Microbial community agent and method for preparing liquid vinegar using the same

Abstract

This invention provides a microbial community inoculant and a method for preparing liquid vinegar, relating to the field of microbial fermentation technology. The microbial community inoculant of this invention includes acetic acid bacteria, lactic acid bacteria, and yeast. The preparation method includes: inoculating rice with the microbial community inoculant after liquefaction and saccharification, and then carrying out micro-aerobic fermentation and aerobic fermentation to obtain liquid vinegar. During the micro-aerobic fermentation process, yeast consumes dissolved oxygen, grows, and accumulates a certain amount of alcohol. Simultaneously, lactic acid bacteria obtain a favorable acid-producing environment, accumulating lactic acid and other substances that enhance the flavor of vinegar. Acetic acid bacteria can both grow in this environment and continuously accumulate acetic acid using the slowly produced alcohol from yeast. The microbial community inoculant of this invention has the effect of increasing the content of flavor substances and enhancing the taste of liquid fermented vinegar.

Description

Technical Field

[0001] This invention belongs to the field of microbial fermentation technology, and particularly relates to a microbial community inoculant and a method for preparing liquid vinegar. Background Technology

[0002] Acetic acid bacteria, as one of the important industrial microorganisms, are mainly used in the brewing of vinegar, enzymes, and fruit vinegar beverages. Through the fermentation of microorganisms, the alcohol in the raw materials is oxidized into acetic acid, giving the product a unique taste. In addition, various physiologically active substances are produced during the fermentation process, which, along with their special taste and health benefits, make acetic acid bacteria fermented products widely popular.

[0003] Vinegar is an essential condiment in daily life. Traditional processing methods are divided into solid-state fermentation and liquid-state fermentation. Vinegar produced by solid-state fermentation has a superior flavor, but the process takes several months, and its cumbersome production process limits its mechanization and large-scale development. The international market mainly uses liquid-state fermented vinegar. Liquid-state fermentation is simple and fast, using a segmented semi-continuous fermentation method, which only requires 12-24 hours of fermentation before the product can be divided and discharged. However, the semi-continuous rapid fermentation mode and the use of a single strain of bacteria, such as Hu Niang 1.01 fermentation, result in insufficient flavor compounds in the vinegar. The single acetic acid taste is pungent and astringent, which greatly limits the development of acetic acid bacteria fermented products.

[0004] Currently, liquid fermented vinegar first uses yeast to convert liquefied saccharified sugars into alcohol under anaerobic conditions, and then uses acetic acid bacteria to convert the alcohol into acetic acid under aerobic conditions. This two-step fermentation process increases the operational steps and control complexity of vinegar brewing. Therefore, there is an urgent need to invent a method for preparing liquid vinegar that can improve the content of flavor compounds in the product and simplify the fermentation process. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a microbial community inoculant and a method for preparing liquid vinegar, which simplifies the operation steps of acetic acid-related products, increases the content of flavor substances, and enhances the taste of liquid fermented vinegar by utilizing the microbial community inoculant.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a microbial community inoculant for preparing liquid vinegar, comprising acetic acid bacteria, lactic acid bacteria, and yeast; wherein the acetic acid bacteria are pasteurized acetic acid bacteria or malodorous acetic acid bacteria; the yeast is brewer's yeast; and the lactic acid bacteria are any two or more of Lactobacillus helveticus, Lactobacillus plantarum, Lactobacillus casei, or Lactobacillus pentosus.

[0008] Preferably, the mass ratio of the acetic acid bacteria, lactic acid bacteria and yeast is 3:(5-15):(1-2).

[0009] Preferably, the viable count of the acetic acid bacteria is >50 billion / g; the viable count of the lactic acid bacteria is >100 billion / g; and the viable count of the yeast is >20 billion / g.

[0010] This invention also provides a method for preparing liquid vinegar using the above-mentioned microbial community inoculant, comprising: soaking rice, mixing it sequentially with liquefying enzyme and saccharifying enzyme, and after liquefaction and saccharification, adding the above-mentioned microbial community inoculant, first performing micro-aerobic fermentation, and then performing aerobic fermentation to obtain the liquid vinegar; the micro-aerobic fermentation is carried out at a rotation speed of 50-60 r / min, a time of 16 h-3 d, and a temperature of 25-40 °C.

[0011] Preferably, the aerobic fermentation is carried out at a speed of 120-150 r / min, for a time of 1-10 days, and at a temperature of 25-40℃.

[0012] Preferably, the inoculum amount of the microbial community agent is 0.01%-0.5%.

[0013] Preferably, during the soaking process, the mass ratio of rice to water is 1:(2-5).

[0014] Preferably, the liquefaction process involves a pH value of 6.0-6.5, a temperature of 80-90°C, and a time of 10-30 minutes.

