A method for improving the quality of strong-flavor medium-high temperature Daqu by using a farinaceous wheat raw material rich in anthocyanins

Abstract

The present application belongs to the technical field of brewing, and particularly relates to a method for improving the quality of strong-flavor medium-high temperature Daqu by using floury wheat rich in anthocyanins, which selects floury wheat varieties with anthocyanin content not less than 60 nmol / g and floury rate not less than 70% as the raw material for making Daqu, or adds not less than 0.03 g of exogenous anthocyanins per kilogram to ordinary floury wheat raw material, and then goes through the processes of material moistening, crushing, mixing, mechanical Daqu making, Daqu fermentation and drying to obtain strong-flavor medium-high temperature Daqu. The present application significantly improves the quality of Daqu by using the antioxidant and microecological regulation functions of anthocyanins in the solid-state fermentation system. Compared with the Daqu made from Chuanzimei 901, the Daqu made from Chuanmai 98 has an increase of 15.61% in total sensory score, 17.93% in cross section score and 17.97% in aroma score; when 0.03 g of exogenous anthocyanins is added per kilogram, the total sensory score is increased by 11.74%. The present application is simple to operate, compatible with the existing Daqu making process, and has a good industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of brewing technology, and in particular relates to a method for improving the quality of strong-aroma medium-high temperature koji using anthocyanin-rich floury wheat raw materials. Background Technology

[0002] Daqu (fermentation starter) is the core fermenting agent in traditional Chinese liquor brewing, hailed as the "bone of liquor." Made primarily from wheat, Daqu undergoes processes such as moistening, crushing, mixing, pressing, and fermentation. It is rich in various microbial flora, including molds, bacteria, and yeasts, as well as a variety of functional enzymes such as saccharifying enzymes, liquefying enzymes, and esterifying enzymes. The quality of Daqu directly determines the aroma, taste, and yield of the liquor.

[0003] Wheat, as the main raw material for Daqu (a type of starter culture), has a significant impact on the quality of the starter culture due to its varietal characteristics. Existing research shows that quality indicators of wheat, such as starch content, protein content, hardness, and flour content, are closely related to the sensory quality of Daqu. Practice has found that soft wheat with a high flour content and low hardness is more conducive to the growth and reproduction of microorganisms during the starter culture process, making it the preferred raw material for producing high-quality Daqu. Therefore, current research and selection of starter culture raw materials mainly revolve around the aforementioned conventional quality characteristics.

[0004] Anthocyanins are a class of water-soluble natural pigments widely found in plants, possessing various bioactive functions such as strong antioxidant activity, free radical scavenging, and regulation of microbial communities. Studies have shown that anthocyanins can serve as natural antioxidants and functional ingredients in food processing, and have been applied in various foods such as bread, noodles, and biscuits. In the field of fermented foods, anthocyanins exhibit a complex two-way interaction with microorganisms. The polyphenolic structure of anthocyanins endows them with broad-spectrum antibacterial activity, selectively inhibiting the growth of some harmful microorganisms while promoting the proliferation of beneficial bacteria. Simultaneously, enzymes secreted by microorganisms during fermentation can hydrolyze bound anthocyanins into more bioactive aglycone forms. The antioxidant, antibacterial, and microecological regulation functions of anthocyanins have been studied in liquid fermentation systems (such as wine and beer), and some studies have also reported the effects of purple wheat as a raw material for koji making on the microbial community structure of soy sauce-flavored koji. However, the aforementioned studies only focused on the analysis of microbial community diversity, failing to address the impact of anthocyanins on core quality indicators such as the sensory quality (appearance, cross-section, aroma, etc.) and enzyme activity of Daqu (a type of starter culture), and further failing to propose any technical solutions for improving Daqu quality using anthocyanins. Research on the mechanism of action of anthocyanins in solid-state fermentation systems, especially in the Daqu cultivation and fermentation process, remains lacking.

[0005] In conclusion, developing a method to improve the quality of strong-aroma medium-high temperature koji using anthocyanin-rich powdered wheat as a koji-making raw material is of great significance for making up for the deficiencies in the existing koji-making raw material selection standards, enhancing the sensory quality of strong-aroma koji, and increasing the industrial value of brewed wine. Summary of the Invention

[0006] The purpose of this invention is to provide a method for improving the quality of strong-aroma medium-high temperature koji using anthocyanin-rich floury wheat raw materials. This method selects anthocyanin-rich floury wheat varieties as the raw materials for making strong-aroma medium-high temperature koji, in order to solve the problems of loose cross-sectional structure, single aroma, and low sensory quality of koji in the prior art.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for improving the quality of strong-aroma medium-high temperature koji using anthocyanin-rich floury wheat raw materials, comprising the following steps: Step 1: Raw Material Selection. Anthocyanin-rich floury wheat grains are selected as the raw material for koji making, and the wheat grains are stored in a warehouse for 2-3 months before being put into production. The anthocyanin-rich floury wheat variety has an anthocyanin content of not less than 60 nmol / g and a flour content of not less than 70%, preferably the anthocyanin-rich floury wheat variety Chuanzimai 901.

