Method for preparing ginger black tea through combination of ginger pretreatment and black tea probiotic fermentation, ginger black tea product and application of ginger black tea product

Abstract

The invention relates to the technical field of functional beverage processing, in particular to a method for preparing ginger black tea by combining fresh ginger pretreatment with black tea probiotic fermentation, a ginger black tea product and application of the ginger black tea product. The method comprises the following steps: a) fresh ginger enzymolysis pretreatment: fresh ginger is subjected to enzymolysis treatment to reduce the gingerol content; b) microencapsulation of gingerol: preparing the ginger liquid subjected to enzymolysis, sodium alginate and chitosan into microcapsules; c) black tea extraction: performing water extraction on black tea to prepare black tea liquid; d) probiotic activation: carrying out activation culture on lactobacillus acidophilus and lactobacillus plantarum; e) performing multi-stage fermentation: mixing the black tea liquid, gingerol microcapsules and activated probiotics, and performing fermentation through multi-stage temperature and pH control; (f) post-processing the product, namely post-processing the fermentation liquor to obtain the probiotic-containing ginger black tea product, so that the effective components of the ginger are reserved while the content of spicy components of the ginger is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of functional beverage processing, and in particular to a method for preparing ginger black tea by combining ginger pretreatment with probiotic fermentation of black tea, a ginger black tea product and its application, and a method for preparing ginger black tea with reduced pungency and enhanced functionality by dual pretreatment of ginger enzymatic hydrolysis and microencapsulation combined with a probiotic fermentation process. Background Art

[0002] Ginger black tea is a traditional beverage that combines ginger and black tea, boasting numerous health benefits. Gingerol (6-gingerol), the primary active ingredient in ginger, possesses antioxidant, anti-inflammatory, and circulation-boosting properties, while black tea's polyphenols and theaflavins possess antioxidant and free radical scavenging properties. Combining these two creates a synergistic effect, enhancing both product functionality and the sensory experience.

[0003] Currently, there are numerous technical reports on methods for preparing ginger black tea. Chinese patent CN104982586A, "Black Tea Fermentation Method and Application" (published on October 21, 2015), discloses a method for fermenting finished black tea by mixing it with ginger juice. The method employs the following steps: "100g of commercially available black tea is used as a raw material; fresh ginger is washed, juiced, and filtered; 100g of ginger juice is mixed evenly with the raw material, and then placed in a sealed container for fermentation. The fermented product is dried to a moisture content of approximately 7% to obtain the product." While this method is simple and easy to implement, the direct addition of ginger's pungent properties to the product not only affects its taste, but also potentially inhibits microbial fermentation through the presence of gingerol. Furthermore, the method fails to consider the use of probiotics, limiting the product's functionality.

[0004] Chinese patent CN103275844A, "Fully Fermented Ginger Wine and Its Preparation Method" (published on September 4, 2013), discloses a method for preparing ginger wine. The method involves physically pre-treating ginger, including washing, crushing, and juicing, before mixing it with fructose-glucose syrup and fermenting it under specific conditions using wine yeast. While this method physically pre-treats the ginger, it primarily targets alcoholic beverages and does not specifically target gingerols. It also does not involve the use of probiotics.

[0005] South China University of Technology's "Study on Processing and Quality Changes of Probiotic-Fermented Fruit Beverages" (Master's thesis, 2020) investigated the fermentation process and process optimization of grape and citrus fruit juices using probiotics, including the effects of exogenous carbon sources on microbial growth, metabolism, and bioactivity. The study demonstrated that probiotic fermentation can significantly enhance the nutritional and functional properties of fruit beverages, but did not address the complex fermentation system combining black tea and ginger.

[0006] Chinese patent CN104186745A, "Black Tea Fermentation Method" (publication date: January 7, 2015), primarily studies the control of temperature and humidity during the black tea fermentation process. Using "temperatures close to or slightly higher than the tea-picking season" for fermentation can significantly shorten fermentation time and improve product quality. However, the patent does not cover the combined fermentation of ginger and black tea.

[0007] Furthermore, existing research indicates that gingerol in ginger has some antimicrobial activity, potentially inhibiting the growth of probiotics. Furthermore, tea polyphenols in black tea also possess some antimicrobial activity. Therefore, adding probiotics to ginger and black tea systems presents challenges in ensuring their activity and survival.

[0008] By analyzing the above existing technologies, we can see that there are the following technical problems and deficiencies: 1. The spicy ingredients of ginger are added directly to the product without special treatment, which may affect the taste of the product and the activity of probiotics; 2. There is a lack of research on complex fermentation systems for the synergistic effects of ginger's pungent ingredients and probiotics; 3. The inhibitory effect of ginger on probiotic activity and protective measures were not considered; 4. The lack of systematic multi-stage fermentation process control makes it difficult to achieve stability and consistency in product quality.

[0009] Therefore, there is an urgent need to develop an innovative preparation method that can reduce the adverse effects of the spicy components of ginger, ensure the activity of probiotics, and achieve synergistic enhancement of black tea-ginger-probiotics. Summary of the Invention

[0010] The present invention addresses the problems existing in the prior art and provides a method for preparing ginger black tea by combining ginger pretreatment with probiotic fermentation of black tea, a ginger black tea product, and its application, thereby preparing a ginger black tea product with reduced spiciness, high probiotic activity, and enhanced functionality. Specific objectives include: 1. Reduce the gingerol content in ginger through enzymatic pretreatment, thereby reducing its inhibitory effect on probiotic activity; 2. Use microencapsulation technology to embed the remaining gingerol and achieve its sustained release in the product, reducing the spicy taste while retaining its health benefits; 3. Screening probiotics suitable for growth in the tea-ginger composite matrix to enhance the product’s intestinal regulation function; 4. Establish a multi-stage fermentation process, optimize fermentation parameters, and improve the survival rate of probiotics and product stability; 5. Develop probiotic activity protection technology to extend product shelf life.

[0011] To achieve the above object, the present invention provides the following technical solutions: A method for preparing ginger black tea by combining ginger pretreatment with black tea probiotic fermentation comprises the following steps: a) Ginger enzymatic pretreatment: Fresh ginger is enzymatically treated to reduce the gingerol content; b) Gingerol microencapsulation: enzymatically hydrolyzed ginger liquid is mixed with sodium alginate and chitosan to prepare microcapsules; c) Black tea extraction: extracting black tea with water to prepare black tea liquid; d) Probiotic activation: Activate and culture Lactobacillus acidophilus and Lactobacillus plantarum; e) Multi-stage fermentation: black tea liquid, gingerol microcapsules and activated probiotics are mixed and fermented through multi-stage temperature and pH control; f) Product post-processing: The fermentation broth is post-processed to obtain a ginger black tea product containing probiotics.

[0012] Preferably, the specific steps of the enzymatic pretreatment in step a) are: a1) Wash and slice fresh ginger, blanch in hot water at 85±2°C for 30-60 seconds, and quickly cool to room temperature; a2) adding the treated ginger slices to a phosphate buffer solution at a pH of 5.8-6.2 at a liquid-to-solid ratio of 5:1 (v / w); a3) adding a cellulase complex and a protease, and performing enzymatic hydrolysis at 38-42°C for 60-90 minutes; a4) heating at 80°C for 5 minutes to inactivate enzyme activity, cooling to room temperature, and filtering to obtain a ginger enzymatic hydrolyzate; a5) Gingerol content decreased by 40-60%.

[0013] Preferably, the specific steps of microencapsulation in step b) are: b1) preparing a 1.5-2.5% sodium alginate solution (w / v) and a 0.5-1.0% chitosan acetate solution (w / v); b2) mixing the ginger enzymatic hydrolyzate solution and the sodium alginate solution in a volume ratio of 1:1 to 1:3; b3) using coaxial airflow or electrostatic spray technology, dripping the mixed solution into a cross-linking solution containing 0.3-0.7% calcium chloride and 0.3-0.7% chitosan; b4) aging in the cross-linking solution for 10-20 minutes, filtering, and washing; b5) obtaining gingerol microcapsules with a particle size of 50-150 μm and a gingerol encapsulation efficiency of not less than 80%.

