Probiotic fermented black coffee and preparation method thereof

Abstract

The invention provides probiotic fermented black coffee and a preparation method thereof, and belongs to the technical field of coffee beverages. The preparation method of the probiotic fermented black coffee comprises the following steps: 1) grinding coffee beans, and extracting to obtain a coffee concentrated solution; (2) adding a composite nitrogen source and a composite carbon source into the coffee concentrated solution, and then adding composite probiotics for fermentation treatment; 3) sterilizing the fermented coffee to obtain the probiotic fermented black coffee. Through the compound probiotic fermentation treatment, the nutritional value and functionality of the coffee are remarkably improved, and the prepared black coffee is remarkably reduced in bitterness and astringent taste, and has softer mouth feel and richer flavor.

Description

Technical Field

[0001] This invention relates to the field of coffee beverage technology, and in particular to a probiotic-fermented black coffee and its preparation method. Background Technology

[0002] Coffee, as one of the world's most consumed beverages, contains caffeine, chlorogenic acid, and other components that offer stimulating and antioxidant benefits. However, traditional coffee suffers from a limited flavor profile and a pronounced bitterness, and its proteins are mostly present in large molecular form, resulting in low digestibility and absorption by the human body. Current technologies for functionalizing coffee primarily focus on two aspects: first, fermenting the coffee beans themselves (such as anaerobic fermentation or yeast fermentation) to improve their flavor characteristics; and second, adding exogenous functional components, such as dietary fiber and vitamins, to coffee beverages.

[0003] However, existing technologies have significant limitations: 1. Fermentation treatment of coffee beans: This mainly focuses on the fresh coffee cherries or the initial processing stage, aiming to influence the chemical composition of coffee beans to optimize the flavor after roasting (such as acidity and body), rather than systematically creating new health-promoting substances in the final beverage. 2. Exogenous addition methods: The added functional components may have poor integration with the coffee matrix, resulting in issues such as flavor separation and stability. Furthermore, this is a physical mixing process that does not alter the large molecular structure of coffee, which is not easily absorbed. Therefore, developing a systematic fermentation method that can directionally modify the coffee matrix, endogenously create entirely new health-promoting components through biotransformation, and fundamentally improve its sensory quality is a pressing technical problem that needs to be solved in this field. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing probiotic fermented black coffee, which transforms the large molecular proteins in coffee that are difficult to absorb into easily absorbed active coffee peptides, while improving the flavor of coffee, reducing bitterness, and achieving a dual enhancement of coffee functionality and flavor.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing probiotic-fermented black coffee, comprising the following steps: 1) After grinding the coffee beans, extract the coffee concentrate; 2) Add a complex carbon source and a complex nitrogen source to the coffee concentrate, and then add a complex probiotic for fermentation. 3) The fermented coffee is sterilized to obtain the probiotic fermented black coffee.

[0006] Preferably, the coffee beans roasted in step 1) have an Agtron value of 55-65, and the grinding is done to a mesh size of 20-40.

[0007] Preferably, the extraction in step 1) is performed by hot percolation at 85-95°C, with a material-to-liquid ratio of 1 g: 15-25 mL, and the soluble solids content of the coffee concentrate is 8%-15%.

[0008] Preferably, the composite carbon source in step 2) is a mixture of glucose and maltose in a mass ratio of 1~2:1~2, and the amount added is 1%~2% of the mass of coffee concentrate; the composite nitrogen source is a mixture of yeast extract powder and soybean protein peptide in a mass ratio of 1~2:1~2, and the amount added is 0.3%~0.8% of the mass of coffee concentrate.

[0009] Preferably, the compound probiotics in step 2) are prepared by combining Lactobacillus rhamnosus GG, Saccharomyces boulardii, and Lactobacillus plantarum in a mass ratio of 1.5~2.5:0.5~1:1~1.5, with a total inoculum of (3~5)×10⁻⁶. 8 CFU / mL.

[0010] Preferably, the fermentation treatment in step 2) is carried out at 32℃~37℃ and pH 5.5~6.5 for 36~60 h, with stirring once every 4~6 hours for 5~10 min at a speed of 100~150 r / min.

[0011] Preferably, the sterilization process in step 3) involves rapidly heating to 95~105℃ and sterilizing for 10~20 minutes.

[0012] The present invention also provides a probiotic fermented black coffee prepared by the above preparation method.

