Beer with high foam retention and preparation method thereof

Abstract

The invention relates to the technical field of beer preparation, and particularly discloses beer with high foam retention and a preparation method thereof. The preparation method of the beer with high foam retention comprises the following steps: crushing malt, adding water for dipping, heating for saccharification, filtering to obtain first wort, boiling, adding humulus lupulus before boiling, cooling after boiling, filtering to obtain second wort, adding beer yeast for fermentation to obtain beer fermentation liquor, and filtering to obtain the beer with high foam retention. After fermentation is completed, 0.12-0.15% of a foam enhancer is added into the beer fermentation liquor, stirring and dispersing are performed to form uniform slurry, cold storage and filtering are performed to obtain clear beer, canning sterilization and finished product packaging are performed to obtain the beer, and the foam enhancer comprises glycosylated chickpea protein peptide and bacterial cellulose polysaccharide microgel balls. The beer prepared by the preparation method provided by the invention can generate richer and finer beer foam, and has good foam stability and wall hanging property.

Description

Technical Field

[0001] This application relates to the field of beer preparation technology, and more specifically, to a beer with high foam retention and a method for preparing the same. Background Technology

[0002] Beer is a low-alcohol beverage made primarily from malt and water, with hops and bitters as flavorings and bitterings, through saccharification and microbial fermentation. It is rich in CO2. Beer foam, often called the "flower of beer," is a key visual indicator of beer quality. Its stability directly impacts the consumer's drinking experience. A clean, fine, rich, and stable beer foam provides a fresh and refreshing visual experience, a tactile experience on the lips and mouth, and an olfactory experience from the bursting of the foam, stimulating the consumer's desire to drink. Excellent foam retention also enhances the beer's body and freshness.

[0003] In the existing technology, beer preparation usually relies on traditional brewing processes, including steps such as malting, boiling, fermentation and maturation. To improve foam retention, common methods include adjusting the raw material ratio, such as screening barley malt and wheat malt with high foam-positive protein content, or optimizing fermentation conditions, such as controlling temperature and pH, and introducing foam enhancers.

[0004] Regarding the aforementioned technologies, the inventors discovered that, in terms of raw materials, relying on high-protein malt or additives can improve foam stability in the short term, but often leads to an imbalance in beer flavor, such as introducing off-flavors or affecting fermentation efficiency. It may also trigger allergen issues, which is inconsistent with modern health-conscious consumption trends. In terms of process optimization, existing methods mostly focus on adjusting a single step and lack overall synergistic effects. For example, excessively extending the fermentation time can increase foam persistence, but it will sacrifice the freshness of the beer and production efficiency, and increase energy costs. In addition, the foam enhancers used in existing technologies are usually chemical products, which pose certain safety hazards and may introduce chemical residues, affecting the natural properties of beer and threatening its stability. Summary of the Invention

[0005] In order to prolong the foam retention of beer and improve its taste and flavor, this application provides a beer with high foam retention and a method for preparing the same.

[0006] In a first aspect, this application provides a method for preparing beer with high foam retention, employing the following technical solution: A method for preparing a beer with high foam retention includes the following steps: S1: After crushing the malt, soak it in water, heat it to saccharify it, filter it and obtain the first wort; S2: Boil the first wort, add hops before the boiling is finished, cool and filter after boiling to obtain the second wort; S3: Add brewer's yeast to the second wort for fermentation to obtain beer fermentation liquid; S4: After fermentation, add 0.12-0.15% of foam enhancer to the beer fermentation liquid, stir and disperse into a uniform slurry, and obtain clarified beer after cold storage and filtration. After canning, sterilization and finished product packaging, the foam enhancer includes glycosylated chickpea protein peptides and bacterial cellulose polysaccharide microgel balls.

[0007] The foam retention of beer mainly depends on the synergistic effect between malt-derived foaming proteins such as LTP1 and hop isomerization product isohexolone. This interaction includes hydrophobic interactions as well as hydrogen and ionic bonds between the polar groups of isohexolone and the charged groups of protein amino acid residues (such as lysine), thereby forming a stable complex network at the bubble interface.

[0008] Glycosylated chickpea protein peptides use chickpea protein as a plant protein source, which has high bioavailability and a balanced amino acid structure. It is rich in lysine, which is lacking in cereal proteins. By mild enzymatic hydrolysis to expose hydrophobic regions and amino groups of lysine residues, the glycosylated chickpea protein peptides obtained by glycosylation modification mimic the glycosylation state of natural LTP1. They have a stable interfacial structure, can act as anchoring sites to synergize with the original LTP1 in beer, and have strong interfacial activity and the ability to effectively bind with isohylocereus, thereby enhancing the foaming ability of beer.

[0009] Bacterial cellulose polysaccharide microgel spheres provide a three-dimensional nanofiber network with high water retention and porosity. The microgel spheres have extremely small particle sizes, which can effectively fill the gaps in foam or adsorb onto the surface of bubbles to form a solid particle interface film. This prevents the aggregation and rupture of bubbles, enhances the overall mechanical strength of beer foam, and makes the foam structure more stable. At the same time, its high water retention can slow down liquid film drainage by locking in water, keeping the foam moist and prolonging its durability and significantly extending the time it can adhere to the wall.

