Method for controlling precipitation of yellow wine and application of method

Abstract

The invention discloses a method for controlling precipitation of yellow rice wine and application thereof, and belongs to the technical field of fermentation wine brewing. According to the method, low-temperature freezing treatment of freezing for 3-7 days under the condition of-4-4 DEG C and freezing and filtering treatment of filtering treatment by using a membrane with the molecular weight cut-off of 10-100kDa are carried out in the yellow wine production process, and one time of low-temperature freezing and membrane filtering are recorded as one time of freezing and filtering circulation; and carrying out pulsed electric field treatment under the conditions that the electric field intensity is 5-15kV / cm, the pulse width is 2-10 microseconds and the pulse frequency is 200-500Hz. The three technologies are co-processed and applied to the improvement of the stability of the yellow rice wine. The method can effectively remove key easy-to-precipitate groups in the yellow wine, change the particle size, distribution and charge quantity of protein colloid in the yellow wine, and reduce the turbidity and centrifugal precipitation rate of the yellow wine, thereby greatly improving the stability of the yellow wine.

Description

Technical Field

[0001] The invention relates to the technical field of fermentation and winemaking, and in particular to a method for controlling the precipitation of yellow rice wine and an application thereof. Background Art

[0002] Huangjiu, as a treasure of Chinese wine culture, has a history that can be traced back thousands of years. It is one of the three oldest brewed wines in the world, along with world-renowned wine and beer. However, during the transportation, storage and sales of bottled Huangjiu on the market, secondary turbidity frequently occurs, which greatly affects consumer acceptance and has an impact on market sales.

[0003] The turbidity of rice wine can be divided into two categories according to its causes: biological and non-biological. Biological turbidity mainly comes from the active microorganisms during the brewing process, which causes the wine to be contaminated, and the wine becomes turbid and difficult to remove by filtration. Non-biological turbidity is caused by the interaction between substances such as proteins, polysaccharides, polyphenols and metal ions that are rich in rice wine. Protein, as a key component of rice wine, forms a colloidal network through charge stabilization, which brings a unique taste and rich nutritional value to rice wine. The protein molecules in rice wine are usually positively charged, while other substances such as polyphenols in the wine are negatively charged. When these two oppositely charged substances meet, an electrical neutralization reaction occurs to form electrically neutral macromolecules, which causes the wine to become turbid and lose gloss, and eventually settle to the bottom. This charge interaction is one of the key mechanisms for the charge stability of rice wine. At the same time, when disturbed by external conditions (such as temperature, pH value, shear force, etc.), its equilibrium state may also be broken, resulting in colloidal coagulation. In addition, proteins, polysaccharides and some small molecular compounds aggregate in the rice wine system through hydrogen bonds, hydrophobic interactions and electrostatic effects, further destroying the stability of the system. Non-biological precipitation has become a common problem in the industry that affects the quality of rice wine.

[0004] Although there are many technical means to control the stability of rice wine, they have not yet completely overcome the problem of non-biological turbidity of rice wine, resulting in the easy formation of precipitation during long-term storage. Some technologies may not only bring the risk of secondary contamination to rice wine, but also significantly reduce the total protein and polyphenol content in rice wine, which may weaken the color and flavor of rice wine and have an adverse effect on its physical and chemical properties and aroma components. At the same time, some technical means are often accompanied by high equipment energy consumption and high application and maintenance costs during implementation, which brings considerable economic pressure to rice wine production companies. Therefore, it is particularly urgent to explore a new method that is more efficient, economical and can fundamentally solve the problem of rice wine stability. Summary of the invention

[0005] In view of the problem of secondary turbidity of bottled yellow wine in the process of storage, transportation, sales, etc. in the prior art, the present invention provides a method for controlling the precipitation of yellow wine and its application. The present invention can remove the easily precipitated substances in the yellow wine, improve the colloidal stability of the bottled yellow wine, and maintain the flavor and sensitive components of the yellow wine.

[0006] The technical solution of the present invention is as follows:

[0007] The first object of the present invention is to provide a method for controlling the precipitation of rice wine, the method comprising the steps of low temperature freezing, membrane filtration, and pulse electric field;

[0008] The processing conditions of low temperature freezing are: freezing at -4 to 4°C for 3 to 7 days;

[0009] The ultrafiltration membrane used in the membrane filtration treatment has a molecular weight cutoff of 10 to 100 kDa, and the membrane filtration temperature is controlled at -4 to 4°C;

[0010] One cryogenic freezing and membrane filtration was regarded as one round of cryofiltration, and the cycle was 1 to 6 rounds;

[0011] The treatment conditions of the pulse electric field are: electric field intensity of 5 to 15 kV / cm, pulse width of 2 to 10 μs, and pulse frequency of 200 to 500 Hz.

