Distilled liquor added with bamboo leaf powder and preparation method of distilled liquor

Abstract

The invention relates to the technical field of wine brewing, and discloses a bamboo leaf powder added distilled liquor and a preparation method thereof, and the distilled liquor is prepared from 75-85 parts of grain powder and 15-25 parts of enzyme-deactivated bamboo leaf powder. The preparation method comprises the following steps: mixing the raw materials to obtain a dry mixture; adding a compound enzyme preparation containing cellulase and pectinase, preserving heat at 50-55 DEG C, performing enzymolysis and moistening, destroying a fiber structure and converting fermentable sugar; cooking the moistened material, and adding a saccharifying enzyme for saccharifying; primary fermentation is performed at 28-32 DEG C, and then secondary fermentation is performed at 22-25 DEG C; during distillation, foreshot with the expected wine yield of 1.5%-2.0% is intercepted and abandoned to remove methanol, fractions with the volume of 50% or above are collected to obtain raw wine, and the wine is obtained through ageing. The raw material utilization rate and the wine yield are improved through enzymolysis, the methanol content is controlled through temperature-variable fermentation and precise cut distillation, the raw and green taste of bamboo leaves is eliminated, and the finished wine has the unique composite style of bamboo fragrance and grain fragrance.

Description

Technical Field

[0001] This invention relates to the field of brewing technology, specifically to a distilled spirit with added bamboo leaf powder and its preparation method. Background Technology

[0002] Distilled spirits are primarily made from grains through solid-state fermentation and distillation. With increasing demand for flavorful and health-promoting spirits, the use of plant resources such as bamboo leaves to brew new types of baijiu (Chinese white liquor) has become a research hotspot. Bamboo leaves are rich in flavonoids, polysaccharides, and trace elements, possessing high development value.

[0003] In existing technologies, the application of bamboo leaves is mainly achieved through soaking or distillation. Soaking is a physical extraction method; the flavor compounds in bamboo leaves have not undergone microbial metabolic transformation, resulting in poor integration with the base liquor and insufficient aroma stability. Furthermore, prolonged soaking easily dissolves excessive tannins and chlorophyll degradation products, leading to a noticeable bitterness and raw, grassy taste in the liquor. Distillation utilizes steam to carry aromas, but can only extract volatile components, leaving a large amount of non-volatile bioactive substances in the bamboo leaves unutilized, resulting in significant resource waste.

[0004] A few attempts have been made to use bamboo leaves directly as a raw material for fermentation, but the following technical bottlenecks exist: First, bamboo leaves have a high cellulose content and a low starch content, and their cell walls are dense. Under conventional fermentation conditions, yeast has difficulty accessing and utilizing the internal nutrients, and the fermentation system lacks sufficient sugar sources, resulting in insufficient fermentation power and generally low raw material utilization and alcohol yield. Second, fresh bamboo leaves contain polyphenol oxidase and pectin. Without targeted pretreatment and process control, endogenous enzymatic reactions can produce oxidative off-flavors, and pectin is easily degraded during fermentation to produce methanol, increasing the safety risks of the finished wine. Summary of the Invention

[0005] The technical problem solved by this invention is that in the prior art, when using bamboo leaves to ferment and prepare distilled liquor, the high cellulose content and low starch content of bamboo leaves result in low raw material utilization and low alcohol yield due to direct fermentation. At the same time, the natural degradation of pectin in bamboo leaves can easily lead to excessive methanol content, and untreated bamboo leaves can easily introduce obvious raw green taste and bitterness, resulting in an uncoordinated flavor in the finished liquor.

[0006] To address the above problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a distilled spirit with added bamboo leaf powder, employing the following technical solution: A distilled spirit with added bamboo leaf powder is made from raw materials comprising the following parts by weight: 75-85 parts grain flour and 15-25 parts bamboo leaf powder.

[0007] The bamboo leaf powder is obtained by blanching, drying and pulverizing fresh bamboo leaves; and the raw materials are subjected to enzymatic hydrolysis and moistening treatment during the preparation of the distilled liquor, which uses a compound enzyme preparation containing cellulase and pectinase.

[0008] By adopting the above technical solution, the present invention constructs a suitable substrate environment for solid-state fermentation using a specific raw material ratio: First, grain flour, as the main carbon source carrier, provides sufficient starch and nitrogen for the growth and reproduction of yeast and ethanol metabolism, ensuring the basic alcohol production capacity of the fermentation system.

