Method for directionally removing ethyl carbamate from white spirit based on pervaporation membrane

Abstract

The invention discloses a method for directionally removing ethyl carbamate from white spirit based on a pervaporation membrane, and belongs to the technical field of white spirit processing. The method specifically comprises the following steps: reducing the alcohol content of high-degree white spirit, pumping into a raw material tank, and heating; the heated feed liquid is pumped into a ceramic tube membrane pipeline through a raw material pump and is divided into a permeation side and a retentate side through pervaporation, and the retentate side feed liquid is pumped into the raw material tank again; feeding the material liquid on the permeation side into cooling equipment, starting a cooling system for cooling, then starting a vacuum pump to receive the wine in sections, and sampling per hour; carrying out EC content detection on the sampled sample, determining that the sample with the EC index and the EC content being less than 100 [mu] g / L is a qualified product, and storing in a warehouse; and if the content is greater than or equal to 100ug / L, putting the unqualified product into a raw material tank for re-filming production. According to the method, the ethyl carbamate can be effectively removed, the loss of the content of main flavor substances of acid ester in the liquor body is small, the flavor substances in the liquor are effectively reserved, and the quality of the liquor is comprehensively improved.

Description

Technical Field

[0001] The invention relates to a method for directionally removing ethyl carbamate from white wine based on a pervaporation membrane, and belongs to the technical field of white wine processing. Background Art

[0002] Ethyl carbamate (EC) is a multi-site carcinogen that can cause lung, lymphoma, liver, and skin cancers in rodents. Ethanol can enhance the carcinogenicity of ethyl carbamate. Since 2007, the International Agency for Research on Cancer has classified EC as a Class 2A carcinogen. EC is an endogenous food safety indicator and has garnered widespread attention from governments, businesses, and academics both domestically and internationally.

[0003] During the brewing and storage of baijiu (white spirits), ethyl carbamate (EC) is a potential carcinogen, drawing increasing attention from both the industry and consumers. Existing technologies primarily address the potential presence of EC in baijiu through detection and production control.

[0004] In terms of liquor production control, existing technologies mainly reduce the production of ethyl carbamate precursors by optimizing the fermentation process, adjusting the fermentation temperature, time and microbial strains; and using physical adsorption, chemical degradation and other methods to reduce the ethyl carbamate content during the aging and blending process of liquor.

[0005] For example, Chinese patent CN115521838A discloses a method for reducing the content of cyanide and ethyl carbamate in the production process of liquor. Specifically, grains are used as raw materials. After moistening, the grains are mixed with mother grains and cooked rice husks. After steaming, the grains are spread out to dry and fermented. After the first fermentation in a cellar, the mash in the cellar is removed and mixed with koji and high-quality liquor. After mixing evenly, the mash is returned to the cellar for a second fermentation. The mother grains are removed and mixed with moistened grains and cooked rice husks. High-quality liquor is added to the pot at the bottom of a steamer barrel, and the liquor is distilled in the steamer. The content of cyanide and ethyl carbamate in the mash during the fermentation process of liquor is significantly reduced by the return fermentation.

[0006] Chinese patent CN111704973A discloses a brewing method for reducing the content of hydrocyanic acid and ethyl carbamate in liquor. Specifically, the peel / pericarp and seed coat of sorghum in the brewing raw materials are removed, which can conveniently and effectively reduce the amount of hydrocyanic acid generated and further reduce the content of ethyl carbamate in the liquor.

[0007] Chinese patent CN117089430A discloses a three-stage method for reducing cyanide and ethyl carbamate in liquor. Specifically, the method comprises reducing the cyanide content in the liquor through secondary copper column distillation to promote the conversion of ethyl carbamate in the liquor; using membrane filtration to carry out segmented enrichment treatment of ethyl carbamate; using activated carbon to adsorb the enriched ethyl carbamate; and compounding the adsorbed sample with other membrane filtered segmented liquor samples. Through the combination of these three stages, cyanide and ethyl carbamate can be reduced simultaneously.