[0010] By adopting the above technical solution, the raw materials of the foam enhancer in this application are all natural components, without introducing exogenous chemical synthetic substances, and have high safety. They can be integrated into and enhance the foam stability system of beer itself, and work synergistically with the foaming proteins and isohypogonin in beer. On the one hand, they enhance the foaming ability of beer and increase the amount of foam produced. On the other hand, they can significantly improve the stability of foam formation, while not adversely affecting the original flavor of beer.

[0011] Furthermore, the foam enhancer of this application is added after primary fermentation and before filtration. On the one hand, this avoids the potential adsorption and consumption of the foam enhancer by a large amount of yeast during fermentation, and also avoids the destruction of the activity of natural components by processes such as high-temperature boiling. On the other hand, the carbon dioxide content in the beer fermentation liquid obtained after primary fermentation is already high, and the beer body is relatively calm without the violent convection during fermentation. This is conducive to the more effective and uniform dispersion of the foam enhancer without it being carried away by the rapidly escaping gas. During the subsequent storage period, it has enough time to slowly and fully interact with components such as foaming proteins and isohyperhydrone in the beer to form a stable complex network.

[0012] Optionally, the mass ratio of the glycosylated chickpea protein peptide to the bacterial cellulose polysaccharide microgel spheres is (3-4):(6-7).

[0013] Optionally, the method for preparing the glycosylated chickpea protein peptide includes the following steps: Chickpea protein peptides and inulin were thoroughly mixed in a dry state at a mass ratio of 1:(1.2-1.5) to obtain a blend. The blend was then reacted at a relative humidity of 70-75% and a temperature of 60-65℃ for 4-6 hours. The resulting product was dissolved in water at 2-4℃ and then freeze-dried to obtain the final product.

[0014] By adopting the above technical solution, inulin is used as a sugar donor to glycosylate chickpea protein peptides. The inulin molecule contains free glucose residues at its terminal end, which are covalently bound to the amino group of lysine in chickpea protein peptides through a dry Maillard reaction to form a glycosylated complex.

[0015] Furthermore, the sugar chains of inulin can form a highly viscoelastic hydration layer at the bubble interface through strong chemical bonds with the hydroxyl groups and water molecules of bacterial cellulose polysaccharide microgel spheres, thereby strengthening the cross-linking network of the foam membrane, synergistically delaying membrane drainage, and improving the stability of beer foam.

[0016] Optionally, the method for preparing the chickpea protein peptide includes the following steps: Chickpea protein powder was dispersed in water to obtain a chickpea protein solution with a mass concentration of 5-8%. The pH of the chickpea protein solution was adjusted to 8±0.1. Alkaline protease at 1% mass of chickpea protein powder was added for enzymatic hydrolysis for 1-1.5 hours. After enzyme inactivation, the solution was centrifuged, ultrafiltered, and spray-dried to obtain small molecule chickpea protein peptides with a molecular weight ≤3kDa.

[0017] By employing the above technical solution, chickpea protein is subjected to restricted, mild hydrolysis using alkaline protease at pH 8. This process tends to cleave the carboxyl termini of hydrophobic amino acids such as phenylalanine and leucine, which actively exposes the hydrophobic regions of the protein rather than causing random deformation. By controlling the molecular weight of the generated small peptides to ≤3kDa through ultrafiltration, a large number of amphiphilic small peptides with both hydrophilic and hydrophobic ends are produced, enabling them to migrate to the gas-liquid interface more quickly, rapidly reducing surface tension and forming an initial foam with good elasticity.

[0018] Optionally, the raw materials for the bacterial cellulose polysaccharide microgel balls, by weight, include 1-1.5 parts bacterial cellulose, 2-3 parts β-glucan, 0.3-0.5 parts glycyrrhizic acid and 0.004-0.006 parts glucose oxidase, wherein the bacterial cellulose is obtained by fermentation of Acetobacter xylinum.

[0019] By adopting the above technical solution, bacterial cellulose provides a stable structure as a nanoskeleton. The polysaccharide chains of β-glucan can fill the bacterial cellulose network for entanglement and cross-linking, providing a large number of hydroxyl groups for water retention and subsequent interaction with beer components. Glycyrrhizic acid glycoside is a highly efficient triterpenoid saponin. Its hydrophobic aglycone structure allows it to compete with isohypogonin for binding to foam-destroying molecules such as lipids, preferentially binding to foam-destroying molecules to form micelles, thereby protecting more isohypogonin for binding to foaming proteins and enhancing the ability of beer to generate foam. On the other hand, its mild sweetness can balance the bitterness of hops, further enriching and improving the overall flavor of beer.

[0020] Optionally, the method for preparing the bacterial cellulose polysaccharide microgel spheres includes the following steps: Bacterial cellulose was dispersed in water to obtain a bacterial cellulose dispersion. β-glucan and glycyrrhizin were mixed and dissolved in water to obtain a mixed solution. The bacterial cellulose dispersion and the mixed solution were mixed and homogenized under high pressure to obtain a gel solution. Glucose oxidase was added to the gel solution to carry out an enzymatic cross-linking reaction for 1-1.5 hours. The solution was then sprayed into anhydrous ethanol to solidify and form a microgel ball powder after washing and spray drying.

[0021] By adopting the above technical solution, this application ensures the uniform dispersion of bacterial cellulose through high-pressure homogenization, forming a stable colloid. Under extremely high shear force, β-glucan long chains and glycyrrhizic acid molecules can physically entangle and embed into the nanofiber network of bacterial cellulose, forming a preliminary, uniform hybrid gel. Subsequently, cross-linking is promoted by glucose oxidase, making it more gentle and safe.

