CN114480168B - Bacillus coagulans and application thereof in corn soaking - Google Patents

Abstract

The invention relates to the technical field of corn deep processing, and specifically discloses bacillus coagulans and its application in corn soaking. The preservation number of the bacillus coagulans is CGMCC No.23993. The bacillus coagulans provided by the invention has the characteristics of acid resistance, high temperature resistance, etc., and when used for soaking corn, it can significantly increase the yield of corn starch, shorten the soaking time, and reduce the amount of _SO2 used. In addition, when the Bacillus coagulans provided by the present invention is used for corn soaking, corn kernels do not need to be crushed, and corn soaking can be carried out in one step, which simplifies the process and is more suitable for industrial production applications.

Description

Bacillus coagulans and its application in corn soaking

technical field

The invention relates to the technical field of corn deep processing, in particular to a strain of bacillus coagulans and its application in corn soaking.

Background technique

The production of corn starch is mainly divided into dry method and wet method, among which the wet method is a kind of starch preparation technology that is widely used at present. In the wet process, after soaking the corn kernels, they are coarsely and finely ground to separate the germ, fiber and protein, and finally obtain high-purity cornstarch. Soaking is the first and most important process in the wet process of corn starch production. The effect of soaking has a significant impact on the yield of corn starch.

The purpose of soaking is to soften the corn kernels, destroy or weaken the binding force between protein and starch granules, and free the starch. At present, the conventional corn soaking process usually needs to add a relatively high concentration of SO ₂ (usually around 2000-5000ppm) to the soaking solution to fully destroy the protein network structure wrapped outside the starch. The _SO2 concentration in the corn soaking liquid has a great influence on the corn soaking effect. Generally, the higher the _SO2 concentration, the easier the separation of starch. When the concentration is lower than 1000ppm, its dispersing effect on the protein network is very weak, and the starch separation is difficult. .

However, the use of a large amount of SO ₂ will cause problems such as environmental pollution and equipment corrosion on the one hand, and on the other hand, it will also lead to excessive sulfurous acid residues in starch products, affecting product quality and failing to meet food safety needs. In addition, soaking takes the longest time in the whole corn starch extraction process and consumes a lot of energy, so the length of the soaking cycle has an important impact on the production efficiency of corn starch.

In recent years, in order to improve the efficiency of corn soaking and reduce the use of _SO2 in the process of corn soaking, researchers at home and abroad have developed a corn soaking process using enzyme preparations or bacterial agents for auxiliary soaking. However, the cost of enzyme preparations is high and the conditions of use are harsh, making it difficult to carry out large-scale application under industrial conditions. Moreover, because the temperature required for corn soaking is relatively high (generally around 50°C), when using enzyme preparations or bacterial agents for auxiliary soaking, considering the activity of enzymes or strains, it is usually necessary to adopt a step-by-step soaking method, that is, after using Soaking water containing SO ₂ and soaking water containing enzyme preparations or bacteria agents were used for corn soaking in the soaking stages of different temperature conditions. In addition, in order to obtain a more ideal soaking effect, it is usually necessary to crush the corn kernels when using enzyme preparations or bacterial agents to assist soaking. Therefore, although the use of enzyme preparation or bacterial agent improves the effect of corn soaking and reduces the amount of SO ₂ , it also increases equipment investment and energy consumption, prolongs the process flow, and is not conducive to the improvement of corn starch production efficiency.

Contents of the invention

The purpose of the present invention is to provide a strain of Bacillus coagulans and its application in corn soaking in order to overcome the problems of high _SO usage, long soaking time, and high energy consumption in the corn soaking process existing in the prior art. High temperature, acid resistance, etc., when using the bacterial strain and the bacterial agent prepared based on the bacterial strain in the present invention to soak corn, the soaking time can be shortened and the _SO2 consumption can be reduced. At the same time, compared with the prior art using enzyme preparations or bacteria The method provided by the invention is simpler to operate and easier to industrialize.

In order to achieve the above purpose, one aspect of the present invention provides a strain of Bacillus coagulans, the preservation number of which is CGMCC No. 23993.

The second aspect of the present invention provides an inoculant for improving corn soaking effect, the inoculum contains the Bacillus coagulans as mentioned above.

The third aspect of the present invention provides the application of the above-mentioned Bacillus coagulans or bacterial agent in the deep processing of corn.

The fourth aspect of the present invention provides a corn steeping method, the method comprising inoculating the above-mentioned Bacillus coagulans or the bacterial agent into the corn steeping liquid to carry out corn steeping.

