Grapefruit peel barley beer and method for preparing the same

Abstract

The application belongs to the technical field of food fermentation, and particularly relates to a pomelo peel highland barley beer and a preparation method thereof. The method comprises the following steps: washing, crushing and soaking pomelo peel, adding aspergillus niger liquid for fermentation to obtain pomelo peel fermentation liquid; crushing highland barley malt, adding aspergillus oryzae and sterile water, preheating, two-stage saccharification and reaction termination to obtain wort; mixing the pomelo peel fermentation liquid and the wort and boiling, adding hops before the end of boiling, collecting boiled wort after boiling; adding lager yeast into the boiled wort, performing main wine brewing, cooling, standing and coarse filtering to obtain main wine brewing liquid; performing aging fermentation on the main wine brewing liquid to obtain the pomelo peel highland barley beer. The pomelo peel highland barley beer and the preparation method thereof provided by the application can hydrolyze naringin through induced culture of aspergillus niger, and can perform two-stage saccharification on highland barley malt through aspergillus oryzae, so that the content of beta-glucan in the highland barley malt is reduced, and a beer with coordinated flavor and rich citrus aroma is obtained by using the pomelo peel as a waste resource.

Description

Technical Field

[0001] This application belongs to the field of food fermentation technology, specifically relating to grapefruit peel and highland barley beer and its preparation method. Background Technology

[0002] Barley, belonging to the genus *Hordeum* of the Poaceae family, is a grain primarily grown in high-altitude regions at 4000-5000 meters. It is rich in nutrients, containing various amino acids and trace elements essential for the human body, and is also rich in polysaccharides with health benefits. During barley germination, changes occur in starch, protein, lipids, and polyphenols, specifically a decrease in total starch content, a significant increase in amino acid and functional peptide content, a decrease in total lipid content, and the synthesis of more phenolic compounds. Using barley to brew beer not only leverages its nutritional value but also imparts a unique flavor to the beer. However, the high β-glucan content in barley malt causes a significant increase in the viscosity of the wort after saccharification, making filtration of the wort and fermentation liquid difficult.

[0003] Grapefruit, also known as pomelo, is one of the four major groups of citrus fruits in the world. Its fruit is sour, slightly bitter, and juicy, with high nutritional value, rich in vitamins, minerals, carotenoids, and organic acids. While grapefruit-based beers exist, most use grapefruit pulp or juice; beers using grapefruit peel as a flavoring ingredient are relatively rare. Grapefruit peel, a byproduct of grapefruit, is rich in active substances such as limonene, citral, and citronellol, making it an ideal resource for imparting more flavor and nutritional value to beer. However, grapefruit peel has a high content of naringin, which can easily cause its own bitterness to clash with the bitterness of hops, resulting in a mixed flavor. Furthermore, the inhibitory effect of naringin on brewing yeast can reduce brewing efficiency. Therefore, there are currently few reports on grapefruit peel beer, and no reports on grapefruit peel and barley beer.

[0004] Therefore, a new beer brewing process is needed to overcome the current problem that the high β-glucan content in highland barley malt and the high naringin content in grapefruit peel make it difficult to produce high-quality beer using highland barley malt and grapefruit peel. Summary of the Invention

[0005] The problem this application aims to solve is to provide grapefruit peel and barley beer and its preparation method. By inducing Aspergillus niger to hydrolyze naringin and simultaneously using Aspergillus oryzae to perform two-stage saccharification of barley malt, the content of β-glucan in barley malt is reduced, thereby utilizing grapefruit peel, a waste resource, to obtain a beer with a harmonious flavor and rich in citrus aroma.