[0009] Secondly, bamboo leaf powder plays a dual role within this ratio range: Chemically, it introduces bioactive components such as flavonoids and polysaccharides unique to bamboo leaves, as well as flavor precursors. Physically, the incompletely degraded fiber structure in bamboo leaves acts as a natural loosening agent, increasing the porosity of the mash, improving mass transfer and heat dissipation conditions during solid-state fermentation, and avoiding poor air permeability or excessively rapid local temperature rise caused by excessive viscosity of pure grain fermentation materials, thereby inhibiting the growth of miscellaneous bacteria.

[0010] Experiments have shown that this ratio range achieves a balance between flavor and yield: if the amount of bamboo leaf powder added is less than 15%, the characteristic flavor of bamboo leaves in the finished wine is weak; if the amount of bamboo leaf powder added is more than 25%, the starch concentration per unit volume is insufficient, which makes it difficult to raise the fermentation temperature, significantly reduces the ethanol yield, and excessive tannins and lignin will cause the wine to taste bitter.

[0011] Preferably, the grain powder is selected from one or more of glutinous sorghum, japonica rice, wheat, and peas; the bamboo leaf powder is made from fresh bamboo leaves through blanching, drying, and pulverizing, and the fresh bamboo leaves are selected from one of light bamboo leaves, hemp bamboo leaves, or moso bamboo leaves.

[0012] By adopting the above technical solutions, the quality and harmony of the liquor are further improved: First, the blending of glutinous sorghum (producing aroma), japonica rice (producing purity), and wheat and peas (producing yeast aroma) enriches the composition of alcohols and esters in the base liquor, making the liquor full-bodied and thus masking the rawness that might result from single-leaf fermentation. Second, blanching fresh bamboo leaves is key to improving flavor. High-temperature instantaneous blanching rapidly destroys the activity of endogenous enzymes such as polyphenol oxidase in fresh leaves, blocking enzymatic oxidation reactions and preventing browning and the formation of unpleasant oxidative flavors. At the same time, high temperature promotes the volatilization and dissipation of low-boiling-point substances that cause raw, grassy flavors, such as chlorophyll and chlorophyll aldehyde, and promotes the emergence of high-boiling-point aroma substances, eliminating the roughness of the finished liquor from the source. Third, pulverizing bamboo leaves to a specific mesh size increases the specific surface area of ​​the raw material, allowing exogenous enzyme preparations to fully contact the substrate during subsequent enzymatic hydrolysis, improving the degradation efficiency of cellulose and the dissolution rate of effective components.

[0013] Preferably, the raw material is composed of the following components in parts by weight: 80 parts grain powder and 20 parts bamboo leaf powder.

[0014] By adopting the above technical solution, the fermentation substrate provided by grain starch and the physical support structure provided by bamboo leaf powder achieve optimal synergy. Under this ratio, the acidity of the mash increases gradually during fermentation, the yeast activity is maintained for a long time, and the final mid-stage liquor maintains an alcohol content of over 50% vol while possessing an elegant bamboo aroma, a mellow body, and a methanol content at the lowest possible level.

[0015] Secondly, the present invention provides a method for preparing distilled spirits with added bamboo leaf powder, employing the following technical solution: A method for preparing distilled spirits with added bamboo leaf powder, comprising the following steps: S1. Raw material pretreatment: Fresh bamboo leaves are selected to prepare bamboo leaf powder, and grains are selected to prepare grain powder. They are mixed and stirred evenly in proportion to obtain a dry mixture. S2. Enzymatic hydrolysis of wet material: The activated compound enzyme preparation is sprayed onto the dry mixture and water is added. After stirring evenly, the mixture is piled up and sealed for incubation and enzymatic hydrolysis to obtain the enzymatic hydrolysis wet material. The compound enzyme preparation contains cellulase and pectinase. S3. Cooking and saccharification: The enzymatically hydrolyzed wet material is loaded into a steamer and cooked. After cooling, saccharifying enzyme is added to saccharify the material to obtain saccharified mash. S4. Fermentation: Activated brewing dry yeast is added to the saccharified mash, and the mash is sealed for fermentation to obtain mature mash. S5. Distillation: Rice husks are mixed into the mature mash and the mash is loaded into a still for distillation. The heads of the distillate are discarded, and the fraction with an alcohol content of 50% vol or higher is collected to obtain the mid-stage original liquor. S6. Aging: The original liquor in the middle section is sealed and aged, and after blending and filtration, the distilled liquor with added bamboo leaf powder is obtained.

