Ethanol-turbidity Test Of Rice Wine And Its Mechanism Research

In this paper, the non-biological stability of rice wine, which is the most important factor affecting on rice wine's sediment, has been researched. By studying the relationship between rice wine's non-biological stability and its components (protein, polyphenol, Fe³⁺, polysaccharide etc.), a new detection method named rice wine's ethanol-turbidity test is set up. This method can be used to fast check on the non-biological stability of rice wines. The experiment results are shown as follows:(1) The main factors affecting on rice wine's sediment have been studied: when putting bovine serum albumin(BSA, 68KD) in rice wine sample, the turbidity of rice wine can reach its max, but if go on adding BSA, it would fall instead of rise. A few tannin that is put in rice wine could make the turbidity rise up to 30% , and malysite would make the turbidity of rice wine go on rising until sediment . But adding polysaccharide in rice wine sample the turbidity has no obvious change. Research results and data analysis indicate that the polymer of protein and polyphenol is the primary factor affecting on the non biological stability of rice wine.(2) The new method of rice wine's ethanol-turbidity test has been found: 1～10 ml ethanol is separately added to 10 ml clarified rice wine samples, stirring 1min in high speed by mixer and then the sample is placed for 2 hours in room temperature, at last the transmittance (T) of mixed rice wine is measured by spectrophotometer with the wavelength of 800nm. and the turbidity of rice wine is defined as (1-T)%. The curve of "S"shape would be gotten, with the abscissa representing ethanol adding percent quantities and the ordinate showing turbidities of mixed rice wine. There exists a saltation range of turbidities in the figure, when adding ethanol percent quantities from 40% to 60%, and in this range with same ethanol adding percent quantities, it is found that has lower turbidities of mixed rice wine and better stabilization of rice wine.(3) The different aging basic rice wines and purchasing rice wines are treated by frozen filtration and adding clarify reagents, and then the treated and untreated samples of rice wines analysed with ethanol-turbidity test. The experiment results show that the non-biological stabilities of treated samples are better than that of untreated samples.(4)On the standard of adding 50% ethanol, the turbidities of different rice wines purchasing from supermarket are mensurated. According to the turbidities, rice wines'non-biological stabilities are divided into three level from best to worst, which is well identical with their results obtained from cold cloudy test and destroying treatment.(5) The possible mechanism of ethanol-turbidity test have been studied: The experiment shows that, after ethanol-turbidity test, the contents of polysaccharide,α-amino nitrogen, Fe³⁺ has no obvious change and high molecular protein decreased largely, but protein of molecular weight less than 1000 increased slightly. Total contents of protein and phenol varies, in rice wines of bad non-biological stabilities, both of them manifold, and vice versa. It is considered that ethanol could force the high molecular protein to deposit and destroy the balance of protein + phenol = polymer, which is the primary factor affecting on non-biological stabilities of rice wine.