Prunus humilis fermented juice and preparation method thereof

Abstract

The invention provides fermented cerasus humilis juice and a preparation method thereof, and belongs to the technical field of deep processing of cerasus humilis. The invention provides a preparation method of fermented cerasus humilis juice. The cerasus humilis fruits are used as raw materials, cerasus humilis kernel powder is added in the preparation of cerasus humilis juice, nutritional ingredients of the cerasus humilis fermented juice are increased, and the utilization rate of the cerasus humilis fruits is increased. Lactobacillus plantarum is adopted for fermentation, so that the taste of the cerasus humilis fermented juice is improved, and the functionality is improved; lactobacillus brevis is adopted for fermentation, the effective calcium content is increased, and calcium can be absorbed by the human body more easily. The prepared cerasus humilis fermented juice is good in taste, unique in flavor, rich in content of total phenols and total anthocyanin, improved in oxidation resistance, improved in effective calcium content, easier to absorb by human bodies, free of additional addition of white granulated sugar and cane sugar, green and healthy, and suitable for calcium supplement of people with hyperglycemia.

Description

Technical Field

[0001] This invention belongs to the field of deep processing technology of European plum, specifically relating to a fermented European plum juice and its preparation method. Background Technology

[0002] European plum (Prunus humilis Bunge) is a deciduous shrub belonging to the Rosaceae family and the Prunus genus. Its fruit pulp has a calcium content as high as 512 mg / 100 g, 3 to 10 times that of other fruits, hence its nickname "calcium fruit." European plum fruit has a unique and rich aroma, and is rich in phenolic compounds, amino acids, and trace elements. Its low sugar content makes it suitable for people with high blood sugar to supplement calcium. The kernels, after being shelled, can be used in medicine. Therefore, European plum is very suitable for processing into various products, with significant development value and broad application prospects in the food, nutrition, health, and medical industries. Currently, the market mainly offers primary processed products such as pressed juice, dried fruit, and jam, lacking intensively processed products. The kernels are also wasted. Therefore, developing intensively processed European plum products is essential.

[0003] Microbial fermentation technology is a novel food processing technology that utilizes probiotics such as yeast, lactic acid bacteria, and acetic acid bacteria to ferment European plums, producing products such as European plum vinegar, fruit wine, and fermented juice. This process fully releases nutrients such as sugars, organic acids, minerals, vitamins, enzymes, amino acids, phenols, and alcohols, offering benefits such as enhanced immunity, antioxidant effects, regulation of intestinal flora, and lowering of blood lipids. Therefore, utilizing microbial fermentation technology for the intensive processing of European plums, comprehensively utilizing them, increasing the added value of European plum products, and enriching the European plum market are of significant importance.

[0004] However, current methods for preparing European plum juice only process the plum pulp, failing to fully utilize the plum kernels. Adding kernels to some European plum products can easily lead to a decrease in sensory quality. Therefore, providing a method that utilizes both the plum pulp and the kernels without adversely affecting the product's sensory evaluation is of great significance for the full development of European plum resources. Summary of the Invention

[0005] In view of the deficiencies in the prior art, the purpose of this invention is to provide a method for preparing European plum juice, which can comprehensively utilize the pulp and kernel of European plum, improve the functionality of European plum juice, significantly improve the sensory quality of European plum juice, and improve the resource utilization efficiency of European plum.

[0006] The objective of this invention is achieved through the following technical solution: This invention provides a method for preparing fermented plum juice, comprising the following steps: The pits and pulp of the European plum were separated, the pulp was mixed with water and enzymatically hydrolyzed to prepare European plum pulp; the kernels from the pits were used to prepare European plum kernel powder. After mixing the plum pulp with apple juice, Lactobacillus plantarum was inoculated and fermented to obtain the Lactobacillus plantarum fermentation product. The fermentation product of Lactobacillus plantarum was mixed with Prunus cerevisiae kernel powder and water, and then inoculated with Lactobacillus brevis for fermentation to obtain the fermentation product of Lactobacillus brevis. After blending and filtering, the fermented product of Lactobacillus brevis was used to obtain the fermented juice of Prunus armeniaca.

[0007] Preferably, the *Lactobacillus plantarum* includes *Lactobacillus plantarum* LNJ-HQ-01 with preservation number CGMCC No. 31144; the *Lactobacillus brevis* includes *Lactobacillus brevis* BNCC337373.

[0008] Preferably, the *Lactobacillus plantarum* is inoculated in the form of an activated *Lactobacillus plantarum* bacterial solution; the viability of the activated *Lactobacillus plantarum* bacterial solution is (1.0~2.0) × 10⁻⁶. 9 cfu / mL; the inoculum amount of the activated Lactobacillus plantarum solution is 3%~5% based on the mass of Prunus cerevisiae pulp; The *Lactobacillus brevis* was inoculated in the form of an activated *Lactobacillus brevis* bacterial solution; the viability of the activated *Lactobacillus brevis* bacterial solution was (1.0~2.0) × 10⁻⁶. 9 cfu / mL; the inoculum size of the activated Lactobacillus brevis culture is 3%~5% based on the mass of Lactobacillus plantarum fermentation product.

[0009] Preferably, the fermentation temperature of Lactobacillus plantarum is 30~35℃ and the fermentation time of Lactobacillus plantarum is 40~60h; the fermentation temperature of Lactobacillus brevis is 34~36℃ and the fermentation time of Lactobacillus brevis is 40~60h.

