Method for assisted co-fermentation of banana juice based on tannase-producing lactic acid bacteria
Patent Information
- Application Number
- CN202610860182.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-15
- Publication Date
- 2026-10-16
AI Technical Summary
[0005]本发明的目的在于提供基于产单宁酶乳酸菌辅助共发酵香蕉果汁的方法，用于解决在现有技术中的香蕉发酵果汁的单宁含量较高、涩味明显、香气和滋味协调性有待提高等缺陷的技术问题
1、本发明是采用MRS液体培养基对产单宁酶乳酸菌进行复苏，再经划线纯化、一级种子液培养和二级种子液扩培，使乳酸菌由保藏状态恢复至代谢活跃状态，并调整活菌数浓度，保证后续接入香蕉汁体系中的乳酸菌具有较高活性和较稳定的降涩能力，然后通过离心、洗涤和重悬处理，减少MRS培养基残留物对香蕉果汁风味和澄清度的不利影响；在产单宁酶乳酸菌接种液进入香蕉汁后，通过产单宁酶作用水解部分可水解单宁中的酯键，使大分子单宁转化为较小分子酚酸类物质，降低发酵香蕉果汁中的单宁含量，从而降低其与唾液蛋白结合产生涩感的能力，体现出较好的降涩和改善口感效果。
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Abstract
Description
Technical Field
[0001] This invention relates to the field of fruit juice fermentation technology, and more specifically to a method for co-fermenting banana juice with the assistance of tannin-producing lactic acid bacteria. Background Technology
[0002] Bananas are a nutritious, uniquely flavored, and widely consumed tropical fruit. The pulp contains a variety of nutrients, including sugars, organic acids, dietary fiber, polyphenols, vitamins, and minerals, and has high processing value. However, bananas soften quickly after ripening, have a short storage period, and are prone to browning, rotting, and quality deterioration, resulting in significant fresh fruit loss. Processing bananas into products such as juice and fermented beverages is one of the important ways to increase the added value of bananas and extend the industrial chain.
[0003] Currently, the processing of banana juice or banana fermented beverages typically involves steps such as crushing, enzymatic hydrolysis, blending, fermentation, filtration, and sterilization. However, banana pulp contains high levels of pectin, cellulose, and insoluble solids, resulting in high viscosity and making filtration and clarification difficult. This often leads to problems such as turbidity, sedimentation, or unstable texture in the finished product. Furthermore, bananas contain a certain amount of tannins and other polyphenols, which can easily bind with salivary proteins, producing an astringent taste that affects consumer acceptance. Especially during fermentation, polyphenols, proteins, and colloidal particles may further form complexes, which not only exacerbate the astringency but also affect the product's color, clarity, and storage stability.
[0004] Methods to improve the astringency of fruit juice mainly include adsorption treatment, clarification filtration, enzyme treatment, or microbial fermentation. While adsorption treatment can remove some polyphenols, it easily adsorbs aroma substances and nutrients simultaneously, affecting the product flavor. Simple filtration or clarification treatment mainly targets suspended solids and colloidal particles, with limited effect on the targeted degradation of tannins, which are astringent. Although common lactic acid bacteria or yeast fermentation can improve the sweet and sour balance and fermentation aroma, its ability to degrade tannins is insufficient, making it difficult to stably achieve the goal of reducing astringency. In addition, if the inoculation sequence, inoculation time, and fermentation conditions are not properly controlled, problems such as excessive sourness, insufficient fermentation aroma, residual astringency, or disharmonious product flavor may occur. Summary of the Invention
[0005] The purpose of this invention is to provide a method for co-fermenting banana juice with the assistance of tannin-producing lactic acid bacteria, which solves the technical problems of high tannin content, obvious astringency, and lack of improvement in aroma and flavor harmony in banana fermented juice in the prior art.
