A method for preparing fresh rice wine by using pulse magnetic field sterilization

Abstract

The invention discloses a method for preparing fresh rice wine by pulse magnetic field sterilization, the method comprising the following steps: 1) processing glutinous rice to obtain cooked glutinous rice; 2) mixing the cooked glutinous rice with 0.1-0.3% of distiller's yeast by weight of glutinous rice, fermenting at 28-30°C for 2-3 days, adding 1-4 times of the weight of glutinous rice and stirring evenly, continuing to ferment for 2-7 days, terminating fermentation, and separating to obtain fermented wine; 3) placing the fermented wine in a pulse magnetic field for sterilization to obtain fresh rice wine, wherein the number of pulses is 5-25, the magnetic field intensity is 2-10T, the pulse width is 5-25ms, and the time interval between two pulses is 15s. The invention adopts pulse magnetic field sterilization to avoid the inactivation of sucrose invertase by heat, and the prepared rice wine has a fresh taste, delicious taste, and rich nutrition, solves the long-standing contradiction that the rice wine tastes not fresh and the fresh taste is guaranteed but cannot be preserved for a long time, and provides a new type of rice wine category that meets the health concept of modern consumers.

Description

Technical Field

[0001] The invention belongs to the technical field of wine preparation, and specifically relates to fresh rice wine and a preparation method thereof, and more specifically relates to a method for preparing fresh rice wine by using pulse magnetic field sterilization. Background Art

[0002] Rice wine, also known as sweet wine, fermented glutinous rice or fermented glutinous rice, is a traditional low-alcohol brewed wine in my country. It belongs to the category of yellow wine. It is mainly made from rice, indica rice, red rice, black rice or glutinous rice and other grain rice as raw materials, and is made through microbial fermentation. It is rich in glucose, maltose, amino acids, vitamins, organic acids, polysaccharides and other ingredients. It has the effects of appetizing, relieving greasiness, promoting appetite, promoting fluid production and quenching thirst, invigorating qi and nourishing blood, relaxing muscles and activating blood circulation, nourishing yin and tonifying the kidneys, etc. It has huge market potential and development prospects.

[0003] The rice wine available on the market mainly includes rice wine from Zhejiang Province and Xiaogan rice wine from Hubei Province. Its brewing process mainly includes the following steps: rice selection → rice washing → rice soaking → steaming → cooling → mixing with koji → setting up nest in a vat → heat preservation and saccharification → fermentation → pressing → filtering → sterilization → filling → finished product. Among them, the sterilization process mostly adopts thermal sterilization. Thermal sterilization technology is an important control technology in the field of food processing technology. It mainly kills microorganisms in food and inactivates enzymes in food through high temperature and high heat, so as to achieve the purpose of improving food quality, extending food storage period and ensuring food safety. Thermal sterilization methods mainly include pasteurization and high temperature instantaneous sterilization. However, both processes have inherent defects, such as insensitivity to heat-resistant microorganisms, high energy consumption and fixed investment, difficulty in precise control, and frequent problems such as overheating. More importantly, the high temperature during the thermal sterilization process often leads to deterioration of food quality, mainly including color change, taste change, aroma loss, nutrient destruction, texture change, etc. Compared with high-temperature instantaneous sterilization, pasteurization has a relatively low processing temperature, but due to the long sterilization time, long-term heating will inevitably lead to the decomposition of some heat-sensitive aroma components in the food, the escape of umami substances, and the production of undesirable flavor substances, which changes the original flavor of fresh food and is often accompanied by the "cooked taste" of thermal sterilization.

[0004] With the continuous improvement of living standards, people's awareness of healthy drinking has gradually increased, and a new drinking concept of low-alcohol health, nutrition and health care is taking shape. Because home-brewed rice wine has not been pasteurized, its nutritional content and flavor are far higher than the existing rice wine on the market. However, home-brewed rice wine is greatly affected by climate and environment, and the fermentation rate is low. In addition, the wine does not undergo sterilization, so it contains more bacteria, which makes the rice wine easy to become sour after fermentation due to the bacteria. As a result, the brewed rice wine has the disadvantages of short shelf life, easy aging, and cannot be commercialized. Summary of the invention

[0005] The present invention finds that in the process of preparing rice wine, the traditional heat sterilization process will destroy the flavor of rice wine. In addition to causing the loss of the natural fragrance of rice wine, it will also cause the loss of the natural umami taste of rice wine, produce bitter and mixed taste, and cause the loss of nutrients. The purpose of the present invention is to provide a fresh rice wine and a preparation method thereof, which adopts a specific sterilization method to keep the sucrose invertase in the rice wine positive on the one hand, and reduce the loss of bad flavor or nutrition on the other hand, thereby providing a new type of rice wine with rich nutrition and delicious taste.

[0006] Based on the above description, as a first aspect of the present invention, the present invention provides a method for preparing fresh rice wine.

[0007] Preferably, the method for preparing the fresh rice wine comprises the following steps:

[0008] 1) processing glutinous rice to obtain cooked glutinous rice;

[0009] 2) mixing the cooked glutinous rice with 0.1-0.3% of distiller's yeast based on the weight of the glutinous rice, and fermenting at 28-30° C. for 2-3 days, adding water 1-4 times the weight of the glutinous rice, stirring evenly, and continuing to ferment for 2-7 days, then terminating the fermentation and separating to obtain the fermented wine;

[0010] 3) The fermented wine liquid is placed in a pulsed magnetic field for sterilization to obtain fresh rice wine.

[0011] Preferably, the parameters in the sterilization process in step 3) are set as follows: number of pulses 5-25, magnetic field strength 2-10T, pulse width 5-25ms, wherein the time interval between two pulses is 15s.

[0012] Preferably, the method for preparing the cooked glutinous rice in step 1) is: washing the glutinous rice and soaking it at room temperature for 10-18 hours, steaming the soaked glutinous rice for 20-30 minutes and then cooling it to 30-35°C by rinsing.