[0010] Preferably, the enzymatic hydrolysis preparation comprises: tanninase, cellulase, and pectinase; the tanninase has an enzyme activity of 180~220 u / g; the cellulase has an enzyme activity of 40~60 u / mg; the pectinase has an enzyme activity of 40~60 u / mg; the mass ratio of tanninase, cellulase, and pectinase in the enzymatic hydrolysis preparation is (0.8~1):(0.4~0.6):(1.5~2.0); and the amount of the enzymatic hydrolysis preparation added is 8~10 g / kg based on the weight of the fruit pulp.

[0011] 6. The preparation method according to claim 1 or 5, characterized in that the enzymatic hydrolysis temperature is 45~50℃; and the enzymatic hydrolysis time is 2~2.5h.

[0012] Preferably, when the pulp is mixed with water, the mass ratio of pulp to water is 1:(1~1.5); when the European plum pulp is mixed with apple juice, the amount of concentrated apple juice added is 35~45g / kg based on the mass of the European plum pulp.

[0013] Preferably, when the Lactobacillus plantarum fermentation product is mixed with Prunus cerevisiae kernel powder and water, the amount of Prunus cerevisiae kernel powder added is 50~80g / kg and the amount of water added is 1.5~2.0L / kg, based on the mass of the Lactobacillus plantarum fermentation product.

[0014] Preferably, the formulation includes mixing Lactobacillus brevis fermentation product with black tea extract and apple juice; the amount of black tea extract added is 13-18 g / kg and the amount of concentrated apple juice added is 18-22 g / kg based on the mass of Lactobacillus brevis fermentation product. The filtration includes ultrafiltration membrane filtration.

[0015] The present invention provides a fermented plum juice prepared by the preparation method described in the above technical solution.

[0016] The beneficial effects of this invention are: This invention provides a method for preparing fermented European plum juice, comprising the following steps: separating the European plum pit from the pulp; mixing the pulp with water and preparing European plum pulp through enzymatic hydrolysis; preparing European plum kernel powder from the kernel; mixing the European plum pulp with apple juice and inoculating with *Lactobacillus plantarum* for fermentation to obtain *Lactobacillus plantarum* fermentation product; mixing the *Lactobacillus plantarum* fermentation product with European plum kernel powder and water, and inoculating with *Lactobacillus brevis* for fermentation to obtain *Lactobacillus brevis* fermentation product; and adjusting and filtering the *Lactobacillus brevis* fermentation product to obtain fermented European plum juice. This invention uses European plum fruit as raw material and adds European plum kernel powder to the preparation of European plum juice, increasing the nutritional content of the fermented European plum juice and improving the utilization rate of calcium. In the preparation of fermented European plum juice, this invention uses *Lactobacillus plantarum* (… Lactobacillus plantarum This single-stage fermentation method is suitable for fermenting berries with high acidity, producing acid, releasing total phenols, enhancing antioxidant properties, resulting in a rich fermented flavor, improving the taste and functionality of plum juice; it utilizes Lactobacillus brevis (…). Lactobacillus brevis Secondary fermentation increases the content of effective calcium, including pectin calcium, water-soluble calcium, and alcohol-soluble calcium, making the calcium more easily absorbed by the human body. The preparation method employs a two-strain batch fermentation approach, allowing for precise control of the fermentation process. Concentrated apple juice is added as a carbon source during the *Lactobacillus plantarum* fermentation stage, while *Lactobacillus brevis* fermentation adds *Prunus cerevisiae* kernel powder as a nitrogen source, providing a nutritional basis for microbial growth and reproduction. The results of the examples show that the *Prunus cerevisiae* fermented juice prepared by this invention has a good taste and unique flavor, is rich in total phenols and anthocyanins, has improved antioxidant capacity, and increases the effective calcium content, making it easier for the human body to absorb. No additional white sugar or sucrose is added, making the product green and healthy, suitable for calcium supplementation for people with high blood sugar. Detailed Implementation

[0017] This invention provides a method for preparing fermented plum juice, comprising the following steps: The pits and pulp of the European plum were separated, the pulp was mixed with water and enzymatically hydrolyzed to prepare European plum pulp; the kernels from the pits were used to prepare European plum kernel powder. After mixing the plum pulp with apple juice, Lactobacillus plantarum was inoculated and fermented to obtain the Lactobacillus plantarum fermentation product. The fermentation product of Lactobacillus plantarum was mixed with Prunus cerevisiae kernel powder and water, and then inoculated with Lactobacillus brevis for fermentation to obtain the fermentation product of Lactobacillus brevis. After blending and filtering, the fermented product of Lactobacillus brevis was used to obtain the fermented juice of Prunus armeniaca.

[0018] This invention separates the pit from the pulp of the European plum (Prunus armeniaca), mixes the pulp with water, and prepares European plum pulp through enzymatic hydrolysis; the kernel from the pit is then used to prepare European plum kernel powder. This invention does not have a specific limitation on the source of the European plum; any commercially available product in the art can be used. In this invention, the European plum is preferably selected from mature fruits that are reddish in color, free from mechanical damage and pests. After obtaining the European plum fruit, this invention preferably removes the fruit stalk and then separates the pulp from the pit. This invention does not have a specific limitation on the method of separating the pulp and pit; any conventional separation method in the art can be used.