[0008] However, although these current technologies can control the content of ethyl carbamate in liquor to a certain extent, there are still some shortcomings. For example, optimizing the fermentation process may affect the flavor and taste of the liquor. Physical adsorption backfill and chemical degradation methods may introduce new impurities and change the quality of the liquor. At the same time, these control methods have limited efficiency in removing ethyl carbamate, making it difficult to meet the increasingly stringent limit standards. Summary of the Invention

[0009] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a method for the targeted removal of ethyl carbamate from white wine based on a pervaporation membrane. This method can not only effectively remove ethyl carbamate with a removal rate of more than 80%, but also has a small loss of the main flavor substances of acid esters in the wine body, effectively retaining the flavor substances in the white wine, and comprehensively improving the quality of the white wine.

[0010] In order to achieve the above objectives, the technical solutions provided are as follows:

[0011] The present invention provides a method for directionally removing ethyl carbamate from liquor based on a pervaporation membrane, the method comprising the following steps:

[0012] (1) Pretreatment of raw liquor: reducing the alcohol content of high-proof liquor to 25% vol to 40% vol to obtain reduced-alcohol liquor;

[0013] (2) Raw liquor preheating cycle: the reduced alcohol liquor from step (1) is pumped into the raw material tank and heated to 50°C to 80°C;

[0014] (3) membrane filtration treatment: the heated feed liquid in step (2) is pumped into a ceramic membrane pipe through a raw material pump. The membrane material is a fully aromatic polyamide ceramic membrane. The membrane is divided into a permeate side and a retentate side by pervaporation. The vaporized membrane side is the permeate side, and the remaining feed liquid is the retentate side.

[0015] (4) Circular feeding: the retentate liquid from step (3) is pumped back into the raw material tank;

[0016] (5) Vacuum and cooling: The permeate liquid from step (3) is pumped into the cooling equipment, the cooling system is turned on for cooling, and then the vacuum pump is turned on to collect the wine, and the wine is collected in sections, and samples are taken every hour;

[0017] (6) Blending and combining: The samples taken in step (5) are tested for EC content, and the EC index is that the product with content less than 100ug / L is qualified and stored in the warehouse; the product with content ≥100ug / L is unqualified and put into the raw material tank for re-membrane production.

[0018] In one embodiment, the reduction in the degree of saturation in step (1) is carried out using deionized water or purified water.

[0019] In one embodiment, the alcohol content of the high-proof liquor in step (1) is 60% vol.

[0020] In one embodiment, the alcohol content of the high-proof liquor in step (1) is reduced by 25%.

[0021] In one embodiment, the heating temperature in step (2) is 75°C.

[0022] In one embodiment, the water flux of the wholly aromatic polyamide ceramic membrane in step (3) is 1 to 3 kg / m 2 / h; preferably 1kg / m 2 / h.

[0023] In one embodiment, the cooling temperature in step (5) is to -50°C to -60°C.

[0024] In one embodiment, the vacuum degree of the vacuum pump in step (5) is set to 0.1 to 0.3 standard atmospheres.

[0025] In one embodiment, the speed of the segmented wine collection in step (5) is 1 to 3 kg / min, and the alcohol content of the product is controlled at 60% vol.

[0026] The present invention also provides the application of the above-mentioned method in the quality supervision of liquor production.

[0027] Beneficial effects:

[0028] (1) The present invention provides a method for the targeted removal of ethyl carbamate from liquor using a pervaporation membrane. Specifically, the method involves passing the liquor through a wholly aromatic polyamide ceramic membrane and selectively intercepting EC molecules using pervaporation technology, while having minimal impact on flavor substances (such as esters and alcohols) in the liquor. The method effectively solves the technical problem of the increase in ethyl carbamate during long-term storage of liquor.

[0029] (2) In addition, the present invention reduces the alcohol content of high-proof liquor to 25-40% vol in the raw liquor pretreatment step. The purpose of reducing the alcohol content is to ensure the removal of ethyl carbamate while increasing the volatility coefficient of high-molecular substances, mainly esters, in the feed liquid system, making them easier to pass through the permeable membrane and maximally retaining the flavor components in the liquor.