[0013] Among them, when glutinous rice is soaked in water, the mass ratio of rice to water is 1:2-3.5; among them, the glutinous rice after steaming is required to have complete grains, hard on the outside and soft on the inside, loose and not rotten; the steamed glutinous rice is rinsed with tap water to separate the rice grains and cool them. The rinsing time is appropriately lengthened or shortened according to the amount of glutinous rice, season, and temperature.

[0014] Preferably, in step 2), the fermentation is terminated when the alcohol content of the fermented wine is 6-14% vol, the total sugar content is 10-160 g / L, and the total acid content is 0.5-10 g / L.

[0015] Preferably, the method for separating the fermented wine liquid in step 2) is: subjecting the fermented wine liquid to pressure filtration or centrifugal separation to obtain the fermented wine liquid, and filtering the fermented wine liquid.

[0016] Among them, the separation of fermented wine can be carried out by using a press, a plate and frame filter press, a butterfly centrifuge, etc.

[0017] Preferably, the filtration is carried out using a microporous membrane with a pore size of 0.30-0.50 μm. The pore size of the membrane in the membrane filtration can be adjusted by a person skilled in the art as required.

[0018] In the present invention, the amount of koji used can be adjusted by those skilled in the art as needed. The koji is the koji conventionally used by those skilled in the art. As a preferred embodiment of the present invention, in step 1), the amount of koji used is 0.1-0.3% of the weight of glutinous rice. One of the benefits of this amount is that it can ensure that the glutinous rice is fully fermented, and it can also prevent the amount of koji from being too large, which will cause the wine to have a bitter taste.

[0019] As a second aspect of the present invention, the present invention provides a method for preparing aerated fresh rice wine, wherein a carbonated rice wine category is prepared by injecting gas into the rice wine during the preparation process.

[0020] Preferably, the method for preparing the aerated fresh rice wine comprises the following steps:

[0021] 1) processing glutinous rice to obtain cooked glutinous rice;

[0022] 2) mixing the cooked glutinous rice with 0.1-0.3% of distiller's yeast based on the weight of the glutinous rice, and fermenting at 28-30° C. for 2-3 days, adding water 1-4 times the weight of the glutinous rice, stirring evenly, and continuing to ferment for 2-7 days, then terminating the fermentation and separating to obtain the fermented wine;

[0023] 3) placing the fermented wine in a pulsed magnetic field for sterilization;

[0024] 4) Adding gas to the sterilized fermented wine liquid so that the gas concentration in the fermented wine liquid reaches 2-6 g / L, thereby obtaining aerated fresh rice wine.

[0025] Preferably, the gas is food-grade CO2, N2 or a mixture of CO2 and N2 in a certain proportion.

[0026] The volume ratio of CO2 to N2 in the mixed gas may be any ratio between (1-100):(1-100), for example, 1:1, 1:2, 2:1, 5:95, etc.

[0027] Preferably, the parameters in the sterilization process in step 3) are set as follows: number of pulses 5-25, magnetic field strength 2-10T, pulse width 5-25ms, wherein the time interval between two pulses is 15s.

[0028] Preferably, the method for preparing the cooked glutinous rice in step 1) is: washing the glutinous rice and soaking it at room temperature for 10-18 hours, steaming the soaked glutinous rice for 20-30 minutes and then cooling it to 30-35°C by rinsing.

[0029] Preferably, in step 2), the fermentation is terminated when the alcohol content of the fermented wine is 6-14% vol, the total sugar content is 10-160 g / L, and the total acid content is 0.5-10 g / L.

[0030] Preferably, the method for separating the fermented wine liquid in step 2) is: subjecting the fermented wine liquid to pressure filtration or centrifugal separation to obtain the fermented wine liquid, and filtering the fermented wine liquid.

[0031] Preferably, the filtration is carried out using a microporous membrane with a pore size of 0.30-0.50 μm.

[0032] As the third aspect of the present invention, the purpose of the present invention is to provide a fresh rice wine, which is sterilized by non-thermal sterilization technology during the preparation process instead of thermal sterilization, so that the sucrose invertase in the rice wine will not be inactivated by high temperature, thereby maintaining the fresh flavor of the rice wine, and through non-thermal sterilization, the residual microorganisms in the rice wine meet the national standards, thereby extending the shelf life, thereby providing a new type of rice wine with rich nutritional value and fresh and delicious taste.

[0033] Preferably, the alcohol content of the fresh rice wine is 6-14% vol, and the sucrose invertase is positive.

[0034] Preferably, the total sugar content of the fresh rice wine is 10-160 g / L, and the total acid content is 0.5-10 g / L.

[0035] Preferably, the fresh rice wine comprises two types, unaerated and aerated, that is, by controlling whether gas is added during the preparation of the rice wine, both unaerated and aerated rice wines can be prepared.

[0036] Preferably, the method for preparing the fresh rice wine comprises the following steps:

[0037] 1) processing glutinous rice to obtain cooked glutinous rice;

[0038] 2) mixing the cooked glutinous rice with 0.1-0.3% of distiller's yeast based on the weight of the glutinous rice, and fermenting at 28-30° C. for 2-3 days, adding water 1-4 times the weight of the glutinous rice, stirring evenly, and continuing to ferment for 2-7 days, then terminating the fermentation and separating to obtain the fermented wine;

[0039] 3) The fermented wine liquid is placed in a pulsed magnetic field for sterilization to obtain fresh rice wine.

[0040] Preferably, the parameters in the sterilization process in step 3) are set as follows: number of pulses 5-25, magnetic field strength 2-10T, pulse width 5-25ms, wherein the time interval between two pulses is 15s.

[0041] Preferably, after the pulse magnetic field sterilization treatment, a step of aerating the fermented wine liquid is further included so that the gas concentration in the fermented wine liquid reaches 2-6 g / L.

[0042] Preferably, the gas is food-grade CO2, N2 or a mixture of CO2 and N2 in a certain proportion.