[0022] Optionally, in step S2, the hops are added in two stages: the first addition is 18-20 minutes before the end of boiling, and the second addition is 8-10 minutes before the end of boiling.

[0023] Optionally, the hops are bitter hops, selected from any one of West Chu hops, Courage hops, Magnum hops, and Century hops.

[0024] By adopting the above technical solution, the first addition of hops isomerizes bitter substances and optimizes the content of isohylocereusone, ensuring that it can fully interact with the glycosylated chickpea protein peptides and endogenous LTP1 added in this application to form a stable complex and improve foam retention. The second addition helps to extract aroma, retain volatile aroma substances, and helps to obtain a beer with a balanced bitter and aroma, and a beer with a mellow flavor base.

[0025] Secondly, this application provides a beer with high foam retention, which is prepared by a beer preparation method of this application.

[0026] In summary, this application has the following beneficial effects: 1. This application uses a composite of glycosylated chickpea protein peptides and bacterial cellulose polysaccharide microgel spheres as a foam enhancer. After enzymatic hydrolysis, the small molecule peptides ≤3kDa are modified with inulin glycosylation to form a highly active amphiphilic structure. Functionally, this structure mimics foaming proteins and enhances interfacial stability. It can be rapidly adsorbed at the gas-liquid interface and binds to hop isohypophyllone and foaming proteins through intermolecular forces such as hydrophobic interactions and hydrogen bonds to form a stable foam complex network, constructing a highly viscoelastic foam membrane. The hybrid microgel network constructed by the bacterial cellulose polysaccharide gel spheres mainly acts on the liquid film structure of beer foam. Through its strong water-holding capacity and structural advantages, it delays the merging of liquid film drainage and bubbles, while significantly enhancing the mechanical strength of beer foam. The synergy of the two increases the amount and fineness of beer foam, and also improves the stability, durability, and adhesion of the foam.

[0027] 2. The raw materials for beer brewing and beer foam enhancement in this application are all derived from natural components, without the introduction of exogenous chemical synthetic substances, and have a high degree of safety. Moreover, the added raw materials do not produce off-flavors or cause turbidity in the beer, resulting in a richer flavor profile and a more lasting aroma.

[0028] 3. In this application, hops are added in two stages, which ensures that there is enough isohyperidin to interact with glycosylated chickpea protein peptides and beer endogenous LTP1 to form a stable complex, while also ensuring the aroma and flavor of the beer. The foam enhancer in this application is added after fermentation and before filtration, which is highly compatible with the beer brewing process. Detailed Implementation

[0029] The present application will be further described in detail below with reference to embodiments and comparative examples.

[0030] raw material Unless otherwise specified, all raw materials used in the embodiments and comparative examples in this application are commercially available food-grade products, specifically: Chickpea protein, sourced from Xi'an Heers Peptide Biotechnology Co., Ltd.; Alkaline protease, selected from Ningxia Xiasheng Industrial Group Co., Ltd., FDG-2202; Acetobacter xylinum is CCTCC AB 2016223; β-glucan, selected from oat β-glucan by Shaanxi Taike Biotechnology Co., Ltd.; Glycyrrhizic acid glycoside, selected from Tianqi Biotechnology (Shanxi) Co., Ltd., CAS: 1405-86-3; Glucose oxidase, selected from Ningxia Xiasheng Industrial Group Co., Ltd., FDG-2248; Wheat sprouts, color grade 2-3 EBC; Barley malt, color 4-6 EBC; The brewer's yeast is English ale yeast, Angel CY115.

[0031] Preparation of Glycosylated Chickpea Protein Peptides: Examples 1.1-1.5 Preparation Example 1.1 The preparation method of glycosylated chickpea protein peptides includes the following steps: S1: Disperse chickpea protein powder in water and stir until homogeneous to obtain a chickpea protein solution with a mass concentration of 5%. Add 1M NaOH solution dropwise while continuously stirring to adjust the pH of the solution to 8±0.1. S2: Add 1% (by weight) of alkaline protease of chickpea protein powder to the chickpea protein solution, and perform enzymatic hydrolysis in a constant temperature water bath at 50℃ for 1.5h, maintaining the pH of the system at 8±0.1 during the process. Then, heat the reaction system to 90℃ to inactivate the enzyme, centrifuge, collect the supernatant, and spray dry it after ultrafiltration with a molecular weight cutoff of 3kDa to obtain small molecule chickpea protein peptides with a molecular weight ≤3kDa. S3: Chickpea protein peptides and inulin were thoroughly mixed in a dry state at a mass ratio of 1:1.2 to obtain a blend. Then, a Maillard reaction was carried out at a relative humidity of 75% and a temperature of 60℃ for 4 hours. The reaction product was dissolved in water at 2℃ to terminate the reaction. The mixture was centrifuged again, and the supernatant was collected and freeze-dried to obtain the final product.