Through the above technical scheme, the present invention can achieve the following beneficial effects:

(1) When the Bacillus coagulans provided by the present invention and the bacterial agent prepared based on the strain are used for corn soaking, the soaking effect is good and the starch yield is high.

(2) When the Bacillus coagulans provided by the present invention and the inoculum prepared based on the strain are used for soaking corn, the amount of sulfur dioxide used can be reduced (at most the amount of sulfur dioxide can be reduced to 0), which improves food safety.

(3) The Bacillus coagulans provided by the present invention has the characteristics of high temperature resistance and acid resistance, so that the strain can be inoculated into the corn soaking liquid and can be soaked in one step, that is, it does not need to be separated from the soaking liquid containing sulfur dioxide when soaking the corn. step soaking, and corn soaking does not need to crush the corn. Compared with the existing method of using high-temperature-resistant bacterial agents to assist soaking, the method provided by the invention not only reduces the amount of sulfur dioxide, but also simplifies the operation. The technological process is shortened, energy consumption and processing costs are saved, and it is very conducive to large-scale promotion and use of industrialization.

biological deposit

Bacillus coagulans in the present invention was preserved on November 29, 2021 in the General Microbiology Center of China Microbiological Culture Collection Management Committee (Address: No. 3, No. 1, Beichen West Road, Chaoyang District, Beijing, Microbiological Research, Chinese Academy of Sciences Institute, postal code: 100101) (the abbreviation of the depository unit is CGMCC), and the deposit number is CGMCC No.23993.

Detailed ways

Neither the endpoints nor any values of the ranges disclosed herein are limited to such precise ranges or values, and these ranges or values are understood to include values approaching these ranges or values. For numerical ranges, between the endpoints of each range, between the endpoints of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, these values Ranges should be considered as specifically disclosed herein.

In the present invention, unless otherwise specified, "Bacillus coagulans" and "the Bacillus coagulans" both refer to Bacillus coagulans CGMCC No.23993 provided by the present invention.

In the process of research, the inventors of the present invention accidentally discovered an acid-resistant and high-temperature-resistant Bacillus coagulans. After further research, it was found that the Bacillus coagulans has stable fermentation performance and can utilize sugars to produce lactic acid. Moreover, when the bacterial strain is added to corn soaking water, it can stably improve the corn soaking effect and increase the yield of corn starch.

Based on the above findings, the present invention provides, on the one hand, a strain of Bacillus coagulans, the preservation number of which is CGMCC No. 23993.

The second aspect of the present invention provides an inoculant for improving corn soaking effect, the inoculum contains the Bacillus coagulans as mentioned above.

In the present invention, the content of Bacillus coagulans CGMCC No. 23993 in the inoculum is not particularly limited, as long as the inoculum can improve the soaking effect and increase the yield of corn starch when the inoculum is used for corn soaking.

In the bacteria agent provided by the invention, both can only be active ingredient with Bacillus coagulans CGMCC No.23993, can also be on the basis of main active ingredient with Bacillus coagulans CGMCC No.23993, supplemented with other (can improve corn soaking effect) strains as auxiliary components.

According to a preferred embodiment of the present invention, wherein, the bacterial agent only contains the Bacillus coagulans as an effective component.

In addition to Bacillus coagulans CGMCC No.23993 (and auxiliary bacteria) as an active component, the microbial agent provided by the invention may also contain auxiliary materials. The "adjuvant" refers to non-strain ingredients that have (substantially) no effect on the action and effect of the active ingredient. Preferably, the adjuvant can be a substance that can help prolong the shelf life of the bacterial agent, improve the function and effect of the active components in the bacterial agent, and help the preparation and activity maintenance of the bacterial agent. For example, the auxiliary material may be a desiccant, a protective agent (such as a lyoprotectant, etc.) and the like.

In the present invention, there is no particular limitation on the specific type of the bacterial agent, which may be any existing bacterial agent type in the art that is convenient for use in the corn soaking process. For example, it may be a solid (dry powder) bacterial agent, a liquid bacterial agent, a concentrated (semi-liquid) bacterial agent, and the like.

The third aspect of the present invention provides the application of the above-mentioned Bacillus coagulans or bacterial agent in the deep processing of corn.

The fourth aspect of the present invention provides a corn soaking method, which includes inoculating the above-mentioned Bacillus coagulans or bacterial agent into the corn soaking liquid, and performing corn soaking.

In the present invention, the specific conditions for corn soaking are not particularly limited, and can be adjusted according to the selection of specific raw materials and processes. According to a preferred embodiment of the present invention, the conditions for soaking the corn include: soaking temperature 48-53°C, pH 2-6, soaking time 20-45h. Wherein, pH2-6 means that the initial pH of the corn soaking liquid is 2-6, preferably 2.5-5. For example, it may be 2.5, 2.7, 2.8, 3, 3.2, 3.5, 3.8, 4, 4.5, 4.8, 5, or may be any intermediate value between any two of the above-mentioned numerical values.