[0015] Preferably, the Baume degree is adjusted to 7.0-7.5 before saccharification; the saccharification temperature is 50-60℃ and the time is 1-3h.

[0016] The present invention also provides liquid vinegar obtained by the above preparation method.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] This invention provides a microbial community inoculant, comprising acetic acid bacteria, lactic acid bacteria, and yeast. The preparation method includes: inoculating rice with the microbial community inoculant after liquefaction and saccharification, followed by micro-aerobic fermentation and aerobic fermentation to obtain liquid vinegar. During the micro-aerobic fermentation process, yeast consumes dissolved oxygen, grows, and accumulates a certain amount of alcohol. Simultaneously, lactic acid bacteria obtain a favorable acid-producing environment, accumulating lactic acid and other substances that enhance vinegar flavor. Acetic acid bacteria can both grow in this environment and continuously accumulate acetic acid using the slowly produced alcohol from yeast. The microbial community inoculant of this invention has the effect of increasing the content of flavor substances and enhancing the taste of liquid-fermented vinegar.

[0019] Experimental results show that the liquid vinegar prepared by the present invention has an acetic acid content of 5.6-6.1% and a lactic acid content of 1.5-2.5%, which are significantly higher than those of the comparative example. Attached Figure Description

[0020] Figure 1 This is the HPLC chromatogram of liquid vinegar from Example 2. Detailed Implementation

[0021] This invention provides a microbial community inoculant for preparing liquid vinegar, comprising acetic acid bacteria, lactic acid bacteria, and yeast; wherein the acetic acid bacteria are pasteurized acetic acid bacteria or putrefactive acetic acid bacteria; the yeast is brewer's yeast; and the lactic acid bacteria are any two of Lactobacillus helveticus, Lactobacillus plantarum, Lactobacillus casei, or Lactobacillus pentosus.

[0022] In this invention, the preferred mass ratio of acetic acid bacteria, lactic acid bacteria, and yeast is 3:(5-15):(1-2), more preferably 3:10:2; the viable count of the acetic acid bacteria is preferably >50 billion / g; the viable count of the lactic acid bacteria is preferably >100 billion / g; and the viable count of the yeast is preferably >20 billion / g.

[0023] The microbial community inoculant of this invention is preferably in the form of microbial powder; this invention does not have a special limitation on the source of the microorganisms, which can be prepared by the manufacturer or commercially available products in the field. The microorganisms of this invention are preferably purchased from companies such as Microcare Probiotics (Suzhou) Co., Ltd., Danisco, Chr. Hansen, and Angel Yeast.

[0024] This invention also provides a method for preparing liquid vinegar using the above-mentioned microbial community inoculant, comprising: soaking rice, mixing it sequentially with liquefying enzyme and saccharifying enzyme, and after liquefaction and saccharification, adding the above-mentioned microbial community inoculant, first performing micro-aerobic fermentation, and then performing aerobic fermentation to obtain the liquid vinegar; the micro-aerobic fermentation is carried out at a rotation speed of 50-60 r / min, a time of 16 h-3 d, and a temperature of 25-40 °C.

[0025] In this invention, the inoculum amount of the microbial community agent is preferably 0.01%-0.5%, more preferably 0.15%; the rotation speed of the micro-aerobic fermentation is preferably 60 r / min, the time is preferably 1 day, and the temperature is preferably 30℃; the rotation speed of the aerobic fermentation is preferably 150 r / min, the time is preferably 8 days, and the temperature is preferably 30℃.

[0026] The microaerobic fermentation described in this invention allows yeast to grow, although its growth rate is limited by insufficient dissolved oxygen. However, it also allows the accumulation of a certain amount of alcohol. The yeast consumes dissolved oxygen, while the lactic acid bacteria also obtain a favorable environment for acid production, accumulating lactic acid and other substances that enhance the flavor of vinegar. Under microaerobic conditions, the yeast in this invention can both grow and the lactic acid bacteria can accumulate alcohol. During microaerobic fermentation, the acetic acid bacteria can both grow and continuously accumulate acetic acid using the slowly produced alcohol from the yeast (alcoholic fermentation should be anaerobic, while acetic acid fermentation should be aerobic; traditional fermentation is done separately, first by inoculating yeast for anaerobic preparation, then by inoculating acetic acid bacteria for aerobic vinegar production. This invention achieves a microaerobic equilibrium, allowing both reactions to occur simultaneously). The aerobic conditions described in this invention, i.e., dissolved oxygen, meet the acid production needs of the acetic acid bacteria.

[0027] The preparation method of the present invention can reduce the number of operation steps in the liquid vinegar brewing process, improve work efficiency, increase the degree of mechanization, and increase the variety of organic acids in the liquid vinegar product, thereby enhancing the flavor of the liquid vinegar product.

