Study On The Stability Of Anthocynins In Black Glutinous Rice Wine

Anthocyanin is an important bioactive component in black glutinous rice wine,which endows the wine with unique color and function.However,the anthocyanin in black glutinous rice wine is unstable.Therefore,it is necessary to explore the stability of anthocyanins in black glutinous rice wine.Through the study on the selection of detection methods,stability,photodegradation kinetics and the dynamic change during the brewing process of the total anthocyanin in black glutinous rice wine,it provides guidance for the practical production and storage of black glutinous rice wine,reduces the loss and degradation of anthocyanins and provides scientific theoretical basis for further research and development of high-quality black glutinous rice wine.The experimental results are as follows:1.The determination method of anthocyanin in black glutinous rice wine was studied.The results showed that the three methods for determination of anthocyanin in black glutinous rice wine were 30?,the equilibrium time was 40 min,and the measurement wavelength was 511 nm.The optimum pH for the single pH method and the subtraction method was 0.8,and the pH optimum for the pH differential method was 0.8 and 4.5.Three methods could directly measure the total anthocyanin content of black glutinous rice wine,and the precision is good.The pH differential method has the highest precision among them.The alcohol content of black glutinous rice wine had no effect on the accuracy of the three methods.The high concentration of glucose had different degrees of color protective effect on anthocyanins of black glutinous rice wine.2.The dynamic variation of anthocyanins in the fermentation process of black glutinous rice wine was studied by pH differential method.Compared with the Lin-fan method,the results showed that the Tan-fan method can reduce more losses of anthocyanin.The addition of koji has no obvious effect on the anthocyanin concentration in black glutinous rice wine.The concentration of anthocyanin was decreased during brewing and aging in black glutinous rice wine.The anthocyanin concentration in the saccharification stage was obviously decreased with time.During the fermentation of wine,the anthocyanin concentration did not change significantly.The anthocyanin reduced by about 40%-60%from the initial stage of the pre-fermentation to the end of the fermentation.The anthocyanin concentration decreased steadily and slowly during the aging period.3.The anthocyanin content was taken as an index to study the stability of anthocyanins of black glutinous rice wine during storage.The results showed that the black glutinous rice wine anthocyanins had good stability to low concentrations of K⁺,Fe²⁺and Ca²⁺.Especially,it showed excellent stability to various concentrations of K⁺,extremely unstable to high concentrations of Fe²⁺,relatively sensitive to Cu²⁺,and stable in medium of low pH value of anthocyanin of black glutinous rice wine.Anthocyanin in black glutinous rice wine has poor oxidation resistance,and H₂O₂ will cause it to fade and degrade.Ethanol had no effect on the stability of anthocyanins in black glutinous rice wine.High concentrations of glucose was beneficial to the preservation of anthocyanin in black glutinous rice wine.4.The degradation of anthocyanins in black glutinous rice wine under different light and temperature conditions was discussed in depth,and the corresponding degradation kinetic equations were obtained.The results showed that the anthocyanins of black glutinous rice wine were both poor in light stability and thermal stability.High temperature and strong light can seriously reduce its stability.The photo-thermal degradation accords with the first-order kinetics law.The order of the rate constant of anthocyanin degradation in black glutinous rice wine is as follows:k_{Outdoor daylight}>k_{Indoor bulb light}>k_{Indoor natural light}>k_{Indoor shade};k_100?>k_90?>k_80?>k_70?>k_60?.The thermal degradation rate of anthocyanins in black glutinous rice wine was most sensitive to the temperature reaction at 80?and90?,and the temperature coefficient Q₁₀0 was 3.3482.The activation energy required for thermal degradation anthocyanins in black glutinous rice wine was 90.14 kJ/mol.