Method for quickly esterifying rice vinegar and yellow wine
By using a composite solid acid catalyst and optimizing reaction conditions, the problems of slow esterification rate and low conversion rate of rice vinegar and rice wine were solved, achieving a rapid and efficient esterification reaction. The catalyst can be recycled, reducing production costs and environmental pollution.
Patent Information
- Application Number
- CN202511683156.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-17
- Publication Date
- 2026-02-06
AI Technical Summary
The existing esterification reaction between rice vinegar and Shaoxing wine has a slow rate and low conversion rate. Traditional catalysts pollute the environment and are difficult to recycle, making it difficult to meet the needs of industrial production.
A composite solid acid catalyst, including molecular sieves and sulfonated carbon materials, was used. The reaction temperature and stirring rate were optimized, and the catalyst was prepared by mechanical mixing and sulfonation. The catalyst was then separated by vacuum filtration to achieve its recyclability.
It significantly shortens the esterification reaction time to 2-4 hours, achieves an ethyl acetate conversion rate of over 85%, reduces production costs, minimizes environmental pollution, and makes the catalyst easy to separate and recover.
Abstract
Description
Technical Field
[0001] This invention belongs to the field of food chemical technology, specifically relating to a method for the rapid esterification of rice vinegar and rice wine. Background Technology
[0002] Rice vinegar and rice wine are both traditional fermented foods in my country. Rice vinegar is rich in acetic acid, while rice wine contains a large amount of ethanol. Acetic acid and ethanol can undergo esterification under certain conditions to produce ethyl acetate. Ethyl acetate has a rich fruity aroma and can significantly enhance the flavor and quality of food. Currently, traditional esterification methods for rice vinegar and rice wine are mostly natural fermentation esterification. This method suffers from slow reaction rates, long esterification cycles (usually requiring 15-30 days), and low ethyl acetate conversion rates (generally not exceeding 50%), making it difficult to meet the needs of industrial production. In addition, some improved methods use liquid acids (such as sulfuric acid and hydrochloric acid) as catalysts. Although this can improve the reaction rate to some extent, it has drawbacks such as equipment corrosion, environmental pollution, difficulty in product separation, and the inability to recycle the catalyst. Therefore, developing a high-efficiency, environmentally friendly, and catalyst-recoverable rapid esterification method for rice vinegar and rice wine is of significant practical importance. Summary of the Invention
[0003] In view of the problems of slow reaction rate, low conversion rate and environmental pollution of catalyst in the esterification reaction of rice vinegar and rice wine in the prior art, the present invention provides a method for rapid esterification of rice vinegar and rice wine.
[0004] The technical solution is as follows: A method for rapid esterification of rice vinegar and rice wine includes the following steps: S1 Raw material pretreatment: The rice vinegar and rice wine are filtered separately to remove impurities; filtration removes impurities to avoid interference with the reaction. S2 Raw material mixing: Add the pretreated rice vinegar and rice wine to the reaction vessel and stir evenly; the total acid content of the rice vinegar is 3.5-5.0g / 100mL, and the alcohol content of the rice wine is 12-16% vol; selecting rice vinegar and rice wine within this range can ensure sufficient content of acetic acid and ethanol in the reaction system, providing a good raw material basis for the esterification reaction; S3 Catalyst Addition: A composite solid acid catalyst is added to the reactor; the composite solid acid catalyst includes a molecular sieve and sulfonated carbon material, wherein the purity of the molecular sieve is greater than or equal to 99%.
[0005] S4 Esterification reaction: Raise the temperature inside the reactor to 40-60℃ and stir to carry out the esterification reaction for 2-4 hours; this temperature range can accelerate the reaction rate and at the same time avoid excessive temperature causing the rice vinegar and rice wine to evaporate; S5 Product Separation: After the reaction is complete, the reaction solution is cooled to room temperature, filtered to separate the composite solid acid catalyst, and the ethyl acetate esterification product is obtained.
[0006] The total acid content of the rice vinegar in step S2 is 4.0-4.5g / 100mL, and the alcohol content of the rice wine is 13-15%vol. Raw materials within this range can make the esterification reaction more effective.
[0007] In step S2, the volume ratio of rice vinegar to rice wine is 1:2 to 1:4. Controlling this volume ratio ensures that the ratio of acetic acid to ethanol is within a suitable range, promoting the forward esterification reaction. Furthermore, a volume ratio of 1:3 for rice vinegar to rice wine represents the optimal ratio of acetic acid to ethanol, resulting in the highest esterification conversion rate.
[0008] The molecular sieve mentioned in step S3 includes HZSM-5 molecular sieve with a silicon-to-aluminum ratio of 100-300; the sulfonated carbon material includes sulfonated ordered mesoporous carbon, and the combination of the two results in superior catalytic performance.