[0008] Step 2: Soaking. Add water to the wheat raw material and soak for 12 hours.

[0009] Step 3: Grind the wheat. Grind the moistened wheat until it reaches a plum blossom shape where the heart is rotten but the husk is not. After sieving through a 20-mesh sieve, the fine powder should account for 28% to 35%, preferably 32%.

[0010] Step 4: Mixing. Mix the crushed raw materials with water until evenly combined, controlling the moisture content to be between 36% and 40%, until the mixture can be formed into a ball by hand without sticking to the hands.

[0011] Step 5: Pressing the koji blanks. Feed the raw materials into a mechanical koji press. The pressing pressure is 5-8 kN, and the pressing time is 10-15 seconds. The thickness of the koji blank is 5-8 cm, and the length and width are 30 cm and 20 cm respectively. The feed amount is 4-4.5 kg per koji blank.

[0012] Step 6: Spread out to cool. Spread out the pressed dough for 10-15 minutes to set its shape.

[0013] Step 7: Place the molded koji in the room. Arrange the molded koji in a bucket shape in the room, with four molded koji facing the same direction. Sprinkle rice husks on top and bottom of the molded koji, and finally cover the molded koji with straw mats.

[0014] Step 8: Fermentation of the starter culture. The piled-up starter culture is fermented in the fermentation chamber for 28-35 days. The starter culture is turned over in a timely manner according to the temperature and humidity conditions of the entire fermentation chamber, and the maximum fermentation temperature of the starter culture is controlled between 50-60℃.

[0015] The conditions for fermentation and turning of the koji are as follows: in the early stage, the koji is cultivated at a low temperature, and then turned once after 3-5 days; in the middle stage, the koji is maintained at a high temperature of 50-65℃ for 5-7 days, and then turned or cooled appropriately; in the later stage, the temperature is maintained at no more than 45℃ for 9-12 days; finally, all the koji are piled up and kept at room temperature. The methods for controlling the temperature are turning the koji, opening windows, and sprinkling water.

[0016] The method of turning the koji is as follows: remove the straw mat and turn the koji blanks left and right, up and down; exchange the positions of the koji blanks placed on the outside with the koji blanks placed on the inside, and ferment evenly.

[0017] Step 9: Drying the starter culture. After the starter culture is completed, the starter culture is removed from the starter culture room and naturally dried under ventilated conditions until the moisture content is ≤13% or stored for 2-3 months to obtain anthocyanin-fortified starter culture.

[0018] As another feasible embodiment of the present invention, the raw materials for koji making in step 1 further include the exogenous addition of anthocyanins to ordinary floury wheat raw materials. The addition method is as follows: anthocyanin extract is added to the water used for koji making and stirred evenly, then stirred with the pulverized raw materials. The amount of anthocyanin added is not less than 0.03g per kilogram of raw materials. The anthocyanin extract is derived from one or more of purple wheat, black rice, purple sweet potato, blueberry, black goji berry, and purple cabbage.

[0019] Secondly, the present invention provides a strong-aroma, medium-high temperature Daqu (a type of starter culture) prepared by the above method. The Daqu has a saccharification power of 850-920 U, a liquefaction power of 1.2-2.7 U, and a sensory score of 50-55.

[0020] Thirdly, the present invention provides the application of the strong-aroma type medium-high temperature koji in the brewing of strong-aroma baijiu.

[0021] The present invention has the following beneficial effects: (1) The positive correlation between anthocyanin content in wheat flour grains and the sensory quality of yeast starter was confirmed for the first time. When wheat flour with an anthocyanin content of not less than 60 nmol / g was used as the raw material for yeast starter making, the cross-sectional score of the resulting yeast starter was significantly improved by 17.93% compared with that of ordinary wheat flour, the aroma score was significantly improved by 17.97%, and the total sensory score was significantly improved by 15.61%.