[0012] In one embodiment of the present invention, the membrane filtration process uses a polyethersulfone (PES) ultrafiltration membrane.

[0013] In one embodiment of the present invention, the ultrafiltration membrane is disinfected with a 0.1-0.5 M NaOH solution before use, and then cleaned with pure water and checked for integrity.

[0014] In one embodiment of the present invention, cryofiltration is performed first, and then pulse electric field treatment is performed.

[0015] In one embodiment of the present invention, the method comprises performing one round of freeze filtration and pulse electric field treatment; first freezing at a freezing temperature of -4 to 4°C for 3 to 7 days, then using an ultrafiltration membrane with a molecular weight cutoff of 10 to 100 kDa for membrane filtration treatment at -4 to 4°C, and finally performing pulse electric field treatment at an electric field strength of 5 to 15 kV / cm, a pulse width of 2 to 10 μs, and a pulse frequency of 200 to 500 Hz.

[0016] In one embodiment of the present invention, it includes 2 rounds of freeze filtration and pulse electric field treatment; first freezing at a freezing temperature of -4 to 4°C for 3 to 7 days, then using an ultrafiltration membrane with a molecular weight cutoff of 10 to 100 kDa for membrane filtration treatment at -4 to 4°C, repeating the above operation, and finally pulse electric field treatment under the conditions of electric field strength of 5 to 15 kV / cm, pulse width of 2 to 10 μs, and pulse frequency of 200 to 500 Hz.

[0017] In one embodiment of the present invention, three rounds of freeze filtration and pulse electric field treatment are performed; first, freezing at a freezing temperature of -4 to 4°C for 3 to 7 days, then using an ultrafiltration membrane with a molecular weight cutoff of 10 to 100 kDa for membrane filtration treatment at -4 to 4°C, repeating the above operation twice, and finally pulse electric field treatment under the conditions of an electric field strength of 5 to 15 kV / cm, a pulse width of 2 to 10 μs, and a pulse frequency of 200 to 500 Hz.

[0018] In one embodiment of the present invention, four rounds of freezing filtration and pulse electric field treatment are performed; first, freezing at a freezing temperature of -4 to 4°C for 3 to 7 days, then using an ultrafiltration membrane with a molecular weight cutoff of 10 to 100 kDa for membrane filtration treatment at -4 to 4°C, repeating the above operation three times, and finally performing pulse electric field treatment under the conditions of an electric field strength of 5 to 15 kV / cm, a pulse width of 2 to 10 μs, and a pulse frequency of 200 to 500 Hz.

[0019] In one embodiment of the present invention, it includes 5 rounds of freeze filtration and pulse electric field treatment; first, freezing at a freezing temperature of -4 to 4°C for 3 to 7 days, then using an ultrafiltration membrane with a molecular weight cutoff of 10 to 100 kDa for membrane filtration treatment at -4 to 4°C, repeating the above operation four times, and finally pulse electric field treatment under the conditions of electric field strength of 5 to 15 kV / cm, pulse width of 2 to 10 μs, and pulse frequency of 200 to 500 Hz.

[0020] In one embodiment of the present invention, 6 rounds of freeze filtration and pulse electric field treatment are performed; first, freezing at a freezing temperature of -4 to 4°C for 3 to 7 days, then using an ultrafiltration membrane with a molecular weight cutoff of 10 to 100 kDa for membrane filtration treatment at -4 to 4°C, repeating the above operation five times, and finally pulse electric field treatment under the conditions of an electric field strength of 5 to 15 kV / cm, a pulse width of 2 to 10 μs, and a pulse frequency of 200 to 500 Hz.

[0021] The second object of the present invention is to provide an application of the above method in the storage, transportation or sales of rice wine.

[0022] The beneficial technical effects of the present invention are:

[0023] The method for treating yellow rice wine can reduce the turbidity of bottled yellow rice wine during transportation, storage and sales, remove easily precipitated components (yellow rice wine protein, yellow rice wine polysaccharide, polyphenol, iron ion), improve the colloid stability of yellow rice wine, and maintain the characteristic flavor, organic acid, free amino acid and antioxidant property of yellow rice wine.

[0024] After the treatment, the turbidity and centrifugal sedimentation rate of the yellow wine are reduced to the minimum; the content of easy-to-precipitate components is reduced, especially protein and polysaccharide; the colloid particle size of the yellow wine protein is reduced and the potential is improved.

[0025] The invention can improve the low-temperature freezing treatment efficiency and the stability effect; the flavor and sensitivity of the treated rice wine are not significantly changed, the stability of the rice wine is improved, and the sensory quality of the rice wine is not significantly affected.