Preferably, the soaking time is 30-45h. For example, it may be 30h, 32h, 34h, 36h, 38h, 40h, 42h, 45h, or may be any intermediate value between any two of the above-mentioned numerical values.

In the present invention, there is no limit to the amount of Bacillus coagulans CGMCC No.23993 or the bacterial agent, as long as the corn soaking effect can be improved. According to a preferred embodiment of the present invention, wherein, the inoculation amount of the Bacillus coagulans or the bacterial agent is such that the effective number of viable bacteria of the Bacillus coagulans in the corn soaking liquid is 10 ⁶ -10 ⁸ CFU/mL. 10 ⁶ -10 ⁸ CFU/mL means that the effective viable count of Bacillus coagulans in the corn soaking liquid reaches the level of 10 ⁶ -10 ⁸ , for example, 1×10 ⁶ , 5×10 ⁶ , 8×10 ⁶ , 9.9 ×10 ⁶ , all belong to the 10 ⁶ level. That is, in the present invention, the effective viable count of Bacillus coagulans in the corn steeping liquid ranges from greater than or equal to 1×10 ⁶ CFU/mL to less than 1×10 ⁹ CFU/mL.

Preferably, the inoculation amount of the Bacillus coagulans or the bacterial agent is such that the effective number of viable Bacillus coagulans in the corn soaking liquid is 10 ⁶ -10 ⁷ CFU/mL.

Compared with directly using the (solid) bacterial agent in order to make the bacterial agent more evenly contact with the corn kernels in the corn soaking liquid, so that the corn soaking effect is further improved, according to a preferred embodiment of the present invention, wherein, it can first Prepare the Bacillus coagulans CGMCC No.23993 or the bacterial agent into a uniform aqueous solution (bacterial suspension), and then mix the aqueous solution (bacterial suspension) with the corn soaking liquid. The specific concentration of Bacillus coagulans CGMCC No.23993 (and auxiliary bacteria) in the aqueous solution (bacteria suspension) is not particularly limited, as long as its concentration after mixing with the corn soaking liquid meets the aforementioned requirements.

According to another preferred embodiment of the present invention, wherein, the Bacillus coagulans CGMCC No.23993 or bacterial agent can also be inoculated into the culture medium (expansion culture), to obtain the culture solution containing Bacillus coagulans CGMCC No.23993 , and then mix the culture solution with corn soaking water. There is no particular limitation on the specific concentration of Bacillus coagulans CGMCC No. 23993 in the culture solution, as long as its concentration after mixing with the corn steeping solution meets the aforementioned requirements.

Preferably, the content of Bacillus coagulans CGMCC No. 23993 in the culture solution makes the OD ₆₀₀ value of the culture solution reach above 5, preferably 5-7.

In the present invention, there is no particular limitation on the culture medium used for expansion, as long as it is suitable for the growth and reproduction of Bacillus coagulans. For example, corn steep liquor powder (CSLP) medium and the like can be used.

In the present invention, there are no special restrictions on the conditions for the expansion, which can be adjusted according to the characteristics of Bacillus coagulans CGMCC No. 23993 and the cultivation effect (such as the length of the cultivation time, the expansion effect, etc.). Preferably, the expansion conditions include: temperature 48-52°C, time 20-30h. The expansion culture can be carried out under shaking table conditions (for example, the rotation speed is 100-300 rpm, the shaking table culture scale is 100-1000 mL, etc.).

After further research, the inventors of the present invention found that after inoculating the Bacillus coagulans CGMCC No.23993 provided by the present invention in the corn soaking liquid, the effect of corn soaking can be effectively improved without adding sulfur dioxide, and an ideal corn soaking solution can be obtained. Starch yield. After adding a small amount of sulfur dioxide, the soaking effect of corn can be further improved.

Based on the above findings, according to a preferred embodiment of the present invention, wherein the corn steeping liquid does not contain sulfur dioxide.

According to another preferred embodiment of the present invention, wherein, the corn steeping liquid also contains sulfur dioxide.

In the present invention, the amount of sulfur dioxide is not particularly limited, as long as it can further improve the corn soaking effect. In order to obtain the ideal corn soaking effect, control problems such as nitrite residues caused by the use of sulfur dioxide, improve the food safety of the obtained corn starch, and reduce the impact of sulfur dioxide on the environment and equipment, preferably, the corn soaking The sulfur dioxide content in the liquid should not exceed 1000ppm.