[0043] Preferably, the method for preparing the cooked glutinous rice in step 1) is: washing the glutinous rice and soaking it at room temperature for 10-18 hours, steaming the soaked glutinous rice for 20-30 minutes and then cooling it to 30-35°C by rinsing.

[0044] Preferably, in step 2), the fermentation is terminated when the alcohol content of the fermented wine is 6-14% vol, the total sugar content is 10-160 g / L, and the total acid content is 0.5-10 g / L.

[0045] Preferably, the method for separating the fermented wine liquid in step 2) is: subjecting the fermented wine liquid to pressure filtration or centrifugal separation to obtain the fermented wine liquid, and filtering the fermented wine liquid.

[0046] Preferably, the filtration is carried out using a microporous membrane with a pore size of 0.30-0.50 μm.

[0047] As a fourth aspect of the present invention, the present invention provides the use of pulsed magnetic field sterilization in increasing the lactic acid content of rice wine.

[0048] The present invention group analyzed and measured the physical and chemical indicators of rice wine prepared by different sterilization methods, and unexpectedly found that the lactic acid content in rice wine prepared by pulse magnetic field sterilization method was significantly lower than that in rice wine prepared by heat sterilization such as pasteurization and high-temperature instantaneous sterilization.

[0049] Therefore, the present invention discloses the use of pulse magnetic field sterilization in increasing the lactic acid content of rice wine.

[0050] The beneficial effects of the present invention are:

[0051] (1) The rice wine preparation method of the present invention adopts a pulsed magnetic field for sterilization treatment, so that the prepared rice wine sucrose invertase is positive. Compared with the existing rice wine on the market, the rice wine has the advantages of fresh taste, delicious taste and rich nutrition. It completely solves the long-standing contradiction that the rice wine tastes stale and the fresh taste cannot be preserved for a long time, thereby providing a new type of rice wine category that meets the health concept of modern consumers and has good market development value.

[0052] (2) The present invention prepares a carbonated fresh rice wine by filling gas into rice wine, thereby further enriching the types of rice wine. The carbonated fresh rice wine containing gas can give people a refreshing feeling when drinking, and can be favored by young consumers.

[0053] (3) The lactic acid content in the fresh rice wine prepared by the preparation process of the present invention is significantly higher than that in the rice wine prepared by heat sterilization and the unsterilized rice wine, so that the prepared fresh rice wine has a mellower taste and a better mouthfeel than the rice wine prepared by the traditional process.

[0054] (4) The preparation process of the present invention only adds water without adding fermentation microorganisms during fermentation for 2-3 days, and promotes saccharification and fermentation by controlling the fermentation process, thereby avoiding the increase in bitterness caused by excessive fermentation and the increase in sourness caused by the growth of acetic acid bacteria, thereby ensuring that the fermented rice wine is sweet and delicious, has a unique flavor, and is rich in nutrition. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 It is a process flow chart of fresh rice wine of the present invention.

[0056] Detailed description

[0057] Fresh rice wine

[0058] Fresh wine refers to wine that has not been prepared through heat sterilization processes such as pasteurization, such as draft beer. Because it has not been heat sterilized, the original ingredients of the wine are completely preserved. It has the advantages of rich nutrition, delicious and mellow taste, and strong aroma, and has become a healthy drink favored by consumers. Among them, the positive sucrose invertase is used as a characteristic sign of fresh wine, and the authenticity of fresh wine is identified by detecting the activity of sucrose invertase in the wine. Sucrose invertase is easily inactivated by heat. When the temperature is higher than 60°C, it will be inactivated, and the wine will produce undesirable color changes. Therefore, temperature control in the wine production process is extremely important for the preparation of fresh wine.

[0059] In the present invention, fresh rice wine refers to rice wine that has not been processed by heat treatment methods such as pasteurization. After fermentation, conventional rice wine on the market needs to be pasteurized or sterilized at high temperature to achieve stable storage requirements, but the taste and nutrition of the rice wine are greatly damaged. The present invention provides a new type of rice wine. The rice wine of the present invention does not undergo a heat sterilization process such as pasteurization during the preparation process, but adopts a low-heat or non-heat sterilization process. While ensuring that the microbial indicators in the wine meet the national standards, the freshness and nutrition of the rice wine are retained to a great extent, and the sucrose invertase in the wine is positive, so that the flavor and nutrition of the prepared rice wine are the same as those of freshly brewed unsterilized rice wine.

[0060] Flavor substances

[0061] In the present invention, the flavor substances of rice wine refer to substances that make rice wine present its unique umami taste and / or aroma. After the glutinous rice is steamed and gelatinized, it is converted into fermentable sugars under the action of enzymes in the saccharifying agent. The fermentable sugars are fermented by yeast under anaerobic conditions to convert sugars into alcohol and carbon dioxide. As the fermentation time goes by, organic acids, alcohols, esters, ketones, phenols and free amino acids are generated under the enzymatic reaction and chemical reaction of microorganisms. At the same time, due to the death of microorganisms, various substances are dissolved by the cells, which together constitute the flavor substances of the wine. The flavor substances in rice wine mainly include sugars, amino acids and polypeptides, organic acids, fatty acids, polyphenols, mineral elements, vitamins, alcohols, esters, aldehydes, acids, ketones, etc., among which, they can be divided into two categories: non-volatile flavor substances and volatile flavor substances.

[0062] Non-volatile flavor substances such as amino acids, peptides, organic acids, etc., among which nitrogen-containing substances such as peptides and amino acids are formed by the decomposition of glutinous rice protein by protease. When the nitrogen-containing substances in the wine are high, the wine appears fragrant, delicious and mellow. Amino acids have a variety of tastes such as fresh, sweet, bitter, and astringent, which give rice wine a rich taste level, making it delicious, mellow, rich, soft and coordinated. Among them, the flavor amino acids in rice wine include sweet amino acids (such as threonine Thr, serine Ser, glycine Gly, alanine Ala, proline Pro), bitter amino acids (such as valine Val, cysteine ​​Cys, isoleucine Ile, leucine Leu, methionine Met, lysine Lys, histidine His, arginine Arg, phenylalanine Phe) and umami amino acids (such as aspartic acid Asp and glutamic acid Glu).