[0006] The objective of this invention can be achieved through the following technical solution: a method for co-fermenting banana juice with the assistance of tannin-producing lactic acid bacteria, comprising the following steps: S1. Select ripe bananas free from pests and diseases, peel them, cut them into pieces, and mash them to obtain banana puree; S2. Add pectinase, cellulase and color-protecting agent to banana pulp, perform enzymatic hydrolysis, and then filter to obtain enzymatically hydrolyzed banana pulp; S3. Adjust the soluble solids content of the enzymatically hydrolyzed banana pulp to 14-22°Brix to obtain banana juice. Then, inoculate the banana juice with activated brewer's yeast liquid and ferment. On the 1st to 3rd day after the activation of brewer's yeast, inoculate with tannin-producing lactic acid bacteria liquid and continue fermentation until the soluble solids content in the fermentation liquid changes by no more than 0.2°Brix for 2-3 consecutive days to obtain co-fermentation liquid. S4. Clarify, filter and sterilize the co-fermentation broth to obtain low-astringency fermented banana juice.
[0007] Furthermore, in step S1, the thickness of the banana pieces after cutting is 1-2 cm, and the pulping process involves crushing the banana pieces into a fluid pulp.
[0008] Furthermore, in step S2, the amount of pectinase added is 0.1-0.8% of the banana pulp mass, the amount of cellulase added is 0.1-0.8% of the banana pulp mass, the enzymatic hydrolysis temperature is 50-70℃, and the enzymatic hydrolysis time is 6-8h; the color-protecting agent is potassium metabisulfite, and its addition amount is 50-150mg / L; the filtration includes sequential filtration using an 80-100 mesh filter and a 200-300 mesh filter.
[0009] Furthermore, the activated brewing yeast liquid is obtained by activating brewing yeast in a sucrose solution for 30-60 minutes.
[0010] Furthermore, the ratio of brewing yeast to sucrose solution is 1g:10mL, the mass concentration of sucrose solution is 1-3%, the temperature of sucrose solution is 28-35℃, and during activation, it can be gently shaken once every 10-15 minutes to avoid yeast sedimentation.
[0011] Furthermore, in step S3, the fermentation operation includes: performing low-intensity mixing within 0-24 hours after inoculation, then stopping the mixing, and allowing the mixture to ferment statically under a sterile, breathable membrane, wherein the fermentation temperature is 28-32℃.
[0012] Furthermore, the low-intensity mixing is performed by shaking on a shaker at a speed of 80-160 r / min for 6-10 hours.
[0013] Furthermore, the preparation method of the tannin-producing lactic acid bacteria inoculum is as follows: Take the preserved strain of tannin-producing lactic acid bacteria, inoculate it into MRS liquid medium under aseptic conditions, and culture it at 35-39℃ for 20-30 hours to obtain a revived bacterial solution; purify the revived bacterial solution by streaking it onto MRS solid medium, and incubate it statically at 35-39℃ for 24-28 hours; pick a single colony and inoculate it into MRS liquid medium, and incubate it statically at 35-39℃ for 18-24 hours to obtain a primary seed culture; inoculate the primary seed culture into fresh MRS liquid medium at a volume ratio of 3-5%, and incubate it statically at 35-39℃ for 20-30 hours to obtain a secondary seed culture; centrifuge the secondary seed culture, collect the bacterial cells, wash and resuspend them with sterile physiological saline, and adjust the viable cell count to 10⁸-10⁹ CFU / mL to obtain the tannin-producing lactic acid bacteria inoculum.
[0014] Furthermore, the inoculation volume ratio of the activated brewer's yeast liquid to the tannin-producing lactic acid bacteria inoculation liquid is 1:1, and the total inoculation amount is 3-5% of the banana juice volume.
[0015] Furthermore, the clarification includes taking the supernatant after cold settling the co-fermentation broth at 0-6℃ for 12-48 hours; the filtration is centrifugal filtration, membrane filtration, or a combination of both; and the sterilization treatment is pasteurization at 65-75℃ for 15-30 minutes.
[0016] The present invention has the following beneficial effects: 1. This invention utilizes MRS liquid culture medium to resuscitate tannin-producing lactic acid bacteria. Following streak purification, primary seed culture, and secondary seed culture expansion, the lactic acid bacteria are restored from their stored state to a metabolically active state. The viable cell concentration is adjusted to ensure high activity and stable astringency reduction capabilities of the lactic acid bacteria subsequently inoculated into the banana juice system. Centrifugation, washing, and resuspension are then performed to reduce the adverse effects of MRS medium residues on the flavor and clarity of the banana juice. After the tannin-producing lactic acid bacteria inoculum is added to the banana juice, the tannin-producing enzymes hydrolyze some of the ester bonds in the tannins, converting large tannin molecules into smaller phenolic acids. This reduces the tannin content in the fermented banana juice, thereby decreasing its ability to bind with salivary proteins and produce astringency, resulting in better astringency reduction and improved taste.
