Beer silica gel clarifier, its preparation method and application
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- QILU UNIVERSITY OF TECHNOLOGY (SHANDONG ACADEMY OF SCIENCES)
- Filing Date
- 2024-04-15
- Publication Date
- 2026-06-26
Smart Images
Figure CN118341397B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the technical field of beer brewing, specifically relating to a beer silica gel clarifying agent, its preparation method, and its application. Background Technology
[0002] Beer is a complex colloidal solution with relatively low stability, obtained by fermenting malt and hops. During fermentation, malt releases various proteins, known as free proteins. These free proteins in malt readily polymerize with the polyphenols in hops, forming water-insoluble protein-polyphenol complexes. With prolonged storage, under the influence of oxygen and light, these complexes continue to polymerize, forming a spatial network structure, ultimately producing insoluble colloidal precipitation. This causes irreversible turbidity in the originally clear and refreshing beer, accompanied by darkening of color and aging of the taste. Turbidity in beer severely impacts product quality and consumer sensory acceptance, significantly shortens shelf life, and reduces market competitiveness. Two important types of free proteins released by malt are foam proteins, which are polymers formed from proteins and sugars during beer fermentation. These foam proteins possess strong surface activity and high viscosity, and are crucial for producing dense foam and improving foam stability. The amount of foaming proteins is crucial to the formation and maintenance of beer foam, so foaming proteins need to be retained as much as possible. Another type is specific sensitive proteins that easily produce turbidity, namely turbidity-sensitive proteins. These turbidity-sensitive proteins that affect the senses need to be removed, otherwise flocculent sediments that affect beer quality will be produced.
[0003] Currently, commonly used methods for preventing beer turbidity mainly include the following categories: ① Cold chain production and storage throughout the entire process to delay the polymerization reaction between proteins and polyphenols; ② Adding protein structural analogs such as formaldehyde or polyvinylpyrrolidone (PVPP) to selectively bind and remove polyphenols from the beer; ③ Adding papain to indiscriminately and thoroughly decompose all proteins in the beer. Although the above methods can all achieve the goal of preventing beer turbidity, they often have drawbacks such as high production and storage costs, unstable flavor, low nutritional value, or low foam persistence.
[0004] In fact, the key to avoiding beer turbidity lies in preventing the formation of protein-polyphenol complexes. There are two main approaches: one is to remove specific sensitive proteins in the beer that easily cause turbidity; the other is to remove the corresponding sensitive polyphenols. Polyphenols are important flavor compounds closely related to beer quality, significantly influencing its taste, color, foam persistence, flavor, and stability. A suitable amount of unoxidized polyphenols can give beer a fresh and mellow flavor, and their antioxidant properties have been proven to have positive effects on human health. Therefore, the best approach is to retain as many polyphenols as possible in beer while selectively removing sensitive proteins that easily cause turbidity. This is crucial for maintaining beer flavor, preventing oxidation, and improving nutritional value.
[0005] Therefore, the method of using substances rich in hydroxyl groups, such as silica gel and tannic acid, as protein adsorbents, allowing them to compete with polyphenols in the beer to precipitate and filter out turbidity-sensitive proteins, is increasingly favored. Among these, silica gel adsorbents offer the most significant advantages: no leaching substances, thus not affecting the beer's taste; minimal beer loss; easy filtration after use; and non-toxic and odorless, making it the safest beer clarifying agent currently available. After removing turbidity-sensitive proteins through silica gel adsorption, the shelf life of beer at room temperature can be extended by 180-240 days compared to untreated products, while maintaining extremely high clarity. Furthermore, compared to other adsorbents such as PVPP, silica gel has a significant cost advantage, thus being considered a highly ideal beer clarifying agent.