[0032] Preparation Example 1.2 The preparation method of glycosylated chickpea protein peptides includes the following steps: S1: Disperse chickpea protein powder in water and stir until homogeneous to obtain a chickpea protein solution with a mass concentration of 7%. Add 1M NaOH solution dropwise while stirring continuously to adjust the pH of the solution to 8±0.1. S2: Add 1% (by weight) of alkaline protease of chickpea protein powder to the chickpea protein solution, and perform enzymatic hydrolysis in a constant temperature water bath at 50℃ for 1.2 h, maintaining the pH of the system at 8±0.1 during the process. Then, heat the reaction system to 90℃ to inactivate the enzyme, centrifuge, collect the supernatant, and spray dry it after ultrafiltration with a molecular weight cutoff of 3 kDa to obtain small molecule chickpea protein peptides with a molecular weight ≤3 kDa. S3: Chickpea protein peptides and inulin were thoroughly mixed in a dry state at a mass ratio of 1:1.3 to obtain a blend. Then, a Maillard reaction was carried out at a relative humidity of 70% and a temperature of 65℃ for 6 hours. The reaction product was dissolved in water at 4℃ to terminate the reaction. The mixture was centrifuged again, and the supernatant was collected and freeze-dried to obtain the final product.

[0033] Preparation Example 1.3 The preparation method of glycosylated chickpea protein peptides includes the following steps: S1: Disperse chickpea protein powder in water and stir until homogeneous to obtain a chickpea protein solution with a mass concentration of 8%. Add 1M NaOH solution dropwise while stirring continuously to adjust the pH of the solution to 8±0.1. S2: Add 1% (by weight) of alkaline protease of chickpea protein powder to the chickpea protein solution, and perform enzymatic hydrolysis in a constant temperature water bath at 50℃ for 1 hour, maintaining the pH of the system at 8±0.1. Then, heat the reaction system to 90℃ to inactivate the enzyme, centrifuge, collect the supernatant, and spray dry it after ultrafiltration with a molecular weight cutoff of 3kDa to obtain small molecule chickpea protein peptides with a molecular weight ≤3kDa. S3: Chickpea protein peptides and inulin were thoroughly mixed in a dry state at a mass ratio of 1:1.5 to obtain a blend. Then, a Maillard reaction was carried out at a relative humidity of 70% and a temperature of 65℃ for 5 hours. The reaction product was dissolved in water at 2℃ to terminate the reaction. The mixture was centrifuged again, and the supernatant was collected and freeze-dried to obtain the final product.

[0034] Preparation Example 1.4 The glycosylated chickpea protein peptide differs from that in Example 1.1 in that step S2 specifically involves: Add 1.5% (by weight) of alkaline protease to the chickpea protein solution and perform enzymatic hydrolysis in a constant temperature water bath at 50°C for 2.5 h, maintaining the pH of the system at 8 ± 0.1 during the process. Then, heat the reaction system to 90°C to inactivate the enzyme, centrifuge, collect the supernatant, perform ultrafiltration with a molecular weight cutoff of 3 kDa, and spray dry to obtain small molecule chickpea protein peptides with a molecular weight ≤ 3 kDa. All other steps are the same as in Preparation Example 1.1.

[0035] Preparation Example 1.5 The glycosylated chickpea protein peptide differs from that in Example 1.1 in that step S2 specifically involves: Add 1.5% (by weight) of alkaline protease to the chickpea protein solution and perform enzymatic hydrolysis in a constant temperature water bath at 50°C for 3 hours, maintaining the pH of the system at 8±0.1. Then, heat the reaction system to 90°C to inactivate the enzyme, centrifuge, collect the supernatant, perform ultrafiltration with a molecular weight cutoff of 3kDa, and spray dry to obtain small molecule chickpea protein peptides with a molecular weight ≤3kDa. All other steps are the same as in Preparation Example 1.1.

[0036] Preparation of bacterial cellulose polysaccharide microgel spheres: Examples 2.1-2.6 Preparation Example 2.1 The preparation method of bacterial cellulose polysaccharide microgel spheres includes the following steps: S1: According to mass fraction, 2% glucose, 0.5% peptone, 0.5% yeast extract, 0.27% disodium hydrogen phosphate and 0.15% citric acid are mixed, the pH is adjusted to 6, and the mixture is autoclaved at 120℃ for 20 min to obtain the culture medium. Acetobacter xylinum is inoculated into the culture medium at an inoculation rate of 5%, and the mixture is incubated at 30℃ for 6 days. The cellulose membrane is collected, rinsed with deionized water, and boiled in 1M NaOH solution at 70℃ for 1.5 h to remove residual bacteria and culture medium to obtain crude bacterial cellulose. The crude bacterial cellulose is washed with deionized water until neutral, and then homogenized under high pressure, freeze-dried, pulverized and sieved to obtain bacterial cellulose with a diameter of 50-100 nm and a length of 1-5 μm. S2: Disperse 1 part of bacterial cellulose in deionized water at a material-to-liquid ratio of 1:50 to obtain a bacterial cellulose dispersion. S3: Mix 2 parts β-glucan and 0.3 parts glycyrrhizic acid, and dissolve them in deionized water at a material-to-liquid ratio of 1:50 to obtain a mixed solution; S4: The bacterial cellulose dispersion was mixed with the mixed solution and homogenized under high pressure. Under extremely high shear force, the β-glucan long chain and glycyrrhizic acid molecules physically entangled and embedded in the nanofiber network of bacterial cellulose to obtain a gel solution. S5: Add 0.004 parts of glucose oxidase to the gel solution, adjust the pH to 6±0.1, and carry out the enzymatic cross-linking reaction for 1 h under constant temperature water bath at 35℃ to obtain cross-linked gel; S6: The cross-linked gel is extruded through a nozzle into cold anhydrous ethanol under vigorous stirring to solidify and form a shape. After washing and spray drying, bacterial cellulose polysaccharide microgel ball powder with a particle size of 50-100μm is obtained.