[0022] (2) By eliminating interference from other factors among varieties through the addition of exogenous anthocyanins, it was confirmed that anthocyanins in floury wheat are an important active ingredient for improving the quality of strong-aroma daqu. When exogenous anthocyanins of not less than 0.03 g / kg are added to floury wheat raw materials, the sensory score of the daqu is improved by at least 11.74%, and the cross-sectional score is improved by at least 15.33%.

[0023] (3) It was found that the effect of anthocyanins on the enzyme activity (saccharification power and liquefaction power) of the koji was within a safe and controllable range. Under the recommended addition amount, the saccharification power was maintained above 850U and the liquefaction power was maintained above 1.0U, which met the normal requirements of high-quality koji. Attached Figure Description

[0024] Figure 1 This is a flowchart of the preparation process of the present invention.

[0025] Figure 2 A comparison chart of sensory scores for strong-aroma koji made from Chuanmai 98 and Chuanzimai 901 floury wheat.

[0026] Figure 3 The effect of different anthocyanin addition amounts on the sensory scores of strong-aroma daqu (a type of Chinese liquor). Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0028] Example 1: Comparison of sensory quality of floury wheat varieties with different anthocyanin contents in koji making 1. Source of materials; Two types of floury wheat were used as raw materials for koji making: Chuanmai 98 (a common floury wheat with low anthocyanin content) and Chuanzimai 901 (a floury wheat rich in anthocyanins).

[0029] The grain quality indicators of the two wheat varieties are shown in Table 1.

[0030] Table 1 Grain quality indicators of two wheat varieties Chuanmai 98 10.21 12.36 57.88 78.00 17.86 36.1 802.33 10.55 Sichuan Purple Wheat 901 10.18 11.18 55.73 73.33 21.16 35.9 797.24 66.36 As shown in Table 1, the anthocyanin content of Chuanzimai 901 is 66.36 nmol / g, which is 6.3 times that of Chuanmai 98 (10.55 nmol / g). There are no substantial differences in conventional koji-making quality indicators such as protein content, hardness, flour content, and fineness between the two wheat varieties. The main difference lies in the significant difference in anthocyanin content.

[0031] 2. The process of making koji, such as Figure 1 As shown; (1) Raw material preparation: Wheat grains are stored in the warehouse for 2 months before being put into production.

[0032] (2) Moistening: Add water to the wheat raw material and moisten for 12 hours.

[0033] (3) Grinding: Grind the moistened wheat to achieve a plum blossom shape where the heart is rotten but the skin is not. The degree of grinding is controlled as follows: after passing through a 20-mesh sieve, the fine powder accounts for 32%.

[0034] (4) Mixing: Mix the crushed raw materials with water until they are evenly mixed, and control the moisture content to 38% to achieve the standard of "not sticky when kneaded by hand".

[0035] (5) Pressing the koji blank: Put the raw material into the mechanical koji press, press the pressure of 5~8KN, press the time of 10~15 seconds, the thickness of the koji blank is 6cm, the length and width are 30cm and 20cm respectively, and the amount of material for each koji blank is 4.2kg.

[0036] (6) Spreading and drying: Spread the pressed and shaped shaped blanks and let them dry for 12 minutes to set their shape.

[0037] (7) Placing the molded koji in the room: Arrange the molded koji in a bucket shape in the room, with four molded koji in one direction. Sprinkle rice husks on the top and bottom of the molded koji and finally cover the molded koji with straw mats.

[0038] (8) Fermentation of koji: The koji blanks are fermented in the fermentation room for 28 to 35 days.

[0039] The conditions for turning the koji are as follows: In the early stage, cultivate the koji at a low temperature, turning it once every 3-5 days; in the middle stage, maintain a high temperature for 5-7 days, turning or cooling it appropriately; in the later stage, maintain the temperature no higher than 45℃ for 9-12 days; finally, pile all the koji blanks and keep them at room temperature. The highest temperature at the core of the koji should be controlled at 50-60℃. Temperature control methods include turning the koji, opening windows, and sprinkling water. The turning method is as follows: remove the straw mat and turn the koji blanks left and right, top and bottom; exchange the positions of the koji blanks placed on the outside with those on the inside to ensure even fermentation.

[0040] (9) Drying the starter: After the starter is prepared, the starter is removed from the starter room and dried naturally under ventilation until the moisture content is ≤13%, thus obtaining anthocyanin-enhanced starter.

[0041] Each type of wheat had 12 replicates.