[0006] However, silica gel still faces some unresolved challenges in practical applications. On the one hand, existing silica gel for beer typically adsorbs all types of proteins indiscriminately, exhibiting low selectivity for adsorbing turbidity-sensitive proteins in beer. It cannot effectively distinguish between turbidity-sensitive proteins that need to be removed and foam proteins that need to be retained, making it difficult to selectively adsorb turbidity-sensitive proteins. This easily leads to the loss of foam proteins, resulting in reduced foam and decreased foam persistence, which affects the taste, appearance, and other sensory added value of beer.
[0007] Therefore, there is an urgent need to develop a new type of silica gel with strong adsorption selectivity in order to specifically adsorb turbidity-sensitive proteins in beer. Summary of the Invention
[0008] The purpose of this invention is to address the problem of poor selectivity in the adsorption of turbid proteins by existing beer silica gel, and to provide a method for preparing a beer silica gel clarifying agent. This preparation method can precisely control the pore diameter of the silica gel adsorption material. The silica gel clarifying agent prepared by this method can achieve highly selective adsorption of turbidity-sensitive proteins, thus achieving the purpose of specific adsorption.
[0009] As the two proteins that most significantly affect beer quality, foam proteins and turbidity proteins differ considerably in molecular weight and particle size. Foam proteins have a molecular weight between 50,000 and 100,000 Da, with protein particles around 8-10 nm; while turbidity-sensitive proteins have a molecular weight between 1,000 and 40,000 Da, with a particle size of around 2-4 nm. Existing silica gel adsorbents have relatively large pore sizes, which not only reduces the specific surface area but also allows larger foam protein particles to diffuse into the large pores, resulting in the indiscriminate adsorption of various proteins in the beer and a decrease in the adsorption selectivity of beer turbidity-sensitive proteins.
[0010] If the particle size difference between the two proteins can be used to selectively separate them, by precisely controlling the pore size of the silica adsorbent material to be between that of foam protein and turbid protein, it is possible to block the diffusion of larger foam protein particles into the pores through the smaller pore size, thereby reducing the occurrence of undesirable adsorption; at the same time, it does not affect the diffusion of smaller turbid sensitive proteins into the pores, where they adsorb on the inner surface of the silica, thereby achieving the purpose of selectively removing turbid sensitive proteins.
[0011] It is evident that achieving precise control over the pore size of silica gel has become the key to solving this technical problem. This invention proposes first adding a hydroxyl protectant to the sodium silicate solution used in silica gel preparation, and then adding a catalyst and N-hydroxybenzotriazole at different stages of the reaction process. This method allows for precise adjustment and control of the silica gel pore size within the desired range, effectively distinguishing between turbid proteins that need to be removed and foam proteins that need to be retained in the beer, thus improving beer clarity and quality.
[0012] The specific technical solution is as follows:
[0013] A method for preparing a beer silica gel clarifying agent includes the following steps:
[0014] (1) Preparation of sol:
[0015] First, add a hydroxyl protectant to the raw sodium silicate solution and mix thoroughly. The hydroxyl protectant is one or more of the following: heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, malonic acid, glutaric acid, sebacic acid, or salicylic acid. The molar ratio of hydroxyl protectant to sodium silicate is 0.3-5:1.
[0016] Then, the raw sulfuric acid solution is added to the sodium silicate solution, and the reaction is carried out at room temperature under acidic conditions.
[0017] When the reaction has proceeded to 2%-20% of the total reaction time, a catalyst is added. The catalyst is one or more of dicyclohexylcarbodiimide, diisopropylcarbodiimide, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, or 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide. The molar ratio of catalyst to hydroxyl protectant is 0.5-2.5:1.
[0018] When the reaction has proceeded to 25%-50% of the total reaction time, N-hydroxybenzotriazole is added; wherein the molar ratio of N-hydroxybenzotriazole to hydroxyl protecting agent is 0.2-5:1.
[0019] After the reaction is complete, maintain the pH value at 3-4 to prepare the sol.
