Lactobacillus plantarum, method for increasing content of resistant starch in Chinese chestnut powder through fermentation and application of lactobacillus plantarum

Abstract

The invention belongs to the technical field of food fermentation, and particularly relates to lactobacillus plantarum, a method for increasing the content of resistant starch in Chinese chestnut powder through fermentation and application of the lactobacillus plantarum. The preservation number of the Lactobacillus plantarum CTCF0003 is GDMCC (China General Microbiological Culture Collection Center) No: 65686, and the preservation number of the Lactobacillus plantarum CTCF0003 is GDMCC No: 65686. According to the method, lactobacillus plantarum CTCF0003 is used for simple fermentation, complex enzyme generated by the lactobacillus plantarum CTCF0003 in the fermentation process is utilized, and the fermentation time is controlled to carry out preferential enzymolysis on digestible starch in the Chinese chestnut powder, so that the content of resistant starch in the Chinese chestnut powder is increased, and the Chinese chestnut powder is endowed with unique flavor quality. Meanwhile, the method is simple, convenient, practical, green, safe and efficient, a theoretical basis is provided for development of new Chinese chestnut products and control over product quality and processing technological conditions, and a foundation is provided for development of novel Chinese chestnut resistant starch products.

Description

Technical Field

[0001] The invention belongs to the technical field of food fermentation, and particularly relates to a plant lactobacillus and a method and application thereof for increasing the content of resistant starch in chestnut powder through fermentation. Background Art

[0002] Lactic acid bacteria are closely related to people's daily life and are commonly found in fermented dairy products, vegetable products, meat and other foods. At the same time, lactic acid bacteria are also the most dominant bacteria screened from most fermented starch foods. Lactic acid bacteria have amylase activity, which can degrade starch and directly convert it into low molecular weight sugars, lactic acid and volatiles. Among them, Lactobacillus is the most effective lactic acid bacteria genus for hydrolyzing starch, and Lactobacillus plantarum is the most widely distributed lactic acid bacteria in fermented foods, and has good fermentation performance and the ability to promote flavor formation.

[0003] Resistant starch (RS) refers to starch that cannot be digested and absorbed in the human small intestine, and is only fermented and utilized by intestinal bacteria in the large intestine to produce short-chain fatty acids. Resistant starch is digested slowly, and while increasing satiety, it can effectively reduce the body's postprandial blood sugar concentration. In addition, RS can be absorbed through the intestinal wall and enter the body's circulation to provide energy for the intestinal flora, which can reduce the risk of obesity and improve the intestinal flora. Therefore, increasing the proportion of resistant starch in food can effectively reduce the GI value (glycemic index) of food, thereby helping to control blood sugar levels and maintain people's health. Increasing the RS content in staple foods can be achieved by using raw materials containing natural RS or adopting appropriate processing techniques.

[0004] Chestnut is a plant of the genus Castanea in the Fagaceae family, known as "woody grain". The kernel of chestnut is rich in nutrients, including carbohydrates, proteins, vitamins, minerals, dietary fiber and other nutrients. Chestnut is rich in starch, with a content of up to 80%, and resistant starch accounts for 68.93% of the total starch content. Therefore, chestnut, as a food rich in resistant starch, has attracted much attention in recent years. It has great application potential and good market prospects in the food industry, and is a promising candidate material for modifying chestnut powder to reduce its GI. At present, the preparation methods of resistant starch are mainly concentrated in four methods: physical method, chemical method, enzymatic method and composite modification method. Although the physical method has low cost, the yield of resistant starch prepared is also low. The chemical method involves the use of chemical reagents, which has food safety risks and environmental pollution problems. The cost of the enzymatic method is too high and time-consuming. The composite modification method is more complicated because it combines two or more methods. Therefore, it is crucial to choose an economical and safe preparation method that can give food an ideal texture, good flavor, longer shelf life and rich nutritional value. Summary of the invention

[0005] The purpose of the present invention is to provide a lactobacillus plantarum and a method and application thereof for increasing the content of resistant starch in chestnut powder by fermentation. The present invention can control the fermentation time so that the lactobacillus plantarum CTCF0003 preferentially enzymolyzes the easily digestible starch in the chestnut powder, thereby increasing the content of resistant starch in the chestnut powder.