[0042] 3. Sensory rating method; Referring to the sensory evaluation criteria for strong-aroma Daqu (a type of Chinese liquor), the evaluation is based on three dimensions: appearance, cross-section, and aroma, with maximum scores of 10, 30, and 20 points respectively, for a total sensory score of 60 points. The specific evaluation criteria are as follows: Appearance rating (out of 10): A high score is given for uniform mycelium on the surface of the koji blank, grayish-white or yellowish-brown in color, and no contamination by other bacteria; a low score is given for a rough surface and the presence of other bacteria.

[0043] Cross-section scoring (30 points in total): High score is given for dense cross-section structure, full hyphae, and obvious aroma; low score is given for loose cross-section and no hyphae.

[0044] Aroma rating (out of 20 points): A high score is given for a rich aroma with no off-flavors; a low score is given for a weak aroma or an off-flavor.

[0045] The sensory rating results are shown in Table 2.

[0046] Table 2 Comparison of sensory scores for two types of wheat brewing yeast Chuanmai 98 8.50±0.01 20.92±0.15 15.75±0.18 45.17±0.22 57.43 Sichuan Purple Wheat 901 8.97±0.02 24.67±0.41 18.58±0.26 52.22±0.64 58.81 Increase +5.5% +17.93% +17.97% +15.61% +1.38℃ Depend on Figure 2 As shown in Table 2, the yeast starter prepared using Chuanzimai 901, a floury wheat variety with high anthocyanin content, is significantly superior to the ordinary Chuanmai 98 yeast starter in terms of appearance, cross-section, aroma, and total sensory score (P<0.05). Specifically, the cross-section score increased by 17.93%, the aroma score by 17.97%, and the total sensory score by 15.61%, indicating that anthocyanins have a significant effect on improving the cross-sectional structure and aroma quality of the yeast starter.

[0047] The highest temperature of the koji core of Chuanzimai 901 (58.81℃) is slightly higher than that of Chuanmai 98 (57.43℃), which is 1.38℃ higher. This is conducive to the full formation of koji aroma and the optimization of microbial community.

[0048] The above results indicate that anthocyanin-rich floury wheat varieties can effectively regulate the microbial community structure and promote the proliferation of beneficial bacteria during the koji-making process, thereby improving the cross-sectional structure and aroma quality of the koji.

[0049] Example 2: Verification experiment on the amount of anthocyanins added To further verify that anthocyanins are an effective active ingredient for improving the quality of yeast starter and to eliminate the interference of other trait differences among wheat varieties, this embodiment uses ordinary floury wheat from a yeast starter factory as raw material and adds different doses of anthocyanin extract exogenously during the yeast starter production process to investigate its effect on the quality of yeast starter.

[0050] 1. Experimental design; Set up 3 processing groups: Control group: No anthocyanins added (ordinary flour wheat raw material); Low-dose group: 0.03g of anthocyanins were added per kilogram of raw material (equivalent to an anthocyanin content of approximately 60 nmol / g); High-dose group: 0.1125g of anthocyanins were added per kilogram of raw material (equivalent to an anthocyanin content of approximately 225 nmol / g).

[0051] Each group has 6 repetitions.

[0052] Among them, the anthocyanin extract is derived from blueberries (commercially available blueberry anthocyanin extract, purity ≥25%).

[0053] 2. Addition method and koji-making process; The method for adding anthocyanins is as follows: Add the anthocyanin extract to the water used for koji making according to the above dosage, stir evenly to fully dissolve or disperse the anthocyanins, and then stir and mix with the pulverized raw materials. The remaining koji making steps are the same as in Example 1, and the pressing pressure is 5KN.

[0054] 3. Experimental results; The experimental results are shown in Table 3.

[0055] Table 3. Effects of different anthocyanin addition amounts on the quality of the yeast starter. Sensory total score / points 46.00±0.64 51.40±0.67 52.17±0.71 Cross-sectional score / point 22.83±0.55 26.74±0.58 26.83±0.63 Aroma rating / points 15.17±0.52 16.66±0.65 17.33±0.69 Appearance rating / points 8.0±0.01 8.0±0.01 8.0±0.01 Glycosyl power / U 902 890 858 Liquefaction force / U 2.67 1.45 1.30 Moisture / % 12.11 12.20 12.85 Sensory rating improvement -- +11.74% +13.41% Improved cross-sectional score -- +17.13% +17.52% Depend on Figure 3 As shown in Table 3, the exogenous addition of anthocyanins significantly improved the sensory and cross-sectional scores of the koji (P<0.05). The total sensory score of the low-dose group increased by 11.74% compared with the control group, and that of the high-dose group increased by 13.41%; the cross-sectional scores increased by 17.13% and 17.52%, respectively. There was no significant difference in total sensory score and cross-sectional score between the low-dose group (0.03 g / kg) and the high-dose group (0.1125 g / kg) (P>0.05), indicating that after the anthocyanin addition reached 0.03 g / kg, the marginal effect of further increasing the anthocyanin dosage on quality improvement diminished. The saccharification power and liquefaction power decreased slightly with the increase of anthocyanin addition, but overall remained within the normal process range of high-quality koji enzyme activity (saccharification power ≥850 U, liquefaction power ≥1.2 U), and did not affect the normal function of the koji. There were no significant differences in appearance scores among the treatment groups, indicating that anthocyanins mainly affect the internal structure (cross-section) and aroma quality of Daqu, rather than its surface appearance.