[0006] To solve the above-mentioned technical problems, this application adopts the following technical solution: On the one hand, this application provides a method for preparing grapefruit peel and barley beer, comprising the following steps: After washing and crushing the grapefruit peel, add water to soak it, and then add the induced culture of Aspergillus niger liquid for deglycosylation fermentation to obtain grapefruit peel fermentation liquid; After crushing the barley malt, add Aspergillus oryzae and sterile water for preheating, then carry out two-stage saccharification. After the two-stage saccharification is completed, terminate the reaction, filter and collect the wort. The grapefruit peel fermentation liquid is mixed with the wort and boiled. Hops are added before the boiling is finished, and the liquid is collected after the boiling is finished to obtain boiled wort. Lager yeast is added to the boiled wort for primary fermentation, followed by cooling, settling, and coarse filtration to obtain the primary fermentation liquid. The main fermentation liquid of the brewing is aged and fermented to obtain the grapefruit peel barley beer.

[0007] Furthermore, the viable count of Aspergillus niger in the induced culture solution is 3 × 10⁻⁶. 7 ~5×10 7 CFU / mL.

[0008] Furthermore, the Aspergillus oryzae includes Aspergillus oryzae XMS01, and the viable count of the Aspergillus oryzae is 1×10⁻⁶. 8 ~2×10 8 CFU / g.

[0009] Furthermore, the hops include Haraldau hops.

[0010] Furthermore, the solid-liquid ratio of the grapefruit peel, the water, and the induced culture of Aspergillus niger is 1g:(6~7) mL:(0.5~0.7) mL.

[0011] Furthermore, the weight ratio of the barley malt, the Aspergillus oryzae, and the sterile water is 1:(0.3~0.5):(4~5).

[0012] Furthermore, the inoculum size of the lager yeast is 0.8 × 10⁻⁶. 7 ~1.6×10 7 CFU / mL.

[0013] Furthermore, the wort has a sugar content of 10-14 °P.

[0014] Furthermore, the sugar content of the main fermentation liquid for brewing is 2~3 °P.

[0015] Furthermore, the two-stage saccharification includes a first-stage saccharification at a temperature of 25-28°C for 10-20 minutes and a second-stage saccharification at a temperature of 65-70°C for 20-30 minutes.

[0016] Furthermore, the temperature of the deglycosylation fermentation is 30~32℃, and the fermentation time is 3~4 days.

[0017] Furthermore, the preheating temperature is 20~25℃, and the preheating time is 15~25 min.

[0018] Furthermore, the temperature for terminating the reaction is 75~80℃, and the time for terminating the reaction is 10~20 min.

[0019] Furthermore, the boiling time is 60-70 minutes.

[0020] Furthermore, the hops are added 10-15 minutes before the end of the gelatinization process.

[0021] Furthermore, the temperature of the primary fermentation for brewing is 18~22℃, and the fermentation time is 10~12 days.

[0022] Furthermore, the cooling temperature is 1~3℃.

[0023] Furthermore, the coarse filtration is performed using a 300-400 mesh filter.

[0024] Furthermore, the aging and fermentation temperature is 20~25℃, and the aging and fermentation time is 6~7 months.

[0025] Furthermore, the method for inducing and culturing Aspergillus niger includes: (1) Primary induction: The Aspergillus niger is inoculated into the first induction medium and subjected to the first induction culture to obtain the primary induction culture solution; (2) Secondary induction: The primary induction culture medium is inoculated into the second induction culture medium at an inoculation rate of 5% for secondary induction culture to obtain the induced Aspergillus niger culture.

[0026] For example, the first induction culture medium includes 1% grapefruit peel powder, 0.5% MgSO4·7H2O, 0.5% KCl, 0.01% FeSO4·5H2O, 5% agar, and 1% glucose.

[0027] For example, the second induction medium comprises 5% grapefruit peel powder, 0.5% MgSO4·7H2O, 0.5% KCl, 0.01% FeSO4·5H2O, 5% agar, and 1% glucose.

[0028] For example, the temperature of the first induction culture is 28~30℃, and the time of the first induction culture is 24~36 h.

[0029] For example, the temperature of the second induction culture is 28~30℃, and the time of the second induction culture is 36~48 h.

[0030] On the other hand, this application provides grapefruit peel and barley beer prepared by the above method.