[0017] 2. This invention also utilizes pectinase and cellulase to enzymatically hydrolyze banana pulp, promoting the degradation of pectin, cellulose, and some cell wall structures in the banana pulp, reducing system viscosity, and promoting the release of fermentable sugars and aroma precursors, providing sufficient substrate for subsequent microbial fermentation. Potassium metabisulfite can inhibit enzymatic browning during banana crushing and enzymatic hydrolysis, reducing the polymerization of quinones to form brown pigments, thus helping to maintain the golden or pale yellow appearance of the finished product. After initial inoculation with brewer's yeast, sugars are converted into ethanol, carbon dioxide, and small amounts of esters, higher alcohols, and glycerol, providing the product with a fermented aroma and mellowness. Subsequently, tannin-producing lactic acid bacteria are introduced, which can further produce lactic acid and degrade tannins, creating a more harmonious balance between sourness, sweetness, fermented aroma, and astringency, thereby reducing astringency and improving overall sensory quality while maintaining the banana fruit aroma and fermented flavor.
[0018] 3. This invention also reduces the suspended solids load in the subsequent fermentation broth by removing larger pulp particles, fiber fragments, and insoluble residues through filtration after enzymatic hydrolysis; cold settling after fermentation promotes the aggregation and sedimentation of residual bacteria, pectin fragments, proteins, polyphenol complexes, and colloidal particles; ultrafiltration further retains fine suspended solids, large molecular colloids, protein-polyphenol complexes, and some high molecular weight tannins, thereby improving clarity and helping to reduce the content of astringent substances; pasteurization inactivates residual microorganisms and some enzyme activity, reducing the risk of continued fermentation, gas production, turbidity, or precipitation during subsequent storage, and improving the appearance quality and stability of low-astringency fermented banana juice. Detailed Implementation
[0019] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0020] In this invention, the preservation number of the tannin-producing lactic acid bacteria is CCTCCM20221899; In this invention, the pectinase is food grade and has an effective ingredient content of 99%. In this invention, the effective component content of cellulase is 99%, the heavy metal content is 0.001%, the enzyme activity is 200,000, and the enzyme activity retention rate is 99%. In this invention, the active ingredient content of the brewing yeast is 95%, the model is YFD-SC-068, and the grade is food grade; In this invention, the lactic acid bacteria are food-grade Lactobacillus plantarum with a content of 98%, which is water-soluble and has a concentration of 10 billion / g.
[0021] Example 1 This embodiment provides a method for preparing a tannin-producing lactic acid bacteria inoculum, specifically including the following steps: Step 1: Prepare resuscitation bacterial culture MRS medium and distilled water were mixed to obtain MRS liquid medium with a solid content of 4.9%. Take 0.5g of tannin-producing lactic acid bacteria culture and inoculate it into MRS liquid medium under aseptic conditions. Incubate at 35℃ for 20h to obtain the revived bacterial solution.
[0022] Step 2: Prepare primary seed solution The revived bacterial culture was purified by streaking on MRS solid medium and incubated at 35°C for 24 hours. Single colonies were picked and inoculated into MRS liquid medium and incubated at 35°C for 18 hours to obtain the primary seed culture.
[0023] Step 3: Prepare secondary seed solution At a volume ratio of 3%, the primary seed culture was inoculated into fresh MRS liquid medium and incubated statically at 35°C for 20 hours to obtain the secondary seed culture. Step 4: Prepare inoculum of tannin-producing lactic acid bacteria Centrifuge the secondary seed culture, collect the bacterial cells, wash and resuspend them with sterile physiological saline, and adjust the viable cell count to 10⁸-10⁹ CFU / mL to obtain the tannin-producing lactic acid bacteria inoculation solution.
[0024] Example 2 This embodiment provides a method for preparing a tannin-producing lactic acid bacteria inoculum, specifically including the following steps: Step 1: Prepare resuscitation bacterial culture MRS medium and distilled water were mixed to obtain MRS liquid medium with a solid content of 5.0%. Take 0.7g of tannin-producing lactic acid bacteria culture and inoculate it into MRS liquid medium under aseptic conditions. Incubate at 36.5℃ for 25h to obtain the revived bacterial culture.
