The Study On The Key Aroma Compounds And Influencing Factors During The Aging Process Of Chinese Rice Wine

Chinese rice wine(rice wine),also known as “aged wine”,of which the characteristic is more harmonious after aging.Aging process is the longest time-consuming procedure for the production of rice wine,having a decisive influence on the quality and value of rice wine.At present,the aging of Chinese rice wine still mainly follows the traditional way of storing,using pottery jars,which may cause the prominent problem of high labor intensity,high cost,large loss and unsafe quality control,and those problems seriously affected the production efficiency and industrial level of rice wine.One of the reasons is the lack of understanding of the chemical characteristics as well as formation mechanism of the aroma in aged rice wine,what's more,the lack of theoretical basis for the control of flavor quality in the aging process makes it difficult to promote the use of advanced wine storage technologies such as large cans storage.Therefore,the analysis of the essence of aroma compounds in the aging process of rice wine and the understanding of environmental factors affecting the formation of aroma compounds in aging process of rice wine are both of great significance in enriching the theory of the unique flavor chemistry of rice wine and the guiding the production practice.The study focused on the characteristics and formation rules of the aroma compounds during rice wine aging process as the basic scientific issues.Sensomics was adopt to analyze the mystery of aged aroma of rice wine.The changing rules and influence factors of key aroma compounds in the aging process of rice wine was also studied.The study will provide a substantial basis for further research into the control of flavor during the aging process for rice wine.The following is the main contents and conclusions:(1)The method of sensomics was applied to analyze important aroma compounds in aged rice wine.It is clear that the aged rice wine mainly has the aroma characteristics of caramel,herb and smoky through scientific sensory analysis.The aroma extract dilution analysis(ADEA)was applied to analyze the aroma differences between young and aged rice wine.A total of 45 aroma compounds with flavor factor(FD)?64 were identified,including six aroma compounds which were first identified in rice wine.It was found that the aroma compounds such as sotolon,vanillin,4-vinylguaiacol and methional differ greatly in the young and aged wine according to FD value.And the OAV analysis suggested that 3-methylbutanoic acid,vanillin,butanoic acid and sotolon caused the difference of aroma of the young and aged rice wine.The aroma recombination and aroma omission experiment verified that the key aroma compounds,such as vanillin,3-methylbutanal,sotolon and benzaldehyde made important contributions to the overall aroma of aged rice wine.(2)To clarify the changes of important aroma compounds during the aging process of rice wine and the influence of environmental factors on its formation.It was found that the content of aldehydes,ketones,lactones and phenolic aroma compounds with the aging time showed regular changes.The key aroma compounds such as benzaldehyde,3-methylbutanal,1,1-diethoxyethane,sotolon and vanillin increased significantly with the aging time,and other key aroma compounds like 4-vinylguaiacol and methional significantly decreased with aging time.Through the research on the two most critical environmental factors affecting the aging process of rice wine,the effects of temperature and oxygen on the formation of key aroma compounds during the aging process were described.The results showed that the most important aroma compounds were found to have significant increase after passing 50 °C,such as sotolon.The formation of other key aroma compounds,like benzaldehyde,1,1-diethoxyethane,3-methylbutanal and vanillin was not only affected by temperature,but also greatly affected by oxygen,which verified the important role of the permeability characteristics of pottery jar on the aging of rice wine.(3)To clarify the formation mechanism and the change rules of the key aroma compound(sotolon)during the aging process of rice wine.A method for rapid determination of key “caramel aroma” compound(sotolon)in rice wine by liquid-liquid microextraction(LLME)combined with gas chromatography-mass spectrometry(GC-MS)was developed.The method of characteristics are simple,and rapid,which can meet the needs of batch rapid detection of sotolon in rice wine.In addition,the sugar content and oxygen are not key factors affecting the formation of sotolon in rice wine.At the same time,a preliminary exploration had been made on the formation mechanism of sotolon in rice wine.It was determined that 2-ketobutyric acid might be one of the important precursors forming sotolon in rice wine.