More preferably, the sulfur dioxide content in the corn steeping liquid does not exceed 800ppm. It is preferably 400-800 ppm, more preferably 600-800 ppm.

The inventors of the present invention also found in the process of research that when the Bacillus coagulans CGMCC No. 23993 provided by the present invention is used to inoculate the corn soaking liquid, when the corn is soaked, it is not necessary to crush the corn (grain) to obtain a more ideal soaking effect.

Therefore, based on the above findings, according to a preferred embodiment of the present invention, wherein the method does not include the step of crushing corn.

In addition, the Bacillus coagulans CGMCC No.23993 provided by the present invention has the characteristics of acid resistance and high temperature resistance, so the corn (grains) can be directly soaked in the corn soaking liquid containing Bacillus coagulans CGMCC No.23993 (and SO ₂ ) , using the aforementioned soaking conditions to carry out "one-step" corn soaking.

The present invention will be described in detail below by way of examples. It should be understood that the following examples are only used to further explain and illustrate the content of the present invention by way of example, and are not intended to limit the present invention.

In the following examples, unless otherwise specified, the reagents used were all purchased from regular chemical reagent or biological reagent suppliers, and the purity was chemically pure.

In the following examples, unless otherwise specified, the treatment temperature is room temperature (25±3° C.).

In the following examples, the formula of the corn steep liquor dry powder medium that adopts is: glucose 20g/L, corn steep liquor dry powder 16g/L, triammonium citrate 2g/L, sodium acetate 2g/L, dipotassium hydrogen phosphate 2g/L, Magnesium sulfate 0.2g/L, manganese sulfate 0.05g/L.

Example 1

This example is used to illustrate the isolation, purification and preservation of Bacillus coagulans CGMCC No. 23993 provided by the present invention.

(1) Strain isolation and purification

The inventor of the present invention isolated and obtained a strain of Bacillus coagulans CGMCC No.23993 from the corn soaking liquid used in the countercurrent soaking process in the corn starch production line of COFCO Biochemical Energy (Yum) Co., Ltd. The specific separation and purification process is as follows:

Corn steep liquor dry powder liquid medium is used as enrichment medium, and its composition is: glucose 20g/L, beef extract 10g/L, peptone 10g/L, yeast extract 5g/L, triammonium citrate 2g/L, sodium acetate 5g /L, dipotassium hydrogen phosphate 2g/L, magnesium sulfate 0.2g/L, manganese sulfate 0.05g/L.

Take COFCO Biochemical Energy (Yumshu) Co., Ltd., 0.5mL of corn soaking solution from the countercurrent soaking process of corn soaking for 6h, put it in the enrichment medium, and carry out subculture in a constant temperature incubator at 50±2℃, and culture for each subculture for 24h .

After 20 passages, the growth of the bacteria tended to be stable, and a microbial flora with high temperature resistance, acid resistance, lactic acid production capacity and stable flora structure was isolated from it. A single colony DUT21 was isolated from the above-mentioned microbial flora by streaking, separation, and purification on a plate, and was identified by 16s rDNA full sequence comparison (consigned to Sangon Bioengineering (Shanghai) Co., Ltd.), and the strain DUT21 was condensed spores Bacillus coagulans.

(2) Strain preservation

The isolated Bacillus coagulans (Bacillus coagulans) DUT21 was preserved on November 29, 2021 in the General Microbiology Center of the China Committee for the Collection of Microbial Cultures (Address: No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, Microbiology, Chinese Academy of Sciences Research Institute, postal code: 100101) (the abbreviation of the depository unit is CGMCC), and the deposit number is CGMCC No.23993.

Example 2

This example is used to illustrate the improvement of the corn soaking effect of Bacillus coagulans CGMCC No.23993 provided by the present invention.

Bacillus coagulans DUT21 was cultured with corn steep liquor dry powder medium, and the specific culture conditions included: 200rpm shaker culture at a temperature of 50±2°C for 24 hours to obtain DUT21 culture medium for use. The OD ₆₀₀ value of the DUT21 culture solution was detected to be about 6.1±0.7 (the effective number of viable bacteria equivalent to DUT21 was about 6.08×10 ⁸ CFU/mL).

(1) Effect of Bacillus coagulans DUT21 inoculation amount on corn soaking effect

The inoculation amount of the DUT21 culture solution is 4 volume%, 6 volume%, 8 volume%, 10 volume%, 12 volume%, and the total volume is 150mL (remainder is filled with sterile water). A certain amount of SO ₂ is introduced into the soaking liquid so that the concentration of SO ₂ in the soaking liquid is 1000 ppm. Add 40 g of corn grains to the corn soaking liquid, and soak at 50±2°C for 44 hours to obtain a soaking mixture.