[0031] This application has the following beneficial effects: 1. The method for preparing grapefruit peel and highland barley beer provided in this application utilizes Aspergillus niger after induced culture to treat grapefruit peel. This not only reduces the content of naringin in the subsequent fermentation system and lowers the risk of unbalanced bitterness in beer, but also enables Aspergillus niger to utilize grapefruit peel to generate soluble proteins and flavor substances, giving the final beer higher nutritional value and flavor.

[0032] 2. Adding Aspergillus oryzae during the saccharification of barley malt can effectively solve the problem of excessive β-glucan content in barley malt, avoiding slow fermentation and poor filtration in the later stages, and successfully achieving efficient production of grapefruit peel barley beer. Detailed Implementation

[0033] The technical solutions in some embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments provided in this application, all other embodiments obtained by those skilled in the art are within the scope of protection of this application.

[0034] Hereinafter, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature.

[0035] In describing some embodiments, the expression "A and / or B" may be used. It is readily understood that "A and / or B" includes the following three combinations: A only, B only, and a combination of A and B.

[0036] In describing some embodiments, the expressions "at least one of A, B and C" and "at least one of A, B or C" may be used, both of which have the same meaning and include the following combinations of A, B and C: only A, only B, only C, a combination of A and B, a combination of A and C, a combination of B and C, and a combination of A, B and C.

[0037] Experimental materials: 1. Microbial strains Aspergillus niger ( Aspergillus niger ATCC 16404, from the American Center for Type Culture Collection; Aspergillus oryzae XMS01, obtained from China Center for Type Culture Collection, accession number CCTCC NO: M 2018425; Lager yeast S-189 is sourced from Weihai Deco Biotechnology Co., Ltd.

[0038] 2. Culture medium First induction medium: 1% grapefruit peel powder, 0.5% MgSO4·7H2O, 0.5% KCl, 0.01% FeSO4·5H2O, 5% agar, 1% glucose; Second induction medium: 5% grapefruit peel powder, 0.5% MgSO4·7H2O, 0.5% KCl, 0.01% FeSO4·5H2O, 5% agar, 1% glucose.

[0039] Example 1

[0040] Induction culture of Aspergillus niger was performed according to the following steps: S1-1. Primary induction: The Aspergillus niger was inoculated into the first induction medium and cultured at 28°C for 36 h to obtain the primary induction culture solution; S1-2. Secondary induction: The primary induction culture medium was inoculated into the secondary induction culture medium at an inoculum volume of 5%, and the secondary induction culture was carried out at 28℃ for 48 h to obtain the Aspergillus niger liquid after induction culture. The viable count of the Aspergillus niger liquid was detected to be 4.89 × 10⁻⁶. 7 CFU / mL.

[0041] Example 2

[0042] Induction culture of Aspergillus niger was performed according to the following steps: S1-1. Primary induction: The Aspergillus niger was inoculated into the first induction medium and cultured at 28°C for 30 h to obtain the primary induction culture solution; S1-2. Secondary induction: The primary induction culture medium was inoculated into the secondary induction culture medium at a 5% inoculum size, and the culture was incubated at 28°C for 42 h to obtain the Aspergillus niger induced culture solution. The viable count of the Aspergillus niger induced culture solution was determined to be 3.96 × 10⁻⁶. 7 CFU / mL.

[0043] Example 3

[0044] Induction culture of Aspergillus niger was performed according to the following steps: S1-1. Primary induction: The Aspergillus niger was inoculated into the first induction medium and cultured at 30°C for 24 h to obtain the primary induction culture solution; S1-2. Secondary induction: The primary induction culture medium was inoculated into the secondary induction culture medium at an inoculum volume of 5%, and the secondary induction culture was carried out at 30℃ for 36 h to obtain the Aspergillus niger induced culture solution. The viable count of the Aspergillus niger induced culture solution was detected to be 2.93 × 10⁻⁶. 7 CFU / mL.