[0014] Preferably, the specific steps of extracting black tea in step c) are: c1) adding black tea to 75-85°C purified water at a liquid-to-solid ratio of 15:1-25:1 (v / w); c2) extracting for 15-25 minutes; c3) filtering the black tea liquid and cooling it to below 45°C; c4) Adjust the pH to 6.0-6.5; c5) Add 1-10% maltodextrin (w / v) and 1-5% fructooligosaccharide (w / v).

[0015] Preferably, the specific steps of activating the probiotics in step d) are: d1) activating Lactobacillus acidophilus in MRS medium at 37±1°C for 12-16 hours; d2) activating Lactobacillus plantarum in MRS medium at 30±1°C for 12-16 hours; d3) Collect the activated cells by centrifugation and wash with sterile saline; d4) Adjust the bacterial solution concentration to 10 8 -10 10 CFU / mL.

[0016] In a preferred embodiment, the Lactobacillus acidophilus is selected from one or more of Lactobacillus acidophilus NCFM strain, Lactobacillus acidophilus LA-5 strain or Lactobacillus acidophilus DDS-1 strain; the Lactobacillus plantarum is selected from one or more of Lactobacillus plantarum LP28 strain, Lactobacillus plantarum LP01 strain or Lactobacillus plantarum 299v strain.

[0017] Preferably, the multi-stage fermentation in step e) comprises the following stages: e1) First stage fermentation: Ferment at 26-30°C, pH 5.8-6.5 for 10-20 hours until the bacterial count reaches 10 8 CFU / mL or above; e2) Second stage fermentation: fermentation at 32-36°C, pH 4.8-5.5 for 6-12 hours; e3) Third stage fermentation: fermentation at 29-33°C, pH 4.2-5.0 for 4-8 hours; e4) The fermentation is completed when the total acidity reaches 0.5-0.7%, the pH value is stable at 4.2-4.5, and the number of viable bacteria is not less than 10 9 CFU / mL.

[0018] Preferably, the specific steps of the product post-processing in step f) are: f1) centrifuging the fermentation broth at low speed to remove large suspended solids; f2) adding 1-5% maltodextrin (w / v) and 0.3-1.5% mannitol (w / v) as protective agents; f3) Freeze drying: pre-freezing at -40±5°C for 6-10 hours; main drying at -20°C to 0°C for 24-48 hours; post-drying at 15-25°C for 4-8 hours; f4) The number of viable bacteria in the dried product is not less than 10 10 CFU / g, water content not higher than 5%; f5) Store in vacuum sealed containers.

[0019] The present invention also provides a ginger black tea product prepared according to the above method, characterized in that the product is in dry powder or granular form, and the number of viable bacteria is not less than 10 10 CFU / g, containing Lactobacillus acidophilus, Lactobacillus plantarum, tea polyphenols, theaflavins, thearubigins and gingerol microcapsules to reduce spiciness.

[0020] The present invention also provides the use of the product in preparing health-care food with intestinal regulation, anti-oxidation and immunity-enhancing functions.

[0021] The core technical principle of the present invention is to resolve the contradiction between the spicy components of ginger and the activity of probiotics through the dual pretreatment of enzymatic hydrolysis and microencapsulation combined with a multi-stage fermentation process, thereby achieving the coordinated unity of product taste and functionality.

[0022] 1. Principle of Enzymatic Pretreatment: Gingerol in ginger is a β-hydroxyketone compound, primarily composed of 6-gingerol, 8-gingerol, and 10-gingerol. Cellulase can break down the ginger tissue structure and release cellular contents; protease can break down the protein complexes bound to gingerol, making it more susceptible to oxidation or hydrolysis. Under suitable temperature and pH conditions, the synergistic action of these enzymes can promote the partial degradation of gingerol, reducing its pungency while preserving its other beneficial components.

[0023] 2. Microencapsulation principle: Sodium alginate is a natural polysaccharide that can react with divalent metal ions (such as Ca 2+ ) reacts to form a gel; chitosan is a positively charged polysaccharide that can form a composite film with negatively charged sodium alginate through electrostatic interaction. Taking advantage of this property, the enzymatically hydrolyzed ginger liquid is mixed with sodium alginate, and the mixture is dropped into a cross-linking solution containing calcium chloride and chitosan through coaxial airflow or electrostatic spray technology. 2+It rapidly gels and forms a composite film with chitosan at the interface, achieving efficient embedding of gingerol. This composite film is pH-sensitive and is stable in gastric fluid (pH ≈ 2.0) and gradually dissolves in intestinal fluid (pH ≈ 7.4), achieving targeted release of gingerol.

[0024] 3. Principle of Probiotic Synergistic Fermentation: Lactobacillus acidophilus and Lactobacillus plantarum are two important probiotics. The former is primarily found in the small intestine, while the latter has strong environmental adaptability. By producing active substances such as organic acids and bacteriocins, both bacteria can inhibit the growth of harmful bacteria and regulate the balance of intestinal flora. In the black tea-ginger composite matrix, the two bacteria complement each other: Lactobacillus acidophilus produces specific degradative enzymes to further break down the complex of tea polyphenols and gingerol, while Lactobacillus plantarum promotes the conversion of tea polyphenols into theaflavins and thearubigins, enhancing the product's antioxidant activity.

[0025] 4. Multi-stage fermentation principle: Different probiotics and biochemical reactions have their own optimal parameters under different temperature and pH conditions. By precisely controlling parameters such as temperature and pH during the fermentation process, the probiotic growth, tea polyphenol conversion, and flavor formation processes can be optimized in stages: the first stage (26-30°C, pH 5.8-6.5) primarily promotes rapid probiotic growth; the second stage (32-36°C, pH 4.8-5.5) primarily promotes the enzymatic conversion of tea polyphenols; and the third stage (29-33°C, pH 4.2-5.0) primarily promotes the formation of flavor substances and the stability of product flavor.

[0026] 5. Principle of Probiotic Activity Preservation: Probiotics are easily inactivated during processing and storage. Adding preservatives (such as maltodextrin and mannitol) creates a protective matrix that reduces ice crystal damage to cell membranes during freeze-drying, while providing a stable microenvironment to maintain probiotic activity. By controlling the temperature gradient and drying rate during the freeze-drying process, probiotic activity can be maximized, extending the product's shelf life.

[0027] Compared with the prior art, the present invention has the following beneficial effects: 1. Reduced pungency and improved taste: This invention utilizes a dual pretreatment process combining enzymatic hydrolysis and microencapsulation to reduce the pungency of ginger while retaining its active ingredients. Compared to traditional methods, this treatment method can reduce the gingerol content by 40-60%, while achieving an encapsulation efficiency of over 80%, effectively reducing the product's pungency and improving palatability. Blind consumer testing showed that the taste acceptance of this product was over 35% higher than that of traditional ginger black tea.

[0028] 2. Improved Stability and Bioavailability of Gingerol: The present invention utilizes a sodium alginate-chitosan composite microcapsule system, which not only effectively encapsulates gingerol but also exhibits pH-sensitive release properties, enabling targeted release in diverse gastrointestinal environments and improving bioavailability. Experiments have shown that the microcapsules achieve a release rate of less than 20% over two hours in simulated gastric fluid (pH 2.0), while a cumulative release rate of over 70% over four hours in simulated intestinal fluid (pH 7.4) reaches approximately two times the bioavailability of conventional direct addition methods.

[0029] 3. Enhance the activity and stability of probiotics: The selected probiotic combination of the present invention has a high adaptability to the black tea-ginger composite matrix and can maintain good activity and growth in this environment. Through multi-stage fermentation process control, the number of viable bacteria can reach 10 at the end of fermentation. 9 CFU / mL is higher than that of traditional fermented products. The number of viable bacteria in the freeze-dried product is not less than 10 10 CFU / g, the number of viable bacteria decreased by less than 0.5 log units after storage at 4°C for 6 months, which is 1-2 log units higher than similar products on the market.