[0009] The molecular sieve in the composite solid acid catalyst described in step S3 has a mass percentage of 5%-10%.
[0010] The catalyst contains 0.5~3 mmol / g of sulfonic acid (molar content of sulfonic acid group -SO3H).
[0011] The composite solid acid catalyst is obtained by mechanically mixing molecular sieves and sulfonated carbon materials.
[0012] The composite solid acid catalyst can also be obtained by the following method, including the following steps: S01 Molecular sieve pretreatment: The molecular sieve is soaked in citric acid solution, ultrasonically cleaned, and then dried. SO2 carbon source loading: The pretreated molecular sieve is dispersed in a glucose solution and stirred to form a mixture; S03 carbonization molding: The mixture is transferred to a reaction vessel and hydrothermally reacted at 150-200℃ for 6-8 hours. The product is separated and dried to obtain a molecular sieve and carbon precursor complex. Carbonization is then carried out to obtain a molecular sieve and carbon complex. S04 In-situ sulfonation: The composite of molecular sieve and carbon is immersed in an aqueous solution of aminosulfonic acid (sulfonating agent), stirred at 60-75℃ for 4-5.5h, washed with water until neutral, and then vacuum dried to obtain a composite solid acid catalyst.
[0013] The mixed solution in SO2 also includes a surfactant, which includes sucrose fatty acid esters at a concentration of 0.5-2 mol / L, to assist in mesoporous formation.
[0014] The concentration of the citric acid solution described in S01 is 1-2.5 mol / L, and the mass-to-volume ratio of HZSM-5 molecular sieve to citric acid solution is 1:400-600 (g / ml).
[0015] The concentration of glucose solution in SO2 is 0.5-1.5 mol / L, and the mass-to-volume ratio of HZSM-5 molecular sieve to glucose solution is 1:4-6 (g / ml).
[0016] The carbonization temperature in SO3 is 400-600℃, and the carbonization time is 1-4 hours. The concentration of the aminosulfonic acid aqueous solution in SO4 is 1 mol / L, and the mass-to-volume ratio of HZSM-5 molecular sieve to aminosulfonic acid aqueous solution is 1:400-550 (g / ml).
[0017] In step S3, the amount of the composite solid acid catalyst added is 2-5% of the total mass of the rice vinegar and rice wine mixture. Furthermore, the amount of the composite solid acid catalyst added is 3-4% of the total mass of the rice vinegar and rice wine mixture; within this range, the catalytic effect is better and the cost is reduced.
[0018] The stirring rate in step S4 is 200-400 r / min. A suitable stirring rate can ensure that the raw materials and catalyst are in full contact, thereby further improving the reaction efficiency.
[0019] In step S4, the reaction temperature is 50-55℃ and the stirring rate is 300-350 r / min. Under these conditions, the reaction rate and conversion rate reach the optimal equilibrium.
[0020] In step S5, the filtration is performed using vacuum filtration with a pore size of 0.22-0.45 μm, which can improve filtration efficiency and catalyst separation effect.
[0021] It also includes regenerating the separated composite solid acid catalyst by solvent extraction; the solvent is ethanol.
[0022] The total acid content of the rice vinegar is calculated as acetic acid, in accordance with GB18187.
[0023] The beneficial effects of this invention are as follows: This invention shortens the esterification reaction time to 2-4 hours by adding a composite solid acid catalyst and optimizing the reaction temperature and stirring rate, far reducing the time to 15-30 days compared to traditional natural fermentation esterification. High conversion rate: Ethyl acetate conversion can reach over 85%, significantly higher than the traditional method's below 50%. The composite solid acid catalyst exhibits high catalytic activity and selectivity. The molecular sieve has a regular pore structure, providing a good reaction environment, while the sulfonated carbon material surface contains numerous acidic sites, significantly improving catalytic efficiency. Furthermore, the catalyst does not cause equipment corrosion problems, is easy to separate and recover, and can be reused, reducing production costs and environmental pollutant emissions. Detailed Implementation
[0024] The preparation method of the composite catalyst in the examples includes the following steps: (1) Pretreatment: 1g of HZSM-5 (purity greater than 99%) was soaked in 500ml of 1mol / L citric acid aqueous solution for 2h, ultrasonically cleaned and dried to introduce hydroxyl groups (-OH) on the surface to enhance the binding with carbon source; (2) Carbon source loading: The pretreated HZSM-5 was dispersed in 5 mL of glucose aqueous solution (carbon source, concentration 20%, food grade), stirred for 1 h, and then 0.5 g of food grade sucrose fatty acid ester was added to assist in mesopore formation. Stirring was continued for 2 h to obtain a mixture. (3) Carbonization and molding: The mixture was transferred to the reactor and hydrothermally reacted at 180℃ for 6 hours. The product was filtered, washed and dried to obtain the HZSM-5 and carbon precursor complex. Then, it was carbonized at 450℃ for 3 hours under N2 atmosphere (heating rate 5℃ / min) to obtain the HZSM-5 and mesoporous carbon complex. (4) In-situ sulfonation: The composite of HZSM-5 and mesoporous carbon was immersed in 500 ml of 5% aminosulfonic acid aqueous solution (food grade sulfonating agent), stirred at 60°C for 4 h, washed with water until neutral, and then vacuum dried to obtain the composite solid acid catalyst.