[0020] (2) Gel preparation: The sol obtained in step (1) is first aged and soaked in alkali, and then washed with a mixed solution composed of sodium carbonate aqueous solution and ethanol to obtain a gel; wherein the concentration of sodium carbonate aqueous solution is 1.5-2 mol / L; the volume ratio of sodium carbonate aqueous solution to ethanol is 0.5-1:1. By washing and re-hydrolyzing and reducing, silanol groups and free hydroxyl protectants are generated on the surface of silica gel, so as to restore a certain number of hydroxyl groups on the surface of silica gel. This allows for precise control of the silica gel pore structure while maintaining a certain number of surface silanol groups, avoiding affecting the subsequent adsorption of turbidity-sensitive proteins.
[0021] (3) Preparation of beer silica gel clarifying agent: After drying and activating the gel obtained in step (2), the beer silica gel clarifying agent is obtained.
[0022] The specific mechanism of action is as follows: First, a hydroxyl protectant is added to the sodium silicate solution used to prepare silica gel. Then, a catalyst and N-hydroxybenzotriazole are added at different stages of the reaction process to precisely control the degree and rate of esterification reaction between the hydroxyl protectant and the hydroxyl groups. This allows for precise and quantitative temporary protection of the hydroxyl groups on the surface of orthosilicic acid, inhibiting excessive polymerization of orthosilicic acid and making the degree of polymerization highly controllable. This achieves the inhibition of orthosilicic acid dehydration condensation and precise control of the degree of condensation, enabling the pore size of the silica gel clarifying agent to be precisely adjusted within a certain range.
[0023] In the present invention, in the preparation method of the beer silica gel clarifying agent, the molar ratio of catalyst to hydroxyl protectant in step (1) is 1.5:1; the molar ratio of N-hydroxybenzotriazole to hydroxyl protectant is 1:1.
[0024] In this invention, the hydroxyl protectant in step (1) of the preparation method of the beer silica gel clarifying agent is one or more of nonanoic acid, glutaric acid, sebacic acid or salicylic acid.
[0025] In this invention, the preparation method of the beer silica gel clarifying agent, in step (2), the volume ratio of sodium carbonate aqueous solution to ethanol is 1:1.
[0026] In the preparation method of the beer silica gel clarifying agent of the present invention, the washing temperature in step (2) is 25-30℃.
[0027] In the preparation method of the beer silica gel clarifying agent of the present invention, the drying temperature in step (3) is 120-180℃ and the drying time is 12-24h.
[0028] In the present invention, the preparation method of the beer silica gel clarifying agent, the activation calcination temperature in step (3) is 450-550℃ and the calcination time is 10-12h.
[0029] A silica gel clarifying agent for beer, prepared by the above-described method; the silica gel clarifying agent for beer has a pore size of 4-5.5 nm and a specific surface area of 620-780 m². 2 / g, with a pore volume of 0.8-1.0mL / g.
[0030] The above-mentioned application of silica gel clarifying agent in beer clarification, wherein the mass ratio of silica gel clarifying agent to beer is 1:10-15.
[0031] The beneficial effects of this invention are as follows: The preparation method of this invention temporarily protects the hydroxyl groups by adding a hydroxyl protectant to the raw material sodium silicate solution in advance, and by adding a catalyst and N-hydroxybenzotriazole at different stages of the subsequent reaction process. This achieves highly controllable polymerization of orthosilicic acid and controllable adjustment of the silica gel pore structure, allowing the pore size of the silica gel adsorbent to be precisely adjusted within a certain range. By obtaining smaller pores, the turbid proteins that need to be removed and the foam proteins that need to be retained in the beer can be effectively distinguished, thus improving the clarity of the beer and enhancing its quality.
[0032] When silanol groups are needed, washing with a specific mixed solution allows the hydroxyl groups that were temporarily protected during the reaction to be released and restored, thus retaining a large number of hydroxyl groups for the adsorption of cloudy proteins in beer.