[0030] (3) Compared with other existing ceramic membranes, the fully aromatic polyamide ceramic membrane used in the present invention has the best effect and is easy to operate. It can not only effectively remove ethyl carbamate, but also effectively retain the flavor substances in the white wine. Compared with other ceramic membranes, they either do not have the ability to intercept EC molecules, or while intercepting EC molecules, they cause a large loss of flavor substances in the white wine, requiring the activated carbon adsorption backfill of the residual side at a later stage, resulting in poor EC removal effect and complicated operation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is the technical roadmap for the directional removal of ethyl carbamate from white wine based on the pervaporation membrane of the present invention. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention. The following specific embodiments further describe the present invention.

[0033] The source of the raw materials involved in the present invention:

[0034] The fully aromatic polyamide ceramic membrane was purchased from Nanjing Jiusi High-Tech Co., Ltd., with a water flux of 1-3 kg / m 2 / h.

[0035] Example 1

[0036] A method for directionally removing ethyl carbamate from liquor based on a pervaporation membrane comprises the following steps:

[0037] (1) Pretreatment of raw liquor: Using purified water to reduce the alcohol content of high-proof liquor from 60% vol to 25% vol to obtain reduced-proof liquor;

[0038] (2) Raw liquor preheating cycle: the reduced alcohol liquor obtained in step (1) is pumped into the raw material tank and heated to 75°C;

[0039] (3) Membrane filtration treatment: The heated liquid in step (2) is pumped into the ceramic membrane pipeline through the raw material pump. The membrane material is a fully aromatic polyamide ceramic membrane. The membrane water flux is adjusted to 1 kg / m 2 / h, and is divided into a permeate side and a retentate side through pervaporation, wherein the vaporized liquid passing through the membrane is the permeate side, and the remaining liquid is the retentate side;

[0040] (4) Circular feeding: the retentate liquid from step (3) is pumped back into the raw material tank;

[0041] (5) Vacuum and cooling: The permeate side liquid from step (3) is pumped into a cooling device, and the cooling system is turned on to reduce the liquid temperature to -50°C; the vacuum pump is turned on to collect the wine, and the vacuum degree of the system is adjusted to 0.1 standard atmospheres. The wine collection speed is adjusted to 1 kg / min, and the wine is collected in sections. Samples are taken every hour, and the alcohol content of the product is controlled at 60% vol.

[0042] (6) Blending and combining: The samples in step (5) are tested for EC content, and the EC index is that the product with content less than 100ug / L is qualified and stored in the warehouse; the product with content ≥100ug / L is unqualified and put into the raw material tank for re-membrane production.

[0043] Example 2

[0044] A method for directionally removing ethyl carbamate from liquor based on a pervaporation membrane comprises the following steps:

[0045] (1) Pretreatment of raw liquor: Using purified water to reduce the alcohol content of liquor from 60% vol to 35% vol to obtain reduced alcohol liquor;

[0046] (2) Raw liquor preheating cycle: the reduced alcohol liquor obtained in step (1) is pumped into the raw material tank and heated to 50°C;

[0047] (3) Membrane filtration treatment: The heated liquid in step (2) is pumped into the ceramic membrane pipeline through the raw material pump. The membrane material is a fully aromatic polyamide ceramic membrane. The membrane water flux is adjusted to 2 kg / m 2 / h; the permeate side and the retentate side are separated by permeation vaporization, wherein the vaporized liquid passing through the membrane is the permeate side, and the remaining liquid is the retentate side;

[0048] (4) Circular feeding: the retentate liquid from step (3) is pumped back into the raw material tank;

[0049] (5) Vacuum and cooling: The permeate liquid from step (3) is pumped into a cooling device, and the cooling system is turned on to reduce the liquid temperature to -50°C; the vacuum pump is turned on to collect the wine, and the vacuum degree of the system is adjusted to 0.3 standard atmospheres. The wine collection speed is adjusted to 3 kg / min, and the wine is collected in sections. Samples are taken every hour, and the alcohol content of the product is controlled at 60% vol.