[0016] By adopting the above technical solution, this invention introduces a crucial bio-enzymatic hydrolysis step before the cooking process in traditional solid-state brewing, solving the problem of dense and difficult-to-degrade bamboo leaf fibers through step-by-step processing. First, the enzymatic hydrolysis during the moistening stage utilizes biocatalysis to pre-disrupt the dense cell wall structure of the bamboo leaves, releasing active substances such as flavonoids and polysaccharides encapsulated in the fibers, while simultaneously converting some large-molecule cellulose into fermentable sugars or short-chain oligosaccharides. Second, the material after enzymatic hydrolysis has a looser texture, allowing for more uniform water penetration and more thorough starch gelatinization during subsequent cooking, thereby improving the efficiency of saccharifying enzymes. Finally, through the combination of fermentation and distillation, the effective components of the bamboo leaves are efficiently transferred to the liquor, achieving a balance between high alcohol yield and unique flavor.

[0017] Preferably, in step S2, the compound enzyme preparation is composed of cellulase and pectinase, with a weight ratio of cellulase to pectinase of (60-70):(30-40), and the amount of the compound enzyme preparation added is 0.1% to 0.3% of the total weight of the dry mixture; the specific operation of the incubation enzymatic hydrolysis is as follows: add warm water to the total moisture content to 50% to 60%, and incubate the enzymatic hydrolysis at a temperature of 50℃ to 55℃ for 4h to 6h.

[0018] By adopting the above technical solution, the present invention constructs a composite enzymatic hydrolysis environment adapted to the bamboo leaf-grain mixed matrix. Its mechanism of action is to balance "saccharification" and "impurity removal": Firstly, bamboo leaves are rich in cellulose, and the utilization rate of direct fermentation is low.

[0019] This method utilizes a high proportion (60-70%) of cellulase to act on the cellulose microfibrils of bamboo leaf cell walls, breaking β-1,4-glycosidic bonds. This process not only disrupts the integrity of the cell wall and promotes the dissolution of intracellular flavor substances, but also degrades recalcitrant cellulose into a carbon source that can be utilized by yeast, directly increasing the alcohol yield of the raw material. Secondly, the proportion of pectinase is strictly controlled to not exceed 40%. Although pectinase helps with the disintegration and softening of plant tissues, the pectin degradation process is the main source of methanol in distilled spirits. This method limits the amount of pectinase to ensure the moistening effect while limiting the activity of pectin methyl esterase, preventing a surge in methanol content in the fermentation precursor. Thirdly, the process parameters of 50℃~55℃ and 4h~6h are set based on the optimal reaction range of the two enzymes mentioned above. Under these conditions, the enzyme activity is at its peak, enabling the pretreatment of the substrate to be completed before the proliferation of mesophilic microorganisms (such as lactic acid bacteria).

[0020] Preferably, in step S4, the fermentation adopts a variable temperature fermentation process: first, the primary fermentation is carried out at 28℃~32℃ for 7 days, and then the temperature is lowered to 22℃~25℃ to continue the secondary fermentation for 23 days~53 days, with a total fermentation cycle of 30 days~60 days.

[0021] By employing the above technical solution, the metabolic flow of yeast is regulated through staged temperature control: During the primary fermentation stage (the first 7 days), maintaining a relatively high temperature (28℃~32℃) is conducive to the rapid proliferation of brewing yeast and the glycolysis pathway, allowing the yeast population to quickly become the dominant flora, inhibiting the growth of other microorganisms, and simultaneously rapidly consuming sugar to produce ethanol. In the secondary fermentation stage, the temperature is lowered to 22℃~25℃ and the fermentation time is extended, reducing the yeast's metabolic rate and decreasing the formation of higher alcohols (fusel oils). Simultaneously, the low-temperature environment is conducive to esterification reactions, promoting the accumulation of flavor compounds such as ethyl acetate, resulting in a more delicate aroma in the wine.

[0022] Preferably, in step S5, the specific operation of discarding the heads is as follows: a fraction equivalent to 1.5% to 2.0% of the expected alcohol yield is collected and discarded separately as heads for methanol removal.

[0023] By adopting the above technical solution, a distillation and impurity removal measure targeting the fermentation characteristics of bamboo leaves was implemented: Since bamboo leaves contain a certain amount of pectin and lignin, the amount of byproducts such as methanol and acetaldehyde generated during fermentation is slightly higher than in pure grain fermentation. Given that methanol and acetaldehyde have lower boiling points than ethanol, they tend to accumulate in the heads fraction during the initial distillation stage. Therefore, this invention sets a removal ratio of 1.5% to 2.0% (slightly higher than the removal ratio for conventional grain spirits). This ratio effectively removes most of the methanol and low-boiling-point impurities, ensuring that the finished spirit meets safety standards in terms of hygiene indicators, while avoiding the loss of high-quality mid-stage spirit due to excessive removal.