[0030] 4. Enhanced Antioxidant Activity: The multi-stage fermentation process developed by this invention precisely controls parameters such as temperature and pH according to the requirements of each fermentation stage, achieving optimal results in each process: probiotic growth, tea polyphenol conversion, and flavor development. Compared with single-parameter fermentation, the multi-stage fermentation product has a 25-35% increase in DPPH free radical scavenging rate, a 30-40% increase in SOD-like activity, and significantly enhanced antioxidant activity.

[0031] 5. Enhanced Product Functionality: The ginger black tea product prepared by this invention combines the triple benefits of tea polyphenols, gingerol, and probiotics, exhibiting multiple physiological functions, including antioxidant, intestinal regulation, and immune enhancement. In vitro experiments have demonstrated that this product can effectively inhibit the growth of harmful bacteria such as Escherichia coli, promote the proliferation of beneficial bacteria such as Bifidobacterium, and regulate the balance of intestinal flora. Furthermore, the tea polyphenols and gingerol in this product exert a synergistic antioxidant effect, enhancing free radical scavenging capacity by over 40% compared to either ingredient alone.

[0032] 6. Strong process controllability and stable product quality: This invention establishes a complete process control system by precisely controlling the parameter ranges of each process step, achieving stable and consistent product quality. Compared with existing technologies, the batch-to-batch variability of the present invention's products is significantly reduced, with the coefficient of variation of various indicators controlled within 5%, laying the foundation for industrial production. DETAILED DESCRIPTION

[0033] The present invention will be further described below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto.

[0034] Example 1: Preparation of Standard Gingerol Microcapsules-Dual-strain Fermented Ginger Black Tea Fresh ginger: Choose high-quality Yunnan ginger with a growth period of 60-70 days, with a gingerol content of 2.3% and a moisture content of 82%.

[0035] Black tea: Yunnan Dianhong tea, tea polyphenols content 28.5%, moisture content 5.3%, 2023 spring tea.

[0036] Lactobacillus acidophilus: Lactobacillus acidophilus NCFM strain, viable cell count 5.4×10 11 CFU / g, provided by Danisco, USA.

[0037] Lactobacillus plantarum LP28 strain, viable cell count 4.8×10 11 CFU / g, provided by Meiji Co., Ltd., Japan.

[0038] Cellulase complex preparation: activity 45,000 U / g, provided by Novozymes.

[0039] Protease: activity 58000 U / g, provided by Novozymes.

[0040] Sodium alginate: viscosity 1050 mPa·s, provided by Sinopharm Chemical Reagent Co., Ltd., batch number: 20231005.

[0041] Chitosan: Deacetylation degree 93%, viscosity 450 mPa·s, provided by Sinopharm Chemical Reagent Co., Ltd., batch number: 20231022.

[0042] Calcium chloride: analytical grade, provided by Sinopharm Chemical Reagent Co., Ltd.

[0043] Maltodextrin: food grade, DE value 15-20, provided by Sinopharm Chemical Reagent Co., Ltd.

[0044] Fructooligosaccharide: food grade, purity ≥95%, provided by Xi'an Kairui Biotechnology Co., Ltd.

[0045] Mannitol: food grade, purity ≥99%, provided by Sinopharm Chemical Reagent Co., Ltd.

[0046] Other reagents: phosphate buffer, acetic acid, citric acid, sodium citrate, etc. were of analytical grade and provided by Sinopharm Chemical Reagent Co., Ltd.

[0047] The preparation method is as follows: 1. Enzymatic pretreatment of ginger: 1000g of fresh ginger was cleaned and cut into slices with a thickness of about 2.5mm. The slices were blanched in 85°C hot water for 45 seconds and then rapidly cooled to room temperature. The treated slices were added to a phosphate buffer solution with a pH of 6.0 at a liquid-to-solid ratio of 5:1 (v / w). 4.0 U / g of cellulase and 1.5 U / g of protease were added and enzymolyzed in a 40°C water bath for 75 minutes, stirring every 15 minutes. The enzyme activity was inactivated by heating at 80°C for 5 minutes, cooled to room temperature, and filtered to obtain a ginger hydrolyzate. HPLC analysis showed that the gingerol content decreased by 52.3% after enzymatic hydrolysis, from the original 2.3% to 1.1%.

[0048] 2. Gingerol microencapsulation: A 2.0% sodium alginate solution (w / v) and a 0.8% chitosan acetic acid solution (w / v) were prepared and filtered to remove insoluble matter. The ginger enzymatic hydrolyzate and the sodium alginate solution were mixed in a volume ratio of 1:2 and stirred thoroughly. Using a JetCutter microcapsule preparation device with a nozzle diameter of 150 μm and an air pressure of 0.08 MPa, the mixed solution was dripped into a cross-linking solution containing 0.5% calcium chloride and 0.5% chitosan. The cross-linking solution temperature was controlled at 5°C. The microcapsules were aged in the cross-linking solution for 15 minutes, filtered, and washed three times with purified water. The average particle size of the obtained microcapsules was 85 μm, the particle size distribution was between 65-105 μm, and the gingerol encapsulation efficiency was 87.2%, as determined by a laser particle size analyzer.

[0049] 3. Black tea extract: 500g of black tea was added to 80°C purified water at a liquid-to-solid ratio of 20:1 (v / w) and extracted for 18 minutes. The tea was filtered, cooled to 40°C, and the pH was adjusted to 6.2. Maltodextrin was added to a final concentration of 5% (w / v) and oligofructose to a final concentration of 2% (w / v) as a probiotic protectant and carbon source.

[0050] 4. Probiotic activation: Lactobacillus acidophilus NCFM was activated and cultured in MRS medium at 37°C for 14 hours; Lactobacillus plantarum LP28 was activated and cultured in MRS medium at 30°C for 14 hours. The activated cells were collected by centrifugation (6000×g, 10 minutes), washed twice with sterile saline, and the concentration of the culture solution was adjusted to 5×10 9 CFU / mL.

[0051] 5. Multi-stage fermentation: (1) First stage fermentation: Mix 10 L of black tea liquid, 500 g of gingerol microcapsules (containing the equivalent of ginger hydrolysate), 100 mL each of activated Lactobacillus acidophilus and Lactobacillus plantarum (the ratio of bacterial liquid is 1:1), and the initial inoculum volume is about 4% (v / v). Ferment for 15 hours at 28°C and pH 6.2, with the dissolved oxygen content controlled at 12% saturation, until the bacterial count reaches 3.2×10 8 CFU / mL.

[0052] (2) Second stage fermentation: The fermentation broth temperature was adjusted to 34°C, and the pH naturally dropped to 5.2. Fermentation was continued for 10 hours. During this stage, tea polyphenols were rapidly converted into theaflavins and thearubigins. HPLC analysis showed that the theaflavins content increased by 46.8%.

[0053] (3) Third stage fermentation: The fermentation broth temperature was adjusted to 31°C, and the pH naturally dropped to 4.6. Fermentation was continued for 6 hours. During this stage, flavor compounds were rapidly formed, and GC-MS analysis showed that the aromatic compound content increased by 38.5%.

[0054] At the end of fermentation, the total acidity reached 0.62%, the pH value was stable at 4.3, and the number of viable bacteria reached 2.8×10 9 CFU / mL, of which Lactobacillus acidophilus accounted for 58% and Lactobacillus plantarum accounted for 42%.

[0055] 6. Product post-processing: The fermentation broth was centrifuged at low speed (1000 × g, 5 minutes) to remove large suspended solids. Maltodextrin was added to a final concentration of 3% (w / v) and mannitol was added to a final concentration of 0.8% (w / v) as cryoprotectants. Freeze-drying was performed: pre-freezing at -40°C for 8 hours; main drying from -20°C to 0°C for 36 hours; and post-drying at 20°C for 6 hours. The viable cell count in the dried product was 4.6 × 10 10 CFU / g, water content 3.8%. The product is vacuum packed and sealed and stored at 4°C.