[0006] The invention provides a Lactobacillus plantarum (Lactiplantibacillus plantarum) CTCF0003. The preservation number of the Lactobacillus plantarum CTCF0003 is GDMCC No: 65686.

[0007] The present invention also provides the use of the Lactobacillus plantarum CTCF0003 in the preparation of resistant starch.

[0008] The present invention also provides a bacterial agent, comprising the fermentation product of the above-mentioned Lactobacillus plantarum CTCF0003.

[0009] The invention also provides application of the bacterial agent in preparing resistant starch.

[0010] The present invention also provides a method for increasing the content of resistant starch in chestnut powder, comprising the following steps: mixing the above-mentioned Lactobacillus plantarum CTCF0003 or the above-mentioned bacterial agent with chestnut powder to form a fermentation sample, fermenting the fermentation sample, and obtaining chestnut powder with increased resistant starch content.

[0011] As a preferred embodiment, the chestnut powder is prepared by freeze-drying chestnuts and then crushing them.

[0012] As a preferred solution, the moisture content of the chestnuts after freeze-drying is less than 10%.

[0013] As a preferred embodiment, the amount of Lactobacillus plantarum CTCF0003 added to the fermentation sample is 6 to 8 Log CFU / mL of viable bacteria.

[0014] As a preferred embodiment, the fermentation sample also includes sterile water, and the mass volume ratio of the chestnut powder to the sterile water is 20-30 g:45-55 mL.

[0015] As a preferred embodiment, the fermentation temperature is 35-39° C., the fermentation time is 6-48 hours, and the fermentation speed is 100-140 rpm.

[0016] Beneficial effects: The present invention provides a plant lactobacillus, and the deposit number of the plant lactobacillus (Lactiplantibacillus plantarum) CTCF0003 is: GDMCC No: 65686. The present invention uses plant lactobacillus CTCF0003 through simple fermentation, utilizes the complex enzyme produced by plant lactobacillus CTCF0003 during the fermentation process, and preferentially hydrolyzes the easily digestible starch in chestnut powder by controlling the fermentation time, thereby increasing the content of resistant starch in chestnut powder and giving chestnut powder a unique flavor quality. At the same time, the method of the present invention is simple, practical, green, safe, and efficient, providing a theoretical basis for the development of new chestnut products, the control of product quality and processing conditions, and providing a basis for the development of new chestnut resistant starch products.

[0017] The rapid development of bioprocessing technology in recent years has provided feasibility for the bioprocessing of chestnuts. The method of increasing the content of resistant starch in chestnut powder of the present invention has a very broad development and application prospect. Bioprocessing can make full use of the functional components in chestnuts, which is of great significance for increasing the added value of chestnuts. Therefore, the preparation method disclosed in the present invention can be applied to the green preparation of chestnut resistant starch.

[0018] Collection Instructions

[0019] Lactobacillus plantarum CTCF0003, the strain is deposited in Guangdong Microbiological Culture Collection Center (GDMCC for short), the address is: 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou, the preservation date is December 30, 2024, and the preservation number is GDMCC No: 65686. DETAILED DESCRIPTION

[0020] The invention provides a Lactobacillus plantarum (Lactiplantibacillus plantarum) CTCF0003. The preservation number of the Lactobacillus plantarum CTCF0003 is GDMCC No: 65686.

[0021] The present invention also provides the use of the Lactobacillus plantarum CTCF0003 in the preparation of resistant starch.

[0022] The plant lactobacillus CTCF0003 of the present invention can synthesize various enzyme systems including α-amylase, maltogenic amylase, amylopullanase and the like in the cell and release them into the matrix where they are located. Through these starch converting enzymes, the easily digestible starch molecules in the chestnut powder are directly or indirectly converted into oligosaccharides, thereby increasing the proportion of chestnut resistant starch content and giving the chestnut powder good flavor quality. The chestnut resistant starch obtained by the method has the advantages of being economical, green and environmentally friendly.

[0023] The present invention also provides a bacterial agent, comprising a fermentation product of the above-mentioned Lactobacillus plantarum CTCF0003. As a specific embodiment, the Lactobacillus plantarum CTCF0003 can be grown in an MRS liquid culture medium (MRS liquid culture medium formula: peptone 10.0 g, beef extract 5.0 g, yeast powder 4.0 g, glucose 20.0 g, Tween-80 1.0 mL, K 2 HPO 4 7H 2 O 2.0g, CH 3 COONa·3H 2 O 5.0g, triammonium citrate 2.0g, MgSO 4 7H 2 O 0.2g, Mn SO 4 ·4H 2 O 0.05g, pH 6.2-6.4, distilled water 1000mL, 121℃ high pressure steam sterilization for 20min) for activation culture, the culture conditions are 37℃ shaking incubator at 120rpm for 24h.