[0024] This invention provides a distilled spirit with added bamboo leaf powder and its preparation method. It has the following beneficial effects: 1. This invention solves the problem of raw bamboo leaves easily producing a raw, grassy taste and inconsistent style when added to wine by using specific raw material ratios and blanching pretreatment technology. It endows the finished wine with a refined bamboo aroma and grain aroma composite style. The mass ratio of grain powder to bamboo leaf powder is limited to (75-85):(15-25), which ensures the balance of carbon and nitrogen sources in the fermentation system and maintains normal fermentation dynamics. Combined with the blanching process, it effectively deactivates the polyphenol oxidase activity in bamboo leaves, removes low-boiling-point substances such as green leaf alcohol that cause raw, grassy taste, prevents the generation of oxidative bad taste, and makes the final product mellow and elegant in taste.

[0025] 2. This invention utilizes a compound enzymatic hydrolysis and moistening technology to significantly improve the utilization rate, alcohol yield, and dissolution efficiency of active ingredients in bamboo leaf raw materials. Targeting the characteristics of bamboo leaves with high fiber content and low starch content, cellulase and pectinase are introduced for synergistic treatment before steaming and cooking. This disrupts the dense cell wall structure of bamboo leaves, which not only promotes the release of bioactive components such as bamboo leaf flavonoids, but also converts some cellulose into fermentable sugars that can be utilized by yeast, compensating for the lack of starch source. Thus, a high yield of raw wine is obtained with low starch input.

[0026] 3. This invention employs a variable-temperature fermentation process combined with a quantitative distillation removal strategy to effectively control methanol content and establish a safe and stable industrial production method. Addressing the risk of increased methanol levels due to the degradation of bamboo leaf pectin, the invention controls fusel oil production through variable-temperature fermentation with higher initial temperatures followed by lower final temperatures. Furthermore, it sets a head-cutting ratio of 1.5% to 2.0% of the expected yield from the initial feed, precisely removing harmful byproducts such as methanol and acetaldehyde. This ensures that the finished wine meets safety standards in terms of hygiene indicators and guarantees quality stability between production batches. Detailed Implementation

[0027] Examples 1-3: Example 1: This embodiment provides a distilled spirit with added bamboo leaf powder and its preparation method, including the following steps: S1. Select fresh bamboo leaves, clean them after removing impurities, place them in 95℃ steam for 60 seconds to kill the green, dry them to a moisture content of 8%, pulverize them using an ultra-fine pulverizer and pass them through an 80-mesh sieve to obtain bamboo leaf powder; separately select glutinous sorghum, pulverize it and pass it through a 20-mesh sieve to obtain grain powder; put them into a mixer at a mass ratio of 85% grain powder to 15% bamboo leaf powder and stir evenly to obtain a dry mixture. S2. Prepare a compound enzyme preparation containing cellulase (70%) and pectinase (30%), the amount of which is 0.1% of the total weight of the dry mixture; after activating the compound enzyme preparation by dissolving it in a small amount of 35°C warm water, spray it into the dry mixture, and add 50°C warm water to make the total moisture content 50%. After stirring evenly, pile it up and seal it, and keep it in a 50°C environment for 4 hours for enzymatic hydrolysis to obtain the enzymatically hydrolyzed material. S3. The enzymatically hydrolyzed material is loaded into a steamer and cooked under normal pressure for 40 minutes. After being removed from the steamer, it is cooled to 28°C by blowing air. 0.8% of the total weight of the raw material is added to the saccharifying enzyme. After stirring evenly, the mixture is piled up and saccharified for 24 hours until the product temperature rises to 32°C and the material has a sweet taste, thus obtaining the saccharified mash. S4. Add 0.3% of activated brewing dry yeast to the saccharified mash, put it into a fermentation earthenware jar and seal it, controlling the moisture content of the jar to 55%; first, carry out primary fermentation at 28℃ for 7 days, then cool down to 22℃ and continue secondary fermentation for 23 days (total fermentation cycle 30 days) to obtain mature mash. S5. Mix 15% of steamed rice husks into the mature mash, load it into a still and distill over a low heat; collect and discard the fraction equivalent to 1.5% of the expected alcohol yield as the head (to remove methanol), then collect the fraction with an alcohol content of 50% vol or higher as the middle section of the base liquor, and discard the tail liquor with an alcohol content of less than 50% vol. S6. Place the middle section of the original liquor in a ceramic jar, seal and age it in a cool, dry place for 6 months. After blending and filtration, you will get a distilled liquor with added bamboo leaf powder.

