A method for semi-solid brewing of Luzhou-flavor liquor with antioxidant activity

Abstract

The application discloses a method for brewing semi-solid state Luzhou-flavor liquor with antioxidant activity, which comprises the following steps: adding high-gluten corn bran obtained by regulating the milling and steaming procedure into low-gluten corn, and adding composite reinforcing strains to the corn, so as to brew Luzhou-flavor liquor with good antioxidant activity and improved flavor quality. The composite reinforcing strains are composed of Saccharomycopsis fibuligera and Bacillus subtilis. The method for brewing Luzhou-flavor liquor with high antioxidant activity comprises the following steps: adding high-gluten corn bran obtained by the specific milling and steaming procedure into low-gluten corn, and adding composite reinforcing strains with specific amount and proportion to semi-solid state fermentation with specific Luzhou-flavor Daqu, so as to obtain liquor with antioxidant activity of more than 80% and meeting the national standard of semi-solid state Luzhou-flavor liquor.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of liquor brewing, and particularly relates to a method for semi-solid brewing of Luzhou-flavor liquor with antioxidant activity, and more particularly to a method for semi-solid brewing of Luzhou-flavor liquor with antioxidant activity by adding back highland barley skin to regulate tannin content in highland barley system and compound reinforcing strains. BACKGROUND

[0002] Liquor is a traditional fermented food in China, and has a history of more than 2000 years. In addition to containing a variety of flavoring substances, liquor also contains some potential functional ingredients such as antioxidant active substances. It has been found that phenolic substances in liquor such as guaiacol and 2,4-di-tert-butyl phenol are related to antioxidant activity, immune enhancement and triglyceride reduction. Liquor brewing requires the participation of various microorganisms from the brewing environment, Daqu and pit. During the fermentation process, microorganisms metabolize various enzymes, which convert starch, protein and other compounds in raw materials into functional active ingredients and other trace ingredients in liquor. The improvement of liquor quality is achieved by isolating and screening reinforcing strains for reinforcing koji making, reinforcing artificial pit mud and functional microorganism expansion and addition.

[0003] Tannin is a polyphenol compound with high molecular weight, which is divided into hydrolytic tannin, condensed tannin and complex tannin, and is an indispensable source of unique flavor substances and functional substances of liquor. Highland barley seeds mainly exist in highland barley seed coat, most of which belong to condensed tannin, also known as proanthocyanidin, which is condensed by catechin and epicatechin monomers. Tannin in highland barley forms small molecular phenolic substances through enzymatic action, and generates some phenolic acids under the catalysis of related enzymes, and then further decarboxylation to form volatile phenolic substances such as guaiacol and 2,4-di-tert-butyl phenol with antioxidant activity. The content of tannin is affected by processing methods. Mechanical treatment during rice milling releases tannin in seed coat. In addition, research shows that heat treatment can affect the content of seed tannin. During extraction, proper heat treatment helps the release of tannin, and treatment at 100℃ for 30 min can degrade more than 70% of tannin.

[0004] Highland barley tannin has certain correlation with liquor quality. Appropriate amount of tannin can inhibit the growth of miscellaneous bacteria in the fermentation system and enrich the flavor of the liquor body, but excessive tannin content can inactivate amylase and reduce microbial protein metabolism, affecting the formation of flavor components in the liquor body. The utilization of tannin in the fermentation process is also affected by microorganisms. Liu Rui's research on the addition of 0.1% proanthocyanidin to highland barley for brewing Xiaoqu liquor showed that the content of ethyl acetate and ethyl lactate in the liquor was 8 times and 1.8 times higher than that of the control group, respectively, and the proportion was coordinated, and the content of fusel oil in Xiaoqu liquor was also controlled. However, no polyphenols were detected in the volatile substances of the liquor, indicating that the microorganisms in the Xiaoqu used in the study did not help the generation of proanthocyanidins in highland barley to form polyphenols in liquor, and further proving that the generation of polyphenols from proanthocyanidins in highland barley requires a specific microbial community structure.

[0005] The quality of baijiu is affected by many factors, including fermentation microorganisms and raw and auxiliary materials. There are many types of microorganisms involved in baijiu brewing, and the nutritional composition of raw and auxiliary materials varies greatly. In addition, baijiu brewing involves a series of complex biochemical reactions. At present, there is no mature technology to obtain strong-aroma baijiu with antioxidant activity. Summary of the Invention

[0006] The purpose of this invention is to improve the antioxidant activity of baijiu (Chinese liquor). It provides a process for producing strong-aroma baijiu by controlling the rice milling and steaming process to obtain sorghum husks with high tannin content, which are then added back to sorghum rice with low tannin content. Different strains obtained through screening and compounding are then combined with strong-aroma koji (a type of starter culture) for semi-solid-state fermentation. This method involves compounding different strains isolated from strong-aroma koji with the starter culture and inoculating it into a fermentation system using low-tannin sorghum rice with added sorghum husks as raw material. Fermentation yields strong-aroma baijiu with high antioxidant activity and good drinking quality. In the preparation process, sorghum husks and sorghum rice with different tannin contents are obtained by controlling the rice milling and steaming process, and then added back in proportion while simultaneously compounding different strains for brewing, thereby improving the antioxidant activity of the baijiu. This invention creatively alters the tannin content of the raw material system by removing and adding sorghum husks, and by compounding different strains isolated from strong-aroma koji with the starter culture during fermentation, thus maintaining the quality of the baijiu while improving its antioxidant activity.

[0007] One of the objectives of this invention is to provide a method for regulating the tannin content in a sorghum system to produce high-quality baijiu with high antioxidant activity.

[0008] The method for regulating the tannin content in a sorghum system provided by this invention includes the following steps:

[0009] By controlling the degree of peeling during milling, glutinous sorghum is used to obtain sorghum rice with low tannin content and sorghum husk with high tannin content. The obtained sorghum rice and sorghum husk are crushed and moistened separately, and then steamed. The cooked sorghum husk powder is added back to the crushed cooked sorghum rice to adjust the tannin content in the sorghum system.