[0037] Preparation Example 2.2 The preparation method of bacterial cellulose polysaccharide microgel spheres includes the following steps: S1: According to mass fraction, 2% glucose, 0.5% peptone, 0.5% yeast extract, 0.27% disodium hydrogen phosphate and 0.15% citric acid are mixed, the pH is adjusted to 6, and the mixture is autoclaved at 120℃ for 20 min to obtain the culture medium. Acetobacter xylinum is inoculated into the culture medium at an inoculation rate of 5%, and the mixture is incubated at 30℃ for 6 days. The cellulose membrane is collected, rinsed with deionized water, and boiled in 1M NaOH solution at 70℃ for 1.5 h to remove residual bacteria and culture medium to obtain crude bacterial cellulose. The crude bacterial cellulose is washed with deionized water until neutral, and then homogenized under high pressure, freeze-dried, pulverized and sieved to obtain bacterial cellulose with a diameter of 50-100 nm and a length of 1-5 μm. S2: Disperse 1.2 parts of bacterial cellulose in deionized water at a material-to-liquid ratio of 1:50 to obtain a bacterial cellulose dispersion; S3: Mix 2.5 parts β-glucan and 0.4 parts glycyrrhizic acid, and dissolve them in deionized water at a material-to-liquid ratio of 1:50 to obtain a mixed solution; S4: The bacterial cellulose dispersion was mixed with the mixed solution and homogenized under high pressure. Under extremely high shear force, the β-glucan long chain and glycyrrhizic acid molecules physically entangled and embedded in the nanofiber network of bacterial cellulose to obtain a gel solution. S5: Add 0.005 parts of glucose oxidase to the gel solution, adjust the pH to 6±0.1, and carry out the enzymatic cross-linking reaction for 1.2 h under constant temperature water bath at 35℃ to obtain cross-linked gel; S6: The cross-linked gel is extruded through a nozzle into cold anhydrous ethanol under vigorous stirring to solidify and form a shape. After washing and spray drying, bacterial cellulose polysaccharide microgel ball powder with a particle size of 50-100μm is obtained.

[0038] Preparation Example 2.3 The preparation method of bacterial cellulose polysaccharide microgel spheres includes the following steps: S1: According to mass fraction, 2% glucose, 0.5% peptone, 0.5% yeast extract, 0.27% disodium hydrogen phosphate and 0.15% citric acid are mixed, the pH is adjusted to 6, and the mixture is autoclaved at 120℃ for 20 min to obtain the culture medium. Acetobacter xylinum is inoculated into the culture medium at an inoculation rate of 5%, and the mixture is incubated at 30℃ for 6 days. The cellulose membrane is collected, rinsed with deionized water, and boiled in 1M NaOH solution at 70℃ for 1.5 h to remove residual bacteria and culture medium to obtain crude bacterial cellulose. The crude bacterial cellulose is washed with deionized water until neutral, and then homogenized under high pressure, freeze-dried, pulverized and sieved to obtain bacterial cellulose with a diameter of 50-100 nm and a length of 1-5 μm. S2: Disperse 1.5 parts of bacterial cellulose in deionized water at a material-to-liquid ratio of 1:50 to obtain a bacterial cellulose dispersion; S3: Mix 3 parts β-glucan and 0.5 parts glycyrrhizic acid, and dissolve them in deionized water at a material-to-liquid ratio of 1:50 to obtain a mixed solution; S4: The bacterial cellulose dispersion was mixed with the mixed solution and homogenized under high pressure. Under extremely high shear force, the β-glucan long chain and glycyrrhizic acid molecules physically entangled and embedded in the nanofiber network of bacterial cellulose to obtain a gel solution. S5: Add 0.006 parts of glucose oxidase to the gel solution, adjust the pH to 6±0.1, and carry out the enzymatic cross-linking reaction for 1.5 h under constant temperature water bath at 35℃ to obtain cross-linked gel; S6: The cross-linked gel is extruded through a nozzle into cold anhydrous ethanol under vigorous stirring to solidify and form a shape. After washing and spray drying, bacterial cellulose polysaccharide microgel ball powder with a particle size of 50-100μm is obtained.

[0039] Preparation Example 2.4 The preparation method of bacterial cellulose polysaccharide microgel powder includes the following steps: S1: According to mass fraction, 2% glucose, 0.5% peptone, 0.5% yeast extract, 0.27% disodium hydrogen phosphate and 0.15% citric acid are mixed, the pH is adjusted to 6, and the mixture is autoclaved at 120℃ for 20 min to obtain the culture medium. Acetobacter xylinum is inoculated into the culture medium at an inoculation rate of 5%, and the mixture is incubated at 30℃ for 6 days. The cellulose membrane is collected, rinsed with deionized water, and boiled in 1M NaOH solution at 70℃ for 1.5 h to remove residual bacteria and culture medium to obtain crude bacterial cellulose. The crude bacterial cellulose is washed with deionized water until neutral, and then homogenized under high pressure, freeze-dried, pulverized and sieved to obtain bacterial cellulose with a diameter of 50-100 nm and a length of 1-5 μm. S2: Mix 1 part bacterial cellulose, 2 parts β-glucan and 0.3 parts glycyrrhizic acid, and stir evenly to obtain bacterial cellulose polysaccharide microgel powder.

