A method for removing formaldehyde from liquor

Abstract

This invention relates to the field of food technology, specifically to a method for removing formaldehyde from baijiu (Chinese liquor). The method utilizes pectin-amyledionated L-lysine, prepared by ball milling, as a formaldehyde adsorbent. The ball milling process, through mechanochemical effects initiating the amidation reaction and ultrafine grinding, plays a crucial role in enhancing adsorption performance. Experiments have demonstrated that this is a highly efficient, selective, and simple method for reducing formaldehyde content in baijiu while perfectly preserving its flavor.

Description

Technical Field

[0001] This invention relates to the field of food technology, and specifically to a method for removing formaldehyde from baijiu (Chinese liquor). Background Technology

[0002] Baijiu is a traditional Chinese distilled spirit. During its fermentation process, microorganisms not only produce large amounts of ethanol, but ethanol can also be oxidized to produce acetaldehyde, acetic acid, and further ethyl acetate, among other products. Additionally, trace amounts of formaldehyde (HCHO) may be produced. Formaldehyde is a highly reactive small molecule that is harmful to the human body and carcinogenic at high concentrations, posing a potential threat to human health with long-term intake. International chemical safety guidelines recommend a permissible concentration of formaldehyde in products of 2.6 mg / L. my country's standard for fermented wines and their blended wines (GB2758-2012) limits formaldehyde content in beer to less than 2.0 mg / L. Therefore, effectively reducing the formaldehyde content in baijiu is a key aspect of improving its food safety and quality.

[0003] Currently, methods for reducing formaldehyde content in baijiu (Chinese liquor) mainly include distillation purification, activated carbon adsorption, and oxidant oxidation. However, these methods have some drawbacks: distillation is energy-intensive and may lead to the loss of flavor substances; activated carbon adsorption, while effective, has poor selectivity and may simultaneously adsorb important aroma and flavor substances such as esters and acids in baijiu, seriously affecting the original style of the liquor; oxidant methods (such as using potassium permanganate or ozone) may introduce new chemical residues, posing safety risks, and the reaction conditions require strict control.

[0004] Pectin (9000-69-5) is a natural heteropolysaccharide from plant cell walls, mainly composed of α-1-4-D-galacturonic acid units. It is a white to yellow powder with a relative molecular weight of approximately 30-400 kDa. It exhibits good water solubility and biocompatibility, but is insoluble in organic solvents such as ethanol and ether. Pectin is considered a prebiotic dietary fiber, meeting many regulations regarding its health applications in the pharmaceutical industry. Its main applications are as a gelling agent, thickener, stabilizer, and emulsifier.

[0005] L-Lysine (56-87-1) is an essential amino acid for humans and mammals. The human body cannot synthesize it and must obtain it from food. L-Lysine is a natural food preservative with advantages such as broad spectrum, high efficiency, and heat resistance. Its molecule contains two primary amino groups (-NH2). These primary amino groups can undergo nucleophilic addition reactions with the carbonyl groups on formaldehyde molecules to generate stable Schiff bases or hydroxymethyl derivatives, thereby capturing formaldehyde. However, L-Lysine itself is readily soluble in water, and while its solubility in ethanol is low, it will swell and disperse. Adding it directly to spirits will form a gel-like substance that is difficult to remove completely through simple filtration, potentially leading to secondary residues.

[0006] Therefore, developing a highly efficient, specific, and residue-free formaldehyde removal method that does not affect the flavor of baijiu has significant practical application value. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for reducing the formaldehyde content in baijiu that is efficient, selective, easy to operate, and can perfectly preserve the flavor of baijiu.

[0008] The technical solution of the present invention is as follows: The present invention provides a method for removing formaldehyde from liquor, which uses pectin-amiditized L-lysine adsorbent to adsorb formaldehyde, characterized by comprising the following steps:

[0009] 1. Mix L-lysine and pectin at a mass ratio of (1:1-1:10), preferably (1:3-1:6).

[0010] 2. Add a small amount of water to the mixture as a reaction medium and grinding aid. The amount of water added is 1%-10% of the total mass of the mixture.

[0011] 3. Place the above mixture in a ball mill, maintain the temperature at 40-50℃, and ball mill at a speed of 200-500 rpm for 6-24 hours;

[0012] 4. After ball milling, the product is removed to obtain wet pectin-amylated L-lysine adsorbent. After drying in an oven at 40°C for 10 hours to remove methanol, it is made into powder for later use.

[0013] Thirdly, the present invention provides a method for reducing the formaldehyde content in baijiu (Chinese liquor), characterized by comprising the following steps:

[0014] S1 Add formaldehyde adsorbent pectin amidation L-lysine to the liquor to be treated;

[0015] S2 is placed in a constant temperature water bath and stirred until fully reacted;

[0016] After the S3 reaction is completed, solid-liquid separation is performed, and the clarified liquor is collected to obtain a liquor with low formaldehyde content.