[0063] The organic acids in rice wine mainly include lactic acid, acetic acid, tartaric acid, oxalic acid, fumaric acid, succinic acid, malic acid, etc. Organic acids are both aroma and flavoring substances in rice wine. Together with other aroma and flavoring substances, they form the unique taste and aroma of rice wine. In addition, organic acids can enhance the thickness of rice wine, reduce sweetness, and have the function of buffering and coordinating other flavor components. Rice wine with low acid content tastes light and the body of the wine is not harmonious; if the acid content is too high, the sour taste will affect the overall flavor of the wine, and the proportion of various acids will also have a greater impact on the wine. Among organic acids, acetic acid is a volatile acid. For volatile acids, the smaller the molecular weight, the softer the taste, and the larger the molecular weight, the stronger the irritation; lactic acid, succinic acid, malic acid, tartaric acid, oxalic acid, etc. are non-volatile acids, which can increase the mellowness of the wine.

[0064] The volatile flavor substances in rice wine are the main substances that constitute the aroma of rice wine, including alcohol, ester, acid / aldehyde, alkane / olefin and other substances. The aroma components are trace components in the composition of rice wine, but this component has a great influence on the flavor of rice wine. Among the volatile aroma components, the content of higher alcohols and esters is relatively high, accounting for more than 60% of the aroma components, followed by alkanes / olefins, and the content of aldehydes, ketones, acids and other phenolic substances is relatively small.

[0065] Low-heat or non-thermal sterilization

[0066] Low-heat sterilization refers to treating food at a relatively low temperature to kill microorganisms in the food. In the present invention, low-heat sterilization refers to a sterilization treatment temperature of less than 60°C.

[0067] Non-thermal sterilization, also known as cold sterilization, is a new sterilization technology that does not use heat to kill microorganisms. It can not only ensure the microbial safety of food, but also better maintain the inherent nutrients, texture, color and freshness of food, meeting consumers' requirements for food nutrition and original flavor. The following are the main low-heat and non-thermal sterilization methods suitable for the present invention.

[0068] 1. Microwave sterilization

[0069] Microwave radiation is a type of low-energy electromagnetic radiation that has thermal and electromagnetic effects on organisms. The thermal effect refers to the fact that under the action of a strong microwave magnetic field, the spatial structure of microorganisms changes or is destroyed due to the increase in their cell temperature, thereby denaturing their proteins and losing their biological activity; the electromagnetic effect refers to the fact that the high-frequency electromagnetic field radiation generated by microwaves penetrates the cell walls of microorganisms, destroys the DNA and protein molecular structures in the microbial cells, and causes the death of the microorganisms; of the above two effects, the electromagnetic effect plays a dominant role and can kill microorganisms at a lower temperature. In the present invention, the device used for microwave sterilization is a YQ36S-05 microwave sterilizer, the microwave operating frequency is 2450MHz, the microwave power is 36±5%kW, and the device performs real-time temperature measurement and control through an infrared temperature control system throughout the entire process; the parameters in the sterilization process are set so that the microwave energy received by the fermented wine is 84-124 kilojoules / L, and the sterilization temperature is 45-58°C. In the present invention, the microwave sterilization process is divided into two stages, including a temperature rise sterilization stage and a constant temperature sterilization stage. In the temperature rise sterilization stage, the temperature of the fermented wine detected by the microwave sterilizer is controlled by a program to rise to a set temperature, even if the temperature rises to 45-58°C, and the temperature rise sterilization time is 2-10min; in the constant temperature sterilization stage, the temperature of the fermented wine is maintained at 45-58°C, and the constant temperature sterilization time is 10-20min.

[0070] 2. High-voltage pulsed electric field sterilization (pulsed electric field, PEF)

[0071] The high-voltage pulse electric field is a field under which the appearance of the negative pulse wave peak forms a rapidly changing pressure on the cell membrane, loosens its structure, and synergizes with the positive pulse peak to quickly destroy the permeability of the cell membrane and inhibit microorganisms. In the present invention, the high-voltage pulse electric field device used is OSU-4L, and the pulse parameters are: electric field intensity of 30-40 kV / cm, number of pulses of 50-100, pulse width of 10-40 μs, pulse frequency of 500-1000 Hz, and treatment time of 100-150 μs.

[0072] 3. Plasma sterilization technology

[0073] Plasma is an ionized gaseous substance composed of atoms deprived of some electrons and positive and negative electrons generated after the atoms are ionized. It is divided into high-temperature plasma and low-temperature plasma. There are many hypotheses about the sterilization mechanism of plasma. It may be that the cell membrane is destroyed by charge discharge, or a large amount of ultraviolet rays generated during the formation of plasma destroy the genetic material of microorganisms, causing the death of microorganisms. Plasma sterilization has the advantages of low sterilization temperature, fast sterilization speed and simple operation. The low-temperature plasma device used in the present invention is a dielectric barrier discharge low-temperature plasma (Nanjing Suman Plasma Technology Co., Ltd.), with a processing frequency of 5 to 10 kHz, a processing air gap spacing of 5 to 15 nm, a processing power of 30 to 50 W, a processing time of 5 to 15 min, and a processing temperature of room temperature.

[0074] 4. Radiation sterilization

[0075] Radiation sterilization technology uses electron rays, X-rays, gamma rays and radioactive isotopes in electromagnetic waves to sterilize the skin. 60 Co and 37 The method of killing microorganisms with Cs rays has the basic function of destroying the DNA or cell membrane of microorganisms and achieving the sterilization effect by interfering with the metabolism of microorganisms. It has the advantages of high sterilization efficiency, wide application range, time saving and cost saving. In the present invention, the use of 60 The sterilization was carried out in a Co radiation sterilizer (Yunnan Huayuan Nuclear Radiation Technology Co., Ltd.), with a radiation dose of 5 to 20 kGy and an irradiation time of 15 to 30 min.