[0033] The preparation method described in this invention improves the controllability of silicone channel size to a new level and can simultaneously protect the number of silanol groups. Attached Figure Description
[0034] Figure 1 This is a SEM image of the beer silica gel clarifying agent described in this invention. Detailed Implementation
[0035] The technical solution of the present invention will be described in detail below.
[0036] Example 1
[0037] The preparation method of the beer silica gel clarifying agent includes the following specific steps:
[0038] (1) Preparation of sol:
[0039] First, salicylic acid, a hydroxyl protectant, is added to a 40wt% sodium silicate solution and mixed thoroughly; wherein the molar ratio of salicylic acid to sodium silicate is 1:1.
[0040] Then, a 55wt% sulfuric acid solution of the raw material is added to the sodium silicate solution, and the reaction is carried out at 25°C and pH 3.
[0041] When the reaction has proceeded for 12 minutes (5% of the total reaction time), the catalyst diisopropylcarbodiimide is added; the molar ratio of diisopropylcarbodiimide to salicylic acid is 1.5:1.
[0042] When the reaction has proceeded for 72 minutes (30% of the total reaction time), N-hydroxybenzotriazole is added; wherein the molar ratio of N-hydroxybenzotriazole to salicylic acid is 1:1.
[0043] After 4 hours of reaction, the reaction was completed, and the pH was maintained at 3 to prepare the sol.
[0044] (2) Preparation of gel: First, the sol obtained in step (1) is aged at 65℃ for 1.5h; then, it is soaked in a 35wt% KOH solution for 10min, and then washed with a mixed solution composed of sodium carbonate aqueous solution and ethanol to obtain the gel. The concentration of sodium carbonate aqueous solution is 2mol / L; the volume ratio of sodium carbonate aqueous solution to ethanol is 1:1.
[0045] (3) Preparation of beer silica gel clarifying agent: After drying the gel obtained in step (2) at 120°C for 24 hours, it is placed in a muffle furnace at 550°C for high-temperature activation for 10 hours to obtain the beer silica gel clarifying agent.
[0046] The obtained beer silica gel clarifying agent was used for beer clarification, and the mass ratio of the beer silica gel clarifying agent to beer was 1:15.
[0047] Example 2
[0048] The preparation method of the beer silica gel clarifying agent includes the following specific steps:
[0049] (1) Preparation of sol:
[0050] First, nonanoic acid, a hydroxyl protectant, is added to a 40wt% sodium silicate solution and mixed thoroughly; wherein the molar ratio of nonanoic acid to sodium silicate is 0.5:1.
[0051] Then, a 55wt% sulfuric acid solution of the raw material is added to the sodium silicate solution, and the reaction is carried out at 25°C and pH 3.
[0052] When the reaction has proceeded for 24 minutes (10% of the total reaction time), the catalyst dicyclohexylcarbodiimide is added; the molar ratio of dicyclohexylcarbodiimide to nonanoic acid is 0.5:1.
[0053] When the reaction has proceeded for 1.8 hours (45% of the total reaction time), N-hydroxybenzotriazole is added; wherein the molar ratio of N-hydroxybenzotriazole to hydroxyl protecting agent is 0.5:1.
[0054] After 4 hours of reaction, the reaction was completed, and the pH was maintained at 3 to prepare the sol.
[0055] (2) Preparation of gel: First, the sol obtained in step (1) is aged at 65°C for 1.5 h; then, it is soaked in a KOH solution with a mass fraction of 35 wt% for 10 min, and then washed with a mixed solution composed of sodium carbonate aqueous solution and ethanol to obtain the gel.
[0056] The concentration of the sodium carbonate aqueous solution was 1.5 mol / L; the volume ratio of sodium carbonate aqueous solution to ethanol was 0.8:1.
[0057] (3) Preparation of beer silica gel clarifying agent: After drying and activating the gel obtained in step (2), the beer silica gel clarifying agent is obtained.
[0058] The obtained beer silica gel clarifying agent was used for beer clarification, and the mass ratio of the beer silica gel clarifying agent to beer was 1:12.