[0017] Preferably, the method for reducing formaldehyde content in baijiu is characterized in that the amount of formaldehyde adsorbent pectin-amylated L-lysine added is 5 g to 10 g per liter of baijiu (based on dry matter).

[0018] Preferably, the method for reducing formaldehyde content in liquor is characterized by a reaction temperature of 20-40℃ and a reaction time of 10-60 minutes.

[0019] Preferably, the method for reducing formaldehyde content in liquor is characterized in that the solid-liquid separation is filtration.

[0020] Furthermore, the ball mill is a planetary ball mill, and the grinding balls are made of zirconium oxide, stainless steel, or ceramic.

[0021] Furthermore, the ball milling reaction in step 3 promotes the amidation reaction between the amino groups on the L-lysine molecules and the carboxyl groups on the pectin molecules, while achieving extreme mixing and particle size refinement, greatly increasing the exposure of reactive sites.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1. This invention utilizes the reaction of free amino groups in pectin-amylated L-lysine with formaldehyde to generate Schiffbase adducts, which can be completely removed by filtration, ensuring safety and leaving no residue, and achieving high formaldehyde removal efficiency. Furthermore, pectin-amylated L-lysine does not adsorb the main flavor compounds in baijiu, thus preserving the original flavor of the baijiu.

[0024] 2. High adsorption efficiency: The ball milling process not only achieves mixing but also promotes the covalent bonding (amidation) of the carboxyl groups of pectin with the amino groups of L-lysine through mechanochemical effects, retaining a large number of free amino groups in the product. Simultaneously, this process grinds the material to the micron or nanometer level, greatly increasing the specific surface area and reactive sites, thereby significantly improving the formaldehyde capture efficiency and reaction rate. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to specific examples, but the scope of protection of the present invention is not limited thereto:

[0026] Example 1: Preparation of pectin-amylated L-lysine adsorbent:

[0027] 1. Weigh 5g of L-lysine and 20g of pectin powder and place them in a 500mL ball mill jar.

[0028] 2. Add 0.25g (1% of the total mass of the mixture) of pure water to the container.

[0029] 3. Add an appropriate amount of zirconia grinding balls to the jar, seal the jar and fix it on the planetary ball mill, maintain the temperature at 40-50℃, and ball mill at 350 rpm for 6 hours.

[0030] 4. After ball milling, 24.5g of a slightly moist, uniform white powder product was obtained, which is the pectin-amylated L-lysine adsorbent. It was then dried in an oven at 40℃.

[0031] Example 2: Removal of formaldehyde from baijiu (Chinese liquor)

[0032] Take 1L of baijiu (the initial formaldehyde content was tested to be 3.5mg / L) into a beaker.

[0033] 1. Weigh 10g of the pectin-amylated L-lysine powder prepared in Example 1 and add it to the liquor.

[0034] 2. Place the beaker in a 25°C constant temperature water bath and stir at 150 rpm for 60 minutes.

[0035] 3. After the reaction is complete, the mixture is vacuum filtered, and the filtrate is collected to obtain a clear and transparent wine.

[0036] Example 3:

[0037] The difference between this embodiment and Embodiment 1 is that the amount of pectin-amylated L-lysine powder added is 0.5g, while the rest is the same as in Embodiment 1.

[0038] Example 4:

[0039] The difference between this embodiment and Embodiment 1 is that the amount of pectin-amylated L-lysine powder added is 1g, while the rest is the same as in Embodiment 1.

[0040] Example 5:

[0041] The difference between this embodiment and Embodiment 1 is that the amount of pectin-amylated L-lysine powder added is 1.5g, while the rest is the same as in Embodiment 1.

[0042] Example 6:

[0043] The difference between this embodiment and Embodiment 1 is that the amount of pectin-amylated L-lysine powder added is 2g, while the rest is the same as in Embodiment 1.

[0044] Formaldehyde content determination:

[0045] The formaldehyde content in the treated wine samples was detected by liquid chromatography (GB 5009.307-2025), and the results are shown in Table 1.

[0046] 1. Instruments

[0047] High-performance liquid chromatograph (HPLC): equipped with a diode array detector or an ultraviolet detector.

[0048] 2. Steps

[0049] Sample preparation: Accurately pipette 5.00 mL of sample into a 50 mL plastic centrifuge tube, accurately add 20 mL of derivatizing solution, tighten the cap, vortex to mix, place in a constant temperature water bath shaker, shake at 25℃±1℃ for 1 h to ensure uniform mixing.

[0050] Add 8g of sodium chloride to the above test solution, vortex for 30s, centrifuge at 4000 rpm for 5 min, and transfer the supernatant to a 20mL volumetric flask. Add 10mL of acetonitrile to the centrifuge tube, vortex for 30s, centrifuge at 4000 rpm for 5 min, combine the supernatants, and dilute to the mark with acetonitrile. Mix well. Filter through a 0.45μm organic filter membrane for liquid chromatography determination.