[0076] 5. Ultrasonic sterilization

[0077] Ultrasonic sterilization refers to the use of sound waves with a frequency greater than 20kHz to treat food, which kills bacteria, inactivates viruses, and inhibits enzyme activity through the mechanical and chemical effects of ultrasound. In the present invention, the ultrasonic sterilization device used is an SB-5200-DTD ultrasonic sterilizer, Ningbo Xinzhi Biotechnology Co., Ltd., with an ultrasonic power of 40-200W, a processing temperature of 20-40°C, and a processing time of 5-20min.

[0078] 6. Ultraviolet sterilization

[0079] The ultraviolet radiation causes the DNA of microorganisms to be cross-linked, preventing DNA from unwinding and replicating, and inhibiting the reproduction of microorganisms. The ultraviolet sterilization device used in the present invention is an MRC-250B intelligent artificial ultraviolet climate box (Shanghai Baidian Instrument Equipment Co., Ltd., Philips low-pressure ultraviolet lamp), with a radiation power of 10-40W, a radiation distance of 5-10cm, and a radiation time of 10-30min.

[0080] 7. Ultra-high pressure (UHP) sterilization

[0081] Ultra-high pressure technology refers to the use of water or other fluid media as a medium for transmitting pressure at room temperature or mild heating conditions, using 100-1000MPa pressure to treat food, inactivate enzymes, proteins, starch and other macromolecular substances in food, and kill bacteria and other microorganisms in food. The ultra-high pressure sterilization equipment used in the present invention is HPP600MPA / 3L, Baotou Kefa High Pressure Technology Co., Ltd., and the parameters are set as follows: treatment temperature 20-35°C, treatment pressure 300-450MPa, and pressure holding time 5-25min.

[0082] 8. Pulse magnetic field sterilization

[0083] Pulse magnetic field sterilization is sterilization using strong magnetism at room temperature. The device is mainly composed of an infusion tube and a spiral coil added to the outside. When the material passes through the infusion tube, the microorganisms in the material are killed by the generated magnetic induction intensity of 2-10T. The pulse magnetic field sterilization device used in the present invention is a HSM-S20 pulse strong magnetic field device, with a voltage range of 0-2.0kV, a magnetic flux range of 0-4.22T, a time interval between two pulses of 15s, and parameter settings: the number of pulses is 5-25, the magnetic field intensity is 2-10T, and the pulse width is 5-25ms.

[0084] When the present invention prepares fresh rice wine by adopting the above-mentioned different sterilization methods, it is unexpectedly found that different sterilization methods will have different effects on different flavor substances in the rice wine, thereby having a certain impact on the flavor and taste of the rice wine. DETAILED DESCRIPTION

[0085] The following is a more detailed description of the present invention in conjunction with the following embodiments. It should be understood that the implementation of the present invention is not limited to the following embodiments, and any modifications and / or changes made to the present invention will fall within the scope of protection of the present invention.

[0086] In the present invention, unless otherwise specified, all parts and percentages are weight units, and all equipment and raw materials can be purchased from the market or are commonly used in the industry. Unless otherwise specified, the methods used in the embodiments are general techniques in the art. SA402B electronic tongue (equipped with 2 reference electrodes and 5 taste sensors, Japan Insent Co., Ltd.), internal solution, reference solution, anion solution, cation solution and pretreatment solution were purchased from Japan Insent Co., Ltd.

[0087] Example 1

[0088] A method for preparing fresh rice wine mainly comprises the following steps:

[0089] (1) soaking rice: select fresh glutinous rice without mold, remove dust, husk and other debris attached to the surface of the rice grains, add water to the glutinous rice so that the mass ratio of glutinous rice to water is 1:2, and soak at room temperature for 10 hours;

[0090] (2) Steaming: Steam the soaked glutinous rice for 20 minutes;

[0091] (3) Rinse: Rinse the steamed glutinous rice with tap water to separate the rice grains and cool them down so that the temperature of the glutinous rice is maintained at 30°C;

[0092] (4) Fermentation: Put glutinous rice and distiller's yeast into a fermentation tank in sequence and stir them evenly, wherein the amount of distiller's yeast added is 0.1% of the weight of the glutinous rice, and carry out stacking fermentation at 28° C. for 2 days, then add water 1 times the weight of the raw material glutinous rice, stir them evenly, and continue to keep warm and ferment at 28° C. for 2 days before terminating the fermentation;

[0093] (5) Pressing: The fermented mash is pressed with a press to separate the wine liquid and the lees, and the wine liquid obtained after pressing is filtered with a microporous membrane with a pore size of 0.30 μm;

[0094] (6) Sterilization: The filtered fermented wine was placed in a pulsed magnetic field, with the number of pulses set to 5, the magnetic field strength to 10 T, the pulse width to 25 ms, and the time interval between two pulses to 15 s;

[0095] (7) Filling: The sterilized wine is filled at low temperature and pressure by a negative pressure filling machine to obtain the finished product.

[0096] Example 2

[0097] A method for preparing fresh rice wine mainly comprises the following steps:

[0098] (1) soaking rice: select fresh glutinous rice without mold, remove dust, husk and other debris attached to the surface of rice grains, add water to the glutinous rice so that the mass ratio of glutinous rice to water is 1:3, and soak at room temperature for 15 hours;

[0099] (2) Steaming: Steam the soaked glutinous rice for 25 minutes;

[0100] (3) Rinse: Rinse the steamed glutinous rice with tap water to separate the rice grains and cool them down, so that the temperature of the glutinous rice after being rinsed is maintained at 32°C;

[0101] (4) Fermentation: Put glutinous rice and koji into a fermentation tank in sequence and stir them evenly, wherein the amount of koji added is 0.2% of the weight of the glutinous rice, and carry out stacking fermentation at 30° C. for 3 days, then add water twice the weight of the raw glutinous rice, stir them evenly, and continue to keep warm and ferment at 30° C. for 4 days before terminating the fermentation;

[0102] (5) Pressing: The fermented mash is pressed with a press to separate the wine liquid and the lees, and the wine liquid obtained after pressing is filtered with a microporous membrane with a pore size of 0.35 μm;

[0103] (6) Sterilization: The filtered fermented wine was placed in a pulsed magnetic field, with the number of pulses set to 10, the magnetic field strength to 8 T, the pulse width to 20 ms, and the time interval between two pulses to 15 s;

[0104] (7) Filling: The sterilized wine is filled at low temperature and pressure by a negative pressure filling machine to obtain the finished product.