[0013] Beneficial effects

[0014] This invention utilizes a compound probiotic system composed of *Lactobacillus rhamnosus* GG, *Saccharomyces boulardii*, and *Lactobacillus plantarum*. This system forms a synergistic metabolic system that not only effectively increases the content of active ingredients such as indole-3-lactic acid (≥50 μg / mL) and γ-aminobutyric acid (≥80 μg / mL), but also converts large-molecule proteins in coffee into small-molecule active coffee peptides (peptides with a molecular weight ≤3000 Da accounting for ≥70%), significantly enhancing the nutritional value and functionality of coffee. Indole-3-lactic acid possesses strong anti-inflammatory and intestinal barrier protection functions, γ-aminobutyric acid can soothe nerves and help lower blood pressure, and active coffee peptides are easily absorbed by the human body, supplementing essential amino acids and realizing the multifunctionality of coffee. The novel flavor substances produced during fermentation synergistically interact with the original flavor components of coffee, giving it a smoother and more complex flavor profile, reducing the bitterness score from 8.5 points for traditional black coffee to below 3.1 points. The preparation method of this invention is simple, uses mild conditions, is suitable for industrial production, and produces products with good stability and a long shelf life. Detailed Implementation

[0015] 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.

[0016] Example 1

[0017] High-quality Arabica coffee beans with a medium roast Agtron value of 60 were selected, requiring a moisture content of ≤12%, and free from mold and off-odors. The coffee beans were ground to 30 mesh, and water was added at a ratio of 1g:20mL. The mixture was hot-filtered at 90℃ for 25 minutes, yielding a coffee liquid with a soluble solids content of 12%. 1% by weight of a complex carbon source (composed of glucose and maltose in a 1:1 mass ratio) and 0.5% by weight of a complex nitrogen source (composed of yeast extract and soy protein peptides in a 1:1 mass ratio) were added to the coffee liquid. The pH was adjusted to 6.0, and a complex probiotic mixture of *Lactobacillus rhamnosus* GG, *Saccharomyces boulardii*, and *Lactobacillus plantarum* in a 1.5:0.5:1 mass ratio (total inoculum of 4×10⁻⁶) was added. 8 The probiotic-fermented black coffee (CFU / mL) was fermented at 37°C for 48 hours, with stirring for 10 minutes every 4 hours at a stirring speed of 120 r / min. After fermentation, it was sterilized at 100°C for 15 minutes to obtain probiotic-fermented black coffee.

[0018] Example 2

[0019] High-quality Arabica coffee beans with a medium roast Agtron value of 55 were selected, requiring a moisture content of ≤12%, and free from mold and off-odors. The coffee beans were ground to 20 mesh, and water was added at a ratio of 1g:20mL. The mixture was hot-permeated at 90℃ for 25 minutes, yielding a coffee liquid with a soluble solids content of 8%. 1% by weight of a complex carbon source (composed of glucose and maltose in a 1:1 mass ratio) and 0.5% by weight of a complex nitrogen source (composed of yeast extract and soy protein peptides in a 1:1 mass ratio) were added to the coffee liquid. The pH was adjusted to 6.0, and a complex probiotic mixture of *Lactobacillus rhamnosus* GG, *Saccharomyces boulardii*, and *Lactobacillus plantarum* in a 2:1:1.5 mass ratio (total inoculum of 4×10⁻⁶) was added. 8 The probiotic-fermented black coffee (CFU / mL) was fermented at 37°C for 36 hours, with stirring for 10 minutes every 4 hours at a stirring speed of 120 r / min. After fermentation, it was sterilized at 100°C for 15 minutes to obtain probiotic-fermented black coffee.

[0020] Example 3

[0021] High-quality Arabica coffee beans with a medium roast Agtron value of 65 were selected, requiring a moisture content of ≤12%, and free from mold and off-odors. The coffee beans were ground to 40 mesh, and water was added at a ratio of 1g:25mL. The mixture was hot-permeated at 90℃ for 25 minutes, yielding a coffee liquid with a soluble solids content of 15%. 1% by weight of a complex carbon source (composed of glucose and maltose in a 1:1 mass ratio) and 0.5% by weight of a complex nitrogen source (composed of yeast extract and soy protein peptides in a 1:1 mass ratio) were added to the coffee liquid. The pH was adjusted to 6.0, and a complex probiotic mixture of *Lactobacillus rhamnosus* GG, *Saccharomyces boulardii*, and *Lactobacillus plantarum* in a 2.5:1:1.5 mass ratio (total inoculum of 4×10⁻⁶) was added. 8 The probiotic-fermented black coffee (CFU / mL) was fermented at 37°C for 60 hours, with stirring for 10 minutes every 4 hours at a stirring speed of 120 r / min. After fermentation, it was sterilized at 100°C for 15 minutes to obtain probiotic-fermented black coffee.

[0022] Comparative Example 1

[0023] The only difference from Example 1 is that the compound probiotics are replaced with fermentation using a single Lactobacillus rhamnosus GG, and the rest of the steps are the same as in Example 1.