[0045] Example 4

[0046] Prepare grapefruit peel and barley beer using the following method: S2-1. Wash and crush 3 kg of grapefruit peel, add 18 L of water and soak at room temperature for 12 h, then add 1.5 L of Aspergillus niger liquid obtained in Example 1 and ferment at 30℃ for 3 days. Use Aspergillus niger to hydrolyze most of the naringin in grapefruit peel to obtain grapefruit peel fermentation liquid. S2-2. Crush 5 kg of highland barley malt and pass it through a 60-mesh sieve, then add 1.5 kg of live bacteria with a count of 1×10⁻⁶. 8 CFU / g of Aspergillus oryzae XMS01 was added to 20 L of sterile water at 20°C and stirred for 15 min for preheating. Then, a first-stage saccharification was carried out at 25°C for 20 min to allow Aspergillus oryzae to fully utilize the barley malt for pre-fermentation, thereby reducing the β-glucan content in the raw material while increasing the content of flavor substances. Then, the temperature was raised to 70°C for 20 min for a second-stage saccharification. After saccharification, the temperature was raised to 75°C and held for 10 min to terminate the reaction. After filtration, wort with a sugar content of 10.2 °P was obtained. S2-3. The grapefruit peel fermentation liquid is mixed with the wort and boiled for 60 minutes. Halado hops are added 15 minutes before the end of boiling, and the liquid is collected to obtain boiled wort. S2-4. With 0.8×10 7 The lager yeast was inoculated into the boiled wort at an inoculation rate of CFU / mL. After 10 days of primary fermentation at 18°C, the temperature was lowered to 3°C and then allowed to stand for 2 hours. The mixture was then coarsely filtered through a 400-mesh filter to obtain a primary fermentation liquid with a sugar content of 2.9 °P. S2-5. Transfer the brewing main fermentation liquid to a stainless steel tank and age it at 20°C for 6 months to obtain the all-barley malt craft beer.

[0047] Example 5

[0048] Prepare grapefruit peel and barley beer using the following method: S2-1. Wash and crush 3 kg of grapefruit peel, add 18 L of water and soak at room temperature for 12 h, then add 1.8 L of Aspergillus niger liquid obtained in Example 2 and ferment at 32℃ for 4 days. Use Aspergillus niger to hydrolyze most of the naringin in grapefruit peel to obtain grapefruit peel fermentation liquid. S2-2. Crush 5 kg of highland barley malt and pass it through a 60-mesh sieve, then add 2.0 kg of live bacteria with a count of 1.5 × 10⁻⁶. 8 CFU / g of Aspergillus oryzae XMS01 was added to 23 L of sterile water at 23°C and stirred for 20 min for preheating. Then, a first-stage saccharification was carried out at 25°C for 15 min to allow Aspergillus oryzae to fully utilize the barley malt for pre-fermentation, thereby reducing the β-glucan content in the raw material while increasing the content of flavor substances. Then, the temperature was raised to 65°C for a second-stage saccharification for 25 min. After saccharification, the temperature was raised to 75°C and held for 15 min to terminate the reaction. After filtration, wort with a sugar content of 12.7 °P was obtained. S2-3. The grapefruit peel fermentation liquid is mixed with the wort and boiled for 65 minutes. Halado hops are added 10 minutes before the end of boiling, and the liquid is collected to obtain boiled wort. S2-4. With 1.2×10 7 Lager yeast was inoculated into the boiled wort at an inoculation rate of CFU / mL. After 12 days of primary fermentation at 20°C, the temperature was lowered to 1°C and then allowed to stand for 2 hours. The mixture was then coarsely filtered through a 350-mesh filter to obtain a primary fermentation liquid with a sugar content of 2.5 °P. S2-5. Transfer the brewing main fermentation liquid to a stainless steel tank and age and ferment at 25°C for 6 months to obtain the all-barley malt craft beer.