[0026] The wine was stored at a constant temperature of 20°C for 12 months, and the changes in key indicators such as turbidity and centrifugal sedimentation rate were continuously monitored. The stability of the rice wine treated with the combined method of the present invention has been significantly improved. The turbidity of the rice wine was significantly reduced, and the amount of precipitation was greatly reduced. The components in the rice wine that are easy to cause precipitation, such as proteins, polysaccharides, polyphenols, and iron ions, were effectively removed. The protein colloid particle size distribution was uniform, the charge was far away from the isoelectric point, and the stability of the system was enhanced. In addition, the physical and chemical indicators of the rice wine treated with the method of the present invention all meet the relevant national standards, and there is no obvious adverse effect on the characteristic flavor, organic acids, free amino acids and antioxidant properties of the rice wine, and the basic quality and unique flavor of the rice wine are successfully retained. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a diagram of the sensory changes before and after rice wine processing. DETAILED DESCRIPTION

[0028] The present invention is described in detail below in conjunction with the accompanying drawings and embodiments.

[0029] The ultrafiltration membranes involved in the following examples are all from Minimate TM The EVO tangential flow filtration system was purchased from PALL, Inc., USA.

[0030] The rice wine (three-year-old traditional semi-dry rice wine) involved in the following embodiments was purchased from a local supermarket.

[0031] The Coomassie brilliant blue, bovine serum albumin, gallic acid, fulin-phenol, Na2CO3, hydroxylamine hydrochloride, o-phenanthroline, sodium acetate and potassium permanganate involved in the following examples were purchased from Sinopharm Chemical Reagent Co., Ltd.

[0032] The detection methods involved in the following implementation cases are as follows:

[0033] 1. Determination of rice wine turbidity

[0034] At a wavelength of 800nm, with distilled water as a reference (the turbidity of distilled water is zero), the transmittance T is measured, and 1-T is taken as the turbidity of rice wine.

[0035] A=-lgT (1)

[0036] Where: A is absorbance; T is transmittance.

[0037] 2. Centrifugal Sedimentation Rate Determination

[0038] Accurately measure 10 mL of rice wine into a centrifuge tube and centrifuge at 5000 r / min for 15 min to separate the precipitate and supernatant.

[0039] R%=m2 / m1×100 (2)

[0040] Where: R% is the centrifugal sedimentation rate; m1 represents the sample mass (g); m2 represents the sedimentation mass (g).

[0041] 3. Particle size and potential determination

[0042] Take 1mL of clear and transparent rice wine sample into the sample pool, and the measurement parameters are as follows:

[0043] Dispersant Name: Alcohol; Dispersant RI: 1.360; Material RI: 1.330; Viscosity: 1.1000; Material Absorption: 0.01; Detector Angle: 90.00; Particle Refractive Index: 1.460; Dispersant Refractive Index: 1.330.

[0044] 4. Determination of protein, polysaccharide, polyphenol and iron ion content in rice wine

[0045] Protein determination by Coomassie Brilliant Blue method: prepare 6 protein standard solutions with different concentration gradients, add 5 mL of Coomassie Brilliant Blue solution to each, use 1.0 mL of distilled water as a blank control, and measure the absorbance at a wavelength of 595 nm.

[0046] Determination of polyphenols by the Folin-phenol method: prepare 5 gallic acid standard solutions with different concentration gradients, add 1 mL of Folin-phenol reagent to each solution, then add 3 mL of 2% Na2CO3 solution after 3 minutes, and place at room temperature in the dark for 2 hours with appropriate ultrasonic vibration. Add 1 mL of Folin-phenol preparation and 2% Na2CO3 to 47 mL of distilled water as a blank control, and measure the absorbance at 760 nm.

[0047] Determination of iron ions by the o-phenanthroline method: prepare 7 iron standard solutions with different concentration gradients, add 1 mL of 10% hydroxylamine hydrochloride solution, 2.5 mL of o-phenanthroline solution and 5 mL of sodium acetate solution to each, let stand for 10 to 15 minutes, use distilled water as a blank control, and measure the absorbance at 510 nm.

[0048] Determination of polysaccharide content: The polysaccharide content is the difference between total sugar and reducing sugar. The total sugar is determined by referring to the detection method in the national standard GB / T13662-2018 "Yellow Wine", and the reducing sugar is determined by referring to the potassium permanganate titration method in the national standard GB 5009.7-2016.

[0049] 5. Physical and chemical indicators of rice wine

[0050] Wash the electrode with water, then wash the electrode twice with the test solution, use filter paper to absorb the liquid beads attached to the outside of the electrode, adjust the test solution temperature to 25℃, and measure directly until the pH reading is stable for 1 minute, and record it. Or measure at room temperature and convert it to pH at 25℃. The result is expressed to one decimal place.