[0059] Example 3
[0060] The preparation method of the beer silica gel clarifying agent includes the following specific steps:
[0061] (1) Preparation of sol:
[0062] First, sebacic acid, a hydroxyl protectant, is added to a 40wt% sodium silicate solution and mixed thoroughly; wherein the molar ratio of sebacic acid to sodium silicate is 4:1.
[0063] Then, a 55wt% sulfuric acid solution of the raw material is added to the sodium silicate solution, and the reaction is carried out at 25°C and pH 2.
[0064] When the reaction has proceeded for 36 minutes (20% of the total reaction time), the catalyst 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide is added; the molar ratio of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide to sebacate is 2:1.
[0065] When the reaction has proceeded for 1.5 hours (50% of the total reaction time), N-hydroxybenzotriazole is added; wherein the molar ratio of N-hydroxybenzotriazole to hydroxyl protecting agent is 3:1.
[0066] After 3 hours of reaction, the reaction was completed, and the pH was maintained at 4 to obtain the sol.
[0067] (2) Preparation of gel: First, the sol obtained in step (1) is aged at 65°C for 1.5 h; then, it is soaked in a KOH solution with a mass fraction of 35 wt% for 10 min, and then washed with a mixed solution composed of sodium carbonate aqueous solution and ethanol to obtain the gel.
[0068] The concentration of the sodium carbonate aqueous solution is 2.0 mol / L; the volume ratio of sodium carbonate aqueous solution to ethanol is 0.5:1.
[0069] (3) Preparation of beer silica gel clarifying agent: After drying and activating the gel obtained in step (2), the beer silica gel clarifying agent is obtained.
[0070] The obtained beer silica gel clarifying agent was used for beer clarification, and the mass ratio of the beer silica gel clarifying agent to beer was 1:10.
[0071] Example 4
[0072] The difference from Example 1 is that the hydroxyl protecting agent in step (1) is glutaric acid.
[0073] The others are the same as in Example 1.
[0074] Comparative Example 1
[0075] The difference from Example 3 is that the molar ratio of sebacic acid, the hydroxyl protectant, to sodium silicate in step (1) is 6:1.
[0076] The others are the same as in Example 3.
[0077] Comparative Example 2
[0078] The difference from Example 1 is that the order in which the catalysts diisopropylcarbodiimide and N-hydroxybenzotriazole are added is reversed. The specific procedure is as follows:
[0079] In step (1), N-hydroxybenzotriazole is added when the reaction has proceeded to 5% of the total reaction time.
[0080] When the reaction has proceeded to 30% of the total reaction time, the catalyst diisopropylcarbodiimide is added.
[0081] The others are the same as in Example 1.
[0082] Comparative Example 3
[0083] The difference from Example 1 is that the carboxylic acid in step (1) is lauric acid.
[0084] The others are the same as in Example 1.
[0085] The relevant indicators of the beer silica gel clarifying agents prepared in each embodiment and comparative example are detailed in Table 1.
[0086] Table 1. Relevant Indicators of Various Beer Silica Clarifying Agents
[0087] Aperture (nm) <![CDATA[Specific surface area (m 2 / g)]]> Pore volume (mL / g) Example 1 4.2 775.8 1.0 Example 2 5.1 660.6 0.9 Example 3 5.4 620.6 0.8 Example 4 5.1 657.9 0.8 Comparative Example 1 6.8 488.6 0.5 Comparative Example 2 7.1 471.3 0.5 Comparative Example 3 6.7 495.9 0.6
[0088] Experimental Example 1
[0089] I. Experimental Objective: To investigate the effect of the timing of catalyst addition on silica gel clarifying agent in beer.
[0090] II. Experimental Methods: Following the preparation method steps described in Example 1, the single variable was set as follows: the catalyst diisopropylcarbodiimide in step (1) was 1%, 2%, 5%, 10%, 20%, and 25% of the total reaction time. Other steps and conditions were the same as in Example 1.