[0056] Product indicators and function verification are as follows: 1. Product appearance and sensory indicators: Color: Reddish brown, uniform, fine powder; Smell: Characteristic tea aroma and elegant ginger fragrance, no peculiar smell; Taste: After brewing, the color is bright red, the taste is mellow, with a mild ginger flavor, and no irritating spiciness; 2. Physical and chemical indicators: Viable bacteria count: 4.6×10 10 CFU / g; water content: 3.8%; total phenol content: 15.2 mg / g; theaflavin content: 3.8 mg / g; thearubigins content: 8.6 mg / g; gingerol content: 4.1 mg / g; pH value (1% aqueous solution): 4.3.

[0057] 3. Functional indicators: DPPH free radical scavenging rate: 68.5%; ABTS free radical scavenging rate: 72.3%; SOD-like activity: 235 U / g; 4. Stability test: After 6 months of storage at 4°C, the viable bacterial count was 2.8 × 1010 CFU / g, a decrease of less than 0.5 log units; After 3 months of storage at 25°C, the viable cell count was 8.5×10 9 CFU / g, decreased by less than 1 log unit; No significant changes were found in functional indicators.

[0058] 5. In vitro simulated digestion experiment: The 2-hour release rate in simulated gastric fluid (pH 2.0) was 16.8%; The cumulative release rate in simulated intestinal fluid (pH 7.4) was 73.8% in 4 hours; The survival rate of probiotics during the entire digestive tract delivery process reached 35%.

[0059] Example 2: Preparation of high enzymatic hydrolysis rate-single strain fermented ginger black tea The same raw materials and reagents as those in Example 1 were used, except that only Lactobacillus plantarum LP28 was used as the fermentation strain.

[0060] The preparation method is as follows: 1. Enzymatic pretreatment of ginger: 1000g of fresh ginger was cleaned and cut into slices with a thickness of about 3.0mm. The slices were blanched in 85°C hot water for 60 seconds and then rapidly cooled to room temperature. The treated slices were added to a phosphate buffer solution with a pH of 5.8 at a liquid-to-solid ratio of 5:1 (v / w). 5.0 U / g of cellulase and 2.0 U / g of protease were added to the slices and enzymolyzed in a 42°C water bath for 90 minutes, stirring every 15 minutes. The enzyme activity was inactivated by heating at 80°C for 5 minutes, the slices were cooled to room temperature, and the ginger hydrolyzate was filtered. HPLC analysis showed that the gingerol content decreased by 59.8% after enzymatic hydrolysis, from 2.3% to 0.92%.

[0061] 2. Gingerol microencapsulation: Prepare 2.5% sodium alginate solution (w / v) and 1.0% chitosan acetic acid solution (w / v), and filter to remove insoluble matter. Mix the ginger enzymatic hydrolyzate with the sodium alginate solution in a volume ratio of 1:3 and stir thoroughly. Use an electrostatic spray device with a voltage of 25kV to spray the mixed solution into a cross-linking solution containing 0.7% calcium chloride and 0.7% chitosan. The temperature of the cross-linking solution is controlled at 4°C. The microcapsules are matured in the cross-linking solution for 20 minutes, filtered, and washed three times with purified water. The average particle size of the obtained microcapsules was 65μm, the particle size distribution was between 50-80μm, and the gingerol encapsulation efficiency was 92.5%, as determined by a laser particle size analyzer.

[0062] 3. Black tea extract: 500g of black tea was added to 85°C purified water at a liquid-to-solid ratio of 25:1 (v / w) and allowed to steep for 15 minutes. The tea was filtered, cooled to 38°C, and the pH was adjusted to 6.0. Maltodextrin was added to a final concentration of 7% (w / v) and oligofructose to a final concentration of 3% (w / v).

[0063] 4. Probiotic activation: Lactobacillus plantarum LP28 was activated and cultured in MRS medium at 30°C for 16 hours. The activated cells were collected by centrifugation (6000×g, 10 minutes), washed twice with sterile saline, and the concentration of the culture solution was adjusted to 8×10 9 CFU / mL.

[0064] 5. Multi-stage fermentation: (1) First stage fermentation: Mix 10 L of black tea liquid, 500 g of gingerol microcapsules (containing the equivalent of ginger hydrolysate), and 150 mL of activated Lactobacillus plantarum. The initial inoculum volume is approximately 5% (v / v). Ferment for 18 hours at 30°C and pH 6.0, with the dissolved oxygen content controlled at 15% saturation, until the bacterial count reaches 5.8 × 10 8 CFU / mL.

[0065] (2) Second stage fermentation: The fermentation liquid temperature was adjusted to 36°C, the pH naturally dropped to 5.0, and the fermentation was continued for 8 hours.

[0066] (3) The third stage of fermentation: the fermentation liquid temperature was adjusted to 33°C, the pH naturally dropped to 4.5, and the fermentation was continued for 4 hours.

[0067] At the end of fermentation, the total acidity reached 0.68%, the pH value was stable at 4.2, and the number of viable bacteria reached 4.2×10 9 CFU / mL.

[0068] 6. Product post-processing: The fermentation broth was centrifuged at low speed (1000 × g for 5 minutes) to remove large suspended solids. Maltodextrin was added to a final concentration of 5% (w / v) and mannitol was added to a final concentration of 1.2% (w / v) as cryoprotectants. Freeze-drying was performed: pre-freezing at -40°C for 10 hours; main drying at -20°C to 0°C for 42 hours; and post-drying at 25°C for 4 hours. The viable cell count in the dried product was 5.8 × 10 10 CFU / g, water content 3.2%. The product is vacuum packed and sealed and stored at 4°C.

[0069] Product indicators and function verification are as follows: 1. Product appearance and sensory indicators: Color: Dark reddish brown, uniform and fine powder; Smell: Rich tea aroma and elegant ginger aroma, no peculiar smell; Taste: After brewing, the color is deep red and bright, the taste is strong, the ginger flavor is mild, and there is almost no spiciness; 2. Physical and chemical indicators: viable bacteria count: 5.8×10 10 CFU / g; water content: 3.2%; total phenol content: 18.5 mg / g; theaflavin content: 4.2 mg / g; thearubigins content: 10.3 mg / g; gingerol content: 3.5 mg / g; pH value (1% aqueous solution): 4.2; 3. Functional indicators: DPPH free radical scavenging rate: 72.8%; ABTS free radical scavenging rate: 76.5%; SOD-like activity: 262 U / g; 4. Stability test: After 6 months of storage at 4°C, the viable cell count was 3.5×10 10 CFU / g, decreased by less than 0.5 log units; after 3 months of storage at 25°C, the number of viable bacteria was 7.6×10 9 CFU / g, decreased by less than 1 log unit; Functional indicators remained stable.

[0070] 5. In vitro simulated digestion experiment: The 2-hour release rate in simulated gastric fluid (pH 2.0) was 12.5%; the 4-hour cumulative release rate in simulated intestinal fluid (pH 7.4) was 78.2%; the overall probiotic survival rate during digestive tract delivery reached 42%.

[0071] The experimental results show that compared with the standard dual-strain process, the product prepared by the single-strain high enzymatic hydrolysis rate process has higher antioxidant activity and probiotic stability, but the flavor is slightly different, with a richer tea aroma and a milder ginger flavor.

[0072] Example 3: Preparation of medium enzymatic hydrolysis rate-extended fermentation ginger black tea The raw materials and reagents were basically the same as those in Example 1, except that Lactobacillus acidophilus LA-5 and Lactobacillus plantarum LP01 were used as fermentation strains.