[0010] The milling time is 30-50 seconds. The resulting sorghum rice has a tannin content that is 12%-25% lower than that of the original glutinous sorghum, while the sorghum husk has a tannin content that is 70%-80% higher. The sorghum rice and sorghum husk are crushed with different particle size controls, and the raw sorghum rice and sorghum husk are weighed separately, so that the tannin content of the mixed whole dry material system of sorghum rice and sorghum husk is 0.72%-0.90%.

[0011] The steaming process involves steaming the moistened sorghum rice under atmospheric pressure for 45-120 minutes until the material becomes cooked and changes color to obtain cooked sorghum rice crumbs; then steaming the crushed sorghum husk powder under atmospheric pressure for 10-20 minutes to obtain cooked sorghum husk powder.

[0012] The second object of the present application is to provide a kind of reinforced composite microbial species that can be compounded with Daqu, to produce high antioxidant activity and high quality Baijiu.

[0013] The reinforced composite microbial species provided by the present application is composed of Saccharomycopsis fibuligera and Bacillus subtilis,

[0014] The classification name of Saccharomycopsis fibuligera is Saccharomycopsis fibuligera, which is preserved in the China General Microbiological Culture Collection Center, with a preservation number of CGMCC No.2.877;

[0015] The classification name of Bacillus subtilis is Bacillus subtilis, which is preserved in the China General Microbiological Culture Collection Center on October 27, 2023, with a preservation number of CGMCC No.28796;

[0016] The Luzhou-flavor Daqu is a product of Anhui Gujinggong Liquor Co., Ltd.;

[0017] The Saccharomycopsis fibuligera is added in the form of Saccharomycopsis fibuligera seed liquid;

[0018] The Bacillus subtilis is added in the form of Bacillus subtilis seed liquid;

[0019] The Saccharomycopsis fibuligera seed liquid is prepared by the following method:

[0020] The Saccharomycopsis fibuligera is inoculated into YPD liquid medium from a slope, and seed liquid is obtained by oscillation culture at 28℃ for 24-36h, and the concentration of the seed liquid is adjusted to OD 600nm value 0.36-0.37;

[0021] The Bacillus subtilis seed liquid is prepared by the following method:

[0022] The Bacillus subtilis is inoculated into PCA liquid medium from a slope, and seed liquid is obtained by oscillation culture at 37℃ for 20-24h, and the concentration of the seed liquid is adjusted to OD 600nm value 0.36-0.37;

[0023] In the composite reinforced microbial species, the weight ratio of Saccharomycopsis fibuligera seed liquid to Bacillus subtilis seed liquid can be (2-5):(3-4).

[0024] The application of the above-mentioned composite reinforced microbial species in the semi-solid brewing of Luzhou-flavor Baijiu and the improvement of the antioxidant activity of semi-solid brewed Luzhou-flavor Baijiu also belongs to the protection scope of the present application.

[0025] The still another object of the present application is to provide a method for semi-solid brewing of Luzhou-flavor Baijiu with antioxidant activity.

[0026] The method for brewing semi-solid liquor with antioxidant activity provided by the application comprises the following steps:

[0027] (1) Culture of fermentation strains

[0028] ① Single-strain liquid seed culture

[0029] The Saccharomycopsis homobiotica is inoculated from the slant to the YPD liquid medium, and seed liquid is obtained by oscillation culture at 28°C for 24-36h, and the concentration of the seed liquid is adjusted to OD 600nm value 0.36-0.37;

[0030] The Bacillus subtilis is inoculated from the slant to the PCA liquid medium respectively, and seed liquid is obtained by oscillation culture at 37°C for 20-24h, and the concentration of the seed liquid is adjusted to OD 600nm value 0.36-0.37;

[0031] ② Preparation of compound fortified bacteria

[0032] The Saccharomycopsis homobiotica seed liquid and the Bacillus subtilis seed liquid are mixed into a compound bacteria suspension according to the weight ratio of (2-5):(3-4);

[0033] (2) Preparation of fermentation system:

[0034] ① The peeling degree of waxy highland is controlled by regulating the rice milling time for 30-50s, and highland rice with tannin content 12%-25% lower than that of the original waxy highland and highland skin with tannin content 70%-80% higher than that of the original waxy highland are obtained, and the waxy highland rice and highland skin are crushed with different particle sizes, and the waxy highland rice and highland skin are weighed so that the tannin content of the mixed whole highland rice and highland skin dry material system is 0.72%-0.90%;

[0035] ② Highland rice moistening and steaming: 60% tap water (based on the dry material highland rice) is added to the crushed dry material highland rice, and the rice is moistened for 5-15h; the moistened highland rice is steamed in the air for 45-120min until the material becomes cooked and colored to obtain cooked highland rice fragments;

[0036] ③ Highland skin powder steaming: 30%-40% tap water (based on the dry material highland skin) is added to the crushed dry material highland skin (highland skin powder), and the material is steamed in the air for 10-20min to obtain cooked highland skin powder;

[0037] ④ Mixing: tap water or distilled water with a mass of 2.6-3.4 times the mass of the dry material highland rice is taken, and the cooled cooked highland rice fragments, cooked highland skin powder, 30% strong-flavor Daqu and 4.0%-7.2% compound bacteria suspension (based on the dry material highland rice) are added, and the mixture is sealed for fermentation;

[0038] (3) Fermentation and distillation (liquor brewing):

[0039] Fermentation is carried out at 25-37℃ for 18 days, with the temperature control program being 28℃ on day 1, 33-35℃ on day 2, 30-33℃ on day 3, and 28℃ on days 4-18. Fermentation mash is obtained after 18 days of fermentation. The mash is then directly distilled using a semi-solid method to obtain baijiu with an alcohol content of 45° and above.

[0040] In the above method (2)①, the sorghum rice is crushed to a particle size of about 70% above a 20-mesh sieve, and the sorghum husk is crushed to a particle size of 40-mesh sieve.

[0041] The strong-aroma baijiu prepared by the above method also falls within the scope of protection of this invention.