[0028] The acetic acid fermentation raw materials of the present invention preferably include rice or glutinous rice; during the soaking process, the mass ratio of rice to water is preferably 1:(2-5), more preferably 1:3.

[0029] The pH value of liquefaction in this invention is preferably 6.0-6.5, more preferably 6.3, the temperature is preferably 80-90℃, more preferably 90℃, and the time is preferably 10-30 min, more preferably 10 min; after liquefaction, an enzyme inactivation step is also preferably included, and the enzyme inactivation method is preferably boiling, with a time preferably 10-30 min, more preferably 10 min.

[0030] Preferably, the Baume degree is adjusted to 7.0-7.5 before saccharification, more preferably 7.5; the saccharification temperature is preferably 50-60℃, more preferably 60℃, and the saccharification time is preferably 1-3h, more preferably 1h.

[0031] The present invention also provides liquid vinegar obtained by the above preparation method.

[0032] Experimental results show that the liquid vinegar prepared by the present invention has an acetic acid content of 5.6-6.1% and a lactic acid content of 1.5-2.5%, which are significantly higher than those of the comparative example.

[0033] 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.

[0034] Example 1

[0035] Preparation of microbial community inoculants

[0036] The microbial community inoculant was obtained by mixing pasteurized acetic acid bacteria powder, brewer's yeast, Lactobacillus helveticus powder and Lactobacillus plantarum powder in a weight ratio of 3:10:1:1.

[0037] Example 2

[0038] Preparation of microbial community inoculants

[0039] The microbial community inoculant was obtained by mixing pasteurized acetic acid bacteria powder, brewer's yeast, Lactobacillus helveticus powder and Lactobacillus plantarum powder in a weight ratio of 3:5:0.5:0.5.

[0040] Example 3

[0041] Preparation of microbial community inoculants

[0042] The microbial community inoculant was obtained by mixing pasteurized acetic acid bacteria powder, brewer's yeast, lactobacillus plantarum, lactobacillus helveticus powder and lactobacillus pentosus in a weight ratio of 3:15:0.7:0.7:0.7.

[0043] Example 4

[0044] Preparation method of liquid vinegar

[0045] (1) Soak 250g of glutinous rice until it can be crushed by hand, add 750g of water, adjust the pH to about 6.4, add liquefying enzyme to liquefy; liquefy at 90℃ for 10min; boil for 10min to inactivate the enzyme; then add water to adjust the Baume degree to 7.5, add saccharifying enzyme and saccharify at 60℃ for 1h.

[0046] (2) Add 0.15% of the microbial community inoculant of Example 1 to the saccharified sample and carry out micro-aerobic fermentation for 1 day at a speed of 60 rpm. Then increase the speed to 150 rpm and carry out aerobic fermentation for 8 days to obtain the liquid vinegar.

[0047] Example 5

[0048] Preparation method of liquid vinegar

[0049] (1) Soak 250g of rice until it can be crushed by hand, add 750g of water, adjust the pH to about 6.4, add liquefying enzyme to liquefy; liquefy at 85℃ for 20min; boil for 20min to inactivate the enzyme; then add water to adjust the Baume degree to 7.0, add saccharifying enzyme and saccharify at 55℃ for 2h.

[0050] (2) Add 0.01% of the microbial community inoculant of Example 2 to the saccharified sample and carry out micro-aerobic fermentation for 3 days at a speed of 50 rpm. Then increase the speed to 120 rpm for aerobic fermentation for 10 days. The final product has an acetic acid content of 5.4% and a lactic acid content of 1.5%.

[0051] Example 6

[0052] Preparation method of liquid vinegar

[0053] (1) Soak 250g of rice until it can be crushed by hand, add 750g of water, adjust the pH to about 6.4, add liquefying enzyme to liquefy; liquefy at 80℃ for 30min; boil for 15min to inactivate the enzyme; then add water to adjust the Baume degree to 7.5, add saccharifying enzyme and saccharify at 50℃ for 3h.

[0054] (2) Add 0.5% of the microbial community inoculant of Example 3 to the saccharified sample and carry out micro-aerobic fermentation for 16 hours at a speed of 55 rpm. Then increase the speed to 120 rpm for aerobic fermentation for 3 days. The final product has an acetic acid content of 5.8% and a lactic acid content of 2.0%.

[0055] Comparative Example 1

[0056] The specific implementation method is the same as in Example 4, except that the microbial community inoculant is Pasteurella multocida and Saccharomyces cerevisiae in a mass ratio of 3:10.

[0057] Comparative Example 2

[0058] The specific implementation method is the same as in Example 4, except that the microbial community inoculant is *Lactobacillus pasteurellii* and *Lactobacillus plantarum* in a mass ratio of 3:1:1.

[0059] Comparative Example 3

[0060] The specific implementation method is the same as in Example 4, except that it does not include the micro-aerobic fermentation step. The entire process is carried out at 150 rpm for aerobic fermentation, and the time is 9 days.