[0091] III. Experimental Results: See Table 2 for details.
[0092] Table 2. Relevant Indicators of Various Beer Silica Clarifying Agents
[0093]
[0094]
[0095] Experimental Example 2
[0096] I. Experimental Objective: To investigate the effect of the timing of N-hydroxybenzotriazole addition on silica gel clarifying agents for beer.
[0097] II. Experimental Methods: The preparation method steps described in Example 1 were followed, with the single variable set to 20%, 25%, 30%, 35%, 40%, 50%, and 55% of the total reaction time for N-hydroxybenzotriazole in step (1). Other steps and conditions were the same as in Example 1.
[0098] III. Experimental Results: See Table 3 for details.
[0099] Table 3. Relevant Indicators of Various Beer Silica Clarifying Agents
[0100]
Claims
1. A method for preparing a beer silica gel clarifying agent, characterized in that, Includes the following steps: (1) Preparation of sol: First, add a hydroxyl protectant to the raw sodium silicate solution and mix thoroughly; wherein, the hydroxyl protectant is one or more of heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, malonic acid, glutaric acid, sebacic acid or salicylic acid; the molar ratio of hydroxyl protectant to sodium silicate is 0.3-5:1; Then, the raw sulfuric acid solution is added to the sodium silicate solution, and the reaction is carried out at room temperature under acidic conditions. When the reaction has proceeded to 2%-20% of the total reaction time, a catalyst is added. The catalyst is one or more of dicyclohexylcarbodiimide, diisopropylcarbodiimide, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, or 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide; the molar ratio of catalyst to hydroxyl protecting agent is 0.5-2.5:
1. When the reaction has proceeded to 25%-50% of the total reaction time, N-hydroxybenzotriazole is added; wherein the molar ratio of N-hydroxybenzotriazole to hydroxyl protecting agent is 0.2-5:
1. After the reaction is complete, maintain the pH value at 3-4 to prepare the sol; (2) Preparation of gel: The sol obtained in step (1) is first aged and soaked in alkali, and then washed with a mixed solution composed of sodium carbonate aqueous solution and ethanol to obtain gel; The concentration of the sodium carbonate aqueous solution is 1.5-2 mol / L; the volume ratio of sodium carbonate aqueous solution to ethanol is 0.5-1:
1. (3) Preparation of beer silica gel clarifying agent: After drying and activating the gel obtained in step (2), the beer silica gel clarifying agent is obtained; The activation calcination temperature is 450-550℃, and the calcination time is 10-12h.
2. The method for preparing the beer silica gel clarifying agent according to claim 1, characterized in that, In step (1), the molar ratio of catalyst to hydroxyl protectant is 1.5:1; the molar ratio of N-hydroxybenzotriazole to hydroxyl protectant is 1:
1.
3. The method for preparing the beer silica gel clarifying agent according to claim 1, characterized in that, The hydroxyl protectant in step (1) is one or more of nonanoic acid, glutaric acid, sebacic acid or salicylic acid.
4. The method for preparing the beer silica gel clarifying agent according to claim 1, characterized in that, The volume ratio of sodium carbonate aqueous solution to ethanol in step (2) is 1:
1.
5. The method for preparing the beer silica gel clarifying agent according to claim 1, characterized in that, The washing temperature in step (2) is 25-30℃.
6. The method for preparing the beer silica gel clarifying agent according to claim 1, characterized in that, The drying temperature in step (3) is 120-180℃ and the drying time is 12-24h.
7. A beer silica gel clarifying agent, characterized in that, The beer silica gel clarifying agent is prepared by the preparation method according to any one of claims 1-6; the pore size is 4-5.5 nm and the specific surface area is 620-780 m². 2 / g, with a pore volume of 0.8-1.0mL / g.
8. The application of the silica gel clarifying agent for beer as described in claim 7 in beer clarification, characterized in that, Beer silica gel clarifying agent: the mass ratio of beer is 1:10-15.