[0042] This invention obtains sorghum husks and sorghum rice with different tannin contents by controlling the rice milling and steaming process, and adjusts the tannin content in the sorghum system by adding back sorghum husks. Furthermore, it extensively isolates and screens yeast, lactic acid bacteria, and Bacillus in the Daqu (fermentation starter) used in this invention, obtaining a combination of enhanced microbial strains that, when combined with the Daqu, improve the total ester content and drinking quality of baijiu (Chinese liquor) while simultaneously enhancing its antioxidant activity. By combining sorghum systems with different tannin contents and different strains with strong-aroma Daqu for brewing, the resulting baijiu exhibits excellent aroma, meets the standard for total ester content, and possesses good antioxidant activity. Overall, the DPPH free radical scavenging rate reaches a maximum of 65.86%, and the total reducing power reaches a maximum of 0.319. Attached Figure Description

[0043] Figure 1 This is the total ion chromatogram of the volatile substances in the liquor prepared in Example 1 of the present invention.

[0044] Figure 2 This is the total ion chromatogram of volatile substances in the liquor prepared in Example 2 of the present invention.

[0045] Figure 3 This is the total ion chromatogram of the volatile substances in the liquor prepared in Example 3 of the present invention.

[0046] Figure 4 This is the total ion chromatogram of volatile substances in the liquor prepared in Comparative Example 1 of this invention. Detailed Implementation

[0047] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.

[0048] The experimental methods in the following examples are all conventional methods, and are carried out according to the techniques or conditions described in the literature in the art or according to the product instructions, unless otherwise specified. The materials, reagents, etc. used in the following examples can be obtained commercially, unless otherwise specified.

[0049] Example 1, Back-adding Sorghum Bran Compound Strengthening Strain for Semi-solid Brewing Antioxidant Baijiu

[0050] (1) Culture of Fermentation Strains

[0051] ① Single-strain liquid seed culture

[0052] The Saccharomycopsis fibuligera (S) was inoculated from the slant into YPD liquid medium and cultured at 28°C for 24 h to obtain a seed liquid. The seed liquid was adjusted to an OD 600nm value of 0.36.

[0053] The Bacillus subtilis (BS) was inoculated from the slant into PCA liquid medium and cultured at 37°C for 24 h to obtain a seed liquid. The seed liquid was adjusted to an OD 600nm value of 0.36.

[0054] ② Preparation of compound strengthening inoculum

[0055] The S seed liquid and the BS seed liquid were mixed at a weight ratio of 5:4 to obtain a compound bacterial suspension.

[0056] (2) Preparation of fermentation system

[0057] ① The waxy sorghum was milled for 40 s to obtain sorghum rice with 15% lower tannin content and sorghum bran with 73% higher tannin content. The sorghum rice and the sorghum bran were ground, and the ground sorghum rice had a particle size of which about 70% was above a 20-mesh sieve, and the ground sorghum bran had a particle size of which all passed through a 40-mesh sieve. The ground sorghum rice and the ground sorghum bran were weighed at a ratio of 125 g:26.8 g (w / w) to make the tannin content of the whole dry material system 0.78%;

[0058] ② Sorghum rice moistening and steaming: 60% tap water was added to the ground dry material sorghum rice, and the sorghum rice was moistened for 12 h. The moistened sorghum rice was steamed in air for 60 min until the material turned cooked and colored to obtain cooked sorghum rice pieces;

[0059] ③ Sorghum bran powder steaming: 40% tap water was added to the ground dry material sorghum bran (sorghum bran powder), and the sorghum bran powder was steamed in air for 15 min to obtain cooked sorghum bran powder;

[0060] (4) Mixing: take dry material sorghum 3.0 times the mass of tap water, add cooled mature sorghum rice, mature sorghum skin powder, 30% strong-flavor Daqu and 7.2% complex bacteria suspension (based on dry material sorghum), seal and ferment.

[0061] (3) Fermentation procedure

[0062] The temperature control procedure is 28°C on the first day, 33-35°C on the second day, 30-33°C on the third day, and 28°C on the fourth to eighteenth day. Fermentation is carried out for 18 days to obtain fermented liquor.

[0063] (4) Distillation of Baijiu and quality detection

[0064] The Baijiu distilled by the semi-solid state method is intercepted at 45° and above, and the total ester content (directly measured according to the method in the Baijiu Production Technology Complete Works) is 1.30 g / L, which is higher than the national standard requirement of 0.60 g / L, and the ethyl hexanoate content is 34.68 mg / L; the DPPH free radical scavenging rate of the fermented Baijiu is 65.86%, and the total reducing power is 0.319. The detection results of volatile esters and phenolic substances are shown in Tables 1-2.

[0065] Example 2, semi-solid state brewing of antioxidant Baijiu by adding back sorghum skin complex reinforcing strains

[0066] (1) Culture of fermentation strains

[0067] ① Single strain liquid seed culture

[0068] The same as in Example 1.

[0069] ② Preparation of complex reinforcing inoculum

[0070] The S seed liquid and the BS seed liquid are mixed in a weight ratio of 5:3 to form a complex bacteria suspension.

[0071] (2) Preparation of fermentation system:

[0072] ① Milling of waxy sorghum for 30 s to obtain sorghum rice with 12% lower tannin content than the original sorghum, and milling for 40 s to obtain sorghum skin with 73% higher tannin content than the original sorghum. The sorghum rice and sorghum skin are ground, with the ground sorghum rice having about 70% passing through a 20-mesh sieve and the ground sorghum skin having all passing through a 40-mesh sieve. The ground sorghum rice and sorghum skin are weighed in a ratio of 125g:20.5g (w / w) to make the tannin content of the mixed whole sorghum rice and sorghum skin dry material system 0.78%;

[0073] ② Moistening and steaming of sorghum rice: add 60% tap water (based on dry material sorghum) to the ground dry material sorghum rice and moisten for 12 h; steam the moistened sorghum rice in the air for 60 min until the material becomes mature and colored to obtain mature sorghum rice fragments;

[0074] ③ Steaming of sorghum bran powder: 40% tap water was added to the dry material of sorghum bran (sorghum bran powder), and the mixture was steamed for 15 min to obtain cooked sorghum bran powder;

[0075] ④ Mixing: 3.0 times the mass of tap water was added to the dry material of sorghum, and then the cooled cooked sorghum, cooked sorghum bran powder, 30% strong-flavor Daqu, and 6.4% complex bacterial suspension (based on the dry material of sorghum) were added for fermentation.

[0076] (3) Fermentation procedure

[0077] The same as in Example 1.

[0078] (4) Distillation of liquor and quality detection

[0079] The same as in Example 1.