[0024] The invention also provides application of the bacterial agent in preparing resistant starch.

[0025] The present invention also provides a method for increasing the content of resistant starch in chestnut powder, comprising the following steps: mixing the above-mentioned Lactobacillus plantarum CTCF0003 or the above-mentioned bacterial agent with chestnut powder to form a fermentation sample, fermenting the fermentation sample, and obtaining chestnut powder with increased resistant starch content.

[0026] As a specific embodiment, chestnut powder was fermented using the plant lactobacillus CTCF0003 of the present invention. After 48 hours of fermentation, the pH value of the chestnut powder dropped from 6.17 to 3.78. This is mainly because during the fermentation process, the plant lactobacillus CTCF0003 produced lactic acid and other organic acids, which significantly increased the acidity, proving that the plant lactobacillus CTCF0003 was effectively fermented.

[0027] The chestnut powder of the present invention is prepared by crushing chestnuts after freeze drying, and the moisture content of the chestnuts after freeze drying is less than 10%. As a specific embodiment, the moisture content of the chestnuts can be 9%, 8%, 7%, 6%, 5%, 4%, 3.05%, 3.03%, 3%, 2% or 1%. The present invention reduces the moisture content of chestnuts to less than 10% by freeze drying, thereby ensuring the best retention of nutrients in the chestnut powder, improving the stability and processing adaptability of the chestnut powder, inhibiting the growth of microorganisms, and preventing the corruption of the chestnut powder. As a specific embodiment, the chestnut can be the Zhen'an chestnut in Shaanxi Province.

[0028] The amount of Lactobacillus plantarum CTCF0003 added to the fermentation sample is 6 to 8 Log CFU / mL of viable bacteria. As a specific embodiment, the viable bacteria count can be 6 Log CFU / mL, 7 Log CFU / mL or 8 Log CFU / mL.

[0029] The fermentation sample of the present invention also includes sterile water, and the mass volume ratio of the chestnut powder and the sterile water is 20-30g:45-55mL. As a specific embodiment, the mass volume ratio can be 20g:45mL, 20g:46mL, 20g:47mL, 20g:48mL, 20g:49mL, 20g:50mL, 20g:51mL, 20g:52mL, 20g:53mL, 20g:54mL, 20g:55mL, 25g:45mL, 25g:46mL, 25g:47mL, 25g:48mL, 25g:49mL, 20g:50mL, 20g:51mL, 20g:52mL, 20g:53mL, 20g:54mL, 20g:55mL, 25g:45mL, 25g:46mL, 25g:47mL, 25g:48mL, 25 g: 49mL, 25g: 50mL, 25g: 51mL, 25g: 52mL, 25g: 53mL, 25g: 54mL, 25g: 55mL, 30g: 45mL, 30g: 46mL, 30g: 47mL, 30g: 48mL, 30g: 49mL, 30g: 50mL, 30g: 51mL, 30g: 52mL, 30g: 53mL, 30g: 54mL or 30g: 55mL. In a specific embodiment of the present invention, the activated bacterial agent can be inoculated into sterilized distilled water at an inoculum amount of 2% by volume, shaken well, and then mixed with the sterilized chestnut powder, and stirred evenly to obtain a fermentation sample.

[0030] The fermentation temperature of the present invention is 35-39°C, the fermentation time is 6-48h, and the fermentation speed is 100-140rpm. As a specific embodiment, the fermentation temperature can be 35°C, 36°C, 37°C, 38°C or 39°C; as a specific embodiment, the fermentation time can be 6h, 12h, 18h, 24h, 30h, 36h, 42h or 48h; as a specific embodiment, the speed can be 100rpm, 105rpm, 110rpm, 115rpm, 120rpm, 125rpm, 130rpm, 135rpm or 140rpm. As a specific embodiment, the resistant starch content in the unfermented chestnut powder is 30.53%, and the peak value is 37.82% after fermentation for 36h, indicating that the maximum resistant starch ratio of chestnut powder can be obtained by fermentation time of 36h.