[0019] After obtaining the European plum pulp, the present invention preferably mixes the European plum pulp with water to obtain a European plum pulp-water mixture. As an optional embodiment of the present invention, the mass ratio of the European plum pulp to water can be 1:(1~1.5), or 1:1, 1:1.2, 1:1.3, 1:1.4, or 1:1.5. After obtaining the European plum pulp-water mixture, the present invention preferably pulps the European plum pulp-water mixture to obtain a European plum slurry. The present invention does not specifically limit the pulping method; conventional fermentation methods in the art can be used. As an optional embodiment of the present invention, the pulping speed can be 2890 r / min; the pulping time can be 30~40 min, or 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, or 40 min; the pulping can be performed using a 240-type colloid mill.

[0020] After obtaining the plum pulp, the present invention mixes the plum pulp with an enzymatic hydrolysis preparation for enzymatic hydrolysis to obtain plum pulp. As an optional embodiment of the present invention, the enzymatic hydrolysis preparation includes tanninase, cellulase, and pectinase. In the present invention, the enzyme activity of the tanninase can be 180-220 u / g, or 180, 190, 200, 210, or 220 u / g; the enzyme activity of the cellulase can be 40-60 u / mg, or 40, 50, or 60 u / mg; the enzyme activity of the pectinase can be 40-60 u / mg, or 40, 50, or 60 u / mg. In the present invention, the mass ratio of tanninase, cellulase, and pectinase in the enzymatic hydrolysis preparation can be (0.8-1):(0.4-0.6):(1.5-2.0), or 1:0.5:1.5. As an optional embodiment of the present invention, the amount of the enzymatic hydrolysis preparation added to the plum pulp can be 8-10 g / kg, or 8, 9, or 10 g / kg, based on the weight of the pitted plum fruit (pulp). As an optional embodiment of the present invention, the enzymatic hydrolysis temperature can be 45-50℃, or 45, 46, 47, 48, 49, or 50℃; the enzymatic hydrolysis time can be 2-2.5 h, or 2, 2.1, 2.2, 2.3, 2.4, or 2.5 h. The present invention adds tanninase, cellulase, and pectinase to the plum pulp, which can effectively liquefy the plum pulp, improve the juice yield and utilization rate of the plum, decompose large-molecule tannins, and achieve a de-astringency effect. After enzymatic hydrolysis, the present invention preferably allows the enzymatic hydrolysis product to stand to obtain plum pulp. As an optional embodiment of the present invention, the standing time can be 24 h; the standing temperature can be room temperature; the room temperature can be 23-25℃. The static setting process described in this invention is a subsequent process of enzymatic hydrolysis. During the static setting process, the reaction system is allowed to cool down naturally.

[0021] After obtaining the pits of the European plum fruit, this invention extracts the kernels from the pits to prepare European plum kernel powder. This invention does not have a specific limitation on the method of extracting the kernels; any conventional method in the art can be used. After obtaining the European plum kernels, this invention dries and then pulverizes them. As an optional embodiment of this invention, the drying temperature can be 80℃; the drying time can be 40 minutes. This invention does not have a specific limitation on the pulverizing method; any conventional pulverizing method in the art can be used. As an optional embodiment of this invention, the pulverizing method can be grinding with a grinder. After obtaining the pulverized kernels, this invention preferably sieves the pulverized kernels; the sieve aperture can be 200 mesh. This invention preferably collects the undersize material to obtain European plum kernel powder.

[0022] After obtaining the European plum pulp, this invention mixes the European plum pulp with apple juice, inoculates it with *Lactobacillus plantarum* for fermentation, and obtains *Lactobacillus plantarum* fermentation product. This invention does not specifically limit the preparation method of the apple juice; any conventional apple juice preparation method in the art can be used. As an optional embodiment of this invention, the apple juice preparation method can be: washing, peeling, and corering apples, then mixing them with water and blending to obtain apple pulp; concentrating the apple pulp to obtain apple juice. This invention does not specifically limit the methods for washing, peeling, and corering apples; any conventional methods in the art can be used. After obtaining cored apples, this invention mixes the cored apples with water and blends them; the mass-to-volume ratio of the cored apples to water can be 1 kg:1.2 L. This invention does not specifically limit the blending method; any conventional blending method in the art can be used. After blending, this invention preferably filters the blended liquid to obtain apple pulp. As an optional embodiment of this invention, the filtration can be through a 200-mesh filter. After obtaining the apple pulp, this invention concentrates the apple pulp to obtain apple juice. As an optional embodiment of the present invention, the concentration method can be heating concentration; the heating temperature can be 60~85℃, or 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84 or 85℃. Preferably, the present invention heats and concentrates the apple juice to 1 / 6 of the mass of the apple pulp to obtain apple juice, which can also be called concentrated apple juice. As an optional embodiment of the present invention, when the European plum pulp and apple juice are mixed, the amount of apple juice added can be 35~45g / kg, or 40g / kg, based on the mass of the European plum pulp.