[0025] The HZSM-5 molecular sieve has a silicon-to-aluminum ratio of 150 and a pore size of 0.5-0.6 nm. The composite solid acid catalyst contains 2.32 mmol / g of sulfonic acid, 6% of HZSM-5, and 3.9 nm of mesoporous carbon.
[0026] The sulfonic acid content in the catalyst was determined by acid-base titration.
[0027] Ethyl acetate conversion rate = Amount of ethyl acetate produced (ml) / Total amount of rice wine and vinegar mixture before reaction (ml) × 100%.
[0028] The catalyst regeneration method includes the following steps: The catalyst was mixed with food-grade ethanol at a mass ratio of 1:10, and ultrasonic extraction was performed at 50-60℃ for 1-2 hours (power ≤300W).
[0029] Washing and drying: Wash with deionized water until conductivity <10μS / cm, then vacuum dry at 60-80℃ (vacuum degree -0.08MPa) to prevent residual solvent from evaporating into the food.
[0030] Migration test: The regenerated catalyst must pass the EU 10 / 2011 migration test. The total migration amount is ≤10mg / dm², and the specific migration amount (such as ethanol residue) is ≤0.05mg / kg. Wash with phosphate buffer at pH 9-11 and store at 4°C to avoid enzyme denaturation.
[0031] Example 1
[0032] A method for rapid esterification of rice vinegar and rice wine includes the following steps: Raw material pretreatment: Select rice vinegar with a total acid content of 4.0g / 100mL and Shaoxing wine with an alcohol content of 13% vol, filter them separately with filter membranes to remove impurities, and set them aside for later use.
[0033] Raw material mixing: Add the pretreated rice vinegar and rice wine to the reaction vessel at a volume ratio of 1:3 and stir evenly; Catalyst addition: Add the above-mentioned composite solid acid catalyst to the reactor at a rate of 2% of the total mass of the rice vinegar and rice wine mixture.
[0034] Esterification reaction: The temperature inside the reactor was raised to 50°C, the stirring rate was adjusted to 300 r / min, and the esterification reaction was carried out for 3 hours.
[0035] Product separation: After the reaction was completed, the reaction solution was cooled to room temperature and filtered through a 0.22 μm pore size membrane using vacuum filtration to separate the composite solid acid catalyst, yielding the ethyl acetate esterification product. The conversion rate of ethyl acetate was determined to be 88%.
[0036] Example 2
[0037] A method for rapid esterification of rice vinegar and rice wine includes the following steps: Raw material pretreatment: Select rice vinegar with a total acid content of 4.5g / 100mL and Shaoxing wine with an alcohol content of 15% vol, filter them separately with filter membranes to remove impurities, and set them aside for later use.
[0038] Raw material mixing: Add the pretreated rice vinegar and rice wine to the reaction vessel at a volume ratio of 1:3 and stir well; Catalyst addition: Add the above-mentioned composite solid acid catalyst to the reaction vessel, the amount of which is 4% of the total mass of the rice vinegar and rice wine mixture.
[0039] Esterification reaction: The temperature inside the reactor was raised to 55℃, the stirring rate was adjusted to 350r / min, and the esterification reaction was carried out for 2.5h.
[0040] (5) Product separation: After the reaction was completed, the reaction solution was cooled to room temperature and filtered through a 0.45 μm pore size filter membrane using vacuum filtration to separate the composite solid acid catalyst, thus obtaining the ethyl acetate esterification product. The conversion rate of ethyl acetate in this example was 90%.
[0041] Comparative Example 1 Using the traditional natural fermentation esterification method, the same rice vinegar and rice wine as in Example 1 were selected, mixed at a volume ratio of 1:3, and then naturally fermented and esterified at room temperature for 20 days. The ethyl acetate conversion rate was found to be 45%.