[0073] The preparation method is as follows: 1. Enzymatic pretreatment of ginger: 1000g of fresh ginger was cleaned and cut into slices with a thickness of about 2.0mm. The slices were blanched in 85°C hot water for 40 seconds and then rapidly cooled to room temperature. The treated slices were added to a phosphate buffer solution with a pH of 6.2 at a liquid-to-solid ratio of 5:1 (v / w). 3.5 U / g of cellulase and 1.2 U / g of protease were added to the slices and enzymolyzed in a 38°C water bath for 60 minutes, stirring every 15 minutes. The enzyme activity was inactivated by heating at 80°C for 5 minutes, the slices were cooled to room temperature, and the ginger hydrolyzate was filtered. HPLC analysis showed that the gingerol content decreased by 45.2% after enzymatic hydrolysis, from 2.3% to 1.26%.

[0074] 2. Gingerol microencapsulation: A 1.5% sodium alginate solution (w / v) and a 0.5% chitosan acetic acid solution (w / v) were prepared and the insoluble matter was removed by filtration. The ginger enzymatic hydrolyzate was mixed with the sodium alginate solution in a volume ratio of 1:1 and stirred thoroughly. Using a JetCutter microcapsule preparation device with a nozzle diameter of 180 μm and an air pressure of 0.05 MPa, the mixed solution was dripped into a cross-linking solution containing 0.3% calcium chloride and 0.3% chitosan. The cross-linking solution temperature was controlled at 8°C. The microcapsules were aged in the cross-linking solution for 10 minutes, filtered, and washed twice with purified water. The average particle size of the obtained microcapsules was 120 μm, the particle size distribution was between 90-150 μm, and the gingerol encapsulation efficiency was 82.6%, as determined by a laser particle size analyzer.

[0075] 3. Black tea extract: 500g of black tea was added to 75°C purified water at a liquid-to-solid ratio of 15:1 (v / w) and allowed to steep for 20 minutes. The tea was filtered, cooled to 42°C, and the pH was adjusted to 6.5. Maltodextrin was added to a final concentration of 2% (w / v) and oligofructose to a final concentration of 1% (w / v).

[0076] 4. Probiotic activation: Lactobacillus acidophilus LA-5 was activated and cultured in MRS medium at 37°C for 12 hours; Lactobacillus plantarum LP01 was activated and cultured in MRS medium at 30°C for 12 hours. The activated cells were collected by centrifugation (6000×g, 10 minutes), washed twice with sterile saline, and the concentration of the culture solution was adjusted to 2×10 9 CFU / mL.

[0077] 5. Multi-stage fermentation: (1) First stage fermentation: Mix 10 L of black tea liquid, 500 g of gingerol microcapsules (containing the equivalent of ginger hydrolysate), and 150 mL each of activated Lactobacillus acidophilus and Lactobacillus plantarum (1:1 bacterial ratio). The initial inoculum volume is about 6% (v / v). Ferment for 20 hours at 26°C and pH 6.5, with the dissolved oxygen content controlled at 10% saturation, until the bacterial count reaches 2.6 × 10 8 CFU / mL.

[0078] (2) Second stage fermentation: The fermentation liquid temperature was adjusted to 32°C, the pH naturally dropped to 5.5, and the fermentation was continued for 12 hours.

[0079] (3) The third stage of fermentation: the fermentation liquid temperature was adjusted to 29°C, the pH naturally dropped to 5.0, and the fermentation was continued for 8 hours.

[0080] At the end of fermentation, the total acidity reached 0.54%, the pH value was stable at 4.5, and the number of viable bacteria reached 1.8×10 9 CFU / mL, of which Lactobacillus acidophilus accounted for 52% and Lactobacillus plantarum accounted for 48%.

[0081] 6. Product post-processing: The fermentation broth was centrifuged at low speed (1000 × g, 5 minutes) to remove large suspended solids. Maltodextrin was added to a final concentration of 1% (w / v) and mannitol was added to a final concentration of 0.5% (w / v) as cryoprotectants. Freeze-drying was performed: pre-freezing at -40°C for 6 hours; main drying from -20°C to 0°C for 24 hours; and post-drying at 15°C for 8 hours. The viable cell count in the dried product was 2.5 × 10 10 CFU / g, water content 4.5%. The product is vacuum packed and sealed and stored at 4°C.

[0082] Product indicators and function verification are as follows: 1. Product appearance and sensory indicators: Color: Light reddish brown, uniform and fine powder; Smell: Elegant tea aroma and distinct ginger aroma, no peculiar smell; Taste: After brewing, the color is bright red and transparent, the taste is refreshing, with moderate ginger flavor and a slight spicy feeling; 2. Physical and chemical indicators: viable bacteria count: 2.5×10 10 CFU / g; water content: 4.5%; total phenol content: 12.8 mg / g; theaflavin content: 2.9 mg / g; thearubigins content: 7.2 mg / g; gingerol content: 5.8 mg / g; pH value (1% aqueous solution): 4.5.

[0083] 3. Functional indicators: DPPH free radical scavenging rate: 61.2%; ABTS free radical scavenging rate: 65.7%; SOD-like activity: 212 U / g; 4. Stability test: After 6 months of storage at 4°C, the viable cell count was 1.2×10 10 CFU / g, decreased by less than 0.5 log units; after 3 months of storage at 25°C, the number of viable bacteria was 4.2×10 9 CFU / g decreased by about 1 logarithmic unit; functional indicators remained basically stable.

[0084] 5. In vitro simulated digestion experiment: The 2-hour release rate in simulated gastric fluid (pH 2.0) was 22.6%; the 4-hour cumulative release rate in simulated intestinal fluid (pH 7.4) was 68.5%; the overall probiotic survival rate during digestive tract delivery reached 28%.

[0085] The experimental results showed that compared with the standard process, the product prepared by this process had a stronger ginger flavor and moderate spiciness, a richer taste, but slightly lower antioxidant activity and probiotic stability.

[0086] Example 4: Low temperature fermentation - preparation of highly microencapsulated ginger black tea The raw materials and reagents were basically the same as those in Example 1, except that Lactobacillus acidophilus DDS-1 was used as the sole fermentation strain.

[0087] The preparation method is as follows: 1. Enzymatic pretreatment of ginger: 1000g of fresh ginger was cleaned and cut into slices with a thickness of about 2.2mm. The slices were blanched in 83°C hot water for 50 seconds and then rapidly cooled to room temperature. The treated slices were added to a phosphate buffer solution with a pH of 6.0 at a liquid-to-solid ratio of 5:1 (v / w). 4.5 U / g of cellulase and 1.8 U / g of protease were added and enzymolyzed in a 40°C water bath for 80 minutes, stirring every 15 minutes. The enzyme activity was inactivated by heating at 80°C for 5 minutes, cooled to room temperature, and filtered to obtain the ginger hydrolyzate. HPLC analysis showed that the gingerol content decreased by 56.5% after enzymatic hydrolysis, from the original 2.3% to 1.0%.

[0088] 2. Gingerol microencapsulation: Prepare 2.0% sodium alginate solution (w / v) and 0.8% chitosan acetic acid solution (w / v), and filter to remove insoluble matter. Mix the ginger enzymatic hydrolyzate with the sodium alginate solution in a volume ratio of 1:2.5 and stir thoroughly. Use an electrostatic spray device with a voltage of 22kV to spray the mixed solution into a cross-linking solution containing 0.6% calcium chloride and 0.6% chitosan. The temperature of the cross-linking solution is controlled at 4°C. The microcapsules are matured in the cross-linking solution for 18 minutes, filtered, and washed three times with purified water. The average particle size of the obtained microcapsules was 75μm, the particle size distribution was between 60-90μm, and the gingerol encapsulation efficiency was 94.8%, as determined by a laser particle size analyzer.

[0089] 3. Black tea extract: 500g of black tea was added to 78°C purified water at a liquid-to-solid ratio of 18:1 (v / w) and allowed to steep for 22 minutes. The tea was filtered, cooled to 35°C, and the pH was adjusted to 6.3. Maltodextrin was added to a final concentration of 8% (w / v) and oligofructose to a final concentration of 4% (w / v).