[0025] Step 2: Prepare primary seed solution The revived bacterial culture was purified by streaking on MRS solid medium and incubated statically at 36.5℃ for 26 h. Single colonies were picked and inoculated into MRS liquid medium and incubated statically at 36.5℃ for 21 h to obtain the primary seed culture.
[0026] Step 3: Prepare secondary seed solution At a volume ratio of 4%, the primary seed culture was inoculated into fresh MRS liquid medium and incubated statically at 36.5℃ for 25 hours to obtain the secondary seed culture. Step 4: Prepare inoculum of tannin-producing lactic acid bacteria Centrifuge the secondary seed culture, collect the bacterial cells, wash and resuspend them with sterile physiological saline, and adjust the viable cell count to 10⁸-10⁹ CFU / mL to obtain the tannin-producing lactic acid bacteria inoculation solution.
[0027] Example 3 This embodiment provides a method for preparing a tannin-producing lactic acid bacteria inoculum, specifically including the following steps: Step 1: Prepare resuscitation bacterial culture MRS medium and distilled water were mixed to obtain MRS liquid medium with a solid content of 5.1%. Take 1g of tannin-producing lactic acid bacteria culture and inoculate it into MRS liquid medium under aseptic conditions. Incubate at 39℃ for 30h to obtain the revived bacterial solution.
[0028] Step 2: Prepare primary seed solution The revived bacterial culture was purified by streaking on MRS solid medium and incubated at 39°C for 28 hours. Single colonies were picked and inoculated into MRS liquid medium and incubated at 39°C for 24 hours to obtain the primary seed culture.
[0029] Step 3: Prepare secondary seed solution At a volume ratio of 5%, the primary seed culture was inoculated into fresh MRS liquid medium and incubated statically at 39°C for 30 hours to obtain the secondary seed culture. Step 4: Prepare inoculum of tannin-producing lactic acid bacteria Centrifuge the secondary seed culture, collect the bacterial cells, wash and resuspend them with sterile physiological saline, and adjust the viable cell count to 10⁸-10⁹ CFU / mL to obtain the tannin-producing lactic acid bacteria inoculation solution.
[0030] Example 4 This embodiment provides a method for co-fermenting banana juice with the assistance of tannin-producing lactic acid bacteria, specifically including the following steps: Step S1: Prepare banana pulp Select ripe, disease-free bananas, peel them, and cut them into 1cm thick pieces. Then crush the banana pieces into a fluid pulp to obtain banana pulp.
[0031] Step S2: Preparation of enzymatic hydrolysate Weigh out 0.1g of pectinase and 0.1g of cellulase according to the following weight proportions and add them to 100g of banana pulp. Then add potassium metabisulfite, a color-protecting agent, to the banana pulp at a concentration of 50mg / L. Raise the enzymatic hydrolysis temperature to 50℃ and enzymatically hydrolyze for 6 hours. Then filter the solution through an 80-mesh filter and further filter the filtrate through a 200-mesh filter to obtain enzymatically hydrolyzed banana pulp.
[0032] Step S3: Prepare activated brewing yeast liquid Mix brewing yeast and 1 wt% sucrose solution at a ratio of 1 g: 10 mL, and activate at 28°C for 30 min, gently shaking once every 10 min during the activation to prevent yeast sedimentation, thus obtaining activated brewing yeast solution.
[0033] Step S4: Prepare co-fermentation broth Distilled water was added to the enzymatically hydrolyzed banana pulp to adjust the soluble solids content to 14°Brix, thus obtaining banana juice. Weigh out 15 mL of activated brewer's yeast solution by volume and inoculate it into 1000 mL of banana juice. Shake on a shaker at 80 r / min for 6 hours, stop mixing, cover with a sterile breathable membrane, and let it ferment at 28°C. On the first day after inoculation with activated brewer's yeast, inoculate with 15 mL of tannin-producing lactic acid bacteria solution prepared in Example 1, shake on a shaker at 80 r / min for 6 hours, stop mixing, cover with a sterile breathable membrane, and let it ferment at 28°C. Continue fermentation until the soluble solids content in the fermentation broth changes by no more than 0.2°Brix for two consecutive days to obtain the co-fermentation broth.