[0031] When the chestnut powder of the present invention is fermented by Lactobacillus plantarum CTCF0003 for 36 hours, Lactobacillus plantarum CTCF0003 can consume reducing sugars in the chestnut powder, and the mixed enzymes such as amylase and debranching enzyme metabolized by the Lactobacillus plantarum CTCF0003 can decompose substances such as protein and digestible starch, thereby increasing the mass fraction of resistant starch in the chestnut powder. Therefore, preparing chestnut resistant starch by fermenting chestnut powder with Lactobacillus plantarum CTCF0003 is a very simple, practical, green, safe and efficient method for increasing the mass fraction of resistant starch, and can give the chestnut powder the advantage of flavor quality, provide a theoretical basis for the development of new chestnut products, the control of product quality and processing conditions, and provide a basis for the development of new chestnut resistant starch products.

[0032] To further illustrate the present invention, a plant lactobacillus and a method and application of increasing the resistant starch content in chestnut powder by fermentation provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0033] Unless otherwise specified, the present invention has no special requirements for the preparation raw materials, and commercially available products known to those skilled in the art can be used.

[0034] Example 1

[0035] The method for increasing the content of resistant starch in chestnut flour by using Lactobacillus plantarum CTCF0003 provided by the present invention comprises the following steps:

[0036] (1) Preparation of chestnut powder: Fresh chestnuts from Zhen'an, Shaanxi Province were freeze-dried (water content: 3.03%), then shelled and skinned. Whole chestnut kernels without insect pests or black spots were selected and ground into powder using a universal grinder. The powder was passed through a 100-mesh sieve to obtain chestnut powder for later use.

[0037] (2) Activated bacterial agent: Lactobacillus plantarum CTCF0003GDMCC No: 65686 was added to MRS liquid medium (MRS liquid medium formula: peptone 10.0 g, beef extract 5.0 g, yeast powder 4.0 g, glucose 20.0 g, Tween-80 1.0 mL, K 2 HPO 4 7H 2 O 2.0g, CH 3 COONa·3H 2 O 5.0g, triammonium citrate 2.0g, MgSO 4 7H 2 O 0.2g, Mn SO 4 ·4H 2O 0.05g, pH 6.3, distilled water 1000mL, 121℃ high pressure steam sterilization for 20min), and the culture conditions were 37℃ shaking in 120rpm for 24h.

[0038] (3) Sterilization: Take 25g of chestnut powder and put it into a 100mL conical flask. Take another conical flask and pour 50mL of distilled water. Sterilize them with high pressure steam at 115℃ for 15min. Cool to room temperature and wait for inoculation and fermentation.

[0039] (4) Inoculation and fermentation: The bacterial agent obtained in step (2) was inoculated into the sterilized distilled water in step (3) at a volume ratio of 2%, shaken, and then mixed with the sterilized chestnut powder, stirred evenly to obtain a fermentation sample (the amount of the strain added to the fermentation sample was 7 Log CFU / mL of viable bacteria), and the fermentation sample was fermented at 37° C. and 120 rpm for 48 h. Three replicates were set.

[0040] (5) During the fermentation process, samples were taken at 0 h, 6 h, 12 h, 24 h, 36 h, and 48 h, and the pH value at different time points was measured with a pH meter. The chestnut powder was then placed in an oven at 40 °C and dried to constant weight, and the content of resistant starch and amylose in the fermented chestnut powder was measured.