[0080] The semi-solid state distilled liquor was collected at 45° and above, and the total ester content (directly measured according to the method in the Complete Book of Liquor Production Technology) was 1.12 g / L, and the ethyl hexanoate content was 28.62 mg / L. The DPPH free radical scavenging rate of the fermented liquor was 55.93%, and the total reducing power was 0.286. The detection results of volatile esters and phenolic substances are shown in Tables 1-2.

[0081] Example 3, semi-solid state brewing of antioxidant liquor by adding back sorghum bran and complex strain

[0082] (1) Culture of fermentation strains

[0083] ① Single strain liquid seed culture

[0084] The same as in Example 1.

[0085] ② Preparation of complex strain

[0086] The S seed liquid and the BS seed liquid were mixed in a weight ratio of 5:3 to form a complex bacterial suspension.

[0087] (2) Preparation of fermentation system:

[0088] ① The waxy sorghum was milled for 40 s to obtain sorghum with 15% lower tannin content and sorghum bran with 73% higher tannin content. The sorghum and sorghum bran were ground to a particle size of 20 mesh, with about 70% of the sorghum passing through the 20 mesh sieve and all of the sorghum bran passing through the 40 mesh sieve. The ground sorghum and sorghum bran were weighed at a ratio of 125 g:40.2 g (w / w) to make the tannin content of the mixed whole sorghum and sorghum bran dry material system 0.83%;

[0089] ② Steaming of the soaked sorghum: 60% tap water was added to the ground dry sorghum and soaked for 12 h. The soaked sorghum was then steamed for 60 min to obtain cooked sorghum;

[0090] ③ Steaming of the ground sorghum bran: 40% tap water was added to the ground dry sorghum bran and steamed for 15 min to obtain cooked sorghum bran;

[0091] ④ Mixing: 3.0 times the mass of tap water was added to the ground dry sorghum, and the cooked sorghum bran, 30% Luzhou-flavor Daqu, and 6.4% complex microbial suspension were added to the mixture and sealed for fermentation.

[0092] (3) Fermentation procedure

[0093] The same as in Example 1.

[0094] (4) Distillation of the liquor and quality detection

[0095] The same as in Example 1.

[0096] The semi-solid state distilled liquor was collected at 45° and above, and the total ester content (directly measured according to the method in the Complete Book of Liquor Production Technology) was 1.10 g / L, and the ethyl hexanoate content was 33.91 mg / L. The DPPH free radical scavenging rate of the fermented liquor was 53.27%, and the total reducing power was 0.306. The detection results of volatile esters and phenolic substances are shown in Tables 1-2.

[0097] Comparative Example 1: Semi-solid state brewing of liquor from raw waxy sorghum

[0098] (1) Preparation of the fermentation system:

[0099] ① No rice milling was performed, and the ground raw waxy sorghum was used as the fermentation raw grain, and the particle size of the ground raw waxy sorghum was about 70% on the 20 mesh sieve;

[0100] ② Soaking: tap water was added to the fermentation raw grain, and the water addition ratio was 60% (based on the raw waxy sorghum), and the soaking time was 12 h;

[0101] ③ Steaming: the soaked raw waxy sorghum was steamed for 60 min to obtain cooked sorghum;

[0102] ④ Mixing: 3.0 times the mass of tap water was added to the raw waxy sorghum, and the cooked sorghum and 30% Luzhou-flavor Daqu (based on the raw waxy sorghum) were added to the mixture and sealed for fermentation.

[0103] (2) Fermentation procedure

[0104] The same as in Example 1.

[0105] (3) Distillation of the liquor and quality detection

[0106] The same as Example 1.

[0107] The semi-solid method was used to distill liquor, and liquor with an alcoholicity of 45° or above was collected. The total ester content (directly measured according to the method in the Liquor Production Technology Book) was 0.88 g / L, and the ethyl caproate content was 23.50 mg / L. The DPPH free radical scavenging rate of the fermented liquor was 22.86%, and the total reducing power was 0.177. The determination results of volatile esters and phenolic substances are shown in Tables 1-2.

[0108] Comparative Example 2: Kernels of Sorghum Bicolor (L.) Moench were used to brew liquor by the semi-solid method alone.

[0109] (1) Preparation of fermentation system:

[0110] ①Milling kernels of Sorghum Bicolor (L.) Moench for 40 s to obtain kernels of Sorghum Bicolor (L.) Moench with a tannin content 15% lower than that of the original kernels and bran with a tannin content 73% higher than that of the original kernels. The kernels and bran were crushed, and the particle size of the crushed kernels was about 70% above a 20-mesh sieve, and the particle size of the crushed bran was all through a 40-mesh sieve. The crushed kernels and bran were weighed according to a ratio of 125 g:26.8 g (w / w) to make the tannin content of the whole dry material system 0.78%;

[0111] ②Moistening and steaming the kernels: 60% tap water was added to the crushed dry material of the kernels, and the kernels were moistened for 12 h. After moistening, the kernels were steamed in the air for 60 min until the material turned cooked and colored to obtain cooked kernel fragments;

[0112] ③Steaming the bran: 40% tap water was added to the crushed dry material of the bran, and the bran was steamed in the air for 15 min to obtain cooked bran powder;

[0113] ④Mixing: 3.0 times the mass of tap water was added to the dry material of the kernels, and the cooked kernel fragments, cooked bran powder, and 30% strong-flavor Daqu (based on the dry material of the kernels) were added after cooling, and the mixture was sealed for fermentation.

[0114] (2) Fermentation procedure

[0115] The same as Example 1.

[0116] (3) Distillation of liquor and quality detection

[0117] The same as Example 1.

[0118] The semi-solid method was used to distill liquor, and liquor with an alcoholicity of 45° or above was collected. The total ester content (directly measured according to the method in the Liquor Production Technology Book) was 1.03 g / L, and the ethyl caproate content was 25.95 mg / L. The DPPH free radical scavenging rate of the fermented liquor was 39.47%, and the total reducing power was 0.231. The determination results of volatile esters and phenolic substances are shown in Tables 1-2.

[0119] Example 3, semi-solid brewing liquor using single enhanced strain

[0120] (1) Culture of fermentation strain

[0121] ① Liquid seed culture of single strain

[0122] The same as Example 1.