[0049] Example 6

[0050] Prepare grapefruit peel and barley beer using the following method: S2-1. Wash and crush 3 kg of grapefruit peel, add 21 L of water and soak at room temperature for 12 h, then add 2.1 L of Aspergillus niger liquid obtained in Example 3 and ferment at 32℃ for 4 days. Use Aspergillus niger to hydrolyze most of the naringin in grapefruit peel to obtain grapefruit peel fermentation liquid. S2-2. Crush 5 kg of barley malt and pass it through a 60-mesh sieve, then add 2.5 kg of live bacteria with a count of 2×10⁻⁶. 8CFU / g of Aspergillus oryzae XMS01 was added to 25 L of sterile water at 25°C and stirred for 25 min for preheating. Then, a first-stage saccharification was carried out at 28°C for 10 min to allow Aspergillus oryzae to fully utilize the barley malt for pre-fermentation, thereby reducing the β-glucan content in the raw material while increasing the content of flavor substances. Then, the temperature was raised to 65°C for a second-stage saccharification for 30 min. After saccharification, the temperature was raised to 80°C and held for 20 min to terminate the reaction. After filtration, wort with a sugar content of 13.7 °P was obtained. S2-3. The grapefruit peel fermentation liquid is mixed with the wort and boiled for 70 minutes. Halado hops are added 10 minutes before the end of boiling, and the liquid is collected to obtain boiled wort. S2-4. With 1.6×10 7 The lager yeast was inoculated into the boiled wort at an inoculation rate of CFU / mL. After 12 days of primary fermentation at 22°C, the temperature was lowered to 1°C and then allowed to stand for 2 hours. The mixture was then coarsely filtered through a 300-mesh filter to obtain a primary fermentation liquid with a sugar content of 2.1 °P. S2-5. Transfer the brewing main fermentation liquid to a stainless steel tank and age it at 25°C for 7 months to obtain the all-barley malt craft beer.

[0051] Comparative Example 1 The method for preparing grapefruit peel and barley beer in this comparative example is the same as in Example 1, except that the only difference between Comparative Example 1 and Example 1 is: In S2-1, no deglycosylation fermentation is carried out; the grapefruit peel soaked for 12 hours is directly used as one of the raw materials for subsequent boiling.

[0052] Comparative Example 2 The method for preparing grapefruit peel and barley beer in this comparative example is the same as in Example 1, except that the only difference between Comparative Example 2 and Example 1 is: In S2-2, without adding Aspergillus oryzae, the second-stage saccharification is carried out directly and then filtered to obtain wort.

[0053] Experimental Example 1: Determination of Physicochemical Indices The physicochemical properties of the craft beers prepared in Examples 4-6 and Comparative Examples 1-2 were measured, and the results are shown in Table 1.

[0054] Table 1 Physicochemical Indicators

[0055] Experiment Example 2: Sensory Analysis Scoring Five tasters were invited to score the craft beers prepared in Examples 4-6 and Comparative Examples 1-2 according to the sensory analysis method of GB / T 4928-2008 "Beer Analysis Methods" (average value was taken). The scoring results are shown in Comparison 2.

[0056] Table 2 Sensory Ratings

[0057] As can be seen from Tables 1 and 2, in preparing grapefruit peel barley beer, this application first uses Aspergillus niger to reduce the content of naringin in grapefruit peel, thereby lowering the bitterness value of the final beer and generating more flavor substances. Then, by dividing saccharification into two stages and adding Aspergillus oryzae in the first stage for auxiliary saccharification, it can ensure that the β-glucan in barley malt is effectively consumed, so that the subsequent brewing main fermentation process can have a better fermentation environment, and the final beer has a rich aroma and flavor.

[0058] The above description is merely a preferred embodiment of this application. It should be understood that this application is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or the technology or knowledge in related fields. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of this application should be within the protection scope of the appended claims.