[0056] Based on comprehensive sensory quality and enzyme activity indicators, the optimal addition amount of anthocyanins to floury wheat raw materials is no less than 0.03 g / kg. This embodiment, through exogenous addition, eliminates interference from other factors such as protein and gluten content among wheat varieties, independently verifying that anthocyanins themselves are an effective active ingredient for improving the quality of strong-aroma Daqu (a type of Chinese koji).

[0057] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for improving the quality of strong-aroma medium-high temperature koji using anthocyanin-rich floury wheat raw materials, characterized in that, Anthocyanin-rich floury wheat is selected as the raw material for making strong-aroma medium-high temperature koji. The anthocyanin content of the grains of the floury wheat is not less than 60 nmol / g, and the flour content is not less than 70%.

2. The method for improving the quality of strong-aroma medium-high temperature koji using anthocyanin-rich floury wheat raw materials according to claim 1, characterized in that, The floury wheat is Sichuan Purple Wheat 901.

3. The method for improving the quality of strong-aroma medium-high temperature koji using anthocyanin-rich floury wheat raw materials according to claim 1, characterized in that, The method specifically includes: adding water to moisten the anthocyanin-rich wheat grains; crushing the moistened grains into a plum blossom shape with a rotten core but intact outer skin; adding water and stirring until evenly mixed, controlling the moisture content at 36%~40%; pressing into koji blanks; spreading the koji blanks out to cool and shape; fermenting for 28~35 days, controlling the maximum fermentation temperature of the koji at 50~60℃; after fermentation, removing the koji blanks from the fermentation room and drying them until the moisture content is ≤13%.

4. A method for improving the quality of strong-aroma medium-high temperature koji using anthocyanin-rich floury wheat raw materials according to claim 3, characterized in that, The pressing and molding process uses mechanical pressing, with a pressing pressure of 5~8KN and a pressing time of 10~15 seconds. The thickness of the blank is 5~8cm, and the length and width are 30cm and 20cm respectively. The amount of material fed into each blank is 4~4.5kg.

5. A method for improving the quality of strong-aroma medium-high temperature koji using anthocyanin-rich floury wheat raw materials according to claim 3, characterized in that, The conditions for turning the koji during fermentation are as follows: in the early stage, the koji is cultivated at a low temperature and turned once after 3 to 5 days; in the middle stage, the koji is maintained at a high temperature of 50-65℃ for 5 to 7 days, and then turned or cooled down; in the later stage, the temperature is maintained at no more than 45℃ for 9 to 12 days; finally, all the koji blanks are piled up and kept at room temperature. The method for turning the koji is as follows: remove the straw mat, turn the koji blanks left and right and up and down, and exchange the positions of the koji blanks placed on the outside with the koji blanks placed on the inside.

6. A method for improving the quality of strong-aroma medium-high temperature koji using anthocyanin-rich floury wheat raw materials according to claim 5, characterized in that, The method further includes the step of adding anthocyanins exogenously to ordinary floury wheat raw materials. The method of adding anthocyanins exogenously is as follows: add anthocyanins to the water for making koji and stir evenly, and then stir and mix them with the crushed raw materials.

7. A method for improving the quality of strong-aroma medium-high temperature koji using anthocyanin-rich floury wheat raw materials according to claim 6, characterized in that, The amount of anthocyanins added shall not be less than 0.03g per kilogram of raw material.

8. A method for improving the quality of strong-aroma medium-high temperature koji using anthocyanin-rich floury wheat raw materials according to claim 6, characterized in that, The anthocyanin extract is derived from one or more of the following: purple wheat, black rice, purple sweet potato, blueberry, black goji berry, and purple cabbage.

9. The application of anthocyanin-fortified yeast prepared according to any one of claims 1-8 in the brewing of strong-aroma baijiu.

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