[0051] Refer to the national standard GB / T13662-2018 "Yellow Wine" for the detection methods of rice wine alcohol content, non-sugar solids, total acid, amino acid nitrogen and total sugar.

[0052] 6. Antioxidant activity test of rice wine

[0053] DPPH free radical scavenging experiment: accurately prepare 0.1mmol / L DPPH solution, 50μg / mL and 100μg / mL ascorbic acid (VC) solution, add 2mL of 0.1mmol / L DPPH·ethanol solution and 1.5mL of different samples to be tested in the test tube, mix and react for half an hour, and measure the absorbance at 517nm as A1; replace the sample with an equal volume of water and measure its absorbance as A3; replace the DPPH·ethanol solution with an equal volume of anhydrous ethanol and measure the absorbance as A2, repeat three times. Ascorbic acid is used as a positive control

[0054] DPPH free radical scavenging rate % = [1-(A1-A2)] / A3×100 (4)

[0055] Hydroxyl radical scavenging experiment: accurately prepare 9mmol / L salicylic acid, 9mmol / L ferrous sulfate, and 8.8mmol / L hydrogen peroxide, add 2mL of sample to a test tube, then add 1mL each of salicylic acid and FeSO4, and finally add 2mL of hydrogen peroxide, mix well, and place in a 37℃ water bath for half an hour. The absorbance at 510nm is A1; replace the sample with the same volume of water, and measure its absorbance as A2; replace hydrogen peroxide with the same volume of water, and measure its absorbance as A3. Take ascorbic acid as the positive control. Hydroxyl radical scavenging rate % = [A2(A1-A3)] / A2×100(5)

[0056] ABTS free radical scavenging experiment: accurately prepare 7.4mmol / L ABTS stock solution, mix equal volumes of ABTS solution and 2.6mmol / L potassium persulfate solution, and adjust the absorbance of ABTS stock solution at 734nm to about 0.70 with anhydrous ethanol, which is A0. Mix 2mL of ABTS dilution with 0.20mL of sea grape polyphenol solution of different concentrations, react at room temperature for 6 minutes, and measure the absorbance value A at 734nm. Ascorbic acid is used as a positive control

[0057] ABTS free radical scavenging rate % = (A0-A) / A0×100 (6)

[0058] 7. Detection of volatile components in rice wine

[0059] Sample pretreatment: Take 2 mL of wine sample, add 4 mL of ultrapure water and 2.5 g of NaCl, place in a 20 mL headspace bottle, add 10 μL of internal standard (2-octanol, 100 mg / L), and seal quickly. Equilibrate at 50°C for 5 min, extract at 300 r / min for 45 min, inject without split flow, desorb at 250°C for 5 min, and then analyze by GC-MS.

[0060] GC conditions: injection port temperature was 250°C; initial column temperature was 40°C and maintained for 2 min; temperature was increased to 230°C at 5°C / min and maintained for 10 min; carrier gas was high-purity helium (>99.999%), flow rate was 1.0 mL / min.

[0061] MS conditions: electron ionization (EI) source; current 50 μA; electron energy 70 eV; transfer line temperature 240°C; ion source temperature 280°C; scanning mass range 33-350 amu.

[0062] 8. Sensory evaluation of rice wine

[0063] Ten professionally trained sensory tasters were selected to conduct sensory evaluation on the five flavor evaluation keywords of acetic acid, sweetness, bitterness, umami, and astringency, and the seven aroma evaluation keywords of sour aroma, floral aroma, nutty aroma, mellow aroma, malt aroma, fruity aroma, and vanilla aroma of rice wine, and scored the intensity of the aroma on a scale of 0 (very weak) to 10 (very strong), with untreated rice wine as a reference.

[0064] Example 1

[0065] A method for controlling the precipitation of rice wine comprises the following steps:

[0066] The rice wine was first frozen at -4°C for 5 days, then filtered using an ultrafiltration membrane with a molecular weight cutoff of 50 kDa, and the ultrafiltration temperature was controlled below 4°C, i.e., one round of freezing filtration cycle was performed, and finally pulsed electric field treatment was performed under the conditions of electric field strength of 10 kV / cm, pulse width of 5 μs, and pulse frequency of 400 Hz, and the flow rate was controlled to be 20 mL / min to ensure consistent effective treatment time. The treated rice wine was placed at 20°C for 12 months.