[0028] Example 2: This embodiment provides a distilled spirit with added bamboo leaf powder and its preparation method, including the following steps: S1. Select fresh bamboo leaves, clean them to remove impurities, place them in boiling water at 98℃ for 90 seconds to blanch them, dry them to a moisture content of 6%, pulverize them using an ultra-fine pulverizer and pass them through a 100-mesh sieve to obtain bamboo leaf powder; separately select japonica rice and sorghum in a 1:1 ratio, pulverize them and pass them through a 30-mesh sieve to obtain grain powder; add the grain powder and bamboo leaf powder in a mixer at a mass ratio of 80% grain powder to 20% bamboo leaf powder and stir evenly to obtain a dry mixture; S2. Prepare a compound enzyme preparation containing cellulase (65%) and pectinase (35%), the amount of which is 0.2% of the total weight of the dry mixture; after activating the compound enzyme preparation by dissolving it in a small amount of 38°C warm water, spray it into the dry mixture, and add 52°C warm water to make the total moisture content 55%. After stirring evenly, pile it up and seal it, and keep it in a 52°C environment for 5 hours for enzymatic hydrolysis to obtain the enzymatically hydrolyzed material. S3. The enzymatically hydrolyzed material is loaded into a steamer and cooked under normal pressure for 50 minutes. After being removed from the steamer, it is cooled to 30°C by forced air. 1.0% of the total weight of the raw material is added to the saccharifying enzyme. After stirring evenly, the mixture is piled up and saccharified for 30 hours until the product temperature rises to 33°C and the material has a sweet and slightly sour taste, thus obtaining the saccharified mash. S4. Add 0.4% of activated brewing dry yeast to the saccharified mash, put it into a stainless steel fermentation tank and seal it, controlling the moisture content of the mash to 58%; first, perform primary fermentation at 30℃ for 7 days, then cool down to 24℃ and continue secondary fermentation for 38 days (total fermentation cycle 45 days) to obtain mature mash. S5. Mix 18% of steamed rice husks into the mature mash, load it into a still and distill over a low heat; collect and discard the fraction equivalent to 1.8% of the expected alcohol yield as the head (to remove methanol), then collect the fraction with an alcohol content of 50% vol or higher as the middle section of the base liquor, and discard the tail liquor with an alcohol content of less than 50% vol. S6. Place the middle section of the original liquor in a ceramic jar, seal and age it in a cool, dry place for 9 months. After blending and filtering, you will get a distilled liquor with added bamboo leaf powder.

[0029] Example 3: This embodiment provides a distilled spirit with added bamboo leaf powder and its preparation method, including the following steps: S1. Select fresh bamboo leaves, clean them to remove impurities, place them in 100℃ steam for 120 seconds to blanch them, dry them to a moisture content of 5%, pulverize them using an ultra-fine pulverizer and pass them through a 120-mesh sieve to obtain bamboo leaf powder; separately select wheat and peas in a 4:1 ratio, pulverize them and pass them through a 40-mesh sieve to obtain grain powder; add the grain powder and bamboo leaf powder in a mixer at a mass ratio of 75% grain powder to 25% bamboo leaf powder and stir evenly to obtain a dry mixture; S2. Prepare a compound enzyme preparation containing cellulase (60%) and pectinase (40%), the amount of which is 0.3% of the total weight of the dry mixture; after activating the compound enzyme preparation by dissolving it in a small amount of 40°C warm water, spray it into the dry mixture, and add 55°C warm water to the total moisture content to 60%, stir evenly, stack and seal, and keep it in a 55°C environment for 6 hours for enzymatic hydrolysis to obtain the enzymatically hydrolyzed material; S3. The enzymatically hydrolyzed material is loaded into a steamer and cooked under normal pressure for 60 minutes. After being removed from the steamer, it is cooled to 32°C by forced air. 1.2% of the total weight of the raw material is added to the saccharifying enzyme. After stirring evenly, the mixture is piled up and saccharified for 36 hours until the product temperature rises to 35°C and the material has a sweet taste and obvious sour taste, thus obtaining the saccharified mash. S4. Add 0.5% of activated brewing dry yeast to the saccharified mash, pack it into a mud pit and seal it, controlling the moisture content of the mash to 60%; first, perform primary fermentation at 32℃ for 7 days, then cool down to 25℃ and continue secondary fermentation for 53 days (total fermentation cycle 60 days) to obtain mature mash. S5. Mix 20% of steamed rice husks into the mature mash, load it into a still and distill over a low heat; collect and discard the fraction equivalent to 2.0% of the expected alcohol yield as the head (to remove methanol), then collect the fraction with an alcohol content of 50% vol or higher as the middle section of the base liquor, and discard the tail liquor with an alcohol content of less than 50% vol. S6. Place the middle section of the original liquor in a ceramic jar, seal and age it in a cool, dry place for 12 months, then blend and filter to obtain the distilled liquor with added bamboo leaf powder.