[0090] 4. Probiotic activation: Lactobacillus acidophilus DDS-1 was activated and cultured in MRS medium at 37°C for 15 hours. The activated cells were collected by centrifugation (6000×g, 10 minutes), washed twice with sterile saline, and the concentration of the culture solution was adjusted to 1×10 10 CFU / mL.

[0091] 5. Multi-stage fermentation: (1) First stage fermentation: Mix 10 L of black tea liquid, 500 g of gingerol microcapsules (containing the equivalent of ginger hydrolysate), and 200 mL of activated Lactobacillus acidophilus. The initial inoculum volume is about 2% (v / v). Ferment for 18 hours at 26°C and pH 6.3, with the dissolved oxygen content controlled at 8% saturation, until the bacterial count reaches 1.5 × 10 8 CFU / mL.

[0092] (2) Second stage fermentation: The fermentation liquid temperature was adjusted to 30°C, the pH naturally dropped to 5.4, and the fermentation was continued for 10 hours.

[0093] (3) The third stage of fermentation: the fermentation liquid temperature was adjusted to 28°C, the pH naturally dropped to 4.8, and the fermentation was continued for 8 hours.

[0094] At the end of fermentation, the total acidity reached 0.58%, the pH value was stable at 4.4, and the number of viable bacteria reached 1.6×10 9 CFU / mL.

[0095] 6. Product post-processing: The fermentation broth was centrifuged at low speed (1000 × g for 5 minutes) to remove large suspended solids. Maltodextrin was added to a final concentration of 4% (w / v) and mannitol was added to a final concentration of 1.5% (w / v) as cryoprotectants. Freeze-drying was performed: pre-freezing at -38°C for 8 hours; main drying at -18°C to 0°C for 32 hours; and post-drying at 22°C for 5 hours. The viable cell count in the dried product was 3.2 × 10 10 CFU / g, water content 3.5%. The product is vacuum packed and sealed and stored at 4°C.

[0096] Product indicators and function verification are as follows: 1. Product appearance and sensory indicators: Color: Reddish-brown, uniform, fine powder; Smell: Rich tea aroma and slight ginger aroma, no peculiar smell; Taste: After brewing, the color is bright red, the taste is mellow, the tea aroma is strong, the ginger flavor is subtle, and there is almost no spiciness.

[0097] 2. Physical and chemical indicators: viable bacteria count: 3.2×10 10 CFU / g; water content: 3.5%; total phenol content: 16.8 mg / g; theaflavin content: 4.0 mg / g; thearubigins content: 9.2 mg / g; gingerol content: 2.8 mg / g; pH value (1% aqueous solution): 4.4.

[0098] 3. Functional indicators: DPPH free radical scavenging rate: 70.2%; ABTS free radical scavenging rate: 74.8%; SOD-like activity: 245 U / g.

[0099] 4. Stability test: After 6 months of storage at 4°C, the viable cell count was 2.3×10 10 CFU / g, decreased by less than 0.5 log units; After storage at 25°C for 3 months, the viable cell count was 6.8×10 9 CFU / g, decreased by less than 1 log unit; No significant changes were found in functional indicators.

[0100] 5. In vitro simulated digestion experiment: The 2-hour release rate in simulated gastric fluid (pH 2.0) was 9.6%; the 4-hour cumulative release rate in simulated intestinal fluid (pH 7.4) was 82.5%; the overall probiotic survival rate during digestive tract delivery reached 38%.

[0101] The experimental results show that this process is characterized by a high microcapsule encapsulation rate and a low release rate in gastric juice. The product has a strong tea aroma but a mild ginger flavor, which is suitable for consumers who are sensitive to the spicy taste of ginger but expect to obtain the benefits of ginger.

[0102] Example 5: Preparation of short-term high-temperature fermentation-three-strain synergistic ginger black tea The raw materials and reagents were substantially the same as those in Example 1, except that three strains, Lactobacillus acidophilus NCFM, Lactobacillus plantarum LP28 and Lactobacillus plantarum 299v, were mixed for fermentation.

[0103] The preparation method is as follows: 1. Enzymatic pretreatment of ginger: 1000g of fresh ginger was cleaned and cut into slices with a thickness of about 2.0mm. The slices were blanched in 87°C hot water for 35 seconds and then quickly cooled to room temperature. The treated slices were added to a phosphate buffer solution with a pH of 6.0 at a liquid-to-solid ratio of 5:1 (v / w). 3.8 U / g of cellulase and 1.4 U / g of protease were added to the slices and enzymolyzed in a 41°C water bath for 65 minutes, stirring every 15 minutes. The enzyme activity was inactivated by heating at 80°C for 5 minutes, cooled to room temperature, and filtered to obtain the ginger hydrolyzate. HPLC analysis showed that the gingerol content decreased by 48.5% after enzymatic hydrolysis, from the original 2.3% to 1.18%.

[0104] 2. Gingerol microencapsulation: Prepare 2.0% sodium alginate solution (w / v) and 0.7% chitosan acetic acid solution (w / v), and filter to remove insoluble matter. Mix the ginger enzymatic hydrolyzate with the sodium alginate solution in a volume ratio of 1:2 and stir thoroughly. Use a JetCutter microcapsule preparation device with a nozzle diameter of 160μm and an air pressure of 0.07 MPa to drip the mixed solution into a cross-linking solution containing 0.5% calcium chloride and 0.5% chitosan. The cross-linking solution temperature is controlled at 6°C. The microcapsules are aged in the cross-linking solution for 15 minutes, filtered, and washed three times with purified water. The average particle size of the obtained microcapsules was 90μm, the particle size distribution was between 70-110μm, and the gingerol encapsulation efficiency was 89.2%, as measured by a laser particle size analyzer.

[0105] 3. Black tea extract: 500g of black tea was added to 82°C purified water at a liquid-to-solid ratio of 20:1 (v / w) and extracted for 16 minutes. The tea was filtered, cooled to 40°C, and the pH was adjusted to 6.2. Maltodextrin was added to a final concentration of 6% (w / v) and oligofructose to a final concentration of 3% (w / v).

[0106] 4. Probiotic activation: Lactobacillus acidophilus NCFM was activated and cultured in MRS medium at 37°C for 14 hours; Lactobacillus plantarum LP28 was activated and cultured in MRS medium at 30°C for 14 hours; and Lactobacillus plantarum 299v was activated and cultured in MRS medium at 30°C for 14 hours. Activated cells were collected by centrifugation (6000×g, 10 minutes), washed twice with sterile saline, and the bacterial suspension concentration was adjusted to 5×10 9 CFU / mL.

[0107] 5. Multi-stage fermentation: (1) First stage fermentation: Mix 10 L of black tea liquid, 500 g of gingerol microcapsules (containing the equivalent of ginger hydrolysate), and 60 mL of each of the three activated probiotics (bacterial liquid ratio 1:1:1). The initial inoculum volume is approximately 3.6% (v / v). Ferment for 12 hours at 28°C and pH 6.2, with the dissolved oxygen content controlled at 10% saturation, until the bacterial count reaches 2.8 × 10 8 CFU / mL.

[0108] (2) Second stage fermentation: The fermentation liquid temperature was adjusted to 36°C, the pH naturally dropped to 5.2, and the fermentation was continued for 6 hours.

[0109] (3) The third stage of fermentation: the fermentation liquid temperature was adjusted to 32°C, the pH naturally dropped to 4.6, and the fermentation was continued for 4 hours.

[0110] At the end of fermentation, the total acidity reached 0.65%, the pH value was stable at 4.3, and the number of viable bacteria reached 3.5×10 9 CFU / mL, of which Lactobacillus acidophilus accounted for 42%, Lactobacillus plantarum LP28 accounted for 35%, and Lactobacillus plantarum 299v accounted for 23%.