[0034] Step S5: Prepare low-astringency fermented banana juice The co-fermentation broth was allowed to settle at 0℃ for 12 hours. The supernatant was collected and filtered using an ultrafiltration membrane with a pore size of 50-100 nm. The supernatant was then placed in an environment at 65℃ for pasteurization for 15 minutes to obtain low-astringency fermented banana juice.
[0035] Example 5 This embodiment provides a method for co-fermenting banana juice with the assistance of tannin-producing lactic acid bacteria, specifically including the following steps: Step S1: Prepare banana pulp Select ripe, disease-free bananas, peel them, and cut them into 1.5cm thick pieces. Then crush the banana pieces into a fluid pulp to obtain banana puree.
[0036] Step S2: Preparation of enzymatic hydrolysate Weigh out 0.45g of pectinase and 0.45g of cellulase according to the following proportions and add them to 100g of banana pulp. Then add potassium metabisulfite as a color-protecting agent at a concentration of 50-150mg / L to the banana pulp. Raise the enzymatic hydrolysis temperature to 6℃ and hydrolyze for 7 hours. Then filter the solution through a 90-mesh filter and further filter the filtrate through a 260-mesh filter to obtain the enzymatically hydrolyzed banana pulp.
[0037] Step S3: Prepare activated brewing yeast liquid The brewing yeast and 2wt% sucrose solution were mixed at a ratio of 1g:10mL and activated at 31℃ for 45min. During this period, the mixture was gently shaken every 13min to prevent the yeast from settling, thus obtaining the activated brewing yeast solution.
[0038] Step S4: Prepare co-fermentation broth Distilled water was added to the enzymatically hydrolyzed banana pulp to adjust the soluble solids content to 18°Brix, thus obtaining banana juice. Weigh out 20 mL of activated brewer's yeast solution by volume and inoculate it into 1000 mL of banana juice. Shake on a shaker at 120 r / min for 8 hours, then stop mixing. Cover with a sterile breathable membrane and let it ferment at 30°C. On the second day after inoculating the activated brewer's yeast, inoculate with 20 mL of the tannin-producing lactic acid bacteria solution prepared in Example 2. Shake on a shaker at 120 r / min for 8 hours, then stop mixing. Cover with a sterile breathable membrane and let it ferment at 30°C. Continue fermenting until the soluble solids content in the fermentation broth changes by no more than 0.2°Brix over two consecutive days to obtain the co-fermentation broth.
[0039] Step S5: Prepare low-astringency fermented banana juice The co-fermentation broth was allowed to settle at 3°C for 30 hours. The supernatant was collected and filtered using an ultrafiltration membrane with a pore size of 50-100 nm. The supernatant was then placed in an environment at 70°C for pasteurization for 25 minutes to obtain low-astringency fermented banana juice.
[0040] Example 6 This embodiment provides a method for co-fermenting banana juice with the assistance of tannin-producing lactic acid bacteria, specifically including the following steps: Step S1: Prepare banana pulp Select ripe, disease-free bananas, peel them, and cut them into 2cm thick pieces. Then crush the banana pieces into a fluid pulp to obtain banana pulp.
[0041] Step S2: Preparation of enzymatic hydrolysate Weigh out 0.8g of pectinase and 0.8g of cellulase according to the following weight proportions and add them to 100g of banana pulp. Then add potassium metabisulfite as a color-protecting agent at a concentration of 150mg / L to the banana pulp. Raise the enzymatic hydrolysis temperature to 70℃ and hydrolyze for 8 hours. Then filter the solution through a 100-mesh filter and further filter the filtrate through a 300-mesh filter to obtain the enzymatically hydrolyzed banana pulp.
[0042] Step S3: Prepare activated brewing yeast liquid Mix brewing yeast and 3wt% sucrose solution at a ratio of 1g:10mL, and activate at 35℃ for 60min, gently shaking once every 15min to prevent yeast sedimentation, to obtain activated brewing yeast solution.