[0123] ② Preparation of compound enhanced inoculum

[0124] Mix S seed liquid and BS seed liquid in a weight ratio of 5:4 to form a compound bacterial suspension.

[0125] (2) Preparation of fermentation system

[0126] ① Do not add back during milling, use crushed original nuxiao sorghum as fermentation raw grain, and the crushed particle size is 20 mesh, with about 70% on the 20 mesh sieve;

[0127] ② Material moistening: add tap water to the fermentation raw grain, with a water addition ratio of 60% (based on original nuxiao sorghum), and the material moistening time is 12 h;

[0128] ③ Material steaming: steam the moistened original nuxiao sorghum for 60 min in the air until the material is cooked and colored to obtain cooked sorghum;

[0129] ④ Mixing: mix 3.0 times the mass of tap water with the mixed inoculum, add the cooled cooked sorghum, 30% Luzhou-flavor Daqu, and 7.2% compound enhanced inoculum (based on original nuxiao sorghum), and seal for fermentation.

[0130] (3) Fermentation procedure

[0131] The same as Example 1.

[0132] (4) Distillation of liquor and quality detection

[0133] The same as Example 1.

[0134] Semi-solid distilled liquor was obtained, and the liquor with an angle of 45° and above was collected. The total ester content (directly measured according to the method in the Complete Book of Liquor Production Technology) was 1.08 g / L, and the ethyl hexanoate content was 24.71 mg / L. The DPPH free radical scavenging rate of the fermented liquor was 43.54%, and the total reducing power was 0.208. The results of determination of volatile esters and phenolic substances are shown in Tables 1-2.

[0135] Example 4, semi-solid brewing liquor using compound enhanced strain in a low-tannin system with back-added sorghum bran

[0136] (1) Culture of fermentation strain

[0137] ① Liquid seed culture of single strain

[0138] The same as Example 1.

[0139] Preparation of compound strain

[0140] The S seed liquid and the BS seed liquid were mixed in a weight ratio of 5:4 to form a compound bacterial suspension.

[0141] (2) Preparation of fermentation system:

[0142] ① The waxy sorghum was milled for 50 s to obtain sorghum rice with a tannin content 25% lower than that of the original sorghum, and milled for 40 s to obtain sorghum bran with a tannin content 73% higher than that of the original sorghum. The sorghum rice and the sorghum bran were ground, and the ground sorghum rice had a particle size of which about 70% was above 20 mesh, and the ground sorghum bran had a particle size of which all passed through 40 mesh. The ground sorghum rice and the ground sorghum bran were weighed in a proportion of 125 g: 13.6 g (w / w) respectively, so that the tannin content of the mixed dry material system was 0.66%;

[0143] ② Sorghum rice moistening and steaming: 60% tap water was added to the ground dry material sorghum rice, and the rice was moistened for 12 h; the moistened sorghum rice was steamed in air for 60 min until the material turned cooked and colored to obtain cooked sorghum rice pieces;

[0144] ③ Sorghum bran powder steaming: 40% tap water was added to the ground dry material sorghum bran (sorghum bran powder), and the bran was steamed in air for 15 min to obtain cooked sorghum bran powder;

[0145] ④ Mixing: 3.0 times the mass of tap water of the dry material sorghum rice was added to the cooked sorghum rice pieces, the cooked sorghum bran powder, 30% strong aroma Daqu, and 7.2% compound strain, and the mixture was sealed for fermentation.

[0146] (3) Fermentation procedure

[0147] The same as Example 1.

[0148] (4) Distillation of liquor and quality detection

[0149] The same as Example 1.

[0150] The semi-solid state distilled liquor was collected, and the total ester content (measured directly according to the Liquor Production Technology Book) was 0.97 g / L, and the ethyl hexanoate content was 26.64 mg / L; the DPPH free radical scavenging rate of the fermented liquor was 37.29%, and the total reducing power was 0.282. The determination results of volatile esters and phenolic substances are shown in Tables 1-2.

[0151] Example 5, semi-solid state brewing of liquor by adding back sorghum bran with high tannin content and compound strain

[0152] (1) Cultivation of fermentation strain

[0153] ① Single-strain liquid seed culture

[0154] The same as Example 1.

[0155] ② Preparation of compound strain

[0156] The S seed liquid and the BS seed liquid were mixed in a weight ratio of 5:4 to form a compound bacterial suspension.

[0157] (2) Preparation of fermentation system:

[0158] ① The waxy sorghum was milled for 40 s to obtain sorghum rice with a tannin content 15% lower than that of the original sorghum and sorghum bran with a tannin content 73% higher than that of the original sorghum. The sorghum rice and the sorghum bran were ground separately. The ground sorghum rice had a particle size of which about 70% passed through a 20-mesh sieve, and the ground sorghum bran had a particle size of which all passed through a 40-mesh sieve. The ground sorghum rice and the ground sorghum bran were weighed in a proportion of 125 g:89.8 g (w / w) respectively so that the tannin content of the mixed dry material system was 0.95%;

[0159] ② Sorghum rice moistening and steaming: 60% tap water was added to the ground dry material sorghum rice, and the mixture was moistened for 12 h. The moistened sorghum rice was steamed in air for 60 min until the material turned cooked and colored to obtain cooked sorghum rice pieces.

[0160] ③ Sorghum bran powder steaming: 40% tap water was added to the ground dry material sorghum bran (sorghum bran powder), and the mixture was steamed in air for 15 min to obtain cooked sorghum bran powder.

[0161] ④ Mixing: 3.0 times the mass of tap water of the dry material sorghum rice was added to the cooled cooked sorghum rice pieces, the cooked sorghum bran powder, 30% strong aroma Daqu, and 7.2% compound strain, and the mixture was sealed for fermentation.

[0162] (3) Fermentation procedure

[0163] The same as Example 1.

[0164] (4) Distillation of liquor and quality detection

[0165] The same as Example 1.

[0166] The semi-solid state method was used to distill liquor, and the liquor with an alcohol degree of 45° or above was collected. The total ester content (directly measured according to the Liquor Production Technology Book) was 0.95 g / L, and the ethyl hexanoate content was 25.49 mg / L. The DPPH free radical scavenging rate of the fermented liquor was 43.10%, and the total reducing power was 0.292. The determination results of volatile esters and phenolic substances are shown in Tables 1-2.