[0024] Comparative Example 2

[0025] The only difference from Example 1 is that the compound probiotics are replaced with fermentation using a single Saccharomyces boulardii; the rest of the steps are the same as in Example 1.

[0026] Comparative Example 3

[0027] The only difference from Example 1 is that the compound probiotics are replaced with fermentation using a single Lactobacillus plantarum; the rest of the steps are the same as in Example 1.

[0028] Comparative Example 4

[0029] The only difference from Example 1 is that Lactobacillus rhamnosus GG in the compound probiotic is replaced with Lactobacillus casei, and the rest of the steps are the same as in Example 1.

[0030] Comparative Example 5

[0031] The only difference from Example 1 is that Saccharomyces boulardii in the compound probiotics is replaced with Saccharomyces cerevisiae; the rest of the steps are the same as in Example 1.

[0032] Test case

[0033] 1. Active ingredient detection

[0034] The contents of indole-3-lactic acid and γ-aminobutyric acid were determined by high performance liquid chromatography (HPLC), and the molecular weight distribution of active coffee peptides (the proportion of peptides with a molecular weight ≤3000 Da) was determined by gel filtration chromatography. The results are shown in Table 1 below. The control group (CK) was black coffee (without fermentation) purchased from the market and prepared by conventional methods.

[0035] Table 1. Detection results of active ingredients in coffee in each group

[0036] As shown in Table 1 above, the contents of indole-3-lactic acid and γ-aminobutyric acid, as well as the proportion of active coffee peptides in the fermented coffee of Examples 1-3 of this invention, were significantly higher than those in the comparative examples. The content of active ingredients in single-strain fermentation (Comparative Examples 1-3) was extremely low, indicating that a single strain cannot achieve efficient metabolism. After replacing any strain in the compound probiotics (Comparative Examples 4-5), the content of active ingredients decreased significantly, proving that there is a synergistic effect among the three strains selected in this invention, which can synergistically promote the generation of active substances and protein conversion. Moreover, this synergistic effect is specific and the strains cannot be replaced arbitrarily.

[0037] 2. Flavor Sensory Evaluation

[0038] Thirty professional sensory evaluators were invited to score the samples based on three dimensions: bitterness, smoothness, and flavor complexity (out of 10 points, with lower bitterness scores being better and higher smoothness and flavor complexity scores being better). The results are shown in Table 2 below: Table 2 Sensory ratings of coffee in each group

[0039] As shown in Table 2, the fermented coffee of the present invention exhibits significantly reduced bitterness, greatly improved smoothness and flavor complexity, and an excellent overall score. In contrast, the flavor performance of the comparative examples is poor, further demonstrating the importance of the synergistic effect of the compound probiotics in improving coffee flavor.

[0040] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a probiotic fermented black coffee, characterized by, The method comprises the following steps: 1) grinding coffee beans to obtain coffee concentrate; 2) adding a composite carbon source and a composite nitrogen source to the coffee concentrate, and then adding a composite probiotic for fermentation treatment; 3) sterilizing the fermented coffee to obtain the probiotic fermented black coffee.

2. The production method according to claim 1, wherein In step 1), the coffee beans have a roasting degree of Agtron value 55-65, and the grinding is to 20-40 mesh.

3. The production method according to claim 1, wherein In step 1), the extraction is by hot percolation at 85-95℃, with a material-liquid ratio of 1 g:15-25 mL, and the soluble solid content of the coffee concentrate is 8%-15%.

4. The production method according to claim 1, wherein In step 2), the composite carbon source is a mixture of glucose and maltose at a mass ratio of 1-2:1-2, and the addition amount is 1%-2% of the mass of the coffee concentrate; the composite nitrogen source is a mixture of yeast extract powder and soybean protein peptide at a mass ratio of 1-2:1-2, and the addition amount is 0.3%-0.8% of the mass of the coffee concentrate.

5. The production method according to claim 1, wherein The complex probiotics in step 2) are obtained by compounding Lactobacillus rhamnosus GG, Saccharomyces boulardii and Lactobacillus plantarum at a mass ratio of 1.5-2.5:0.5-1:1-1.5, and the total inoculation amount is (3-5)×10 8 CFU / mL.

6. The production method according to claim 1, wherein In step 2), the fermentation treatment is carried out at 32-37℃ and pH 5.5-6.5 for 36-60 h, with stirring every 4-6 hours for 5-10 min at a speed of 100-150 r / min.

7. The production method according to claim 1, wherein In step 3), the sterilization treatment is rapid heating to 95-105℃ for 10-20 min.

8. The probiotic fermented black coffee prepared by the preparation method of any one of claims 1-7.

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