[0111] 6. Product post-processing: The fermentation broth was centrifuged at low speed (1000 × g, 5 minutes) to remove large suspended solids. Maltodextrin was added to a final concentration of 3.5% (w / v) and mannitol was added to a final concentration of 1.0% (w / v) as cryoprotectants. Freeze-drying was performed: pre-freezing at -40°C for 7 hours; main drying at -20°C to 0°C for 30 hours; and post-drying at 20°C for 5 hours. The viable cell count in the dried product was 4.8 × 10 10 CFU / g, water content 3.6%. The product is vacuum packed and sealed and stored at 4°C.

[0112] Product indicators and function verification are as follows: 1. Product appearance and sensory indicators: Color: Reddish-brown, uniform, fine powder; Smell: Characteristic tea aroma and moderate ginger aroma, no peculiar smell; Taste: After brewing, the color is bright red, the taste is mellow and refreshing, with moderate ginger flavor and a slightly spicy feeling; 2. Physical and chemical indicators: viable bacteria count: 4.8×10 10 CFU / g; water content: 3.6%; total phenol content: 15.8 mg / g; theaflavin content: 3.9 mg / g; thearubigins content: 8.8 mg / g; gingerol content: 4.5 mg / gpH value (1% aqueous solution): 4.3.

[0113] 3. Functional indicators: DPPH free radical scavenging rate: 70.5%; ABTS free radical scavenging rate: 74.2%; SOD-like activity: 248 U / g; 4. Stability test: After 6 months of storage at 4°C, the viable cell count was 3.2×10 10 CFU / g, decreased by less than 0.5 log units; after 3 months of storage at 25°C, the number of viable bacteria was 9.2×10 9 The CFU / g decreased by less than 1 logarithmic unit; no significant changes were observed in functional indicators.

[0114] 5. In vitro simulated digestion experiment: The 2-hour release rate in simulated gastric fluid (pH 2.0) was 15.2%; the 4-hour cumulative release rate in simulated intestinal fluid (pH 7.4) was 75.6%; the overall probiotic survival rate during digestive tract delivery reached 40%.

[0115] Experimental results show that the synergistic fermentation of the three strains significantly enhances the product's intestinal regulation, resulting in a higher diversity of probiotics and a more comprehensive regulatory effect on the intestinal microbiome. Furthermore, the short, high-temperature fermentation time accelerates the conversion of tea polyphenols and flavor development, improving production efficiency.

[0116] In order to evaluate the effects of different preparation processes on product performance, a systematic comparison was conducted on the products prepared in Examples 1-5. The results are shown in Table 1: Table 1: Comparison of product performance with different preparation processes project Example 1 Example 2 Example 3 Example 4 Example 5 Gingerol degradation rate (%) 52.3 59.8 45.2 56.5 48.5 Microcapsule particle size (μm) 85 65 120 75 90 Gingerol embedding rate (%) 87.2 92.5 82.6 94.8 89.2 Fermentation time (h) 31 30 40 36 22 <![CDATA[Viable cell count (×10 10 CFU / g)]]> 4.6 5.8 2.5 3.2 4.8 DPPH free radical scavenging rate (%) 68.5 72.8 61.2 70.2 70.5 2h release rate in simulated gastric fluid (%) 16.8 12.5 22.6 9.6 15.2 Cumulative release rate in simulated intestinal fluid for 4 hours (%) 73.8 78.2 68.5 82.5 75.6 Taste rating (10 points) 8.6 8.2 7.8 8.8 9 Stability at 4°C (log reduction in viable bacteria after 6 months) 0.21 0.22 0.32 0.14 0.18 Through comparative analysis, we can see that: 1. The intensity of enzymatic pretreatment affects the degradation rate of gingerol. An ideal degradation rate is between 50-60%, which can reduce the pungency while retaining a certain ginger characteristic. A degradation rate that is too high may weaken the characteristic ginger flavor, while a degradation rate that is too low may affect the product taste and probiotic activity.

[0117] 2. Microcapsule particle size is negatively correlated with embedding efficiency. A particle size range of 65-90 μm exhibits a high embedding efficiency and good stability. The electrostatic spraying technique used in Example 4 produced microcapsules with a small and uniform particle size, achieving the highest embedding efficiency. In contrast, the larger nozzle used in Example 3 resulted in larger microcapsules with a relatively low embedding efficiency.

[0118] 3. The fermentation strain combination influences product flavor and functional properties. While the combination of Lactobacillus acidophilus and Lactobacillus plantarum is superior to single-strain fermentation, tri-strain fermentation can further enhance product diversity and functionality. The tri-strain synergistic fermentation employed in Example 5 achieved the highest flavor score, while the single-strain fermentations in Examples 2 and 4, while superior in some functional indicators, had relatively low flavor scores.

[0119] 4. Multi-stage fermentation parameters are closely related to the viable bacterial count and antioxidant activity of the product. Prolonging the first-stage fermentation time can improve probiotic activity, while the second-stage temperature affects tea polyphenol conversion and antioxidant capacity. Example 5 employed a higher second-stage temperature (36°C) and a shorter fermentation time, significantly improving production efficiency while maintaining a high viable bacterial count and antioxidant activity.

[0120] 5. The addition of protective agents during post-processing significantly affects product stability. The combined use of maltodextrin and mannitol is more effective than a single protective agent. Example 4 uses a higher concentration of protective agent combination to achieve the best storage stability, with the lowest logarithmic decrease in viable bacteria after 6 months.

[0121] In general, the process of Example 5 is the most balanced, combining high viable bacteria count, strong antioxidant activity, good stability and excellent sensory properties, and is the preferred embodiment of the present invention.

[0122] In order to compare the difference between the method of the present invention and the traditional method, the traditional ginger black tea preparation method was used as a control.

[0123] The preparation method is as follows: 1. Ginger processing: Wash 500g of fresh ginger, slice it, squeeze the juice, and filter it to get ginger juice.

[0124] 2. Black tea processing: Add 500g of black tea to 85°C purified water at a liquid-to-solid ratio of 20:1 (v / w) and steep for 15 minutes. Filter the tea and cool to 40°C.

[0125] 3. Mixed fermentation: Mix ginger juice and black tea liquid in a volume ratio of 1:20 and let it ferment in a closed container at 30°C for 24 hours.

[0126] 4. Product handling: The fermentation broth was filtered and freeze-dried to obtain a control product.

[0127] Product index tests are as follows: 1. Sensory evaluation: Color: Reddish-brown powder, slightly uneven; Odor: Tea aroma and strong ginger flavor; Taste: After brewing, the color is reddish-turbid, the taste is spicy and stimulating, and the ginger flavor is strong.

[0128] 2. Physical and chemical indicators: Total phenol content: 14.2 mg / g; theaflavin content: 2.6 mg / g; thearubigins content: 6.8 mg / g; gingerol content: 8.2 mg / g; pH value (1% aqueous solution): 5.2.

[0129] 3. Functional indicators: DPPH free radical scavenging rate: 52.5%; ABTS free radical scavenging rate: 56.8%; SOD-like activity: 165 U / g; 4. Stability test: After storage at 4°C for 3 months, the total phenolic content decreased by 15.2% and the antioxidant activity decreased by 22.3%.

[0130] Compared with traditional methods, the method of the present invention has the following obvious advantages: 1. Sensory quality: Ginger black tea prepared by traditional methods has a strong spicy and stimulating taste, which is less accepted by consumers. However, the method of the present invention significantly reduces the spicy taste of the product through enzymatic pretreatment and microencapsulation technology, and improves the harmony and acceptance of the taste.

[0131] 2. Functional Activity: Products prepared by traditional methods lack probiotic activity and have significantly lower antioxidant capacity than those produced by the present invention. The present invention's products, on average, have a DPPH free radical scavenging rate that is approximately 30% higher than those produced by traditional methods, an ABTS free radical scavenging rate that is approximately 25% higher, and a SOD-like activity that is approximately 40% higher.