[0167] Comparative Example 6: Semi-solid state brewing of liquor by adding sorghum bran and a small amount of strain

[0168] (1) Cultivation of fermentation strain

[0169] ① Single-strain liquid seed culture

[0170] The same as Example 1.

[0171] ② Preparation of compound strain

[0172] The S seed liquid and the BS seed liquid were mixed in a weight ratio of 5:4 to form a compound bacterial suspension.

[0173] (2) Preparation of fermentation system:

[0174] ① The waxy sorghum was milled for 30 s to obtain sorghum rice with a tannin content 12% lower than that of the original sorghum, and milled for 40 s to obtain sorghum bran with a tannin content 73% higher than that of the original sorghum. The sorghum rice and the sorghum bran were ground, and the ground sorghum rice had a particle size of which about 70% was above a 20-mesh sieve, and the ground sorghum bran passed through a 40-mesh sieve. The ground sorghum rice and the ground sorghum bran were weighed in a proportion of 125 g:20.5 g (w / w) to make the tannin content of the whole dry material system 0.78%;

[0175] ② Sorghum rice moistening and steaming: 60% tap water was added to the ground dry material sorghum rice, and the sorghum rice was moistened for 12 h. The moistened sorghum rice was steamed in air for 60 min until the material turned cooked and colored to obtain cooked sorghum rice pieces;

[0176] ③ Sorghum bran powder steaming: 40% tap water was added to the ground dry material sorghum bran (sorghum bran powder), and the sorghum bran powder was steamed in air for 15 min to obtain cooked sorghum bran powder;

[0177] ④ Mixing: 3.0 times the mass of tap water of the dry material sorghum rice was added to the cooled cooked sorghum rice pieces, the cooked sorghum bran powder, 30% strong aroma Daqu, and 2.4% compound bacterial suspension (based on the dry material sorghum rice), and the mixture was sealed for fermentation.

[0178] (3) Fermentation procedure

[0179] The same as Example 1.

[0180] (4) Distillation of liquor and quality detection

[0181] The same as Example 1.

[0182] The semi-solid state method was used to distill liquor, and the liquor with an alcohol degree of 45° or above was collected. The total ester content (directly measured according to the method in the Book of Liquor Production Technology) was 1.06 g / L, and the content of ethyl hexanoate was 24.77 mg / L. The DPPH free radical scavenging rate of the fermented liquor was 35.08%, and the total reducing power was 0.191. The determination results of volatile esters and phenolic substances are shown in Table 1-2.

[0183] Example 7, back-adding sorghum bran complex over-strength strain semi-solid brewing liquor

[0184] Refer to Example 1, adjust the amount of bacteria liquid added

[0185] (1) Culture of fermentation strains

[0186] ① Single-strain liquid seed culture

[0187] The same as Example 1.

[0188] ② Preparation of complex strengthening bacteria

[0189] Mix S seed liquid: BS seed liquid according to a weight ratio of 5:4 to form a complex bacteria suspension.

[0190] 2) Preparation of fermentation system:

[0191] ① Milling waxy sorghum for 40s to obtain sorghum rice with 15% lower tannin content and 73% higher sorghum bran than the original sorghum. Crush the sorghum rice and sorghum bran, respectively. The crushed sorghum rice has a particle size of 20 mesh, with about 70% passing through the 20 mesh sieve. The crushed sorghum bran has a particle size of 40 mesh, with all passing through the 40 mesh sieve. Take 125g of crushed sorghum rice and 26.8g of crushed sorghum bran (w / w) to make the mixed whole sorghum rice and sorghum bran dry material system with a tannin content of 0.78%;

[0192] ② Sorghum rice moistening and steaming: add 60% tap water (based on dry sorghum rice) to the crushed dry material sorghum rice and moisten for 12h; steam the moistened sorghum rice in the air for 60min until the material turns cooked and colored to obtain cooked sorghum rice pieces;

[0193] ③ Sorghum bran powder steaming: add 40% tap water (based on dry sorghum bran) to the crushed dry material sorghum bran (sorghum bran powder) and steam in the air for 15min to obtain cooked sorghum bran powder;

[0194] ④ Mixing: take 3.0 times the mass of tap water of dry sorghum rice, add cooled cooked sorghum rice pieces, cooked sorghum bran powder, 30% strong aroma Daqu, and 8.2% complex bacteria suspension (based on dry sorghum rice), and seal for fermentation.

[0195] (3) Fermentation program

[0196] The temperature control program is 28℃ on the first day, 33-35℃ on the second day, 30-33℃ on the third day, and 28℃ on the fourth to eighteenth days. Ferment for 18 days to obtain fermented mash.

[0197] (4) Distillation of liquor and quality detection

[0198] The semi-solid method distillation liquor, intercept 45° and above liquor, the determination of total ester content (according to the liquor production technology book method directly measured) is 1.06 g / L, higher than the national standard requirements of 0.60 g / L, ethyl caproate content is 27.89 mg / L; Fermented liquor DPPH free radical scavenging rate is 30.98%, total reducing power is 0.180, volatile esters and phenolic substances test results are shown in Table 1-2.

[0199] Comparative example 8, back to add highland millet skin compound different proportion of intensive strain semi-solid brewing liquor

[0200] (1) Fermentation strain culture

[0201] ① Single strain liquid seed culture

[0202] The same as example 1.

[0203] ② Compound intensive strain preparation

[0204] Mix S seed liquid: BS seed liquid according to the weight ratio of 2:1 into compound bacteria suspension.

[0205] 2) Fermentation system preparation:

[0206] ① The waxy highland millet is milled for 40 s to obtain highland millet rice with 15% lower tannin content and highland millet skin with 73% higher tannin content than the original highland millet. The highland millet rice and highland millet skin are crushed respectively. The crushed highland millet rice has a particle size of 20 mesh, of which about 70% is above the 20 mesh sieve. The crushed highland millet skin has a particle size of 40 mesh. The crushed highland millet rice and highland millet skin are weighed in a proportion of 125g:26.8g (w / w) respectively to make the tannin content of the mixed whole highland millet rice and highland millet skin dry material system 0.78%;

[0207] ② Highland millet rice moistening and steaming: add 60% tap water (based on dry material highland millet) to the crushed dry material highland millet, and moisten for 12 hours. Steam the moistened highland millet for 60 minutes in the air to obtain cooked highland millet fragments.

