Study On The Process Of Liquid Fermentation Of Hong Qu Glutinous Rice Wine Brewing

With the high glucoamylase producing Rhizopus oryzae screened from Fujian White Koji as the start stain, through shaking flask fermentation and small scale fermentation in fermentor, the production process of Rhizopus oryzae was optimization. The Rhizopus oryzae yielded was used in liquid fermentation of Fujian Hong Qu glutinous rice wine. The fermentation process was optimized and the changes of microorganism and physical and chemical properties were also studied. Then the optimized liquid fermentation process was used in small scale brewing of Fujian Hong Qu glutinous rice wine. Major results of this study were concluded as followed:1. The fermentation conditions for Rhizopus oryzae were optimzed. The maximum glucoamylase activity were obtained in the following conditions:250mL erlenmeyer flask with 50mL optimized medium, the medium contained 500mL/L liquefied rice starch,5.0g/ L ammonium chloride,1.0 g/L potassium dihydrogenphosphate,0.3g/L magnesium sulfate, 0.4g/L ferrous sulfate and 8.0g/L carbonate calcium, and the initial pH of flask culture was 6.5, fermentation temperature was 32℃, shake speed was 150 rpm and inoculation amount was 5%(v/v). For 48 hours, the activities of glucoamylase reached up to 196.6 U/mL. Based on these conditions, the expanded fermentation production of Rhizopus oryzae in 5L fermentor was also optimzed. The optimal level of stirring rate and aeration was 500rpm and 200 L/h, respectively. Under the optimized fermentation conditions, the glucoamylase activity could reach 263.73U/mL, which increased by 34.1% than the shake flask fermentation.2. Using the liquid Rhizopus oryzae starter, liquid Monascus starter previously developed in our group and liquefied rice instead of traditional solid starter and steamed rice, the technology of liquid fermentation for Hong Qu Glutinous rice wine was establelished. Based on the physicochemical index and sensory evaluation, the process parameters were optimized:with addition of 9mL of the liquid Monascus starter and 2mL of the liquid Rhizopus oryzae starter,100% liquefied rice was fermented for 5 days, then yeast was added and sealed fermented for 15 days. The wine brewed in this process coincided with the national standard. The mechanism of brewing was analyzed by observation of the changes of microorganism physical and chemical properties.3. The process was expanded in 5L fermentor. The changes of microorganism and physical and chemical properties during brewing were consistent with those in shake flask brewing. The Hong Qu Glutinous rice wine brewed in this process coincided with the national standard, and was identified as dry rice wine. Compared with the dry rice wine purchased in local market, the wines brewed in lab had higher scores of sensory evaluation. The wines brewed in lab were more fragrant and smooth, but lacked of the characteristic mellow smell and richness of rice wine.Gas chromatography analysis indicated that the wines brewed in lab had lower amount of characteristic volatile aroma components, and higher amount of total volatile aroma components.In conclusion, liquid fermentation of Hong Qu glutinous rice wine was feasible. The wine brewed in this process smelled fragrant and tasted smooth, with good development potential. This study not only provides the theoretical basis for the mechanized and automatic production of Hong Qu Glutinous rice wine, but also provides a vital significance for the quality control and improvement of Hong Qu Glutinous rice wine and the development of novel Hong Qu Glutinous rice wine as well.