[0023] As an optional embodiment of the present invention, the *Lactobacillus plantarum* includes *Lactobacillus plantarum* LNJ-HQ-01 with preservation number CGMCC No. 31144; the *Lactobacillus plantarum* can be inoculated in the form of an activated *Lactobacillus plantarum* bacterial suspension; the viability of the activated *Lactobacillus plantarum* bacterial suspension can be (1.0~2.0) × 10⁻⁶. 9 cfu / mL, or 10 9cfu / mL. This invention does not specifically limit the preparation method of the *Lactobacillus plantarum* activated bacterial solution; any conventional preparation method in the art can be used. In this invention, based on the mass of the *Prunus cerevisiae* pulp, the inoculum amount of the *Lactobacillus plantarum* activated bacterial solution can be 3%~5%, or 3%, 4%, or 5%. After inoculation, this invention carries out a *Lactobacillus plantarum* fermentation process; the fermentation temperature can be 30~35℃, or 30, 31, 32, 33, 34, or 35℃; the fermentation time can be 40~60 h, or 48 h. After fermentation, this invention obtains a *Lactobacillus plantarum* fermentation product. This invention utilizes *Lactobacillus plantarum* to ferment *Prunus cerevisiae* pulp. The *Lactobacillus plantarum* is used for berry fermentation, producing acid, releasing total phenols, improving antioxidant properties, and producing a rich fermented flavor, which can improve the taste and functionality of fermented *Prunus cerevisiae* juice.

[0024] After obtaining the *Lactobacillus plantarum* fermentation product, this invention mixes the *Lactobacillus plantarum* fermentation product with *Prunus cerevisiae* kernel powder and water, and then inoculates *Lactobacillus brevis* for fermentation to obtain the *Lactobacillus brevis* fermentation product. As an optional embodiment of this invention, when mixing the *Lactobacillus plantarum* fermentation product with *Prunus cerevisiae* kernel powder and water, the amount of *Prunus cerevisiae* kernel powder added can be 50-80 g / kg, or 50, 60, 70, or 80 g / kg, based on the mass of the *Lactobacillus plantarum* fermentation product; the amount of water added can be 1.5-2.0 L / kg, or 1.5, 1.6, 1.7, 1.8, 1.9, or 2.0 L / kg. As an optional embodiment of this invention, the *Lactobacillus brevis* includes *Lactobacillus brevis* BNCC337373. In this invention, the *Lactobacillus brevis* is preferably inoculated in the form of an activated *Lactobacillus brevis* bacterial solution; the bacterial activity of the activated *Lactobacillus brevis* bacterial solution can be (1.0-2.0) × 10⁻⁶. 9 cfu / mL, or 10 9 cfu / mL. This invention does not specifically limit the preparation method of the activated Lactobacillus brevis solution; any conventional preparation method in the art can be used. In this invention, the inoculum amount of the activated Lactobacillus brevis solution can be 3%~5%, or 3%, 4%, or 5%, based on the mass of the Lactobacillus plantarum fermentation product. In this invention, when using Lactobacillus brevis for fermentation, the fermentation temperature can be 34~36℃, or 35℃; the fermentation time can be 40~60h, or 48h. After fermentation, this invention obtains the Lactobacillus brevis fermentation product. This invention utilizes Lactobacillus brevis fermentation to increase the content of effective calcium such as pectin calcium, water-soluble calcium, and alcohol-soluble calcium, making it easier for the human body to absorb and improving the nutritional value of the fruit juice.

[0025] After obtaining the *Lactobacillus brevis* fermentation product, this invention further prepares and filters the fermentation product to obtain *Prunus cerevisiae* fermented juice. As an optional embodiment of this invention, the preparation includes mixing the *Lactobacillus brevis* fermentation product with black tea extract and apple juice. In this invention, based on the mass of the *Lactobacillus brevis* fermentation product, the amount of black tea extract added can be 13-18 g / kg or 15 g / kg; the amount of apple juice added can be 18-22 g / kg or 20 g / kg. This invention does not specifically limit the preparation methods of the black tea extract and apple juice; conventional preparation methods in the art can be used. As an optional embodiment of this invention, the apple juice can be prepared using the method described in the above technical solution. As an optional embodiment of this invention, the black tea extract can be prepared by grinding black tea into powder, mixing it with an ethanol aqueous solution, and extracting it using a Soxhlet extractor to obtain the black tea extract. This invention does not specifically limit the method of grinding the black tea; conventional black tea grinding methods in the art can be used. As an optional embodiment of this invention, the black tea can be ground using a grinding mill. After grinding black tea into powder, black tea pulverizer is obtained. After obtaining the black tea pulverizer, this invention mixes it with an ethanol-water solution. As an optional embodiment of this invention, the volume fraction of ethanol in the ethanol-water solution can be 60%~65%, or 60%, 61%, 62%, 63%, 64%, or 65%. The material-to-liquid ratio when mixing the black tea pulverizer and the ethanol-water solution can be 1g:20mL. When using a Soxhlet extractor for extraction, the number of siphoning cycles can be 5~6. Preferably, this invention mixes the *Lactobacillus brevis* fermentation product with black tea extract and apple juice, followed by coarse filtration; the coarse filtration is preferably performed using a 100-mesh sieve. Adding black tea extract and apple juice for flavoring during formulation can improve the taste and enrich the flavor of the fermented plum juice.

[0026] After coarse filtration, the present invention preferably subjectes the resulting filtrate to ultrafiltration. As an optional embodiment of the present invention, the ultrafiltration is preferably performed using a 100kDa polyvinyl alcohol ultrafiltration membrane. The present invention utilizes ultrafiltration membrane filtration, which does not affect the flavor, taste, and nutritional components of the fermented plum juice, preserves the color of the plum, reduces the turbidity of the juice, and improves storage stability. After ultrafiltration, the present invention yields fermented plum juice, which may also be referred to as a fermented plum beverage.