[0067] Example 2

[0068] A method for controlling the precipitation of rice wine comprises the following steps:

[0069] The rice wine was first frozen at -4°C for 5 days, then filtered using an ultrafiltration membrane with a molecular weight cutoff of 50 kDa, the ultrafiltration temperature was controlled below 4°C, and the above operation was repeated once, i.e., two rounds of freezing and filtration cycles were performed, and finally pulsed electric field treatment was performed under the conditions of electric field strength of 10 kV / cm, pulse width of 5 μs, and pulse frequency of 400 Hz, and the flow rate was controlled to be 20 mL / min to ensure consistent effective treatment time. The treated rice wine was placed at 20°C for 12 months.

[0070] Example 3

[0071] A method for controlling the precipitation of rice wine comprises the following steps:

[0072] The rice wine was first frozen at -4°C for 5 days, then filtered using an ultrafiltration membrane with a molecular weight cutoff of 50 kDa, the ultrafiltration temperature was controlled below 4°C, and the above operation was repeated twice, i.e., 3 rounds of freezing filtration cycles were performed, and finally pulsed electric field treatment was performed under the conditions of electric field strength of 10 kV / cm, pulse width of 5 μs, and pulse frequency of 400 Hz, and the flow rate was controlled to be 20 mL / min to ensure consistent effective treatment time. The treated rice wine was placed at 20°C for 12 months.

[0073] Example 4

[0074] A method for controlling the precipitation of rice wine comprises the following steps:

[0075] The rice wine was first frozen at -4°C for 5 days, and then filtered using an ultrafiltration membrane with a molecular weight cutoff of 50 kDa. The ultrafiltration temperature was controlled below 4°C. The above operation was repeated three times, i.e., 4 rounds of freezing filtration cycles were performed. Finally, the pulsed electric field treatment was performed under the conditions of an electric field strength of 10 kV / cm, a pulse width of 5 μs, and a pulse frequency of 400 Hz. The flow rate was controlled to be 20 mL / min to ensure consistent effective treatment time. The treated rice wine was placed at room temperature of 20°C for 12 months.

[0076] Example 5

[0077] A method for controlling the precipitation of rice wine comprises the following steps:

[0078] The rice wine was first frozen at -4°C for 5 days, then filtered using an ultrafiltration membrane with a molecular weight cutoff of 50 kDa, the ultrafiltration temperature was controlled below 4°C, and the above operation was repeated four times, i.e., 5 rounds of freezing filtration cycles were performed, and finally pulsed electric field treatment was performed under the conditions of electric field strength of 10 kV / cm, pulse width of 5 μs, and pulse frequency of 400 Hz, and the flow rate was controlled to be 20 mL / min to ensure consistent effective treatment time. The treated rice wine was placed at 20°C for 12 months.

[0079] Example 6

[0080] A method for controlling the precipitation of rice wine comprises the following steps:

[0081] The rice wine was first frozen at -4°C for 5 days, and then filtered using an ultrafiltration membrane with a molecular weight cutoff of 50kDa. The ultrafiltration temperature was controlled below 4°C. The above operation was repeated five times, i.e., 6 rounds of freezing and filtration cycles were performed. Finally, the pulsed electric field was treated at an electric field strength of 10kV / cm, a pulse width of 5μs, and a pulse frequency of 400Hz. The flow rate was controlled to be 20mL / min to ensure consistent effective treatment time. The treated rice wine was placed at 20°C for 12 months.

[0082] Example 7

[0083] A method for controlling the precipitation of rice wine comprises the following steps:

[0084] The rice wine was first frozen at -4°C for 5 days, then filtered at 4°C using an ultrafiltration membrane with a molecular weight cutoff of 100 kDa, and finally treated with a pulsed electric field at an electric field strength of 10 kV / cm, a pulse width of 5 μs, and a pulse frequency of 400 Hz, with the flow rate controlled at 20 mL / min to ensure consistent effective treatment time. The treated rice wine was placed at 20°C for 12 months.

[0085] Example 8

[0086] A method for controlling the precipitation of rice wine comprises the following steps:

[0087] The rice wine was first frozen at 4°C for 7 days, then filtered at a temperature below 4°C using an ultrafiltration membrane with a molecular weight cutoff of 30 kDa, and finally treated with a pulsed electric field at an electric field strength of 10 kV / cm, a pulse width of 5 μs, and a pulse frequency of 400 Hz, with a flow rate of 20 mL / min to ensure consistent effective treatment time. The treated rice wine was placed at 20°C for 12 months.

[0088] Example 9

[0089] A method for controlling the precipitation of rice wine comprises the following steps:

[0090] The rice wine was first frozen at 4°C for 7 days, then filtered at a temperature below 4°C using an ultrafiltration membrane with a molecular weight cutoff of 10kDa, and finally treated with a pulsed electric field at an electric field strength of 10kV / cm, a pulse width of 5μs, and a pulse frequency of 400Hz, with a flow rate of 20mL / min to ensure consistent effective treatment time. The treated rice wine was placed at 20°C for 12 months.