[0030] Comparative Example 1: Compared to Example 2, the difference lies in the method of introducing bamboo leaves, using a traditional physical soaking method instead of the enzymatic co-fermentation method. The specific differences are as follows: Preparation of fermented base liquor: In steps S1 and S2, bamboo leaf powder and compound enzyme preparation are not added. Instead, bamboo leaf powder is replaced with grain powder of equal mass to keep the total weight of feed consistent with that in Example 2. The feed is then moistened. Subsequently, the saccharification, fermentation and distillation of a single grain are carried out according to steps S3 to S5 to obtain pure grain base liquor. Bamboo leaf introduction: The bamboo leaf powder obtained in S1 (without blanching and enzymatic hydrolysis, only washed and dried) is directly added to the above pure grain base liquor and soaked in a sealed earthenware jar for 15 days. Finished product acquisition: After soaking, the bamboo leaf residue is removed by filtration, and the filtrate is the finished wine. The specifications of other raw materials and process parameters (such as saccharification temperature, fermentation cycle, etc.) are the same as in Example 2.

[0031] Test Example 1: Process Feasibility and Safety Test; Experimental description: The finished wines prepared in Examples 1, 2, and 3 were selected as the experimental group, and the finished wine prepared in Comparative Example 1 was selected as the control group. The indicators were tested according to GB / T 10345-2007 "Analytical Methods for Baijiu" and GB 2757-2012 "National Food Safety Standard for Distilled Spirits and Blended Spirits". First, the yield of raw materials was determined, and the total alcohol content (65% vol) after fermentation and distillation was calculated for each group. The formula was: Yield = (Total alcohol content (65% vol) / Total weight of raw materials) × 100%. Second, the methanol content was determined using gas chromatography with a PEG-20M capillary column and a flame ionization detector. A 10 mL sample was taken, and n-butyl acetate was added as an internal standard for analysis.

[0032] Experimental data: The test results are shown in Table 1.

[0033] Table 1. Alcohol yield and methanol content detection data for different process groups

[0034] Note: "-" indicates that the item has no corresponding value or is not applicable.

[0035] Results analysis: Comparative Example 1 used whole grain raw materials, with the highest starch content and an alcohol yield of 48.76%. In Examples 1 to 3, the proportion of bamboo leaf powder replacing grain increased from 15% to 25%, and the alcohol yield decreased from 46.24% to 43.05%. If bamboo leaves are only used as filler and do not participate in fermentation, the theoretical decrease in alcohol yield corresponding to replacing 25% of grain in Example 3 should be close to 25%, while the actual measured decrease is about 11.7%. The actual decrease is less than the theoretical decrease, indicating that the compound enzyme preparation breaks down the cell walls of bamboo leaves during the moistening and stacking stage, degrading some cellulose and hemicellulose into reducing sugars, thus supplementing the fermentation substrate.

[0036] Bamboo leaves contain pectin, which releases methanol through the action of pectinase. The methanol content in the example group (0.183 g / L to 0.312 g / L) was higher than that in Comparative Example 1 (0.115 g / L), and showed an increasing trend with the increase of bamboo leaf addition and enzyme dosage. The methanol residue in all examples was lower than the national standard limit (0.60 g / L). In Example 3, with a pectinase content of 40% and a bamboo leaf raw material content of 25%, the methanol content was 0.312 g / L. The operation of removing the first 1.5% to 2.0% of the distillate during the distillation process utilizes the low boiling point of methanol to enrich it in the heads and remove it, thereby significantly reducing the methanol content in the middle section of the original spirit and controlling it within a safe range.

[0037] Test Example 2: Sensory Quality Evaluation; Experimental description: The finished liquors prepared in Examples 1, 2, and 3, and Comparative Example 1 were selected as samples for testing. A sensory evaluation panel consisting of 10 members with national-level baijiu (Chinese liquor) judging qualifications was formed. The evaluation was conducted using a double-blind method, based on GB / T 33405-2016 "Sensory Evaluation Terminology for Baijiu" and relevant aroma scoring standards. Evaluation indicators included color (10 points), aroma (30 points), taste (40 points), and style (20 points), for a total score of 100 points. Color was assessed based on the transparency and hue of the liquor; aroma was assessed based on the integration of bamboo and liquor aromas and the presence of a raw, grassy taste; taste was assessed based on the fullness of the liquor and the presence of bitterness; and style was assessed based on overall harmony. The results were the average of the scores given by the 10 judges, rounded to one decimal place.