[0208] ③ Highland millet skin powder steaming: add 40% tap water (based on dry material highland millet skin) to the crushed dry material highland millet skin (highland millet skin powder), and steam for 15 minutes in the air to obtain cooked highland millet skin powder.

[0209] ④ Mixing: take 3.0 times the mass of tap water of dry material highland millet, add cooled cooked highland millet fragments, cooked highland millet skin powder, 30% strong aroma Daqu, and 7.2% compound bacteria suspension (based on dry material highland millet), and seal for fermentation.

[0210] (3) Fermentation procedure

[0211] The temperature control program is 28℃ on the first day, 33-35℃ on the second day, 30-33℃ on the third day, and 28℃ on the fourth to eighteenth day. Ferment for 18 days to obtain fermented mash.

[0212] (4) Baijiu distillation and quality detection

[0213] The total ester content (directly measured according to the method in the Baijiu Production Technology Complete Book) of the semi-solid method distilled Baijiu, which is intercepted at 45° and above, is 0.97 g / L, higher than the 0.60 g / L required by the national standard, and the ethyl caproate content is 26.33 mg / L; the DPPH free radical scavenging rate of the fermented Baijiu is 44.10%, and the total reducing power is 0.198. The detection results of volatile esters and phenolic substances are shown in Tables 1-2.

[0214] The related detection methods and results of the present application are shown as follows:

[0215] (1) Measurement of alcohol degree: the alcohol degree of different distilled wines was measured by an alcohol refractometer.

[0216] (2) Measurement of sorghum tannin: reference GB / T 15686-2008. The specific method is as follows: about 1 g of sample is weighed to 1 mg accuracy and placed in a centrifugal tube. 20 mL of dimethylformamide solution is taken with a pipette into the centrifugal tube containing the sample, a tight cover is put on and the sample is extracted with a stirrer for 60 min ± 1 min, and then centrifuged at 3000g acceleration for 10 min. 1 mL of supernatant is taken with a pipette into a test tube, and 6 mL of water and 1 mL of ammonia solution are added with a pipette, respectively, and then oscillated with a shaker for a few seconds. After waiting for 10 min ± 1 min, solution 1 is obtained. 1 mL of supernatant is taken with a pipette into a test tube, and 5 mL of water and 1 mL of ammonium iron citrate solution are added, respectively, and then oscillated for a few seconds. After adding 1 mL of ammonia solution again, oscillate and wait for 10 min ± 1 min to obtain solution 2. Solutions 1 and 2 are poured into a colorimetric cell, respectively, with water as a blank control, and the absorbance value is measured at 525 nm. The absorbance value of the sample is the difference between the two absorbance values.

[0217] (3) Measurement of total ester content: reference Baijiu Production Technology Complete Book. The specific method is as follows: 10.0 mL of distilled Baijiu sample is taken into a 100 mL conical flask, 2 drops of phenolphthalein indicator is added, and 0.1 mol / L NaOH standard solution is titrated to pink. The volume of NaOH standard solution consumed is recorded, and then 5.00 mL of 0.1 mol / L NaOH is accurately added. Shake well and put in a few boiling stones or glass beads. Install a condenser tube and condense in a boiling water bath for 30 min. After cooling, use 0.1 mol / L HCl for titration. The endpoint is when the light red color just disappears. Record the volume of HCl standard solution consumed. At the same time, 10.00 mL of ethanol solution is taken for a blank test, and the volume of HCl consumed is recorded.

[0218] (4) Measurement of antioxidant activity:

[0219] Method for determining DPPH free radical scavenging rate

[0220] The sample solution is diluted to 50%, 2 mL of the sample is added to 2 mL of DPPH anhydrous ethanol solution, vortexed, and placed in the dark for 30 min. The B1 is measured at 517 nm with distilled water as a blank solution (adjust 0). The B2 is measured by replacing the DPPH ethanol solution with anhydrous ethanol. The B0 is measured by replacing the sample solution with distilled water. The calculation formula is as follows:

[0221] DPPH free radical scavenging rate (%) = [1-(B1-B2) / B0] x 100%

[0222] Method for determining total reducing power

[0223] 1 mL of the sample solution with different concentrations is taken, 2.5 mL of 0.2 mol / L phosphate buffer solution with pH = 6.6 is added, then 2.5 mL of 1 g / 100 mL potassium ferricyanide solution is added, vortexed, and incubated in a 50℃ water bath for 20 min. Then, 2.5 mL of 10 g / 100 mL trichloroacetic acid is added, centrifuged for 10 min, 3 mL of supernatant is taken, 3 mL of distilled water and 0.6 mL of 0.1 g / 100 mL ferric chloride solution are added in sequence, mixed, and then placed for 10 min. The absorbance A1 is measured at 700 nm. The absorbance A0 is measured by replacing the ferric chloride solution with distilled water as a blank. The reducing power is A1-A0.

[0224] (5) Determination of volatile components: The sample of the fermented mash of the Baijiu of the present application is diluted with deionized water to an alcohol degree of about 10% (actually diluted 5 times), 2 g of NaCl is weighed and added to a 20 mL headspace sample bottle, then 5 mL of the diluted liquor sample is accurately taken and added, 10 μL of 1 mg / mL internal standard solution (4-methyl-2-pentanol) is accurately taken and added, and then the sample is equilibrated at 50℃ by shaking (shaking speed 450 rpm) for 15 min, and then extracted at 50℃ for 45 min. GC-MS analysis is performed after desorption at the GC injection port for 5 min. The chromatographic conditions are as follows: chromatographic column: (DB-WAX UI, 60 m x 0.25 mm, 0.25 μm), injection port temperature: 240℃, programmed temperature: 40℃, hold for 3 min, 3℃ / min, the temperature program is 40℃ for 3 min, then 3℃ / min to 240℃, hold for 10 min. The mass spectrometry conditions are as follows: electron energy 70 eV, ion source temperature 230℃, quadrupole temperature 150℃, scanning range 20-550 m / z, threshold value 100.