[0091] Comparative Example 1

[0092] The untreated rice wine was placed at 20℃ for 12 months.

[0093] Test example:

[0094] 1. Data related to rice wine stability

[0095] (1) Yellow wine turbidity

[0096] The changes in the turbidity of rice wine before and after treatment are shown in Table 1. The turbidity of the comparative example increased significantly during the storage at 20°C for 12 months, the light transmittance of the wine body decreased, and obvious turbidity was produced at the bottom. Compared with the comparative example, although Examples 1, 5, and 6 significantly reduced the turbidity of rice wine, the turbidity of rice wine increased slightly with the storage time, and the turbidity rose to about 0.04 after 12 months of room temperature storage. Example 3 showed the lowest turbidity, and the turbidity did not change significantly after being stored at 20°C for 12 months, and remained below 0.035, which had a significant effect on improving the turbidity of rice wine.

[0097] (2) Centrifugal sedimentation rate of rice wine

[0098] The changes in the centrifugal sedimentation rate of rice wine before and after treatment are shown in Table 1. The centrifugal sedimentation rate of the comparative example increased significantly with the storage time, and increased to about 4% at 12 months. The centrifugal sedimentation rates of Examples 1-6 were all lower than those of the comparative example. Similar to the changes in the turbidity of rice wine, the centrifugal sedimentation rate of the rice wine in Example 3 was the lowest, and did not change much after being stored at 20°C for 12 months, always below 1.5%; and although Examples 1-2 and 4-6 could also significantly reduce the centrifugal sedimentation rate of rice wine, the effect was not as good as that of Example 3, and it would slowly increase over time.

[0099] (3) Components that are easy to precipitate in rice wine

[0100] The changes in the content of the easily precipitated components of the rice wine before and after the treatment are shown in Table 1. The protein content of the rice wine after treatment (among the 6 groups of examples) did not change much, but there was a significant difference between the examples and the comparative examples. Compared with the comparative example, the protein content of Examples 1-6 decreased. The combined treatment can remove most of the easily precipitated proteins in the rice wine, and the protein content was reduced by about 16.26-22.91%; although the polysaccharide content of Examples 1-6 decreased, it did not change much compared with the comparative example, and the content of polyphenols and iron ions changed little, and the comparative example was not much different from the examples.

[0101] Table 1 Changes in stability indicators

[0102] index Comparative Example 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Turbidity (first day) 0.0426 0.0373 0.0344 0.0308 0.0317 0.0351 0.0355 Turbidity (3 months) 0.0469 0.0395 0.0360 0.0310 0.0348 0.0365 0.0379 Turbidity (6 months) 0.0682 0.0424 0.0382 0.0322 0.0389 0.0391 0.0405 Turbidity (12 months) 0.0755 0.0445 0.0393 0.0325 0.0392 0.0405 0.0438 Centrifugal sedimentation rate % (first day) 1.58 2.05 1.57 1.54 1.59 1.65 1.63 Centrifugal sedimentation rate % (3 months) 2.58 2.18 1.85 1.74 1.78 2.07 2.09 Centrifugal sedimentation rate % (6 months) 3.49 2.32 2.01 1.95 2.04 2.28 2.22 Centrifugal sedimentation rate % (12 months) 4.26 2.58 2.21 2.06 2.32 2.36 2.35 Protein (g / L) 5.9053 4.9451 4.7598 4.6673 4.6567 4.5671 4.5523 Polysaccharide (g / L) 12.2988 10.3828 10.1789 10.1043 10.0843 10.0343 10.0223 Polyphenols (g / L) 0.2249 0.2080 0.2048 0.2024 0.2018 0.2008 02001 Iron ion (mg / L) 0.9491 0.8994 0.8988 0.8927 0.8911 0.8898 0.8852

[0103] 2. Colloidal properties of rice wine

[0104] The changes in the colloidal properties of rice wine before and after treatment are shown in Table 2. Compared with the comparative example, the average particle size and polydispersity index (PDI) of the rice wine colloids in Examples 1-6 are reduced, indicating that the colloidal particles become smaller and the dispersion becomes more uniform; with the increase in the number of repeated freezing and filtration cycles, the average particle size and PDI of the rice wine colloid gradually decrease. For the zeta potential, the potential of the comparative example is positive, indicating that the protein surface in the rice wine carries a small amount of positive charge, and the value is close to 0 (isoelectric point) and the stability is poor, that is, the protein in the rice wine system will aggregate and precipitate over time; the zeta potential of Examples 1-6 is all >25mV, that is, the positive charge of the protein in these 6 groups of rice wine systems increases, the electrostatic repulsion is enhanced, and the protein particles are not easy to aggregate under the action of electrostatic force, among which the potential value of Example 3 is the largest.