[0038] Experimental data: The sensory evaluation results are shown in Table 2.

[0039] Table 2. Statistical table of sensory quality scores for each group

[0040] Results analysis: The total scores of the Example group were all higher than those of Comparative Example 1, with Example 2 scoring the highest (93.1 points).

[0041] Comparative Example 1, which used a physical maceration process, scored 73.3 points, with the main deductions being in taste and aroma. The physical maceration process extracts water-soluble tannins, flavonoids, and chlorophyll from bamboo leaves into the base wine. Tannins have astringent properties, resulting in a bitter and rough taste; chlorophyll and aldehydes give the wine a raw, grassy aroma, masking the ester aroma of the base wine, and also giving it a slightly yellow color.

[0042] The example group employed enzymatic co-fermentation and distillation processes. In terms of taste, Example 2 scored 37.5 points, higher than Comparative Example 1's 28.4 points. The blanching process in the pretreatment stage deactivates polyphenol oxidase, reducing the formation of astringent substances; tannins, flavonoids, and other large-molecule bitter substances are non-volatile and remain in the lees during distillation, not entering the distillate, resulting in a clean and refreshing taste in the finished spirit.

[0043] In terms of aroma, Example 2 scored 27.3 points. During fermentation, cellulase releases phenolic acid precursors such as ferulic acid, which are then metabolized by yeast into volatile flavor compounds such as 4-vinylguaiacol, presenting a bamboo and smoky aroma that blends with ethanol and esters. Example 3, with the largest amount of bamboo leaves added, scored slightly lower (26.9 points) in aroma than Example 2. Excessive bamboo leaf components altered the concentration of precursors in the fermentation system, affecting the proportion of flavor compounds and thus the smoothness of the wine. The process parameters of Example 2 achieved a balance between flavor intensity and body harmony.

[0044] Test Example 3: Qualitative Analysis of Volatile Flavor Compounds; Experimental description: The finished wines prepared in Example 2 and Comparative Example 1 were selected as the analytes. Volatile flavor components were detected using headspace solid-phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS). 8 mL of sample was placed in a 20 mL headspace vial, sodium chloride was added to saturation, and 10 μL of 50 mg / L 2-octanol was added as an internal standard. After equilibration at 50 °C for 30 minutes, the sample was adsorbed using a 50 / 30 μm DVB / CAR / PDMS extraction head for 30 minutes, followed by desorption at 250 °C for 5 minutes at the GC inlet. An HP-5MS flexible quartz capillary column was used. The temperature program was set as follows: initial temperature 40 °C, hold for 3 minutes, increase to 150 °C at 5 °C / min, then increase to 230 °C at 10 °C / min and hold for 10 minutes. Mass spectrometry conditions included an electron impact ion source (EI) with an electron energy of 70 eV and a scan range of 35 amu to 450 amu. Chromatographic peaks were retrieved using the NIST spectral library, and the relative contents of each component were calculated using the internal standard method.

[0045] Experimental data: The results of the detection of some characteristic flavor substances are shown in Table 3.

[0046] Table 3. Comparison of relative contents of key volatile flavor compounds in Example 2 and Comparative Example 1

[0047] Results analysis: Example 2 differs from Comparative Example 1 in its volatile composition. Example 2 detected 4-vinylguaiacol (4.85 mg / L), while Comparative Example 1 did not. Ferulic acid bound to the cell walls of bamboo leaves is released under the action of cellulase and pectinase, and during fermentation, it is converted into 4-vinylguaiacol by ferulic acid decarboxylase secreted by Saccharomyces cerevisiae. This substance has smoky and woody aroma characteristics. Comparative Example 1 used physical soaking, without enzymatic hydrolysis or microbial decarboxylation, and therefore did not generate this conversion product.

[0048] Regarding the raw, grassy flavor compounds, Comparative Example 1 detected (E)-2-hexenal (5.67 mg / L) and phytol (12.33 mg / L). These substances originate from the physical leaching of bamboo leaves. In Example 2, the content of the above substances was low or undetectable. The fermentation process reduces or oxidizes aldehydes; the distillation process retains high-boiling-point macromolecules such as phytol in the lees, preventing them from entering the distillate.

[0049] Regarding esters, the content of ethyl acetate and ethyl hexanoate in Example 2 was higher than that in Comparative Example 1. Enzymatic hydrolysis disrupts the bamboo leaf structure, releasing nitrogen sources and trace elements, and promoting yeast metabolism and esterase activity. Example 2, through a combination of enzymatic hydrolysis, fermentation, and distillation, converts bamboo leaf precursors into aroma compounds and removes some undesirable flavor components.