[0043] Step S4: Prepare co-fermentation broth Distilled water was added to the enzymatically hydrolyzed banana pulp to adjust the soluble solids content to 22°Brix, thus obtaining banana juice. Weigh out 25 mL of activated brewer's yeast solution by volume and inoculate it into 1000 mL of banana juice. Shake on a shaker at 160 r / min for 10 h, stop mixing, cover with a sterile breathable membrane, and let it ferment at 32 °C. On the 3rd day after inoculation with activated brewer's yeast, inoculate with 25 mL of tannin-producing lactic acid bacteria solution prepared in Example 3, shake on a shaker at 160 r / min for 10 h, stop mixing, cover with a sterile breathable membrane, and let it ferment at 32 °C. Continue fermentation until the soluble solids in the fermentation broth change by no more than 0.2 °Brix for 3 consecutive days to obtain the co-fermentation broth.
[0044] Step S5: Prepare low-astringency fermented banana juice The co-fermentation broth was allowed to settle at 6°C for 48 hours. The supernatant was collected and filtered using an ultrafiltration membrane with a pore size of 50-100 nm. The supernatant was then placed in an environment at 75°C for pasteurization for 30 minutes to obtain low-astringency fermented banana juice.
[0045] Comparative Example 1 The difference between this comparative example and Example 6 is that, in the preparation of the tannin-producing lactic acid bacteria inoculum, lactic acid bacteria were used instead of tannin-producing lactic acid bacteria.
[0046] Comparative Example 2 The difference between this comparative example and Example 6 is that, in step S4, the inoculation time of the tannin-producing lactic acid bacteria inoculum is the 5th day after the activation of the brewing yeast.
[0047] Comparative Example 3 The difference between this comparative example and Example 6 is that, in step S4, the tannin-producing lactic acid bacteria inoculum and the activated brewer's yeast liquid are added to the banana juice at the same time.
[0048] Performance testing: Referring to the sensory index requirements in the standard GB / T 30884-2014 "Apple Cider Vinegar Beverages", 10 people (5 men and 5 women) who have received sensory evaluation training were randomly selected to score the five groups of low-astringency fermented banana juices prepared in Examples 4-6 and Comparative Examples 1-3 from four aspects: color, aroma, taste, and texture. A comprehensive scoring method with a total score of 100 points was used. The highest and lowest scores were removed, and the average score was taken as the final sensory evaluation score. The detailed sensory evaluation standards are shown in Table 1.
[0049] Table 1 - Sensory Evaluation Criteria The tannin content in the low-astringency fermented banana juices prepared in Examples 4-6 and Comparative Examples 1-3 was determined according to the standard NY / T 1600-2008 "Determination of Tannin Content in Fruits, Vegetables and Their Products - Spectrophotometric Method". The specific test data are shown in Table 2 below.
[0050] Table 2 - Performance Test Data of Samples Data Analysis: Comparative analysis of the data in the table above shows that the low-astringency fermented banana juice prepared by this invention achieves a color score of 16-17, an aroma score of 18-19, a taste score of 20-23, a texture score of 16-19, and a tannin content of 125.50-141.13 mg / L. All performance test data are superior to the comparative example. This indicates that this invention first enzymatically hydrolyzes the banana pulp using pectinase and cellulase, reducing viscosity and releasing sugars and aroma precursors. Potassium metabisulfite is used to inhibit browning and improve color. Subsequently, the juice is fermented. Yeast ferments first to produce a fermented aroma and mellow taste, then tannin-producing lactic acid bacteria are introduced to produce lactic acid to regulate the flavor and degrade tannins in the banana juice through tannin enzymes, reducing astringency. After fermentation, suspended solids, colloidal particles, and some high-molecular-weight tannins are removed through cold settling, ultrafiltration, and pasteurization, improving product clarity and storage stability. This method utilizes the synergistic effect of enzymatic pretreatment, sequential co-fermentation, and post-treatment steps to give low-astringency fermented banana juice better color, aroma, taste, and texture, while effectively reducing tannin content.
[0051] The above description is merely an example and illustration of the structure of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.