[0105] Example 3

[0106] A method for preparing aerated fresh rice wine mainly comprises the following steps:

[0107] (1) soaking rice: select fresh glutinous rice without mold, remove dust, husk and other debris attached to the surface of the rice grains, add water to the glutinous rice so that the mass ratio of glutinous rice to water is 1:2, and soak at room temperature for 12 hours;

[0108] (2) Steaming: Steam the soaked glutinous rice for 20 minutes;

[0109] (3) Rinse: Rinse the steamed glutinous rice with tap water to separate the rice grains and cool them down so that the temperature of the glutinous rice is maintained at 30°C;

[0110] (4) Fermentation: Put glutinous rice and distiller's yeast into a fermentation tank in sequence and stir them evenly, wherein the amount of distiller's yeast added is 0.1% of the weight of the glutinous rice, and carry out stacking fermentation at 28° C. for 2 days, then add water 4 times the weight of the raw material glutinous rice, stir them evenly, and continue to keep warm and ferment at 28° C. for 5 days before terminating the fermentation;

[0111] (5) Pressing: The fermented mash is pressed with a press to separate the wine liquid and the lees, and the wine liquid obtained after pressing is filtered with a microporous membrane with a pore size of 0.40 μm;

[0112] (6) Sterilization: The filtered fermented wine was placed in a pulsed magnetic field, with the number of pulses set to 15, the magnetic field intensity set to 5 T, the pulse width set to 10 ms, and the time interval between two pulses set to 15 s;

[0113] (7) Filling and aeration: The sterilized wine is filled at low temperature and pressure by a negative pressure filling machine. Purified food-grade CO2 gas is injected during filling to make the gas concentration in the fermented wine reach 2g / L. The CO2 pressure is controlled at 0.05-0.08MPa during aeration to obtain the finished product.

[0114] Example 4

[0115] A method for preparing aerated fresh rice wine mainly comprises the following steps:

[0116] (1) soaking rice: select fresh glutinous rice without mold, remove dust, husk and other debris attached to the surface of rice grains, add water to the glutinous rice so that the mass ratio of glutinous rice to water is 1:3.5, and soak at room temperature for 18 hours;

[0117] (2) Steaming: Steam the soaked glutinous rice for 30 minutes;

[0118] (3) Rinse: Rinse the steamed glutinous rice with tap water to separate the rice grains and cool them down, so that the temperature of the glutinous rice after being rinsed is maintained at 35°C;

[0119] (4) Fermentation: Put glutinous rice and koji into a fermentation tank in sequence and stir them evenly, wherein the amount of koji added is 0.3% of the weight of the glutinous rice, and carry out stacking fermentation at 30° C. for 3 days, then add water 3 times the weight of the raw glutinous rice, stir them evenly, and continue to keep warm and ferment at 30° C. for 7 days before terminating the fermentation;

[0120] (5) Pressing: The fermented mash is pressed with a press to separate the wine liquid and the lees, and the wine liquid obtained after pressing is filtered with a microporous membrane with a pore size of 0.50 μm;

[0121] (6) Sterilization: The filtered fermented wine was placed in a pulsed magnetic field, with the number of pulses set to 25, the magnetic field intensity set to 2T, the pulse width set to 5ms, and the time interval between two pulses set to 15s;

[0122] (7) Filling and aeration: The sterilized wine is filled at low temperature and pressure by a negative pressure filling machine. Purified food-grade N2 gas is introduced during filling to make the gas concentration in the fermented wine reach 6g / L. The N2 pressure is controlled at 0.05-0.08MPa during aeration to obtain the finished product.

[0123] Comparative Example 1

[0124] In this comparative example, the obtained wine was sterilized by pasteurization, the sterilization temperature was 65° C., the sterilization time was 30 min, and the other processes were the same as those described in Example 1.

[0125] Comparative Example 2

[0126] In this comparative example, the obtained wine liquid is sterilized by high temperature instantaneous sterilization method, the sterilization temperature is 130° C., the sterilization time is 5 s, and the other processes are the same as described in Example 1.

[0127] Comparative Example 3

[0128] In this comparative example, the wine obtained by fermentation was not sterilized, and the other processes were the same as those described in Example 1.

[0129] The physical and chemical indices, hygienic indices and sensory qualities of the samples obtained in the embodiments and comparative examples were tested.

[0130] (I) The amino acid ammonia content and free amino acid content of the samples obtained in the examples and comparative examples were analyzed Determination

[0131] Amino acid nitrogen: Determine amino acid nitrogen according to GB / T5009.235-2016.

[0132] Determination of free amino acids: Determine the free amino acid content according to GB / T5009.124-2016.

[0133] The experimental results are shown in Tables 1 and 2.

[0134] Table 1 Determination results of amino acid nitrogen content in different samples

[0135] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Amino acid nitrogen g / L 1.450 1.473 1.391 1.428 1.029 1.107 1.401

[0136] From the experimental results, it can be seen that the content of amino acid nitrogen in the glutinous rice wine obtained by pulse magnetic field sterilization is significantly higher than that by heat sterilization. On the one hand, it may be because the high temperature causes the amino acids and polyphenols in the wine to undergo oxidative browning, resulting in a reduction in free amino acids. On the other hand, heating will destroy the structure of amino acids, causing the loss of some amino acids, resulting in a decrease in nutritional value.

