Study On Preparation Technology And Quality Characteristics Of Brown Rice Wine

Brown rice is a typical whole grain food.The retention rate of brown rice on total rice nutrition is much higher than that of polished white rice.Brown rice contains many active functional ingredients that can effectively prevent chronic diseases such as diabetes and hyperglycemia.However,brown rice is less accepted by consumers due to poor taste and flavor.Sweet rice wine is a kind of popular traditional fermented cereal food in China with sweet and sour taste and unique flavor.The purpose of this paper is to improve the flavor of brown rice and the nutritional properties of glutinous rice wine.In this paper,the preparation of brown rice wine and its changes of flavor substances and nutritional components during fermentation were studied.The quality of brown rice wine and glutinous rice wine were compared.The main results were as follows:The single-factor experiment,orthogonal experiment combined with fuzzy mathematical sensory evaluation were used to optimize the preparation process of brown rice wine.Results showed that the factors such as soaking time,cooking time,added amount of koji,fermentation time,and fermentation temperature have a greater effect on the quality of brown rice wine.The best preparation conditions were soaking of 8 h,cooking of 35 min,addition amount of 0.4% koji(w/w),and fermentation at 35°C for 60 h.GC-MS,GC-O,E-Nose and sensory evaluation were used to explore the overall flavor profile and flavor compounds of brown rice wine during fermentation.Results showed that flavor of brown rice was significantly changed after fermentation.47 kinds of flavor substances were detected in brown rice wine.And 29 kinds of volatile components could be recognized by GC-O.Six components such as ethanol and ethyl butyrate contribute greatly to the flavor of brown rice wine.The correlation between flavor components and sensory attributes was analyzed by Partial least squares regression analysis(PLSR).Results showed that flavor components such as ethanol and ethyl butyrate had a strong positive correlation with fruit and floral aroma of wine.Components such as 2-pentylfuran,methylheptenone have a strong positive correlation with rice aroma.The changes of nutritional components during fermentation was further studied.Results showed nutrients changed significantly during fermentation.The alcohol content and soluble solid content increased significantly during the fermentation period.Macromolecular polysaccharides were gradually degraded into small molecular sugars.The protein molecules were gradually hydrolyzed to cause a significant increase in peptides and amino acids.And there was significant increase in the content of functional components such as GABA and polyphenols.The GABA content of brown rice wine fermented for 60 h was about 4.15 times that of brown rice.Brown rice wine contained various organic acids.By comparing theDose-over-Threshold factors(DoT)of different organic acids,it could be observed that the increase in tartaric acid and acetic acid was the main reason for the increasing acidity during fermentation.The quality of brown rice wine and traditional glutinous rice wine were comparatively analyzed.The results showed that both flavors are mainly alcohols and esters,but brown rice wine brewing flavors are more diverse.Nevertheless,the flavor of brown rice wine was richer and sweeter identified by electronic tongue system(E-Tongue).And the content of nutritional functional components such as GABA,total polyphenols and free amino acids are all higher than glutinous rice wine to varying degrees.In addition,brown rice wine brewing shows a stronger antioxidant capacity.These results indicated that preparation of rice wine with brown rice as raw material can satisfy consumers' pursuit of both flavour and nutrition.