Claims
1. A method for co-fermenting banana juice with tannin-producing lactic acid bacteria, characterized in that, Includes the following steps: S1. Select ripe, disease-free bananas, peel them, cut them into pieces, and pulp them to obtain banana pulp; S2. Add pectinase, cellulase and color-protecting agent to banana pulp, perform enzymatic hydrolysis, and then filter to obtain enzymatically hydrolyzed banana pulp; S3. Adjust the soluble solids content of the enzymatically hydrolyzed banana pulp to 14-22°Brix to obtain banana juice. Then, inoculate the banana juice with activated brewer's yeast liquid and ferment. On the 1st to 3rd day after the activation of brewer's yeast, inoculate with tannin-producing lactic acid bacteria liquid and continue fermentation until the soluble solids content in the fermentation liquid changes by no more than 0.2°Brix for 2-3 consecutive days to obtain co-fermentation liquid. S4. Clarify, filter and sterilize the co-fermentation broth to obtain low-astringency fermented banana juice.
2. The method for co-fermenting banana juice with tannin-producing lactic acid bacteria according to claim 1, characterized in that, In step S1, the thickness of the banana pieces after cutting is 1-2 cm, and the pulping process involves crushing the banana pieces into a fluid pulp.
3. The method for co-fermenting banana juice with tannin-producing lactic acid bacteria according to claim 1, characterized in that, In step S2, the amount of pectinase added is 0.1-0.8% of the banana pulp mass, the amount of cellulase added is 0.1-0.8% of the banana pulp mass, the enzymatic hydrolysis temperature is 50-70℃, and the enzymatic hydrolysis time is 6-8h; the color-protecting agent is potassium metabisulfite, and its addition amount is 50-150mg / L; the filtration includes sequential filtration using an 80-100 mesh filter and a 200-300 mesh filter.
4. The method for co-fermenting banana juice with tannin-producing lactic acid bacteria according to claim 1, characterized in that, The activated brewing yeast liquid is obtained by activating brewing yeast in a sucrose solution for 30-60 minutes.
5. The method for co-fermenting banana juice with tannin-producing lactic acid bacteria according to claim 4, characterized in that, The ratio of brewing yeast to sucrose solution is 1g:10mL, the mass concentration of sucrose solution is 1-3%, the temperature of sucrose solution is 28-35℃, and during activation, it can be gently shaken once every 10-15 minutes to avoid yeast sedimentation.
6. The method for co-fermenting banana juice with tannin-producing lactic acid bacteria according to claim 1, characterized in that, In step S3, the fermentation operation includes: performing low-intensity mixing within 0-24 hours after inoculation, then stopping the mixing and allowing it to ferment statically under a sterile, breathable membrane, wherein the fermentation temperature is 28-32℃.
7. The method for co-fermenting banana juice with tannin-producing lactic acid bacteria according to claim 6, characterized in that, The low-intensity mixing is performed by shaking on a shaker at a speed of 80-160 r / min for 6-10 hours.
8. The method for co-fermenting banana juice with tannin-producing lactic acid bacteria according to claim 1, characterized in that, The preparation method of the tannin-producing lactic acid bacteria inoculum is as follows: Take the preserved strain of tannin-producing lactic acid bacteria, inoculate it into MRS liquid medium under aseptic conditions, and culture it at 35-39℃ for 20-30 hours to obtain the revived bacterial solution; purify the revived bacterial solution by streaking on MRS solid medium, and incubate it statically at 35-39℃ for 24-28 hours; pick a single colony and inoculate it into MRS liquid medium, and incubate it statically at 35-39℃ for 18-24 hours to obtain the primary seed solution; inoculate the primary seed solution into fresh MRS liquid medium at a volume ratio of 3-5%, and incubate it statically at 35-39℃ for 20-30 hours to obtain the secondary seed solution; Centrifuge the secondary seed culture, collect the bacterial cells, wash and resuspend them with sterile physiological saline, and adjust the viable cell count to 10⁸-10⁹ CFU / mL to obtain the tannin-producing lactic acid bacteria inoculation solution.
9. The method for co-fermenting banana juice with tannin-producing lactic acid bacteria according to claim 1, characterized in that, The inoculation volume ratio of the activated brewer's yeast liquid to the tannin-producing lactic acid bacteria inoculation liquid is 1:1, and the total inoculation amount is 3-5% of the banana juice volume.
10. The method for co-fermenting banana juice with tannin-producing lactic acid bacteria according to claim 1, characterized in that, The clarification includes taking the supernatant after cold settling the co-fermentation broth at 0-6℃ for 12-48 hours; the filtration is centrifugal filtration, membrane filtration, or a combination of both; and the sterilization treatment is pasteurization at 65-75℃ for 15-30 minutes.