Claims

1. A method for preparing grapefruit peel and barley beer, characterized in that, Includes the following steps: After washing and crushing the grapefruit peel, add water to soak it, and then add the induced culture of Aspergillus niger liquid for deglycosylation fermentation to obtain grapefruit peel fermentation liquid; After crushing the barley malt, add Aspergillus oryzae and sterile water for preheating, then carry out two-stage saccharification. After the two-stage saccharification is completed, terminate the reaction, filter and collect the wort. The grapefruit peel fermentation liquid is mixed with the wort and boiled. Hops are added before the boiling is finished, and the liquid is collected after the boiling is finished to obtain boiled wort. Lager yeast is added to the boiled wort for primary fermentation, followed by cooling, settling, and coarse filtration to obtain the primary fermentation liquid. The main fermentation liquid of the brewing is aged and fermented to obtain the grapefruit peel barley beer.

2. The method according to claim 1, characterized in that, The viable count of Aspergillus niger in the induced culture solution was 3 × 10⁻⁶. 7 ~5×10 7 CFU / mL; And / or, the Aspergillus oryzae includes Aspergillus oryzae XMS01, and the viable count of the Aspergillus oryzae is 1×10⁻⁶. 8 ~2×10 8 CFU / g; And / or, the hops include Haraldau hops.

3. The method according to claim 2, characterized in that, The solid-liquid ratio of the grapefruit peel, the water, and the induced Aspergillus niger solution is 1 g: (6~7) mL: (0.5~0.7) mL; And / or, the weight ratio of the barley malt, the Aspergillus oryzae, and the sterile water is 1:(0.3~0.5):(4~5); And / or, the inoculation amount of the hops is 0.5~1 g / L; And / or, the inoculum size of the lager yeast is 0.8 × 10⁻⁶. 7 ~1.6×10 7 CFU / mL.

4. The method according to claim 1, characterized in that, The wort has a sugar content of 10~14 °P; And / or, the sugar content of the main fermentation liquid for brewing is 2~3 °P.

5. The method according to claim 1, characterized in that, The two-stage saccharification includes a first-stage saccharification at a temperature of 25-28°C for 10-20 minutes and a second-stage saccharification at a temperature of 65-70°C for 20-30 minutes.

6. The method according to claim 1, characterized in that, The deglycosylation fermentation temperature is 30~32℃, and the deglycosylation fermentation time is 3~4 days; And / or, the preheating temperature is 20~25℃, and the preheating time is 15~25 min; And / or, the temperature for terminating the reaction is 75~80℃, and the time for terminating the reaction is 10~20 min; And / or, the boiling time is 60-70 min; And / or, the hops are added 10-15 minutes before the end of gelatinization; And / or, the temperature of the primary fermentation of the wine is 18~22℃, and the time of the primary fermentation of the wine is 10~12 days; And / or, the cooling temperature is 1~3℃; And / or, the coarse filtration is performed using a 300-400 mesh filter; And / or, the aging and fermentation temperature is 20~25℃, and the aging and fermentation time is 6~7 months.

7. The method according to claim 2, characterized in that, The induction culture method of Aspergillus niger includes: (1) Primary induction: The Aspergillus niger is inoculated into the first induction medium and subjected to the first induction culture to obtain the primary induction culture solution; (2) Secondary induction: The primary induction culture medium is inoculated into the second induction culture medium at an inoculation rate of 5% for secondary induction culture to obtain the induced Aspergillus niger culture.

8. The method according to claim 7, characterized in that, The first induction medium comprises 1% grapefruit peel powder, 0.5% MgSO4·7H2O, 0.5% KCl, 0.01% FeSO4·5H2O, 5% agar, and 1% glucose; And / or, the second induction medium comprises 5% grapefruit peel powder, 0.5% MgSO4·7H2O, 0.5% KCl, 0.01% FeSO4·5H2O, 5% agar, and 1% glucose.

9. The method according to claim 7, characterized in that, The temperature of the first induction culture is 28~30℃, and the time of the first induction culture is 24~36 h; And / or, the temperature of the second induction culture is 28~30℃, and the time of the second induction culture is 36~48 h.

10. Grapefruit peel and barley beer prepared by the method according to any one of claims 1 to 9.

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