[0105] Table 2: Changes in colloidal indicators of rice wine

[0106] index Comparative Example 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Average particle size (nm) 2838 1829 1629 1240 1198 1183 1128 Potential (mV) 2.39 25.40 35.02 41.91 39.12 38.75 38.37 PDI 0.868 0.613 0.559 0.344 0.342 0.340 0.341

[0107] 3. Data related to sensory quality of rice wine

[0108] (1) Physical and chemical indicators of rice wine

[0109] The changes in the physical and chemical indicators of rice wine before and after treatment are shown in Table 3. Compared with the comparative example, the pH values ​​of Examples 1-6 have increased, while the alcohol content, amino acid nitrogen, total sugar, reducing sugar, total acid and non-sugar solids have changed to varying degrees. The alcohol content decreased by 0.2-0.5% vol after treatment, and there was not much difference between the examples and the comparative example; for the change in amino acid nitrogen, although each example was reduced compared with the comparative example, it was all around 0.80 g / L. The changes in the content of total sugar, reducing sugar and total acid are similar, and the content of total sugar, reducing sugar and total acid in each example does not change much; and the non-sugar solid content of Examples 1-6 has no obvious change compared with the comparative example, and only shows a slight decrease. Overall, all the physical and chemical indicators of the rice wine of Examples 1-6 meet the requirements of the national standard for various indicators of rice wine.

[0110] Table 3 Changes of various physical and chemical indicators

[0111] index Comparative Example 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 pH 4.03 4.11 4.11 4.11 4.12 4.12 4.12 Alcohol content (%vol) 16.0 15.8 15.8 15.7 15.7 15.7 15.5 Amino acid nitrogen (g / L) 0.887 0.870 0.873 0.857 0.793 0.797 0.795 Total sugar (g / L) 28.748 27.884 27.639 27.563 27.537 27.296 27.281 Reducing sugar (g / L) 16.449 14.689 13.739 13.326 13.109 13.087 13.079 Total acid (g / L) 4.924 4.775 4.732 4.707 4.673 4.648 4.632 Non-sugar solids (g / L) 37.005 35.979 35.857 35.591 35.399 35.289 35.144

[0112] (2) Volatile components of rice wine

[0113] The changes in the volatile components of rice wine before and after treatment are shown in Table 4. The volatile components of rice wine in Examples 4-6 were reduced, and there were differences compared with the control group, but Examples 1-3 had little effect on the volatile components of rice wine. The contents of substances such as floral and fruity aroma (such as ethyl acetate, ethyl caproate, and phenylacetaldehyde) and almond aroma / malt koji aroma (such as benzaldehyde and furfural) were slightly reduced, and some substances fluctuated slightly; there was no significant difference in the volatile components between Examples 1-3 and Comparative Example 1, indicating that these three groups of technical treatments had no significant effect on the volatile components of rice wine.

[0114] Table 4: Changes in volatile components of rice wine

[0115]

[0116]

[0117] (3) Organic acids and free amino acids in rice wine

[0118] The changes in organic acid and free amino acids in rice wine before and after treatment are shown in Table 5. It can be seen that compared with the comparative example and other examples, the organic acid content of Examples 4-6 has decreased, and there is no obvious change in other examples; overall, the organic acid content of Examples 1-3 has the smallest change compared with Comparative Example 1. The amino acid content of the wine samples after treatment has slightly decreased overall; among them, Examples 1-3 have little change. This shows that the technical treatment has no obvious effect on the organic acid and free amino acids in rice wine.

[0119] Table 5: Changes of organic acids and free amino acids in rice wine

[0120]

[0121]

[0122] (4) Free radical scavenging rate and total antioxidant activity of rice wine

[0123] The changes in the free radical scavenging rate and total antioxidant activity of the rice wine before and after treatment are shown in Table 6. Compared with the comparative example, the free radical scavenging rate and total antioxidant activity of the rice wine of Examples 4-6 were slightly reduced, while there was no significant change in the other examples. The free radical scavenging rate and total antioxidant activity of Examples 1-3 were the smallest difference from the comparative example, which was better than the other groups. In general, there was no significant change in the free radical scavenging rate and total antioxidant activity, indicating that the group technical treatment had no significant effect on the antioxidant activity of the rice wine.

[0124] Table 6: Changes in free radical scavenging rate and total antioxidant capacity of rice wine

[0125]

[0126] (5) Rice wine sensory

[0127] The sensory scoring radar chart of rice wine before and after treatment is as follows Figure 1 As shown. The sourness and bitterness of the rice wine are reduced, making it taste more refreshing; at the same time, the scores of characteristic aromas such as floral and fruity aroma, almond aroma and malt aroma are also slightly reduced. The various flavors and aroma substances of the rice wine in Examples 1-6 are slightly reduced, and the characteristic sensory properties of the rice wine are slightly changed. The overall score is within a reasonable range, especially Example 6, which still maintains a relatively obvious sensory attribute of the rice wine.