[0050] (6) Blending and combining: The samples in step (5) are tested for EC content, and the EC index is that the product with content less than 100ug / L is qualified and stored in the warehouse; the product with content ≥100ug / L is unqualified and put into the raw material tank for re-membrane production.

[0051] Example 3

[0052] A method for directionally removing ethyl carbamate from liquor based on a pervaporation membrane comprises the following steps:

[0053] (1) Pretreatment of raw liquor: Using purified water to reduce the alcohol content of high-proof liquor from 60% vol to 40% vol to obtain reduced-alcohol liquor;

[0054] (2) Raw liquor preheating cycle: the reduced alcohol liquor from step (1) is pumped into the raw material tank and heated to 65°C;

[0055] (3) Membrane filtration treatment: The heated liquid in step (2) is pumped into the ceramic membrane pipeline through the raw material pump. The membrane material is a fully aromatic polyamide ceramic membrane. The membrane water flux is adjusted to 3 kg / m 2 / h; the permeate side and the retentate side are separated by permeation vaporization, wherein the vaporized liquid passing through the membrane is the permeate side, and the remaining liquid is the retentate side;

[0056] (4) Circular feeding: the retentate liquid from step (3) is pumped back into the raw material tank;

[0057] (5) Vacuum and cooling: The permeate side liquid from step (3) is pumped into a cooling device, and the cooling system is turned on to reduce the liquid temperature to -60°C; the vacuum pump is turned on to collect the wine, and the vacuum degree of the system is adjusted to 0.2 standard atmospheres. The wine collection speed is adjusted to 2 kg / min, and the wine is collected in sections. Samples are taken every hour, and the alcohol content of the product is controlled at 60% vol.

[0058] (6) Blending and combining: The samples in step (5) are tested for EC content, and the EC index is that the product with content less than 100ug / L is qualified and stored in the warehouse; the product with content ≥100ug / L is unqualified and put into the raw material tank for re-membrane production.

[0059] Comparative Example 1

[0060] The only difference from Example 1 is that the wholly aromatic polyamide ceramic membrane is omitted from the membrane pipeline in step (3), and other conditions and parameters remain consistent with Example 1.

[0061] Comparative Example 2

[0062] The only difference from Example 1 is that in step (3), the wholly aromatic polyamide ceramic membrane is replaced by a cellulose acetate ceramic membrane, and the other conditions and parameters remain the same as in Example 1.

[0063] Comparative Example 3

[0064] The only difference from Example 1 is that in step (3), the wholly aromatic polyamide ceramic membrane is replaced by a sulfonated polyethersulfone ceramic membrane, and the other conditions and parameters remain the same as those in Example 1.

[0065] Comparative Example 4

[0066] The only difference from Example 1 is that in step (3), the wholly aromatic polyamide ceramic membrane is replaced by a sulfonated polyethersulfone ceramic membrane; in step (4), the retentate side liquid is not pumped into the raw material tank, but is treated separately: 1% by mass activated carbon is added, stirred and adsorbed for 4 hours, and the activated carbon is removed to obtain a filtrate; the filtrate is combined with the wine sample selected in step (5) and the alcohol content of the product is controlled at 60% vol.

[0067] Comparative Example 5

[0068] The only difference from Example 1 is that in step (1), the alcohol content of the high-proof liquor is reduced from 60% vol to 50% vol using purified water to obtain reduced-alcohol liquor. Other conditions and parameters remain the same as in Example 1.

[0069] Result Analysis

[0070] The EC content of the liquor obtained in the embodiment and the comparative example was tested, and the results are shown in Table 1.