[0041] (6) Resistant starch content measurement method: The resistant starch content was determined according to the official AOAC method. In brief, 100 mg of sample was mixed with 4 mL of complex enzyme solution (pH 6.0, containing 1200 U ɑ-amylase (Shanghai Yuanye Biotechnology Co., Ltd., S25975-25g), 12 U glucoamylase (Shanghai Yuanye Biotechnology Co., Ltd., S10017-250g)), and then incubated at 37 °C with continuous shaking for 16 h. After the reaction was completed, 4 mL of 95% ethanol was immediately added to inactivate the enzyme. The precipitate was obtained by centrifugation at 1500 rpm for 10 min and washed 3 times with 50% ethanol. In order to determine the content of RS (resistant starch), the precipitate was dissolved in 2 mL of 2 mol / L KOH and stirred continuously in an ice water bath for 20 min to completely gelatinize it. Then, 8 mL of 1.2 mol / L sodium acetate buffer (pH 3.8 prepared by sodium acetate (Guangdong Guanghua Technology Co., Ltd., 1.01545.020) and glacial acetic acid (Guangdong Guanghua Technology Co., Ltd., 1.14100.058)) and 0.1 mL of glucoamylase solution (1000 U) were added to the completely gelatinized sample, and further enzymolysis was performed in a 50°C water bath for 45 min to obtain an enzymolysis solution. Subsequently, the enzymolysis solution was centrifuged at 3000 r / min for 10 min to take the supernatant, transferred to a 100 mL volumetric flask, and the solution volume was adjusted to 100 mL with distilled water, and mixed thoroughly. The glucose content of the supernatant was determined by 3,5-dinitrosalicylic acid (DNS) method (DNS reagent configuration: the general configuration method is adopted as follows: 6.3 g of 3,5-dinitrosalicylic acid and 262 mL of 2 mol / L NaOH solution were added to 500 mL of hot water solution containing 185 g of potassium sodium tartrate, and then 5 g of crystalline phenol and 5 g of sodium sulfite were added and stirred to dissolve. After cooling, distilled water was added to make the volume to 1000 mL and stored in a brown bottle for one week for use.) The glucose content of the supernatant was determined by the method (Xue Hui. Preparation and Properties of Cassava Resistant Starch [D]. Henan University of Technology, 2013.), and the calculation formula is as follows:

[0042]

[0043] Wherein Gr is the reducing sugar content obtained from the corresponding glucose standard curve or regression equation (Xue Hui. Preparation and property study of cassava resistant starch [D]. Henan University of Technology, 2013.); N is the final volume of the solution (mL); W is the dry mass of the analyzed sample (g); and 0.9 is the coefficient for converting glucose to starch.

[0044] (7) Amylose content measurement method: The amylose content was determined according to the iodine reagent method used in GB7648-1987. Weigh 100 mg of the fermentation sample (based on dry weight) in a 100 mL volumetric flask, add 1 mL of anhydrous ethanol to fully wet the sample, and then add 9 mL of 1.0 mol / L NaOH. Then put the sample into a boiling water bath for 10 min to disperse the sample. Dilute the dispersed sample to 100 mL with deionized water. Subsequently, add 1.0 mL of 1.0 mol / L acetic acid and 1 mL of iodine reagent to 5.0 mL of the diluted sample, and further dilute to 100 mL with deionized water to measure the iodine starch absorbance at 620 nm on a UV-visible spectrophotometer. The relative content of amylose is estimated based on a calibration curve obtained from a series of mixtures of amylopectin standards and amylose standards in different proportions (the calibration curve refers to the calibration curve preparation method in GB7648-1987).

[0045] Results and Analysis:

[0046] 1. The pH results of chestnut powder after fermentation by Lactobacillus plantarum CTCF0003 are shown in Table 1 below: After 48 hours of fermentation, the pH value of chestnut powder dropped from 6.17 to 3.78. It is reported that the decrease in pH during fermentation indicates that the bacteria have effectively fermented the fermented material. The acidity of Lactobacillus plantarum CTCF0003 fermentation in this experiment increased significantly, which proved this and showed that the fermentation was effective. During the fermentation process, the lactic acid and other organic acids produced by Lactobacillus plantarum CTCF0003 may be the main cause of acidification, resulting in a lower pH value.

[0047] Table 1 pH results of chestnut powder after Lactobacillus plantarum fermentation

[0048] Fermentation time (h) pH 0 6.17 6 5.42 12 4.13 24 3.84 36 3.79 48 3.78

[0049] 2. The results of the measurement of chestnut amylose content after fermentation by Lactobacillus plantarum CTCF0003 are shown in Table 2: The amylose content first decreases and then increases. Specifically, the amylose content in the unfermented chestnut powder is 22.08%, which drops to 20.77% at 6h of fermentation, and then gradually increases to 23.17% at 36h of fermentation, and then drops to 21.07% at 48h. The reason may be that the amylase produced during the fermentation of Lactobacillus plantarum CTCF0003 preferentially hydrolyzes the main location of amylose-the amorphous region. As a result, some amylose can be preferentially hydrolyzed, resulting in a decrease in the amylose content at the beginning. Then, when the crystalline region is attacked, the metabolites of Lactobacillus plantarum CTCF0003 cause the degradation and debranching of amylopectin, resulting in the production of substances similar to amylose, and the amylose embedded in the crystalline region will also be released with the hydrolysis of the crystalline region. For this study, it was shown that similar enzymatic hydrolysis also occurred during the fermentation of Lactobacillus plantarum CTCF0003, reaching a maximum at 36h, and amylose was conducive to the formation of resistant starch. After 48h of fermentation, the amylose content decreased, which may be due to the fact that as the fermentation time increased, enzymatic hydrolysis and acid hydrolysis significantly acted on the amorphous region of amylose. As a result, amylose was degraded into soluble molecules such as dextrins and monosaccharides, and escaped from starch granules.