[0128] The embodiments provided above are not intended to limit the scope of the present invention, and the steps described are not intended to limit the execution order thereof. Those skilled in the art may make obvious improvements to the present invention in combination with existing common knowledge, which also fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for controlling the precipitation of rice wine, characterized in that: The method comprises the steps of three combinations of low temperature freezing, membrane filtration and pulse electric field; The processing conditions of low temperature freezing are: freezing at -4 to 4°C for 3 to 7 days; The ultrafiltration membrane used in the membrane filtration treatment has a molecular weight cutoff of 10 to 100 kDa, and the membrane filtration temperature is controlled at -4 to 4°C; One cryogenic freezing and membrane filtration was regarded as one round of cryofiltration, and the cycle was 1 to 6 rounds; The treatment conditions of the pulse electric field are: electric field intensity of 5 to 15 kV / cm, pulse width of 2 to 10 μs, and pulse frequency of 200 to 500 Hz.

2. The method according to claim 1, characterized in that The membrane filtration process uses polyethersulfone ultrafiltration membrane.

3. The method according to claim 1, characterized in that: First, freeze filtration is performed, followed by pulsed electric field treatment.

4. The method according to claim 1, characterized in that: The method comprises one round of freezing filtration and pulse electric field treatment; first freezing at a freezing temperature of -4 to 4°C for 3 to 7 days, then using an ultrafiltration membrane with a molecular weight cutoff of 10 to 100 kDa for membrane filtration treatment at -4 to 4°C, and finally pulse electric field treatment at an electric field strength of 5 to 15 kV / cm, a pulse width of 2 to 10 μs, and a pulse frequency of 200 to 500 Hz.

5. The method according to claim 1, characterized in that The method comprises two rounds of freezing filtration and pulse electric field treatment; first freezing at a freezing temperature of -4 to 4°C for 3 to 7 days, then using an ultrafiltration membrane with a molecular weight cutoff of 10 to 100 kDa for membrane filtration treatment at -4 to 4°C, repeating the above operation once, and finally performing pulse electric field treatment at an electric field strength of 5 to 15 kV / cm, a pulse width of 2 to 10 μs, and a pulse frequency of 200 to 500 Hz.

6. The method according to claim 1, characterized in that The method comprises three rounds of freezing filtration and pulse electric field treatment; first freezing at a freezing temperature of -4 to 4°C for 3 to 7 days, then using an ultrafiltration membrane with a molecular weight cutoff of 10 to 100 kDa for membrane filtration treatment at -4 to 4°C, repeating the above operation twice, and finally performing pulse electric field treatment under the conditions of an electric field strength of 5 to 15 kV / cm, a pulse width of 2 to 10 μs, and a pulse frequency of 200 to 500 Hz.

7. The method according to claim 1, characterized in that The method comprises four rounds of freezing filtration and pulse electric field treatment; first freezing at a freezing temperature of -4 to 4°C for 3 to 7 days, then using an ultrafiltration membrane with a molecular weight cutoff of 10 to 100 kDa for membrane filtration treatment at -4 to 4°C, repeating the above operation three times, and finally performing pulse electric field treatment at an electric field strength of 5 to 15 kV / cm, a pulse width of 2 to 10 μs, and a pulse frequency of 200 to 500 Hz.

8. The method according to claim 1, characterized in that The method comprises 5 rounds of freezing filtration and pulse electric field treatment; first freezing at a freezing temperature of -4 to 4°C for 3 to 7 days, then using an ultrafiltration membrane with a molecular weight cutoff of 10 to 100 kDa for membrane filtration treatment at -4 to 4°C, repeating the above operation four times, and finally performing pulse electric field treatment under the conditions of an electric field strength of 5 to 15 kV / cm, a pulse width of 2 to 10 μs, and a pulse frequency of 200 to 500 Hz.

9. The method according to claim 1, characterized in that: The method comprises 6 rounds of freezing filtration and pulse electric field treatment; first freezing at a freezing temperature of -4 to 4°C for 3 to 7 days, then using an ultrafiltration membrane with a molecular weight cutoff of 10 to 100 kDa for membrane filtration treatment at -4 to 4°C, repeating the above operation five times, and finally performing pulse electric field treatment at an electric field strength of 5 to 15 kV / cm, a pulse width of 2 to 10 μs, and a pulse frequency of 200 to 500 Hz.

10. Use of the method according to any one of claims 1 to 9 in the storage, transportation or sales of rice wine.

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