[0071] Table 1. Contents of EC and flavor substances in liquor obtained in Examples and Comparative Examples

[0072]

[0073]

[0074] As shown in Table 1, in the production process of Examples 1-3, fully aromatic polyamide ceramic membranes were used, and the ethyl carbamate content of the product was 62.35-87.05 ug / L, which was 347.26 ug / L compared with the initial value, and the ethyl carbamate removal rate was 74%-82%, and the loss of the main flavor substances of acid esters in the wine was less; while in Comparative Example 1, no fully aromatic polyamide ceramic membrane was installed, and the ethyl carbamate content remained basically unchanged; Comparative Example 2 used cellulose acetate ceramic membrane; although the loss of the main flavor substances of acid esters in the wine was less, the ethyl carbamate content of the product was 310.58 ug / L, and the removal rate was only 10.56%, which was not ideal; Comparative Example 3 used sulfonated polyethersulfone ceramic membrane, and the ethyl carbamate content of the product was 89.17 ug / L, The removal rate was 74.32%, but significant losses of various flavor components were observed in the liquor, particularly ethyl lactate (32.91%), acetic acid (42.33%), and hexanoic acid (57.46%). Therefore, the results were also unsatisfactory. Comparative Example 4, building on Comparative Example 3, intercepted flavor components from the retentate material via activated carbon adsorption and backfilled them into the liquor. While the EC removal and flavor retention rates also met the expected results, the disadvantages were the complexity of the operation and the need for experienced liquor designers to integrate and blend the components. Comparative Example 5 reduced the alcohol content of high-proof liquor to 50% vol. Although the EC removal rate was 74.01%, significant losses of approximately 50% of the various ester-based high-molecular-weight flavor components were also observed, resulting in unsatisfactory results. These results demonstrate that the fully aromatic polyamide ceramic membrane employed in the present invention can significantly reduce the ethyl carbamate content in liquor while also achieving the goal of upgrading the quality of liquor.

[0075] The embodiments provided above are not intended to limit the scope of the present invention, nor are the steps described to limit their execution order. Any obvious improvements to the present invention made by those skilled in the art in combination with existing common knowledge shall fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for directional removal of ethyl carbamate from liquor based on pervaporation membrane, characterized in that: The method comprises the following steps: (1) Pretreatment of raw liquor: reducing the alcohol content of high-proof liquor to 25% vol to 40% vol to obtain reduced-alcohol liquor; (2) Raw liquor preheating cycle: the reduced alcohol liquor from step (1) is pumped into the raw material tank and heated to 50°C to 80°C; (3) membrane filtration treatment: the heated feed liquid in step (2) is pumped into a ceramic membrane pipe through a raw material pump. The membrane material is a fully aromatic polyamide ceramic membrane. The membrane is divided into a permeate side and a retentate side by pervaporation. The vaporized membrane side is the permeate side, and the remaining feed liquid is the retentate side. (4) Circular feeding: the retentate liquid from step (3) is pumped back into the raw material tank; (5) Vacuum and cooling: The permeate liquid from step (3) is pumped into the cooling equipment, the cooling system is turned on for cooling, and then the vacuum pump is turned on to collect the wine, and the wine is collected in sections, and samples are taken every hour; (6) Blending and combining: The samples taken in step (5) are tested for EC content, and the EC index is that the product with content less than 100ug / L is qualified and stored in the warehouse; the product with content ≥100ug / L is unqualified and put into the raw material tank for re-membrane production.

2. The method according to claim 1, characterized in that The alcohol content of the high-proof liquor in step (1) is 60% vol.

3. The method according to claim 1, characterized in that The alcohol content of the high-proof liquor in step (1) is reduced to 25%.

4. The method according to claim 1, wherein The heating temperature in step (2) is 75°C.

5. The method according to claim 1, wherein The water flux of the fully aromatic polyamide ceramic membrane in step (3) is 1-3 kg / m 2 / h.

6. The method according to claim 1, characterized in that The reduction in the degree of deionization in step (1) is carried out using deionized water or purified water.

7. The method according to claim 1, characterized in that The cooling temperature in step (5) is to -50°C to -60°C.

8. The method according to claim 1, characterized in that The vacuum degree of the vacuum pump in step (5) is set to 0.1 to 0.3 standard atmospheric pressure.

9. The method according to claim 1, characterized in that The speed of the segmented wine collection in step (5) is 1-3 kg / min, and the alcohol content of the product is controlled at 60% vol.

10. Use of the method according to any one of claims 1 to 9 in the quality control of liquor production.

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