[0137] Table 2 Determination results of free amino acid content in different samples

[0138]

[0139] By measuring the free amino acid content, it is found that the content of bitter amino acids and astringent amino acids in rice wine is relatively large, which may have a certain relationship with the taste of rice wine being mainly bitter and astringent. The present invention finds that the content of umami amino acids and sweet amino acids in the rice wine prepared by the method of the present invention is higher than that of Comparative Examples 1 and 2, which may make the taste of the prepared rice wine better than that of Comparative Examples 1 and 2. At the same time, it is found that the content of umami, sweet, bitter and astringent amino acids is close to that of Comparative Example 3, indicating that the taste of the rice wine prepared by the present invention is equivalent to that of freshly brewed rice wine without sterilization treatment.

[0140] The difference in amino acid content depends on many elements. Different sterilization methods may be due to their different mechanisms of action, which may lead to the promotion of the synthesis of certain amino acids or the decomposition of certain amino acids. The specific mechanism needs further study.

[0141] (ii) Determination of the organic acid content of the samples obtained in the examples and comparative examples

[0142] Determine the total acidity with reference to GB / T13662-2018.

[0143] The contents of acetic acid, malic acid, lactic acid, succinic acid and citric acid in glutinous rice wine were determined according to GB / T5009.157-2016 method.

[0144] Table 3 Determination results of organic acid content in different samples

[0145] Components Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Total acid (g / L) 2.22 4.08 6.19 7.12 2.65 2.50 2.36 Acetic acid (mg / L) 3.37 3.24 3.30 3.27 3.25 3.57 3.11 Malic acid(mg / L) 2.69 2.73 2.70 2.60 2.25 2.39 2.50 Lactic acid (mg / L) 15.61 16.03 15.94 15.87 6.54 6.68 6.72 Succinic acid (mg / L) 17.05 16.58 16.51 16.88 15.23 15.74 16.14 Citric acid(mg / L) 4.06 3.94 3.85 3.99 3.75 3.82 3.78

[0146] It can be seen from the experimental results that the content of organic acids in rice wine is relatively high in succinic acid and lactic acid. It is found that the lactic acid content in the rice wine prepared by the method of the present invention is significantly higher than that in the comparative example. It is reported that among the organic acids in rice wine, lactic acid is relatively soft, which can bring good flavor to rice wine and enhance the mellowness of rice wine. The acetic acid taste in rice wine is often not very popular, mostly due to the introduction of too many bacteria in the brewing process. The acetic acid content is too high, which will give the drinker a feeling of sourness. It can be inferred that the rice wine of the present invention may have a mellower taste and better taste due to the increase in lactic acid content. It may be because the pulsed magnetic field can promote the glycolysis of sugars to produce lactic acid.

[0147] (III) Determination of the alcohol content, sugar content and sucrose invertase activity of the samples obtained in the examples and comparative examples

[0148] Alcohol content detection: Determined by distillation specific gravity method.

[0149] Total sugar (measured in glucose): Determine total sugar according to GB / T13662-2018.

[0150] The sucrose invertase activity was determined using sucrose invertase test paper.

[0151] Table 4 Determination results of alcohol content, total sugar and sucrose invertase activity in different samples

[0152] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Alcohol content: % (v / v) 13.3 8.8 6.2 7.6 12.0 12.6 13.2 Total sugar g / L 109.3 128.7 136.7 148.4 103.5 104.3 109.5 Sucrose invertase activity Positive Positive Positive Positive Negative Negative Positive

[0153] It can be seen from the experimental results that the alcohol content of the rice wine prepared by the method of the present invention is between 6% and 14%, the total sugar is greater than 100g / L, and the sucrose invertase is positive, which meets the evaluation standards of fresh wine.

[0154] (IV) Determination of the taste indexes of the samples obtained in the embodiments and comparative examples

[0155] SA 402 electronic tongue was used to measure the sourness, sweetness, bitterness, astringency, saltiness and umami of rice wine. The electronic tongue was equipped with 6 test sensors and 2 reference sensors, among which CAO was used to test sourness, GL1 was used to test sweetness, COO was used to test bitterness, AE1 was used to test astringency, CTO was used to test saltiness, and AEE was used to test umami.

[0156] After activation and self-balancing, the sensor is immersed in the reference solution for 30 seconds to measure the reference potential Vr, and then the sensor is immersed in the sample solution for 30 seconds to measure the sample solution potential Vs. Vs-Vr is the relative intensity value of the sample's sour, sweet, bitter, astringent, salty and umami taste; each sample is measured three times and the average value is taken. The experimental results are shown in the following table:

[0157] Table 5 Relative intensity values ​​of various taste indicators

[0158]

[0159] The results of the electronic tongue measurement showed that the rice wine was mainly astringent and bitter. The relative intensity values ​​of bitterness and astringency of the samples of Comparative Examples 1 and 2 were large, and the relative intensity values ​​of umami were small, indicating that the taste of the samples was mainly astringent and bitter, and the umami was weak. Although the samples of Examples 1-4 were still mainly astringent and bitter, the relative intensity values ​​of astringency and bitterness were significantly reduced compared with Comparative Examples 1 and 2, while the relative intensity value of umami was increased compared with Comparative Examples 1 and 2, indicating that the rice wine prepared by the present invention had a weaker bitter taste, a richer umami, and a more coordinated taste. In addition, by measuring the relative intensity values ​​of the taste indexes of the rice wine of Comparative Example 3, it was found that the taste index of the rice wine of the present invention was close to that of Comparative Example 3, indicating that the pulsed magnetic field sterilization method of the present invention makes the prepared rice wine taste better than the heat sterilization method, and the taste is equivalent to the freshly brewed rice wine that has not been sterilized.