[0027] After obtaining the fermented plum juice, the present invention preferably further includes bottling and sterilizing the fermented plum juice. The present invention does not specifically limit the sterilization method; any conventional sterilization method in the art can be used. As an optional embodiment of the present invention, the sterilization method can be steam sterilization; the sterilization time can be 10-15 minutes, or 10, 11, 12, 13, 14, or 15 minutes.

[0028] This invention provides a fermented plum juice prepared by the method described in the above technical solution. The fermented plum juice provided by this invention has a good taste and unique flavor, is rich in total phenols and anthocyanins, has improved antioxidant capacity, increased effective calcium content, and is more easily absorbed by the human body. It does not contain any added white sugar or sucrose, making it a green and healthy product suitable for calcium supplementation for people with high blood sugar.

[0029] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0030] Example 1 A method for preparing fermented European plum juice, comprising the following steps: (1) Pretreatment of European plum: Select mature European plum fruits with red color, no mechanical damage and no pests, remove bad fruits and fruit stems, remove pits and wash them to obtain clean European plum fruits; mix the obtained European plum fruits with 1.5 times the amount of pure water and pulp them. Use a 240 type colloid mill, speed 2890 r / min, and pulp for 30~40 minutes to obtain European plum pulp.

[0031] Based on the weight of pitted European plum fruit, 9 g / kg of a mixed enzyme was added to the plum pulp. After stirring evenly, enzymatic hydrolysis was carried out. The mixed enzyme consisted of tanninase (200 u / g), cellulase (50 u / mg), and pectinase (50 u / mg) in a mass ratio of 1:0.5:1.5. The enzymatic hydrolysis temperature was 50℃, and the hydrolysis time was 2 hours. After the enzymatic hydrolysis was completed, the mixture was allowed to stand at room temperature for 24 hours to obtain European plum pulp.

[0032] After removing the pits from the European plum fruit using a pitting machine, the European plum kernels are obtained. The European plum kernels are then baked at 80℃ for 40 minutes, ground into powder using a grinder, and passed through a 200-mesh sieve to obtain European plum kernel powder.

[0033] (2) Fermentation of Lactobacillus plantarum: Concentrated apple juice (as a carbon source) and activated Lactobacillus plantarum LNJ-HQ-01 bacterial culture were added to the European plum pulp in a certain proportion. The amount of concentrated apple juice added was 40 g / kg based on the weight of the European plum pulp, and the inoculum amount of activated Lactobacillus plantarum LNJ-HQ-01 bacterial culture was 3%. The mixture was thoroughly mixed and fermented at 30℃ for 48 h.

[0034] Among them, the preservation number of Lactobacillus plantarum LNJ-HQ-01 is CGMCC No.31144, and the public information can be found in patent CN119020209 A.

[0035] The activation method for Lactobacillus plantarum LNJ-HQ-01 is as follows: Lactobacillus plantarum LNJ-HQ-01 is activated twice with MRS liquid medium, each activation temperature is 35℃, and the activation time is 24h each time. After activation, the activated culture medium is obtained. The activated culture medium is centrifuged at 4000r / min for 5min, the supernatant is discarded, and sterile distilled water is added to dilute until the bacterial activity reaches 10. 9 The activated Lactobacillus plantarum LNJ-HQ-01 bacterial solution was obtained at cfu / mL.

[0036] The method for preparing concentrated apple juice is as follows: Red apples are washed, peeled, and cored to obtain cored apples. The cored apples are then mixed with sterile water and pulped using a 240-type colloid mill at 2890 rpm for 30-40 minutes, adding 1.2 L of sterile water per kilogram of apples. After pulping, the apple pulp is obtained. This pulp is then filtered through a 200-mesh screen and concentrated at 85°C to one-sixth of its original mass, yielding concentrated apple juice, also known as apple juice.

[0037] (3) Lactobacillus brevis fermentation: Sterile water, Prunus cerevisiae kernel powder, and activated Lactobacillus brevis culture were added to the Lactobacillus plantarum fermentation product. The amount of sterile water added was 1.5 L / kg, the amount of Prunus cerevisiae kernel powder added was 60 g / kg, and the amount of activated Lactobacillus brevis culture added was 3% based on the mass of the Lactobacillus plantarum fermentation product. Then, fermentation was carried out at 35℃ for 48 h to obtain the Lactobacillus brevis fermentation product.

[0038] Lactobacillus brevis was purchased from Beina Biotechnology, with the strain number BNCC337373.

[0039] The activation method for *Lactobacillus brevis* is as follows: *Lactobacillus brevis* is activated twice with MRS liquid medium, each activation temperature at 35℃, and each activation time at 24 hours. After activation, an activated culture solution is obtained. The activated culture solution is centrifuged at 4000 rpm for 5 minutes, the supernatant is discarded, and sterile distilled water is added to dilute to a bacterial activity level of 10⁻⁶. 9 The activated Lactobacillus brevis culture was obtained at a concentration of cfu / mL.