[0042] Comparative Example 2 Liquid sulfuric acid was used as a catalyst. Rice vinegar and Shaoxing wine, the same as in Example 1, were mixed at a volume ratio of 1:3, and then 3% (by mass) of concentrated sulfuric acid was added. The mixture was reacted at 50°C and 300 rpm for 3 hours. The conversion rate of ethyl acetate was measured to be 82%. However, the reaction solution was highly corrosive, making subsequent processing difficult, and the catalyst could not be recovered.
[0043] Comparative Example 3 Same as Example 1, but using only HZSM-5 (silicon-to-aluminum ratio of 150, pore size of 0.5-0.6 nm) as catalyst, the ethyl acetate conversion rate was found to be 15%.
[0044] As can be seen from the above examples and comparative examples, the method of the present invention can significantly improve the esterification reaction rate and conversion rate of rice vinegar and yellow wine, and the catalyst is environmentally friendly and recyclable, which has obvious advantages.
[0045] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for rapid esterification of rice vinegar and rice wine, characterized in that: Includes the following steps: S1 Raw material pretreatment: Filter rice vinegar and rice wine separately to remove impurities; S2 Raw material mixing: Add the pretreated rice vinegar and rice wine to the reaction vessel and stir evenly; the total acid content of the rice vinegar is 3.5-5.0g / 100mL, and the alcohol content of the rice wine is 12-16% vol; S3 Catalyst Addition: A composite solid acid catalyst is added to the reactor; the composite solid acid catalyst includes a molecular sieve and sulfonated carbon material, wherein the purity of the molecular sieve is greater than or equal to 99%; S4 Esterification reaction: Raise the temperature inside the reactor to 40-60℃ and stir to carry out the esterification reaction for 2-4 hours; S5 Product Separation: After the reaction is complete, the reaction solution is cooled to room temperature, filtered to separate the composite solid acid catalyst, and the ethyl acetate esterification product is obtained.
2. The method for rapid esterification of rice vinegar and rice wine as described in claim 1, characterized in that: In step S2, the total acid content of the rice vinegar is 4.0-4.5 g / 100 mL, and the alcohol content of the rice wine is 13-15% vol; and / or, The volume ratio of rice vinegar and rice wine in step S2 is 1:2 to 1:
4.
3. The method for rapid esterification of rice vinegar and rice wine as described in claim 1, characterized in that: The molecular sieve mentioned in step S3 includes HZSM-5 molecular sieve with a silica-to-alumina ratio of 100-300; the sulfonated carbon material includes sulfonated ordered mesoporous carbon; and / or, the mass percentage of the molecular sieve in the composite solid acid catalyst mentioned in step S3 is 5%-10%; and / or, The catalyst contains 0.5~3 mmol / g of sulfonic acid.
4. The method for rapid esterification of rice vinegar and rice wine as described in claim 1, characterized in that: The amount of composite solid acid catalyst added in step S3 is 2-5% of the total mass of the mixture of rice vinegar and rice wine.
5. The method for rapid esterification of rice vinegar and rice wine as described in claim 1, characterized in that: The composite solid acid catalyst is obtained by mechanically mixing molecular sieves and sulfonated carbon materials; or by the following steps: S01 Molecular sieve pretreatment: The molecular sieve is soaked in citric acid, ultrasonically cleaned, and then dried. SO2 carbon source loading: The pretreated molecular sieve is dispersed in a glucose solution and stirred to form a mixture; S03 carbonization molding: The mixture is transferred to a reaction vessel and hydrothermally reacted at 150-200℃ for 6-8 hours. The product is separated and dried to obtain a molecular sieve and carbon precursor complex. Carbonization is then carried out to obtain a molecular sieve and carbon complex. SO4 In-situ sulfonation: The composite of molecular sieve and carbon is immersed in an aqueous solution of aminosulfonic acid, stirred at 60-75℃ for 4-5.5h, washed with water until neutral, and then vacuum dried to obtain a composite solid acid catalyst.
6. The method for rapid esterification of rice vinegar and rice wine as described in claim 5, characterized in that: The mixed solution in step S02 also includes a surfactant.
7. The method for rapid esterification of rice vinegar and rice wine as described in claim 4, characterized in that: The amount of composite solid acid catalyst added in step S3 is 3-4% of the total mass of the mixture of rice vinegar and rice wine.
8. The method for rapid esterification of rice vinegar and rice wine as described in claim 1, characterized in that: The stirring rate in step S4 is 200-400 r / min; and / or, In step S5, filtration is performed using vacuum filtration with a pore size of 0.22-0.45 μm.
9. The method for rapid esterification of rice vinegar and rice wine as described in claim 1, characterized in that: In step S4, the reaction temperature is 50-55℃ and the stirring rate is 300-350 r / min.
10. The method for rapid esterification of rice vinegar and rice wine as described in claim 1, characterized in that: It also includes regenerating the separated composite solid acid catalyst by solvent extraction.