The soaking mixture was finely crushed and then passed through a 50-mesh sieve and a 200-mesh sieve, and the filtrate was left to stand overnight (room temperature, about 15h), centrifuged (3700rpm, 10min) and dried (50±2°C, dried to constant temperature) Heavy) after processing, cornstarch is obtained.

The following formula was used to calculate the yield of cornstarch obtained with different inoculum sizes, and the specific results are shown in Table 1.

Corn starch yield (%) = (W2/W1) × 100%

In the formula, W2 is the mass of cornstarch obtained (g); W1 is the dry weight of corn after soaking (g).

Table 1

(2) Influence of _{SO2concentration} on soaking effect of corn in soaking liquid

The inoculation amount of the DUT21 culture solution is 10% by volume, and the corn soaking solution with a total volume of 150mL (the remainder is filled up with sterile water) is passed into the soaking solution with different amounts of SO ₂ , so that the SO in the soaking solution ₂ Contents are 0, 400ppm, 600ppm, 800ppm, 1000ppm respectively. Add 40g of corn kernels to the corn soaking liquid and soak at 50±2°C for 44h. Corn starch was prepared by the method in test (1), and the yield of corn starch was calculated. The results are detailed in Table 2.

Table 2

Note: In Table 2, Yield I is the yield of corn starch in the control group soaked only in SO ₂ , and Yield II is the yield of corn starch in the experimental group soaked in combination with Bacillus coagulans and SO ₂ .

(3) The influence of soaking time on corn soaking effect

Adopting the inoculation amount of DUT21 nutrient solution is 10 volume %, and the total volume is 150mL (surplus fills up with sterile water) corn steeping liquid, feeds _SO in this corn steeping liquid Make the sulfur dioxide content in the soaking liquid be 1000ppm. Add 40g of corn kernels to the corn soaking liquid, and soak at 50±2°C for 24h, 30h, 36h, and 40h respectively. Corn starch was prepared by the method in test (1), and the yield of corn starch was calculated. The results are detailed in Table 3.

table 3

Soaking time/h twenty four 30 36 40 Corn starch yield/% 47.0 61.2 63.5 63.2

According to the content in Table 3, it can be seen that in the process of preparing corn starch, when the corn soaking solution containing DUT21 culture solution is used for corn soaking, the corn starch yield of more than 60% can be achieved in only 30 hours. This shows that Bacillus coagulans DUT21 can effectively shorten the corn soaking time and improve the corn soaking effect.

The preferred embodiments of the present invention have been described in detail above, however, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the disclosed content of the present invention. All belong to the protection scope of the present invention.

Claims (14)

1. The bacillus coagulans (Bacillus coagulans) is characterized by having a preservation number of CGMCC No.23993.

2. A microbial inoculum for improving corn soaking effect, which is characterized in that the microbial inoculum contains the bacillus coagulans according to claim 1.

3. The microbial inoculum according to claim 2, wherein the microbial inoculum contains only the bacillus coagulans as an effective component.

4. A microbial agent according to claim 2 or 3, wherein the microbial agent further comprises an auxiliary material.

5. The microbial agent of claim 4, wherein the adjuvant is selected from a desiccant and/or a protectant.

6. Use of bacillus coagulans according to claim 1 or a microbial inoculum according to any one of claims 2-5 in corn further processing.

7. A method for steeping corn, comprising inoculating bacillus coagulans according to claim 1 or a microbial inoculum according to any one of claims 2-5 into a corn steep liquor for steeping corn.

8. The method of claim 7, wherein the corn steep conditions comprise: soaking temperature is 48-53 ℃, pH is 2-6, and soaking time is 20-45h.

9. The method of claim 7, wherein the bacillus coagulans or the microbial inoculum is inoculated in an amount such that the effective viable count of bacillus coagulans in the corn steep liquor is 10 ⁶ -10 ⁸ CFU/mL。

10. The method of claim 9, wherein the bacillus coagulans or the microbial inoculum is inoculated in an amount such that the corn steep liquorThe effective viable count of the bacillus coagulans is 10 ⁶ -10 ⁷ CFU/mL。

11. The method of claim 7 wherein the corn steep water further comprises sulfur dioxide.

12. The method of claim 11 wherein the sulfur dioxide content of the corn steep liquor is no more than 1000ppm.

13. The method of claim 12, wherein the sulfur dioxide content of the corn steep liquor is no more than 800ppm.

14. A method according to any one of claims 7 to 13, wherein the method does not include the step of crushing the corn.