[0160] The production process of rice wine is a complex fermentation process involving multiple microorganisms. During this process, the saccharifying enzyme in the koji hydrolyzes starch and dextrin to increase the sugars in the raw materials that are beneficial to the growth of microorganisms in the koji. At the same time, yeast and mold use sugars for alcohol fermentation. Sugars, amino acids, organic acids, a small amount of alcohols, aldehydes, etc. in the raw materials together constitute the special flavor of rice wine. The inventor speculates that different sterilization methods will have different effects on the metabolites of microorganisms, as well as on the complex reactions between the various components in the wine, such as carbonyl-amine reactions, condensation reactions, decomposition reactions, etc., thereby producing a variety of different flavoring substances, and the various different flavoring substances may have synergistic effects, or may have antagonistic effects or masking effects. Their effects on the flavor of rice wine also need further research.

[0161] (V) Sensory evaluation of samples obtained from the embodiments and comparative examples

[0162] The evaluation panel consists of 10 members. They evaluate the appearance, aroma, taste and overall coordination of the glutinous rice wine. Rinse your mouth with cold boiled water before tasting and taste it in small sips. The evaluation criteria are shown in the table below.

[0163] Table 6 Sensory evaluation standard table of glutinous rice wine

[0164]

[0165] The sensory evaluation results are shown in the following table:

[0166] Table 7 Sensory evaluation results

[0167] project Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Shape and color 23.5 23.0 23.0 23.0 23.0 22.5 23.5 Aroma and Fragrance 22.0 23.0 22.5 23.0 13.5 11.5 23.5 Taste 23.5 23.5 23.0 24.0 13.5 12.5 21.5 Wine Style 23.5 23.5 23.0 24.0 14.0 12.0 22.5 Total score 92.5 93.0 91.5 94.0 64.0 58.5 91.0

[0168] It can be seen from the sensory evaluation results that the rice wine of the present invention is significantly better than Comparative Example 1 and Comparative Example 2 in terms of color, aroma, flavor and wine style, and is close to Comparative Example 3.

[0169] (VI) Testing the samples obtained from the embodiments and comparative examples for health indicators

[0170] Table 8 Hygiene index test results

[0171]

[0172]

[0173] Among them, the total bacterial count was determined according to GB4789.2-2016, and the coliform group was determined according to the second method of GB4789.3-2016. It can be seen that the sanitary index of the rice wine obtained by the pulse magnetic field sterilization treatment of the present invention meets the national standard and is equivalent to the heat sterilization effect, while the rice wine of comparative example 3 does not meet the sanitary index requirements because it is not sterilized.

[0174] (VII) Detection of quality changes during storage at room temperature

[0175] A professional evaluation team conducted a sensory evaluation on rice wine stored at room temperature for a certain period of time, including changes in morphology, color, smell, taste, etc. If the color of the rice wine changes and the smell has an ozone taste, it indicates that its quality has deteriorated. The quality changes of rice wine at different storage times are shown in the following table. It can be seen that the fresh rice wine of the present invention can be stored at room temperature for more than 12 months. In addition, the physical and chemical properties of the rice wine stored for a specific time were tested, and it was found that the amino acid nitrogen, organic acid, total sugar, amino acid content, etc. in the rice wine prepared by the present invention are relatively stable, while the organic acid content and amino acid content in the heat-sterilized rice wine are significantly reduced after storage for 6 months. This is because the various components of the rice wine undergo complex changes during storage, which may be the reaction of the higher alcohols in the wine with the organic acids, resulting in a decrease in the organic acid content.

[0176] Table 9 Changes in rice wine quality with storage time

[0177] Storage time Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Storage for 10 days normal normal normal normal normal normal Start to get bad Storage for 30 days normal normal normal normal normal normal Go bad Storage 3 months normal normal normal normal normal normal － Storage 6 months normal normal normal normal normal normal － Storage for 12 months normal normal normal normal normal normal －

[0178] The present invention discloses a new type of rice wine by optimizing the sterilization method in the rice wine preparation process. The present invention adopts a pulsed magnetic field to sterilize the wine liquid, effectively killing microorganisms while ensuring that the activity of sucrose invertase in the rice wine is not affected, and prepares a fresh rice wine that meets the standards of fresh wine, thereby providing a new type of rice wine that can extend the shelf life and ensure fresh taste and rich nutritional value.

[0179] The above description is only a preferred embodiment of the invention and is not intended to limit the invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the invention should be included in the protection scope of the invention.

Claims

1. A method for increasing the lactic acid content in fresh rice wine by using pulse magnetic field sterilization, characterized in that: The following steps are involved: 1) Processing glutinous rice to obtain cooked glutinous rice: washing the glutinous rice and soaking it at room temperature for 10-18 hours, steaming the soaked glutinous rice for 20-30 minutes, and then cooling it to 30-35° C. by rinsing; 2) mixing the cooked glutinous rice with 0.1-0.3% of distiller's yeast by weight of the glutinous rice, and fermenting at 28-30° C. for 2-3 days, adding water 1-4 times the weight of the glutinous rice, stirring evenly, and continuing to ferment for 2-7 days, and stopping the fermentation when the alcohol content of the fermented wine is 6-14% vol, the total sugar content is 10-160 g / L, and the total acid content is 0.5-10 g / L, and the fermented wine is separated by filter pressing or centrifugation to obtain fermented wine, and filtering the fermented wine by using a microporous membrane with a pore size of 0.30-0.50 μm to separate the fermented wine; 3) The fermented wine liquid is placed in a pulsed magnetic field for sterilization to obtain fresh rice wine; the parameters in the sterilization process are set as follows: pulse number 5-25, magnetic field strength 2-10T, pulse width 5-25ms, wherein the time interval between two pulses is 15s.

2. The method according to claim 1, characterized in that: After the sterilization treatment, the method further includes the step of aerating the fermented wine so that the gas concentration in the fermented wine reaches 2-6 g / L; the gas is CO2, N2 or a mixture of CO2 and N2 in a certain proportion.

3. A fresh rice wine, characterized in that: It is prepared by the method according to any one of claims 1 to 2.

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