[0040] Preparation Example 2.5 The bacterial cellulose polysaccharide microgel spheres differ from those in Preparation Example 2.1 in that they do not include β-glucan. Step S3 specifically involves dissolving 0.3 parts of glycyrrhizic acid in deionized water at a material-to-liquid ratio of 1:50 to obtain a mixed solution. All other steps are the same as in Preparation Example 2.1.

[0041] Preparation Example 2.6 The bacterial cellulose polysaccharide microgel spheres differ from those in Preparation Example 2.1 in that they do not include glycyrrhizic acid. Step S3 specifically involves dissolving two portions of β-glucan in deionized water at a material-to-liquid ratio of 1:50 to obtain a mixed solution. All other steps are the same as in Preparation Example 2.1. Example

[0042] Example 1 A method for preparing beer with high foam retention, comprising the following steps: S1: 30% barley malt and 70% wheat malt by mass percentage are crushed to 200μm, and water is added at a material-to-liquid ratio of 1:3. After stirring and mixing, the mixture is soaked for 13 hours. Then, it is added to a saccharification tank and heated to 40℃ at a rate of 2℃ / min. The temperature is held for 25 minutes, then heated to 55℃ and held for 20 minutes. The temperature is then heated to 70℃ and held for 30 minutes. Finally, the temperature is raised to 78℃ and held for 5 minutes. The mixture is then transferred to a filter tank for filtration to obtain the first wort. S2: Add the first wort to the boiling pot and boil for 70 minutes. Add Xichu hops 18-20 minutes before the end of boiling. Add Xichu hops again 8-10 minutes before the end of boiling. The mass ratio of the first and second additions of hops is 3:1. The total amount of hops added in the two additions is 0.05% of the mass of the first wort. After boiling and cooling, transfer to the filter tank for filtration to obtain the second wort. S3: Add the second wort to the fermentation tank and aerate it. Add brewer's yeast, with a full-tank yeast inoculation volume of 6.5 × 10⁻⁶. 6 The beer fermentation liquid was obtained by sealing and fermenting at 12℃ for 7 days with a concentration of 100 / mL. S4: The glycosylated chickpea protein peptide prepared in Preparation Example 1.1 and the bacterial cellulose polysaccharide microgel spheres prepared in Preparation Example 2.1 were mixed evenly at a mass ratio of 3:7 to obtain a foam enhancer. After fermentation, 0.12% of the foam enhancer was added to the beer fermentation liquid, stirred and dispersed into a uniform slurry, cooled to 2°C and stored for 48 hours. After filtration, clarified beer was obtained, which was then bottled, sterilized and packaged to obtain the final product.

[0043] Example 2 A method for preparing beer with high foam retention differs from Example 1 in that step S4 specifically involves: The glycosylated chickpea protein peptide prepared in Preparation Example 1.2 and the bacterial cellulose polysaccharide microgel spheres prepared in Preparation Example 2.2 were mixed evenly at a mass ratio of 4:6 to obtain a foam enhancer. After fermentation, 0.14% of the foam enhancer was added to the beer fermentation liquid, stirred and dispersed into a uniform slurry, and then allowed to stand for 3 hours. After filtration, clarified beer was obtained. After canning, sterilization, and packaging, the final product was obtained. All other steps were the same as in Example 1.

[0044] Example 3 A method for preparing beer with high foam retention differs from Example 1 in that step S4 specifically involves: The glycosylated chickpea protein peptide prepared in Preparation Example 1.3 and the bacterial cellulose polysaccharide microgel spheres prepared in Preparation Example 2.3 were mixed evenly at a mass ratio of 4:7 to obtain a foam enhancer. After fermentation, 0.15% of the foam enhancer was added to the beer fermentation liquid, stirred and dispersed into a uniform slurry, and then allowed to stand for 3 hours. After filtration, clarified beer was obtained. After canning, sterilization, and packaging, the final product was obtained. All other steps were the same as in Example 1.

[0045] Example 4 A method for preparing beer with high foam retention differs from Example 1 in that the glycosylated chickpea protein peptide used in step S4 is prepared by Example 1.4, while the other steps are the same as in Example 1.

[0046] Example 5 A method for preparing beer with high foam retention differs from Example 1 in that the glycosylated chickpea protein peptide used in step S4 is prepared by Example 1.5, while the other steps are the same as in Example 1.

[0047] Example 6 A method for preparing beer with high foam retention differs from Example 1 in that the bacterial cellulose polysaccharide microgel spheres used in step S4 are prepared using Preparation Example 2.5, while the other steps are the same as in Example 1.

[0048] Example 7 A method for preparing beer with high foam retention differs from Example 1 in that the bacterial cellulose polysaccharide microgel spheres used in step S4 are prepared in Preparation Example 2.6, while the other steps are the same as in Example 1.