[0040] (4) Coarse filtration: Add black tea extract and concentrated apple juice in proportion. The amount of black tea extract added is 15 g / kg and the amount of concentrated apple juice added is 20 g / kg based on the mass of Lactobacillus brevis fermentation product, to obtain a mixed system. Pass the mixed system through a 100-mesh filter.

[0041] The method for preparing concentrated apple juice is the same as step (2).

[0042] The preparation method of black tea extract is as follows: black tea is ground into powder using a black tea grinder, and then passed through a 100-mesh sieve. 65% ethanol aqueous solution is added, with a material-to-liquid ratio of black tea to ethanol aqueous solution of 1g:20mL. Extraction is carried out using a Soxhlet extractor, and the black tea extract is obtained after siphoning 5 times and then refrigerated for later use.

[0043] (5) Ultrafiltration membrane filtration: The mixed system was filtered using a polyvinyl alcohol ultrafiltration membrane with a molecular weight cutoff of 100 kDa, and the membrane flux was maintained at 40~45 L / (m 2 After filtration (·h), the resulting product is European plum fermented juice, i.e., European plum fermented beverage.

[0044] (6) Sterilization: After filling the packaging material of the European plum fermented beverage, steam is passed through for 15 minutes for sterilization.

[0045] Comparative Example 1 A method for preparing a fermented beverage of Prunus cerasifera, the steps are the same as in Example 1, the only difference being that in step (3) no activated Lactobacillus brevis liquid is added, and sterile water and Prunus cerasifera kernel powder are added to the Lactobacillus plantarum fermentation product. The amount of sterile water added is 1.5 L / kg and the amount of Prunus cerasifera kernel powder added is 60 g / kg based on the mass of the Lactobacillus plantarum fermentation product. Then it is placed at 35℃ for 48 h.

[0046] Comparative Example 2 A method for preparing a fermented beverage of European plum, the steps are the same as in Example 1, the only difference being: in step (2), activated Lactobacillus plantarum LNJ-HQ-01 bacterial solution is not added, and concentrated apple juice is added to the European plum pulp in proportion. The amount of concentrated apple juice added is 40g / kg based on the weight of the European plum pulp. Mix evenly and let stand at 30℃ for 48h.

[0047] Comparative Example 3 A method for preparing a fermented beverage of European plum, the steps are the same as in Example 1, the only difference is that: no mixed enzyme is added in step (1), the European plum pulp is directly left to stand at room temperature for 24 hours, and the subsequent process is carried out after obtaining the European plum pulp.

[0048] Comparative Example 4 A method for preparing a fermented plum beverage, the steps are the same as in Example 1, the only difference being that concentrated apple juice is not added in steps (2) and (4).

[0049] Comparative Example 5 A method for preparing a fermented beverage of European plum, the steps are the same as in Example 1, the only difference being that European plum kernel powder is not added in step (3).

[0050] Comparative Example 6 A method for preparing a fermented plum beverage, the steps are the same as in Example 1, the only difference being that: in step (5), a 200-mesh filter is used instead of ultrafiltration membrane filtration.

[0051] Application Example 1 The total phenolic content, total anthocyanin content, antioxidant capacity (DPPH scavenging capacity), tannin content, turbidity, alcohol-soluble calcium content, water-soluble calcium content, pectin calcium content, and sensory evaluation scores of the fermented plum juice of Example 1 and Comparative Examples 1-6 were tested respectively.

[0052] Total phenols were determined using a Total Phenols (TP) kit. Total anthocyanins were determined using the pH differential method; Antioxidant capacity was determined using a DPPH scavenging ability kit. Tannin content was determined using the Folin-Ciocalteu method; Turbidity was measured using a benchtop turbidimeter. Determination of calcium content in different forms: The fermented juice of Prunus cerasifera was mixed with 80% ethanol, ultrapure water and 1 mol / L sodium chloride and extracted with ultrasonic assistance for 2 h to obtain alcohol-soluble calcium, water-soluble calcium and pectin calcium solutions, which were measured by atomic absorption spectrophotometry. The specific scoring rules for sensory evaluation are shown in Table 1.

[0053] Sensory evaluation method: Twenty food professionals were selected to score the fermented plum juice prepared in Example 1 and Comparative Examples 1-6 according to the sensory scoring criteria in Table 1. The specific results are shown in Table 2.

[0054] Table 3 shows the test results of various indicators of the fermented plum juice prepared in Examples 1 and Comparative Examples 1-6.

[0055] Table 1 Sensory evaluation criteria for fermented plum juice

[0056] Table 2 Sensory scores of fermented plum juices from Examples 1 and 6 (Comparative Examples 1-6)

[0057] Table 3. Results of various indicators of the fermented Prunus cerasifera juice prepared in Examples 1 and Comparative Examples 1-6

[0058] Table 3 shows that the total phenols, total anthocyanins, and DPPH scavenging capacity of Comparative Example 2 were significantly reduced, indicating that the first fermentation with *Lactobacillus plantarum* increased the release of total phenols and total anthocyanins, thus enhancing the antioxidant capacity of the fermented plum juice. Tannins are the main source of astringency in the juice; the significantly increased tannin content in Comparative Example 3 indicates that mixed enzymatic hydrolysis can reduce the astringency of the fermented plum juice and improve its taste. The significantly increased turbidity and significantly decreased sensory evaluation score of Comparative Example 6 indicates that ultrafiltration membrane filtration can make the fermented plum juice clearer and brighter, improving the sensory evaluation score by improving the juice's texture and color. The significantly reduced content of effective calcium, including pectin calcium, water-soluble calcium, and alcohol-soluble calcium, in Comparative Example 2 indicates that the second fermentation with *Lactobacillus brevis* can increase the effective calcium content, making it easier for the body to absorb. The significantly decreased sensory evaluation scores of Comparative Examples 4 and 6, combined with the sensory evaluation scores, suggest that concentrated apple juice can improve the taste and flavor of the fermented plum juice.

