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As early as the mid-1970s, China proposed to actively develop low-alcohol liquor with a volume fraction of 40% or less. However, with the decrease of alcohol content, white turbid, Precipitation and other issues. However, with the birth of the separation membrane, this technical problem has also been effectively solved. The separation membrane is a special, selectively permeable, thin layer that allows one or more substances in the fluid to pass through while the other substances are not permeable, thus concentrating and separating and purifying . 1. Classification and characteristics of membranes Membrane structure is divided into symmetrical membrane, asymmetric membrane and composite membrane; according to their different pore size (or intercepted molecular weight), the membrane can be divided into microfiltration membrane, ultrafiltration membrane, nanofiltration Membrane and reverse osmosis membranes; According to the different materials, can be divided into inorganic and organic membranes. Has been developed and applied membrane separation techniques are: microfiltration, ultrafiltration, nanofiltration, reverse osmosis, electrodialysis, gas separation. 2. Application of Membrane Components and Comparison of Their Main Features Membrane modules commonly used in industry include tubular components, hollow fiber membrane modules, plate-frame membrane modules and membrane modules. The performance comparison is shown in Table 2. 3. Membrane separation technology in the application of low liquor turbidity The original liquor in the decline of turbidity occurs mainly for the following two reasons: First, the three kinds of high boiling point alcohol-soluble and insoluble in water, the nature of the unstable senior Fatty acid ethyl ester (ethyl palmitate, ethyl oleate, linoleic acid ethyl ester) in the process of lowering the solubility decreased precipitation, resulting in turbidity; Second, fusel oil with alcohol decreased, the solubility of precipitated precipitation, appear cloudy. In addition, high water hardness, metal ions and hexyl hexanoate can also cause white wine turbidity, loss of light. To make the body clear, it is necessary to remove the polymer from the body. In recent years, membrane separation technology gradually applied to the brewing industry, especially in the application of turbidity of low liquor, not only make the body of the turbid material removed, but also does not affect the flavor of wine, more and more attention by the wineries . 3.1 The application of composite microfiltration membrane in low liquor turbidity removal The composite microfiltration membrane is composed of fiber, activated carbon, diatomaceous earth and film-forming agent. During the process of microfiltration membrane production, the three-dimensional network structure of fiber intertwined thickness Microfiltration membrane skeleton, activated carbon diatomite adsorbed on the fibers, precipitated in the fibers, the entire filter filled with criss-crossing multi-branched small channels, the film formed by the activated carbon and activated carbon structure bonded, So that it can withstand and pass the pressure. Composite microfiltration membrane filtration of low-grade liquor, in its production process, there must be some pressure, this pressure ensures the functional adsorption of composite microfiltration membrane is a deep adsorption, each of the large and small micropores are adsorption, Each wine molecules are adsorbed or go through its micro-pore channels, this exercise stroke, completely guaranteed the low degree of liquor in addition to turbidity thoroughly and completely. In 2001, Sichuan Quanxing Co., Ltd. Lai Deng? J and other 64-degree wine base will be reduced to 28 degrees after the composite microfiltration membrane, frozen at minus 18 ° C for one week is not cloudy, there is loss of light, soft taste, no Water, pure and sweet, the physical and chemical indicators also meet product quality standards. In addition, Zhu Jianhong is equal to the application of newly developed domestic activated carbon composite microfiltration membrane in 2001, effectively filtering off the white turbidity produced by liquor due to descending surface, and can effectively remove or reduce the bitter, spicy and unpleasant taste of wine to make the alcohol and ; Luo Huibo also carried out a comparison of different pore size membrane filtration test and found that the use of low-alcohol liquor pore size 0.22μm membrane filtration, a high degree of white wine with a pore size of 0.45μm membrane filtration can enhance the anti-freezing and natural stability of wine samples, And less trace elements loss. 3.2 ultrafiltration membrane in the application of low liquor turbidity Ultrafiltration membrane either box-type or hollow fiber type, the surface of the membrane are covered with nano-sized pores, the liquid under the action of the driving force through the membrane Of the microporous solution of the material grading screening, to achieve the purpose of turbid separation membrane ultrafiltration process for the dynamic process, the membrane is not blocked easily, you can continue to use for years. As early as 1995, Sun Rongquan applied the ultrafiltration technology to the study of turbidity removal of low-alcohol liquor, and discussed the influence of process flow, structure design and operation parameters on the performance of the ultrafilter. Lu Xiaofeng et al. 0.64m2 HPM64 plate-frame ultrafiltration membrane, the selection of molecular weight cutoff 10000, 30000, 50000 three kinds of specifications of ultrafiltration membrane for sake filtration, at the same time, also carried out the impact of ultrafiltration yield related factors screening test; Zhu Zhiling and other hollow fiber ultrafiltration technology to remove the whiteness due to the turbidity after the drop, the phenomenon of loss of light, and carried out economic analysis, indicating that the filtering effect is good, low operating costs; Shi Hongwen other inorganic (ceramic) film The filtration module is applied to liquor turbidity removal and the optimum process conditions are determined. The filtration module has the advantages of simple process, good effect and low energy consumption, and is easy to control membrane fouling and has good market prospect. Deng Jing et al compared alcohol special carbon, corn starch and membrane filtration in 2006 to reduce the effect of turbidity treatment during liquor degradation. The results showed that liquor special charcoal and membrane filtration treatment liquor better, the combination of the two Up with the economy, the effect is good, the best way is to reduce the base wine before the first membrane filtration, and then with alcohol-based carbon base liquor after mixing, and finally through the membrane filtration. The resulting wine taste coordination, to maintain the original style. 4. Conclusion In summary, membrane separation technology in the low liquor turbidity has great application prospects, has become an important new technology in the brewing industry, improve the impurity removal rate, maintain quality, reduce energy consumption and Processing time, process improvement has shown great potential and application value, with good application prospects. Although the application of membrane separation technology in the field of wine there are still some problems, such as the choice of membrane material less than the number of domestic membrane filtration system manufacturers less, membrane cleaning and recycling of contaminated technology needs to be further improved, However, with the continuous development of new membrane materials, advances in membrane preparation technology and the continuous deepening of basic research on membrane separation processes, the existing problems will certainly be solved.