[0049] Comparative Example Comparative Example 1 A method for preparing beer with high foam retention, comprising the following steps: S1: 30% barley malt and 70% wheat malt by mass percentage are crushed to 200μm, and water is added at a material-to-liquid ratio of 1:3. After stirring and mixing, the mixture is soaked for 13 hours. Then, it is added to a saccharification tank and heated to 40℃ at a rate of 2℃ / min. The temperature is held for 25 minutes, then heated to 55℃ and held for 20 minutes. The temperature is then heated to 70℃ and held for 30 minutes. Finally, the temperature is raised to 78℃ and held for 5 minutes. The mixture is then transferred to a filter tank for filtration to obtain the first wort. S2: The glycosylated chickpea protein peptide prepared in Preparation Example 1.1 and the bacterial cellulose polysaccharide microgel spheres prepared in Preparation Example 2.1 were mixed evenly at a mass ratio of 3:7 to obtain a foam enhancer. The first wort was added to a boiling pot and boiled for 60 minutes. 15 minutes before the end of boiling, Xichu hops were added. 10 minutes before the end of boiling, 0.12% of the foam enhancer by mass of the first wort was added. 5 minutes before the end of boiling, Xichu hops were added again. The mass ratio of the first and second additions of hops was 3:1. The total amount of hops added in the two additions was 0.05% of the mass of the first wort. After boiling and cooling, the mixture was transferred to a filter tank for filtration to obtain the second wort. S3: Add the second wort to the fermentation tank and aerate it. Add brewer's yeast, with a full-tank yeast inoculation volume of 6.5 × 10⁻⁶. 6 The beer was fermented at 12℃ for 7 days with a volume of 1000 ml / mL to obtain beer fermentation liquid. The liquid was then cooled to 2℃ and stored for 48 hours. After filtration, the clarified beer was obtained. After bottling, sterilization, and packaging, the final product was obtained.

[0050] Comparative Example 2 A method for preparing beer with high foam retention differs from Example 1 in that the glycosylated chickpea protein peptides used in step S4 are replaced with an equal mass of unglycosylated chickpea protein peptides obtained in step S2 of Preparation Example 1.1. All other steps are the same as in Example 1.

[0051] Comparative Example 3 A method for preparing beer with high foam retention differs from Example 1 in that glycosylated chickpea protein peptides are not added to the foam enhancer, while all other steps are the same as in Example 1.

[0052] Comparative Example 4 A method for preparing beer with high foam retention differs from Example 1 in that the bacterial cellulose polysaccharide microgel balls used in step S4 are replaced with an equal mass of bacterial cellulose polysaccharide microgel powder prepared in Preparation Example 2.4, while the other steps are the same as in Example 1.

[0053] Comparative Example 5 A method for preparing beer with high foam retention differs from Example 1 in that bacterial cellulose polysaccharide microgel spheres are not added to the foam enhancer, while the other steps are the same as in Example 1.

[0054] Comparative Example 6 A method for preparing beer with high foam retention differs from Example 1 in that no foam enhancer is added, while all other steps are the same as in Example 1.

[0055] Performance testing The beer with high foam retention prepared in Examples 1-7 and Comparative Examples 1-5 were tested for the following beer taste and flavor and beer foam persistence.

[0056] 1. Sensory evaluation: Based on the sensory scoring criteria in Table 1, 10 professionals were selected to comment on the appearance, foam, aroma, and taste of the beer and give corresponding scores. The average value was taken as the final sensory score of each group of beer, and the final results were recorded in Table 2. 2. Foam performance: Refer to the second method of foam retention test in GB / T 4928-2008 Beer Analysis Method: Stopwatch method to test the foam duration of the finished beer prepared in the examples and comparative examples, and record the initial foam height after the beer is poured into a standard glass. Three tests are performed on each group of beer, and the average value is taken as the final result and filled into Table 2.

[0057] Table 1 Table 2 According to the performance test results of Examples 1-3 and Comparative Example 6 in Table 2, the beer prepared by the method of this application has a rich taste and mellow aroma. This application uses glycosylated chickpea protein peptide and bacterial cellulose polysaccharide microgel spheres as a foam enhancer, which significantly improves the foaming performance and foam stability of the beer. The foam height of the finished beer is ≥47.5mm and the foam duration is ≥325s.

[0058] In Comparative Example 3, the foam enhancer did not include glycosylated chickpea protein peptides, resulting in a significant decrease in beer foam performance, with a foam height reaching only 33.8 mm. This indicates that inulin glycosylation modification forms a highly active amphiphilic structure, functionally mimicking foaming proteins and enhancing interfacial stability. It can rapidly adsorb at the gas-liquid interface and, through hydrophobic interactions, hydrogen bonds, and other intermolecular forces, bind with hop isohypophyllone and foaming proteins to form a stable foam complex network, constructing a highly viscoelastic foam membrane that enhances beer foam generation and foam fineness. In Comparative Example 2, the chickpea protein peptides used were not glycosylated, leading to reduced water solubility, interfacial activity, and stability. This resulted in easy aggregation, causing a fragile foam membrane and affecting the beer's clarity.

[0059] In Comparative Example 5, the foam enhancer did not include bacterial cellulose polysaccharide microgel spheres, resulting in a significant decrease in beer foam performance, with a foam height reaching only 37.5 mm. This indicates that the hybrid microgel network constructed from bacterial cellulose polysaccharide gel spheres can effectively act on the liquid film structure of beer foam. Through its strong water-holding capacity and structural advantages, it delays the merging of liquid film drainage and bubbles, significantly enhancing the mechanical strength of beer foam and improving foam stability, durability, and adhesion. In Comparative Example 4, the microgel powder was directly mixed, resulting in a loose structure that could not form a stable network structure, thus reducing the foam stability enhancement effect.