[0059] The fermented plum juice prepared by this invention is a bright, watery red color, with a balanced sweet and sour taste, a distinctive plum aroma, and a smooth, sediment-free texture. The fermented plum juice prepared by the method described in this invention has significant advantages in nutritional value, functional properties, and sensory evaluation, making it suitable for calcium supplementation in people with high blood sugar.

[0060] Comparative Example 7 A method for preparing a fermented plum beverage, comprising the following steps: Prunus cerasifera pulp and Prunus cerasifera kernel powder were prepared using the method in step (1) of Example 1.

[0061] Prunus cerasifera pulp and Prunus cerasifera nut powder were mixed at a mass ratio of 10:0.6. Apple concentrate was then added as a carbon source, with an addition amount of 30 g / kg of apple concentrate per mixture. Lactobacillus fermentation was then added to the mixture. Lactobacillus fermentum The activated bacterial solution (number BNCC194390) was added at a rate of 3%. The mixture was thoroughly mixed and fermented at 35°C for 48 hours.

[0062] The preparation method of the activated Lactobacillus fermentation solution is the same as the activation method of Lactobacillus plantarum LNJ-HQ-01 in Example 1. After fermentation, the solution is filtered through a 200-mesh screen, and then the effective calcium content, including alcohol-soluble calcium, water-soluble calcium, and pectin calcium, as well as the total anthocyanin content, in the fermentation product are measured.

[0063] Comparative Example 8 A method for preparing a fermented plum beverage, comprising the following steps: Prunus cerasifera pulp and Prunus cerasifera kernel powder were prepared using the method in step (1) of Example 1.

[0064] Prunus cerasifera pulp and Prunus cerasifera nut powder were mixed at a mass ratio of 10:0.6. Apple concentrate was added as a carbon source, with an addition amount of 30 g / kg of apple concentrate per unit mass of the mixture. Lactobacillus acidophilus was then added to the mixture. Lactobacillus acidophilus (Item No. BNCC186447) Activated bacterial solution, with an addition amount of 3% of Lactobacillus acidophilus activated bacterial solution. Mix well and ferment at 35℃ for 48 hours.

[0065] The preparation method of the activated Lactobacillus acidophilus bacterial solution is the same as the activation method of Lactobacillus plantarum LNJ-HQ-01 in Example 1. After fermentation, the fermentation product is filtered through a 200-mesh screen, and then the effective calcium content, such as alcohol-soluble calcium, water-soluble calcium, and pectin calcium, as well as the total anthocyanin content, are measured in the fermentation product.

[0066] Application Example 2 The results of the detection of effective calcium such as alcohol-soluble calcium, water-soluble calcium, and pectin calcium, as well as the total anthocyanin content in the fermentation products of Comparative Examples 7 and 8 are shown in Table 4.

[0067] Table 4. Effects of different fermentation strains on various indicators of Prunus armeniaca.

[0068] As shown in Table 4, the effects of fermentation by Lactobacillus fermentum and Lactobacillus acidophilus on improving various indicators are far lower than those of Lactobacillus brevis and Lactobacillus plantarum.

[0069] Comparative Example 9 A method for preparing a fermented plum beverage, comprising the following steps: The preparation method of the European plum fermented beverage is the same as that in Example 1, except that the method of step (1) in Example 1 is used to prepare European plum pulp and European plum kernel powder respectively.

[0070] Prunus cerasifera pulp, prunus cerasifera kernel powder, and sterile water were mixed. The pulp and kernel powder were mixed at a mass ratio of 10:0.6, and 1.5 L / kg of sterile water was added based on the mass of the pulp, resulting in the prunus cerasifera-kernel mixture. A mixed microbial agent was added to the mixture at a ratio of 3% of the total volume. After thorough mixing, fermentation was carried out at 30°C for 48 hours. Following fermentation, subsequent processes included formulation preparation, coarse filtration, and ultrafiltration.

[0071] The preparation methods for the activated Lactobacillus plantarum LNJ-HQ-01 bacterial suspension and the activated Lactobacillus brevis bacterial suspension are the same as in Example 1. The activated Lactobacillus plantarum LNJ-HQ-01 bacterial suspension and the activated Lactobacillus brevis bacterial suspension are mixed at a volume ratio of 1:1 to obtain a mixed bacterial agent.

[0072] Comparative Example 10 A method for preparing a fermented plum beverage, comprising the following steps: The preparation method of the European plum fermented beverage is the same as that in Example 1, except that the method of step (1) in Example 1 is used to prepare European plum pulp and European plum kernel powder respectively.

[0073] Activated Lactobacillus brevis culture was added to the plum pulp in a specific ratio. The inoculum size of the activated Lactobacillus brevis culture was 3% based on the weight of the plum pulp. Fermentation was carried out at 35°C for 48 hours to obtain the Lactobacillus brevis fermentation product.