[0061] Comparative Example 4

[0062] The specific implementation method is the same as in Example 4, except that it does not include an aerobic fermentation step. The entire process is carried out at 60 rpm for micro-aerobic fermentation, and the time is 9 days.

[0063] Comparative Example 5

[0064] (1) Soak 250g of glutinous rice until it can be crushed by hand, add 750g of water, adjust the pH to about 6.4, add liquefying enzyme to liquefy; liquefy at 90℃ for 10min; boil for 10min to inactivate the enzyme; then add water to adjust the Baume degree to 7.5, add saccharifying enzyme and saccharify at 60℃ for 1h.

[0065] (2) Add 0.15% yeast to the saccharified sample and carry out alcoholic fermentation for 5 days under static conditions. Then add acetic acid bacteria and increase the rotation speed to 150 rpm for aerobic fermentation for 8 days to obtain the liquid vinegar.

[0066] Experimental Example 1

[0067] The acetic acid and lactic acid contents of the liquid vinegars prepared in Examples 4-6 and Comparative Examples 1-5 were determined, and the specific results are shown in Table 1. Acetic acid and lactic acid were detected by HPLC. The chromatographic column was Agilent Hi-Plex H, 7.7 × 300 mm, 8 μm (p / n PL1170-6830), the mobile phase was 0.1 M sulfuric acid, the UV detector was 210 nm, and the flow rate was 0.4 mL / min.

[0068] Table 1. Acetic acid and lactic acid content in liquid vinegar of Example 1 and Comparative Examples 1-4

[0069]

[0070] As shown in Table 1, the liquid vinegar of the present invention significantly increases the content of acetic acid and lactic acid compared to the comparative example.

[0071] Experiment Example 2

[0072] Sensory evaluation

[0073] Vinegar Preference Rating Rules: Invite 20 people with sensory evaluation experience to conduct a sensory evaluation of the vinegar. ① Smell the typical aroma of the vinegar; ② Taste the vinegar for its acidity and flavor richness; finally, rate the vinegar according to preference, with 10 points being the highest. Discard the two highest and two lowest scores from the 20 participants and take the average.

[0074] Following the rules described above, sensory evaluations were conducted on the liquid vinegar of Example 4 and Comparative Example 1, as well as commercially available Hengshun 9-degree rice vinegar. The specific results are shown in Table 2.

[0075] Table 2 Sensory ratings of different liquid vinegars

[0076]

[0077] As shown in Table 2, the liquid vinegar prepared by this invention has a rich aroma and a mild taste, and its sensory properties are better than those of commercially available rice vinegar and the liquid vinegar of Comparative Example 1.

[0078] 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 microbial community inoculant for preparing liquid vinegar, characterized in that, The microbial community inoculant is composed of Pasteurella acetic acid powder, Saccharomyces cerevisiae, Lactobacillus helveticus powder and Lactobacillus plantarum powder in a weight ratio of 3:(5-10):(0.5-1):(0.5-1); Alternatively, the microbial community inoculant may be composed of Pasteurella acetic acid powder, Saccharomyces cerevisiae, Lactobacillus plantarum, Lactobacillus helveticus powder, and Lactobacillus pentosaccharide in a weight ratio of 3:15:0.7:0.7:0.

7.

2. The microbial community inoculant according to claim 1, characterized in that, The viable count of acetic acid bacteria is >50 billion / g; the viable count of lactic acid bacteria is >100 billion / g; and the viable count of yeast is >20 billion / g.

3. A method for preparing liquid vinegar using the microbial community inoculant according to any one of claims 1-2, characterized in that, include: Rice is soaked and then mixed with liquefying enzyme and saccharifying enzyme in sequence. After liquefaction and saccharification, the microbial community inoculant described in any one of claims 1-2 is added. Micro-aerobic fermentation is carried out first, followed by aerobic fermentation to obtain the liquid vinegar. The microaerobic fermentation was carried out at a rotation speed of 50-60 r / min, a time of 16 h-3 d, and a temperature of 25-40℃. The aerobic fermentation process is carried out at a speed of 120-150 r / min, a time of 1-10 days, and a temperature of 25-40℃.

4. The method according to claim 3, characterized in that, The inoculum amount of the microbial community agent is 0.01%-0.5%.

5. The method according to claim 3, characterized in that, During the soaking process, the mass ratio of rice to water is 1:(2-5).

6. The method according to claim 3, characterized in that, The liquefaction process involves a pH value of 6.0-6.5, a temperature of 80-90℃, and a time of 10-30 minutes.

7. The method according to claim 3, characterized in that, The Baume degree is adjusted to 7.0-7.5 before saccharification; the saccharification temperature is 50-60℃ and the time is 1-3 hours.

8. Liquid vinegar obtained by the method according to any one of claims 3-7.

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