[0060] Based on the performance test results of Examples 1 and 4-5, it can be seen that the foam enhancer prepared from chickpea protein peptides obtained by incomplete enzymatic hydrolysis has a better effect. This is because incomplete enzymatic hydrolysis yields a mixture of peptides with a wider molecular weight, including small molecule peptides and a small amount of medium molecular weight peptides. This retains longer peptide chains and more protein higher-order structure residues, thus possessing more functional sites and a stronger ability to bind with hop isohydroxypyr and foaming proteins to form a stable foam complex network through intermolecular forces such as hydrophobic interactions and hydrogen bonds. Excessive enzymatic hydrolysis leads to excessive destruction of peptides.

[0061] The performance test results of Examples 1 and 6-7 show that the absence of β-glucan and glycyrrhizin both affect the effect of the foam enhancer. The lack of β-glucan reduces the water retention and network structure stability of bacterial cellulose polysaccharide microgel spheres. The presence of glycyrrhizin, through its hydrophobic aglycone structure, allows it to compete with isohypogonin for binding to foam-destroying molecules such as lipids, preferentially binding to foam-destroying molecules to form micelles, thereby protecting more isohypogonin for binding to foaming proteins, enhancing the beer's foam-generating ability, and improving the beer's taste.

[0062] According to the performance test results of Example 1 and Comparative Example 1, the optimal time to add the foam enhancer of this application is after primary fermentation and before filtration. In Comparative Example 1, the addition time is just before the end of boiling. It can be seen that the foam retention of the beer is significantly reduced, and the taste and flavor of the beer are also affected. This may be because the high temperature conditions destroy the active ingredients in the natural foam enhancer, or it may be because a large amount of yeast adsorbs and consumes the foam enhancer during fermentation, resulting in the loss of the foam enhancer and its inability to fully exert its effect.

[0063] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for preparing beer with high foam retention, characterized in that, Includes the following steps: S1: After crushing the malt, soak it in water, heat it to saccharify it, filter it and obtain the first wort; S2: Boil the first wort, add hops before the boiling is finished, cool and filter after boiling to obtain the second wort; S3: Add brewer's yeast to the second wort for fermentation to obtain beer fermentation liquid; S4: After fermentation, add 0.12-0.15% of foam enhancer to the beer fermentation liquid, stir and disperse into a uniform slurry, and obtain clarified beer after cold storage and filtration. After canning, sterilization and finished product packaging, the foam enhancer includes glycosylated chickpea protein peptides and bacterial cellulose polysaccharide microgel balls.

2. The method for preparing high-foaming beer according to claim 1, characterized in that, The mass ratio of the glycosylated chickpea protein peptides to the bacterial cellulose polysaccharide microgel spheres is (3-4):(6-7).

3. The method for preparing high-foaming beer according to claim 1, characterized in that, The method for preparing the glycosylated chickpea protein peptide includes the following steps: Chickpea protein peptides and inulin were thoroughly mixed in a dry state at a mass ratio of 1:(1.2-1.5) to obtain a blend. The blend was then reacted for 4-6 hours at a relative humidity of 70-75% and a temperature of 60-65℃. The resulting product was dissolved in water at 2-4℃ and then freeze-dried to obtain the final product.

4. The method for preparing high-foaming beer according to claim 3, characterized in that, The method for preparing the chickpea protein peptide includes the following steps: Chickpea protein powder was dispersed in water to obtain a chickpea protein solution with a mass concentration of 5-8%. The pH of the chickpea protein solution was adjusted to 8±0.

1. Alkaline protease at 1% mass of chickpea protein powder was added for enzymatic hydrolysis for 1-1.5 hours. After enzyme inactivation, the solution was centrifuged, ultrafiltered, and spray-dried to obtain small molecule chickpea protein peptides with a molecular weight ≤3kDa.

5. The method for preparing high-foaming beer according to claim 1, characterized in that, The raw materials for the bacterial cellulose polysaccharide microgel balls, by weight, include 1-1.5 parts bacterial cellulose, 2-3 parts β-glucan, 0.3-0.5 parts glycyrrhizic acid and 0.004-0.006 parts glucose oxidase, wherein the bacterial cellulose is obtained by fermentation of Acetobacter xylinum.

6. The method for preparing high-foaming beer according to claim 5, characterized in that, The preparation method of the bacterial cellulose polysaccharide microgel spheres includes the following steps: Bacterial cellulose was dispersed in water to obtain a bacterial cellulose dispersion. β-glucan and glycyrrhizin were mixed and dissolved in water to obtain a mixed solution. The bacterial cellulose dispersion and the mixed solution were mixed and homogenized under high pressure to obtain a gel solution. Glucose oxidase was added to the gel solution to carry out an enzymatic cross-linking reaction for 1-1.5 hours. The solution was then sprayed into anhydrous ethanol to solidify and form a microgel ball powder after washing and spray drying.

7. The method for preparing high-foaming beer according to claim 1, characterized in that, In step S2, the hops are added in two stages: the first addition is 18-20 minutes before the end of boiling, and the second addition is 8-10 minutes before the end of boiling.

8. A beer with high foam retention, characterized in that, The beer is prepared by the high foam retention beer preparation method according to any one of claims 1-7.

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