[0074] Sterile water, Prunus cerevisiae kernel powder, and activated Lactobacillus plantarum LNJ-HQ-01 bacterial culture were added to the Lactobacillus brevis fermentation product. The amount of sterile water added was 1.5 L / kg, the amount of Prunus cerevisiae kernel powder added was 60 g / kg, and the amount of activated Lactobacillus plantarum LNJ-HQ-01 bacterial culture added was 3% based on the mass of the Lactobacillus brevis fermentation product. Fermentation was then carried out at 30℃ for 48 hours to obtain the Lactobacillus plantarum fermentation product. After fermentation, subsequent operations such as formulation preparation, coarse filtration, and ultrafiltration were performed.

[0075] Application Example 3 The results of the detection of effective calcium such as alcohol-soluble calcium, water-soluble calcium, pectin calcium, and total anthocyanin content in the fermented plum beverages of Comparative Examples 9-10 are shown in Table 5.

[0076] Table 5. Effects of Comparative Examples 9 and 10 on various indicators of *Prunus armeniaca*.

[0077] As shown in Table 5, compared with Example 1, the contents of all indicators in the experimental groups of Comparative Examples 9-10 were lower, indicating that the preparation of Prunus cerevisiae fermented beverage by first fermenting with Lactobacillus plantarum and then with Lactobacillus brevis can better give full play to the advantages of the strains and achieve complete fermentation.

[0078] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing fermented European plum juice, characterized in that, Includes the following steps: The pits and pulp of the European plum were separated, the pulp was mixed with water and enzymatically hydrolyzed to prepare European plum pulp; the kernels from the pits were used to prepare European plum kernel powder. After mixing the plum pulp with apple juice, Lactobacillus plantarum was inoculated and fermented to obtain the Lactobacillus plantarum fermentation product. The fermentation product of Lactobacillus plantarum was mixed with Prunus cerevisiae kernel powder and water, and then inoculated with Lactobacillus brevis for fermentation to obtain the fermentation product of Lactobacillus brevis. After blending and filtering, the fermented product of Lactobacillus brevis was used to obtain the fermented juice of Prunus armeniaca.

2. The preparation method according to claim 1, characterized in that, The *Lactobacillus plantarum* includes *Lactobacillus plantarum* LNJ-HQ-01 with preservation number CGMCCNo.31144; the *Lactobacillus brevis* includes *Lactobacillus brevis* BNCC337373.

3. The preparation method according to claim 1 or 2, characterized in that, The *Lactobacillus plantarum* was inoculated in the form of an activated *Lactobacillus plantarum* bacterial solution; the viability of the activated *Lactobacillus plantarum* bacterial solution was (1.0~2.0) × 10⁻⁶. 9 cfu / mL; the inoculum amount of the activated Lactobacillus plantarum solution is 3%~5% based on the mass of Prunus cerevisiae pulp; The *Lactobacillus brevis* was inoculated in the form of an activated *Lactobacillus brevis* bacterial solution; the viability of the activated *Lactobacillus brevis* bacterial solution was (1.0~2.0) × 10⁻⁶. 9 cfu / mL; the inoculum size of the activated Lactobacillus brevis culture is 3%~5% based on the mass of Lactobacillus plantarum fermentation product.

4. The preparation method according to claim 1, characterized in that, The fermentation temperature for Lactobacillus plantarum was 30-35℃, and the fermentation time was 40-60 hours. The fermentation temperature for Lactobacillus brevis was 34-36℃, and the fermentation time was 40-60 hours.

5. The preparation method according to claim 1, characterized in that, The enzymatic hydrolysis preparation includes: tanninase, cellulase, and pectinase; the enzyme activity of the tanninase is 180~220 u / g; the enzyme activity of the cellulase is 40~60 u / mg; the enzyme activity of the pectinase is 40~60 u / mg; the mass ratio of tanninase, cellulase, and pectinase in the enzymatic hydrolysis preparation is (0.8~1):(0.4~0.6):(1.5~2.0); the amount of the enzymatic hydrolysis preparation added is 8~10 g / kg based on the weight of the fruit pulp.

6. The preparation method according to claim 1 or 5, characterized in that, The enzymatic hydrolysis temperature is 45~50℃; the enzymatic hydrolysis time is 2~2.5h.

7. The preparation method according to claim 1, characterized in that, When the pulp is mixed with water, the mass ratio of pulp to water is 1:(1~1.5); when the European plum pulp is mixed with apple juice, the amount of concentrated apple juice added is 35~45g / kg based on the mass of the European plum pulp.

8. The preparation method according to claim 1, characterized in that, When Lactobacillus plantarum fermentation product is mixed with Prunus cerasifera kernel powder and water, the amount of Prunus cerasifera kernel powder added is 50~80g / kg based on the mass of Lactobacillus plantarum fermentation product, and the amount of water added is 1.5~2.0L / kg.

9. The preparation method according to claim 1, characterized in that, The formulation includes mixing Lactobacillus brevis fermentation product with black tea extract and apple juice; based on the mass of Lactobacillus brevis fermentation product, the amount of black tea extract added is 13~18g / kg, and the amount of concentrated apple juice added is 18~22g / kg. The filtration includes ultrafiltration membrane filtration.

10. The fermented plum juice prepared by the preparation method according to any one of claims 1 to 9.

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