[0225] Table 1 Analysis of ester component content in the fermented mash of Examples 1-3 and Comparative Examples 1-8 of the present application

[0226] Table 1 Analysis of ester component content in the fermented mash of Examples 1-3 and Comparative Examples 1-8 of the present application

[0227]

[0228] Note: - means not detected;

[0229] Esters are the main flavoring substances in liquor, and play an important role in volatile components of liquor. By comparing the total ester content of the examples and the comparative examples, it is found that the total ester of the liquor brewed by the method of adding back the husk of sorghum to regulate the tannin content of the complex strain is increased by 25.00%-47.73% compared with the control group (comparative example 1). However, when the husk of sorghum is added back alone (comparative example 2), the tannin content of the husk of sorghum is too low or too high (comparative examples 4 and 5), the complex strain is added alone (comparative example 3) or the amount of the complex strain is too low or too high (comparative examples 6 and 7), the total ester of the liquor is increased by a small margin, and the increase rate is 10.23%-22.73%. In addition, the proportion of the complex strain also has a significant effect on the increase of the total ester content of the liquor (comparative example 8). The characteristic aroma components in the liquor produced by the method of the present application include ethyl acetate, isoamyl acetate (strong fruity and floral aroma), ethyl butyrate (pineapple and banana odor), ethyl hexanoate (strawberry and green apple flavor), ethyl octanoate (fruity aroma), ethyl decanoate (coconut type aroma), ethyl benzoate (fruity aroma), phenethyl acetate, ethyl laurate (peanut aroma), ethyl myristate (fruity aroma), and ethyl palmitate (fruity aroma). Among them, ethyl hexanoate is the main flavoring substance of strong-flavor liquor, and the content of ethyl hexanoate in examples 1, 2 and 3 is increased by 47.57%, 21.79% and 44.30% respectively compared with comparative example 1. It is proved that the method of the present application can increase the content of esters and improve the flavor of liquor on the basis of ensuring the flavor.

[0230] Table 2 Analysis of the content of phenolic components in the fermentation mash of examples 1-3 and comparative examples 1-8 of the present application

[0231]

[0232] Note: - means not detected

[0233] Phenolic substances are important secondary metabolites in plants, which not only have antioxidant effects in the human body, but also have the functions of preventing cardiovascular diseases, helping to recover from alcoholic liver damage and regulating immune function. In the production of liquor, phenolic substances mainly come from the conversion of procyanidins and lignin in the husk of sorghum. The ortho position of the phenolic hydroxyl group in guaiacol has an electron-donating group, which can improve its antioxidant properties; 2,4-di-tert-butyl phenol is a commonly used antioxidant. As can be seen from Table 2, the total phenol content of examples 1, 2 and 3 is increased by 14.85%, 19.89% and 12.66% respectively compared with comparative example 1, which is consistent with the antioxidant activity index of DPPH free radical and total reducing power.

[0234] The application has been described in detail. Those skilled in the art will understand that they can make modifications and alterations to this application without departing from the spirit and scope of the application. Although this application presents specific examples, it is to be understood that further modifications can be made. In general, the application is intended to cover any adaptations or variations of the present application including modifications based on the disclosure of this application as well as changes in the field known to those who are skilled in the art.

Claims

1. A method for semi-solid brewing of Luzhou-flavor liquor with antioxidant activity, comprising the following steps: (1) culture of fermentation strains ① single-strain liquid seed culture The Saccharomycopsis fibuligera was inoculated from the slant to YPD liquid medium, and was cultured at 28°C for 24-36 h to obtain seed liquid, and the concentration of the seed liquid was adjusted to OD 600nm 0.36-0.37; the taxonomic name of the Saccharomycopsis fibuligera is Saccharomycopsis fibuligera : preserved in China General Microbiological Culture Collection Center, and the preservation number is CGMCC No.2.877; The Bacillus subtilis was inoculated into PCA liquid medium from the slant, and seed liquid was obtained by culturing at 37°C for 20-24 h; the concentration of the seed liquid was adjusted to OD 600nm 0.36-0.37; the taxonomic name of the Bacillus subtilis is Bacillus subtilis : preserved in the China General Microbiological Culture Collection Center, and the preservation number is CGMCC No. 28796 ② preparation of compound fortified bacteria mix the Saccharomycopsis fibuligera seed liquid and Bacillus subtilis seed liquid at a weight ratio of (2-5):(3-4) to form a compound bacteria suspension; (2) preparation of fermentation system ① control the peeling degree of waxy sorghum by regulating the milling time for 30-50 s to obtain sorghum grains with 12%-25% lower tannin content and sorghum bran with 70%-80% higher tannin content than the original waxy sorghum, and control the particle size of the sorghum grains and sorghum bran to obtain raw sorghum grain fragments and raw sorghum bran powder, respectively; then take the raw sorghum grain fragments and raw sorghum bran powder so that the tannin content of the mixed raw sorghum grain fragments and raw sorghum bran powder system is 0.72%-0.90%; ② moistening and steaming of raw sorghum grains: add 60% tap water based on the raw sorghum grain fragments to the raw sorghum grain fragments and moisten the grains for 5-15 h; steam the moistened raw sorghum grain fragments in the air for 45-120 min until the material turns cooked and colored to obtain cooked sorghum grain fragments; ③ steaming of raw sorghum bran powder: add 30%-40% tap water based on the raw sorghum bran powder to the raw sorghum bran powder and steam in the air for 10-20 min to obtain cooked sorghum bran powder; ④ mixing: take 2.6-3.4 times the mass of dry sorghum grains of tap water or distilled water, add the cooled cooked sorghum grain fragments, cooked sorghum bran powder, 30% Luzhou-flavor Daqu based on the dry sorghum grains, and 4.0%-7.2% compound bacteria suspension, and seal for fermentation; (3) fermentation and distillation: ferment at 25-37℃ for 18 days, with a temperature control program of 28℃ on the first day, 33-35℃ on the second day, 30-33℃ on the third day, and 28℃ on the fourth to eighteenth days; obtain fermented mash after 18 days of fermentation; directly distill using the semi-solid method and collect liquor with an alcohol degree of 45° and above.

2. The method of claim 1, wherein, In (2)①, the particle size of the sorghum grain powder is 70% above 20 mesh, and the particle size of the sorghum bran powder is all through 40 mesh.

3. Luzhou-flavor liquor prepared by the method of claim 1 or 2.

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