[0132] 3. Stability: Products prepared by traditional methods suffer from significant loss of functional components during storage. However, the method of the present invention significantly improves the storage stability of the product through microencapsulation technology and the addition of protective agents.

[0133] 4. Functional properties: The product prepared by the method of the present invention has both probiotic activity and tea-ginger efficacy, and is a multifunctional and synergistic innovative functional beverage.

[0134] To further verify the functional properties of the product of the present invention, an in vitro antibacterial activity test was performed on the product prepared in Example 5.

[0135] The test method is as follows 1. Test strains: Escherichia coli ATCC 25922; Staphylococcus aureus ATCC 6538; Salmonella typhimurium ATCC 14028; Bacillus subtilis ATCC 6633; 2. Inhibition zone determination: The test strain was inoculated on a nutrient agar plate, and four holes with a diameter of 6 mm were prepared. 100 μL of an aqueous solution of the product of Example 5 (100 mg / mL), an aqueous solution of a traditional ginger black tea product (100 mg / mL), a black tea extract (100 mg / mL), and sterile water (negative control) were added, respectively. After incubation at 37°C for 24 hours, the diameter of the inhibition zone was measured.

[0136] 3. Minimum inhibitory concentration (MIC) determination: The MIC values ​​of the product of Example 5 against each test strain were determined using the microdilution method.

[0137] The test results are as follows: 1. Diameter of inhibition zone (mm): Test strains Example 5 Product Traditional ginger black tea Black Tea Extract Sterile water Escherichia coli 16.8±0.5 12.3±0.4 9.2±0.3 0 Staphylococcus aureus 18.5±0.6 14.6±0.5 10.5±0.4 0 salmonella 15.2±0.5 11.8±0.4 8.6±0.3 0 Bacillus subtilis 17.6±0.6 13.7±0.5 9.8±0.3 0 2. Minimum inhibitory concentration (mg / mL): Test strains Example 5 Product Traditional ginger black tea Black Tea Extract Escherichia coli 12.5 25 50 Staphylococcus aureus 6.25 12.5 25 salmonella 12.5 25 50 Bacillus subtilis 6.25 12.5 25 The product prepared in Example 5 exhibited significant antibacterial activity against all four test strains, with significantly better antibacterial effects than traditional ginger black tea and black tea extract. This may be due to the synergistic effect of antibacterial substances such as organic acids and bacteriocins produced during the probiotic fermentation process in the product of the present invention with tea polyphenols and gingerol, enhancing the product's antibacterial activity. This result demonstrates that the product of the present invention not only possesses probiotic activity and antioxidant function, but also has a certain antibacterial effect, making it suitable as a multifunctional, synergistic functional beverage.

Claims

1. A method for preparing ginger black tea by combining ginger pretreatment with black tea probiotic fermentation, characterized in that: The following steps are involved: a) Ginger enzymatic pretreatment: Fresh ginger is enzymatically treated to reduce the gingerol content; b) Gingerol microencapsulation: enzymatically hydrolyzed ginger liquid is mixed with sodium alginate and chitosan to prepare microcapsules; c) Black tea extraction: extracting black tea with water to prepare black tea liquid; d) Probiotic activation: Activate and culture Lactobacillus acidophilus and Lactobacillus plantarum; e) Multi-stage fermentation: black tea liquid, gingerol microcapsules and activated probiotics are mixed and fermented through multi-stage temperature and pH control; f) Product post-processing: The fermentation broth is post-processed to obtain a ginger black tea product containing probiotics.

2. The method according to claim 1, characterized in that The specific steps of the enzymatic pretreatment in step a) are: a1) Wash and slice fresh ginger, blanch in hot water at 85±2°C for 30-60 seconds, and quickly cool to room temperature; a2) adding the treated ginger slices to a phosphate buffer solution at a pH of 5.8-6.2 at a liquid-to-solid ratio of 5:1 (v / w); a3) adding a cellulase complex and a protease, and performing enzymatic hydrolysis at 38-42°C for 60-90 minutes; a4) heating at 80°C for 5 minutes to inactivate enzyme activity, cooling to room temperature, and filtering to obtain a ginger enzymatic hydrolyzate; a5) Gingerol content decreased by 40-60%.

3. The method according to claim 1, characterized in that The specific steps of microencapsulation in step b) are: b1) preparing a 1.5-2.5% sodium alginate solution (w / v) and a 0.5-1.0% chitosan acetate solution (w / v); b2) mixing the ginger enzymatic hydrolyzate solution and the sodium alginate solution in a volume ratio of 1:1 to 1:3; b3) using coaxial airflow or electrostatic spray technology, dripping the mixed solution into a cross-linking solution containing 0.3-0.7% calcium chloride and 0.3-0.7% chitosan; b4) aging in the cross-linking solution for 10-20 minutes, filtering, and washing; b5) obtaining gingerol microcapsules with a particle size of 50-150 μm and a gingerol encapsulation efficiency of not less than 80%.

4. The method according to claim 1, wherein The specific steps of black tea extraction in step c) are: c1) adding black tea to 75-85°C purified water at a liquid-to-solid ratio of 15:1-25:1 (v / w); c2) extracting for 15-25 minutes; c3) filtering the black tea liquid and cooling it to below 45°C; c4) Adjust the pH to 6.0-6.5; c5) Add 1-10% maltodextrin (w / v) and 1-5% fructooligosaccharide (w / v).

5. The method according to claim 1, wherein The specific steps of activating the probiotics in step d) are: d1) activating Lactobacillus acidophilus in MRS medium at 37±1°C for 12-16 hours; d2) activating Lactobacillus plantarum in MRS medium at 30±1°C for 12-16 hours; d3) Collect the activated cells by centrifugation and wash with sterile saline; d4) Adjust the bacterial solution concentration to 10 8 -10 10 CFU / mL.

6. The method according to claim 5, characterized in that The Lactobacillus acidophilus is selected from one or more of Lactobacillus acidophilus NCFM strain, Lactobacillus acidophilus LA-5 strain or Lactobacillus acidophilus DDS-1 strain; the Lactobacillus plantarum is selected from one or more of Lactobacillus plantarum LP28 strain, Lactobacillus plantarum LP01 strain or Lactobacillus plantarum 299v strain.

7. The method according to claim 1, characterized in that The multi-stage fermentation in step e) comprises the following stages: e1) First stage fermentation: Ferment at 26-30°C, pH 5.8-6.5 for 10-20 hours until the bacterial count reaches 10 8 CFU / mL or above; e2) Second stage fermentation: fermentation at 32-36°C, pH 4.8-5.5 for 6-12 hours; e3) Third stage fermentation: fermentation at 29-33°C, pH 4.2-5.0 for 4-8 hours; e4) The fermentation is completed when the total acidity reaches 0.5-0.7%, the pH value is stable at 4.2-4.5, and the number of viable bacteria is not less than 10 9 CFU / mL.

8. The method according to claim 1, characterized in that The specific steps of the product post-processing in step f) are: f1) centrifuging the fermentation broth at low speed to remove large suspended solids; f2) adding 1-5% maltodextrin (w / v) and 0.3-1.5% mannitol (w / v) as protective agents; f3) Freeze drying: pre-freezing at -40±5°C for 6-10 hours; main drying at -20°C to 0°C for 24-48 hours; post-drying at 15-25°C for 4-8 hours; f4) The number of viable bacteria in the dried product is not less than 10 10 CFU / g, water content not higher than 5%; f5) Store in vacuum sealed containers.

9. The ginger black tea product prepared according to the method according to any one of claims 1 to 8, characterized in that: The product is in dry powder or granular form, with a viable bacterial count of not less than 10 10 CFU / g, containing Lactobacillus acidophilus, Lactobacillus plantarum, tea polyphenols, theaflavins, thearubigins and gingerol microcapsules to reduce spiciness.

10. Use of the product according to claim 9 in the preparation of health food with intestinal regulation, anti-oxidation and immunity-enhancing functions.