[0051] Blank experiment: The steps are the same except that no sample is added.

[0052] Determination: Inject the sample solution into the liquid chromatograph to obtain the corresponding peak area, and obtain the concentration of formaldehyde in the sample solution according to the standard curve.

[0053] Table 1. Formaldehyde content determination results in the examples.

[0054] Results Examples Formaldehyde content Formaldehyde removal rate 2 0.6 mg / L 82.9% 3 0.4 mg / L 88.6% 4 0.2 mg / L 94.3% 5 0.3 mg / L 91.4% 6 0.4 mg / L 88.6%

[0055] Meanwhile, the treated liquor showed no significant difference from the original liquor in terms of aroma, taste, and flavor, proving the excellent flavor preservation ability of the method of the present invention.

[0056] Comparative Example 1: Formaldehyde Removal Effect of L-Lysine

[0057] Take 1L of a certain brand of liquor (the initial formaldehyde content was tested to be 3.5mg / L) into a beaker.

[0058] 1. Weigh out 5g, 10g, 15g, 20g, and 25g of L-lysine respectively and add them to the liquor.

[0059] 2. Place the beaker in a 25°C constant temperature water bath and stir at 150 rpm for 30 minutes.

[0060] 3. After the reaction is complete, the mixture is vacuum filtered (using a 0.45μm filter membrane) to obtain a barely clear liquid.

[0061] 4. The formaldehyde content in the treated wine samples was determined by liquid chromatography (GB 5009.307-2025). The results are shown in Table 2.

[0062] Comparative Example 2: Physical mixing of L-lysine and pectin

[0063] Weigh 5 g of L-lysine and 20 g of pectin powder, and mix them briefly with a regular stirrer for 5 minutes to obtain a physical mixture. Take 10 g of this mixture and treat the same batch of liquor under the same conditions as Comparative Example 1. The results showed that the formaldehyde removal rate was only 35.2%.

[0064] Table 2. Formaldehyde content determination results of Comparative Example 1

[0065] Results of lysine addition Formaldehyde content Formaldehyde removal rate 5g 3.0 mg / L 14.3% 10g 2.8 mg / L 20.0% 15g 2.8 mg / L 20.0% 20g 2.5 mg / L 28.6% 25g 2.6 mg / L 25.7%

[0066] Tables 1 and 2 show that the formaldehyde removal efficiency of pectin-midated L-lysine provided by this invention is significantly higher than that of L-lysine alone. Specifically, the formation of an electrostatic complex by pectin-midated L-lysine improves its stability and reduces its solubility in ethanol, thus increasing the formaldehyde removal efficiency. Comparative Example 2 demonstrates that the ball milling method of this invention, through the mechanochemical effect-induced amidation reaction and ultrafine grinding, plays a crucial role in enhancing the adsorption performance.

[0067] The above are merely some specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. All modifications directly or indirectly derived by those skilled in the art from the disclosure of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A method for removing formaldehyde from liquor, characterized in that, include: A formaldehyde adsorbent was added to the liquor, and after thorough stirring and reaction, solid-liquid separation was performed to remove the formaldehyde adsorbent; the formaldehyde adsorbent was pectin-amylated L-lysine.

2. The method according to claim 1, characterized in that, The formaldehyde adsorbent is added at a rate of 5g to 10g per liter of liquor.

3. The method according to claim 1, characterized in that, The reaction temperature is 20-40℃, the reaction time is 10-60 minutes, and the solid-liquid separation is by filtration.

4. A method for preparing a formaldehyde adsorbent for use in any one of the methods described in claims 1-3, characterized in that, Includes the following steps: S1. Mix L-lysine and pectin at a mass ratio of 1:1 to 1:10; S2 adds 1%-10% water by weight of the mixture as a reaction medium and grinding aid; S3 involves placing the mixture in a ball mill and conducting a ball milling reaction at a temperature of 50-80℃. After S4 ball milling, the formaldehyde adsorbent is dried in a 90℃ oven for 10 hours to obtain the formaldehyde adsorbent.

5. The preparation method according to claim 4, characterized in that, The mass ratio of L-lysine to pectin in step 1 is (1:3) to (1:6).

6. The preparation method according to claim 4, characterized in that, In step 2, the amount of water added is 1%-5% of the total mass of the mixture.

7. The preparation method according to claim 4, characterized in that, The ball mill in step 3 operates at a speed of 200-500 rpm and a milling time of 6-24 hours.

8. The application of L-lysine-amylated pectin prepared by any one of the preparation methods described in claims 4-7 as a formaldehyde adsorbent in the purification of liquor or liquid food.