawing power is 400W, and microwave thawing time is 10min.

4. The method for preparing a blueberry lemon lactic acid bacteria fermented beverage according to claim 1, characterized in that: In step (3), blueberries and lemons are mixed in a mass ratio of 3:

2.

5. The method for preparing a blueberry lemon lactic acid bacteria fermented beverage according to claim 1, characterized in that: In step (3), the concentration of the fruit pulp is adjusted to 30%.

6. The method for preparing a blueberry lemon lactic acid bacteria fermented beverage according to claim 1, characterized in that: In step (3), 3% of the weight of the adjusted pulp sucrose is added.

7. The method for preparing a blueberry lemon lactic acid bacteria fermented beverage according to claim 1, characterized in that: In step (4), a mixture of Lactobacillus plantarum and Lactobacillus rhamnosus is inoculated at 0.8% of the mass of the fruit pulp, wherein the mass ratio of Lactobacillus plantarum to Lactobacillus rhamnosus is 1.5:

1.

8. The method for preparing a blueberry lemon lactic acid bacteria fermented beverage according to claim 1, characterized in that: The inoculated pulp in step (4) is fermented at a constant temperature of 37° C. for 48 hours.

9. The method for preparing a blueberry lemon lactic acid bacteria fermented beverage according to claim 1, characterized in that: The parameters of the ultra-high pressure non-thermal sterilization and the secondary ultra-high pressure non-thermal sterilization in step (3) and step (5) are: pressure 600 MPa, sterilization time 10 min.

10. A blueberry lemon lactic acid bacteria fermented beverage prepared by the method according to any one of claims 1 to 9.

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