Claims

1. A distilled spirit with added bamboo leaf powder, characterized in that, It is made from the following raw materials in parts by weight: 75-85 parts grain flour and 15-25 parts bamboo leaf powder; The bamboo leaf powder is obtained by blanching, drying and pulverizing fresh bamboo leaves; and the raw materials are subjected to enzymatic hydrolysis and moistening treatment during the preparation of the distilled liquor, which uses a compound enzyme preparation containing cellulase and pectinase.

2. The distilled spirit with added bamboo leaf powder according to claim 1, characterized in that, The grain powder is selected from one or a combination of glutinous sorghum, japonica rice, wheat, and peas; the fresh bamboo leaves are selected from one of light bamboo leaves, hemp bamboo leaves, or moso bamboo leaves.

3. A distilled spirit with added bamboo leaf powder according to claim 1, characterized in that, The raw materials consist of the following components in parts by weight: 80 parts grain powder and 20 parts bamboo leaf powder.

4. A method for preparing distilled spirits with added bamboo leaf powder, characterized in that, The method for preparing a distilled spirit with added bamboo leaf powder as described in any one of claims 1-3 comprises the following steps: S1. Raw material pretreatment: Fresh bamboo leaves are selected to prepare bamboo leaf powder, and grains are selected to prepare grain powder. They are mixed and stirred evenly in proportion to obtain a dry mixture. S2. Enzymatic hydrolysis of wet material: The activated compound enzyme preparation is sprayed onto the dry mixture and water is added. After stirring evenly, the mixture is piled up and sealed for incubation and enzymatic hydrolysis to obtain the enzymatic hydrolysis wet material. The compound enzyme preparation contains cellulase and pectinase. S3. Cooking and saccharification: The enzymatically hydrolyzed wet material is loaded into a steamer and cooked. After cooling, saccharifying enzyme is added to saccharify the material to obtain saccharified mash. S4. Fermentation: Activated brewing dry yeast is added to the saccharified mash, and the mash is sealed for fermentation to obtain mature mash. S5. Distillation: Rice husks are mixed into the mature mash and the mash is loaded into a still for distillation. The heads of the distillate are discarded, and the fraction with an alcohol content of 50% vol or higher is collected to obtain the mid-section original liquor. S6. Aging: The original liquor in the middle section is sealed and aged, and after blending and filtration, the distilled liquor with added bamboo leaf powder is obtained.

5. The method for preparing distilled spirits with added bamboo leaf powder according to claim 4, characterized in that, In step S1, the method for preparing the bamboo leaf powder is as follows: after cleaning and removing impurities from fresh bamboo leaves, place them at 95℃~100℃ for 60s~120s to kill the green, dry them to a moisture content of 5%~8%, pulverize them and pass them through an 80-120 mesh sieve.

6. The method for preparing distilled spirits with added bamboo leaf powder according to claim 4, characterized in that, In step S2, the compound enzyme preparation is composed of cellulase and pectinase, with a weight ratio of cellulase to pectinase of (60-70):(30-40), and the amount of the compound enzyme preparation added is 0.1% to 0.3% of the total weight of the dry mixture.

7. The method for preparing distilled spirits with added bamboo leaf powder according to claim 4, characterized in that, In step S2, the specific operation of the incubation enzymatic hydrolysis is as follows: add warm water to the total water content to 50% to 60%, and incubate the enzymatic hydrolysis at a temperature of 50℃ to 55℃ for 4 to 6 hours.

8. The method for preparing distilled spirits with added bamboo leaf powder according to claim 4, characterized in that, In step S3, the amount of saccharifying enzyme added is 0.8% to 1.2% of the total weight of the raw materials, and the saccharification time is 24h to 36h until the product temperature rises to 32℃ to 35℃.

9. The method for preparing distilled spirits with added bamboo leaf powder according to claim 4, characterized in that, In step S4, the fermentation adopts a variable temperature fermentation process: first, the primary fermentation is carried out at 28℃~32℃ for 7 days, and then the temperature is lowered to 22℃~25℃ to continue the secondary fermentation for 23 days~53 days, with a total fermentation cycle of 30 days~60 days.

10. The method for preparing distilled spirits with added bamboo leaf powder according to claim 4, characterized in that, In step S5, the specific operation of discarding the heads is as follows: a fraction equivalent to 1.5% to 2.0% of the expected alcohol production from the feed is collected and discarded separately as heads, thereby removing methanol.

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