[0050] Table 2 Measurement results of chestnut amylose content after Lactobacillus plantarum fermentation

[0051] Fermentation time (h) Amylose content (%) 0 22.08 6 20.77 12 21.12 24 21.62 36 23.17 48 21.70

[0052] 3. The results of measuring the resistant starch content of chestnut after fermentation by Lactobacillus plantarum CTCF0003 are shown in Table 3: The resistant starch content in the unfermented chestnut powder was 30.53%, and reached a peak of 37.82% after 36 hours of fermentation, an increase of 7.29%, and then began to decline, and dropped to 32.61% at 48 hours. This shows that in the early stage of fermentation, Lactobacillus plantarum CTCF0003 grew rapidly and consumed a large amount of easily digestible starch, thereby rapidly increasing the proportion of resistant starch. On the other hand, studies have shown that the amylose in chestnut starch is also conducive to the formation of resistant starch. The amylose content in Table 1 also reached a peak at 36 hours of fermentation. Because amylose is conducive to the formation of resistant starch, the content of resistant starch can also reach its maximum value when fermented for 36 hours.

[0053] Table 3 Measurement results of chestnut resistant starch content after Lactobacillus plantarum fermentation

[0054] Fermentation time (h) Resistant starch content (%) 0 30.53 6 31.53 12 31.75 24 34.88 36 37.82 48 32.61

[0055] In summary, when chestnut powder is fermented with Lactobacillus plantarum CTCF0003 for 36 hours, Lactobacillus plantarum CTCF0003 can consume reducing sugars in chestnut powder, and its metabolized mixed enzymes such as amylase and debranching enzyme can decompose substances such as protein and digestible starch, thereby increasing the mass fraction of resistant starch in chestnut powder. Therefore, using Lactobacillus plantarum CTCF0003 to ferment chestnut powder to prepare chestnut resistant starch is a very simple, practical, green, safe and efficient method for increasing the mass fraction of resistant starch, and can give chestnut powder the advantages of flavor quality, providing a theoretical basis for the development of new chestnut products, the control of product quality and processing conditions, and providing a basis for the development of new chestnut resistant starch products.

[0056] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A Lactobacillus plantarum CTCF0003, characterized in that The deposit number of the Lactobacillus plantarum CTCF0003 is: GDMCC No: 65686.

2. Use of Lactobacillus plantarum CTCF0003 according to claim 1 in the preparation of resistant starch.

3. A bacterial agent, characterized in that: A fermentation product comprising the Lactobacillus plantarum CTCF0003 according to claim 1.

4. Use of the bacterial agent according to claim 3 in the preparation of resistant starch.

5. A method for increasing the content of resistant starch in chestnut flour, characterized in that: The following steps are involved: The Lactobacillus plantarum CTCF0003 described in claim 1 or the bacterial agent described in claim 3 is mixed with chestnut powder to form a fermentation sample, and the fermentation sample is fermented to obtain chestnut powder with increased resistant starch content.

6. The method according to claim 5, characterized in that The chestnut powder is prepared by freeze-drying chestnuts and then crushing them.

7. The method according to claim 6, characterized in that The moisture content of the chestnuts after freeze drying is less than 10%.

8. The method according to claim 5, characterized in that The amount of Lactobacillus plantarum CTCF0003 added to the fermentation sample is 6 to 8 Log CFU / mL of viable bacteria.

9. The method according to claim 5, characterized in that The fermented sample also includes sterile water, and the mass volume ratio of the chestnut powder to the sterile water is 20-30 g:45-55 mL.

10. The method according to claim 5, characterized in that The fermentation temperature is 35-39° C., the fermentation time is 6-48 hours, and the fermentation rotation speed is 100-140 rpm.

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