Studies On The New Technology Of Making Draft Rice Wine By Ultrafiltration

Nowadays, the brewing processes of unpasteurized beer, "draft" sake and wine have already matured, but draft rice wine making has not been studied thoroughly. And draft rice wine was defined as rice wine, which was not heated after fermentation. Based on this, the aim of this paper was to develop a new type product that suited the tide and the modern taste.According to the requirement of draft rice wine making, it was indispensable that some remaining enzymes were removed in draft rice wine making. In the paper, the remaining enzymes in draft rice wine, such as α-amylase, glucoamylase and proteinase, could be effectively removed by ultrafiltration. And the removing ratios were 100%. In addition, the contents of physico-chemical indexes still conformed to China National Standards (Rice wine, GB/T13662-2000), which showed that draft rice wine by ultrafiltration was not changed the intrinsic quality of rice wine and was still provided with the typical characteristic of rice wine.Compared with raw rice wine, the content of protein, polyphenol, iron ion and pentosans, which were connected with the non-biological stability, was decreased in draft rice wine. For example, the effect on removing high molecular protein was obvious, and the removing ratios of high molecular protein and pentosans were 68.96% and 40.61%, respectively. With the decrease of these components, the non-biological stability of draft rice wine was enhanced or improved. And the scattering experiment indicated that the mean size of particles of draft rice wine was decreased from 887.5 nm to 2.7 nm, which was in favor of maintaining the stability of draft rice wine. And the sanitation indexes of rice wine samples before and after ultrafiltration were determined. The result showed that draft rice wine did not exist microorganism. This resulted in the enhancement of the biological stability of draft rice wine. Meanwhile, the probative experiments of four kinds of stability demonstrated that the total stability was enhanced to a certain extend.The staling flavor in draft rice wine was determined, and the relationships between TBA and Eh, conductivity were studied. The results showed that rice wine sample which TBA was high, its conductivity was high and its Eh was low. TBA was higher, and the staling flavor was stronger. Compared with Rice Wine Aged 5 Years and decocted rice wine, TBA and conductivity of draft rice wine were lower, and Eh and RSV were higher. The concentrations of volatile flavor compounds, amino acids and oligose in draft rice wine were analyzed and the flavor of draft rice wine was evaluated. The results showed that in draft rice wine and Rice Wine Aged 5 Years, the flavor intensity of alcohols did not greatly change. But in draft rice wine, the flavor intensity of esters was weaker and the proportion of alcohols to esters was higher. And compared with Rice Wine Aged 5 Years, the concentrations of amino acids and oligose of draft rice wine were lower. These demonstrated that draft rice wine had fresh and mild taste and little staling flavor.Making draft rice wine by ultrafiltration accorded with the requirement of draft rice wine making, and the brewing process was feasible. The processes before fermentation were not changed, so existing equipments could still be used in draft rice wine making, and the cost of equipments that used in making draft rice wine by liquification was decreased. It was feasible to make draft rice wine, which provided with the characteristic of existing rice wine. And it also offered a broad prospect of developing new products.