Research On The Chemical Indexes Of Southern Grapes And Fermentation Engineering Of Wine Without Sulfur Dioxide

Wine, is one of largest consumption of alcoholic beverages in the world. In the wine countries of "new world", grape planting and processing has exceed Europe, and industry value is roaring. But so far, China’s wine market, always controlled by several big joint-venture wine brands in the north, no south wine brands. However, the climate in the south and small hilly region, growing a lot of grape resources, with relatively high acid, low sugar, thick skin and less flesh, just suitable for processing, not be in good use.Traditionally, before the start of the wine fermentation, the grape juice must be adjusted, the total sugar, total acid, at the same time, add SO2、pectinase and other additives, to promote the rapid fermentation. The SO2and increase of acidity, can restrain the growth of the unwanted bacteria but exclude yeasts. In recent years, many wine safety incidents occurred for the excess SO2content, these wines were returned or destroyed, so we wanna if we can ferment without SO2. The southern V.DAVIDII grape grows with high acid, offered the possibility for none SO2fermentation. For the good use of southern grape resources growed in the south of Yangtze River, this paper, design a none SO2fermentation method on the bases of traditional technologies, monitor the fermentation process, determine the different fermentation products at the same time, to testify the feasibility of fermentation of southern grapes without SO2.This paper use various grapes and wines, determine related physical and chemical indexes of them, design a none SO2fermentation method. After raw material selection, use boiled water for sterilization,2～4S. Yeast addition amount, according to the raw material of the weight of1‰, adjust total glucose content of V.DAVIDII grape to230.0g/L, other grapes total acid content to6g/L。Fermenting under the environment of26℃, stirred everyday and press the skins in the liquids. When there’s no amount of bubbles and no obvious separate, use two layer of gauze for fermented liquids filtration, then undergo mal-lactic fermentation, wait until the total glucose content decrease to5g/L, or no white sediments occurred, the second fermentation finished, wine can undergo ageing process. According to these researches, main conclusions are as follows:1. Determine related physical and chemical indexes of the southern and northern grapes, the southern V.DAVIDII wine:water content77.58%, soluble solids content13.73%, total glucose content110.0g/L, total acid7.63g/L, pH3.36.2. Under the environment of26℃, wine with the yeast can start large-scale fermentation in12-24h, and the other groups to start in24-48h, especially natural fermentation group. Determine the physical and chemical indexes of fermented wine, total sugar content1-6g/L, total acid content3-5g/L, alcohol strength8～12°, wine yield rate between60-80%, the total number of colonies and enumeration of coliforms indicators are qualified.3. Explore and identify the RP-HPLC method for quick determination of organic acids and resveratrol in wine. Determine some big brands on the market and self-fermented wines, and compared the content. In organic acids detection, the content of organic acids in all wines is3～19g/L, approximately each wine contains malic acid and lactic acid. In self-fermented wines of third batch, total content of resveratrol in southern wines are apparently higher than the north, the highest is18.92mg/L. In wines of big brands, V.DAVIDII dry red wine from wine centre, the content can be up to112.43mg/L, however, the higher content of resveratrol in northern wine is Dynasty dry red wine,26.86mg/L.4.With HS-SPME/GC-MS method to detect flavor substances. Hunan agricultural university wine center, pure V.DAVIDII wine, has the most flavor type, a total of28species, give priority to alcohols and esters, alcohols in the highest content of3-methyl-1-butanol, was38.81%, and the ester content is higher in the octanoic acid ethyl ester, ethyl caproate, respectively9.90%,7.96%. In self-fermented wines, NO.3-1has the most flavor substance of169kinds, the result is consistent with the sensory evaluation, the kind is more than twice compared with the commericial wines, mainly contain alcohol, ester, ketone,13kinds of alcohol,38.44%,15kinds of ester,30.54%, the highest level of material are ethyl acetate22.95%,3-methyl-2-pentanone,14.54%, they have the rich ketone substance and obvious different from others. In the flavor detection of self-fermented wines, almost all have more than34kinds, mainly contain alcohol and ester. In alcohols, content of ethanol,2-methyl-1-butanol,3-methyl-l-butanol are relatively higher; In esters, content of acetic acid ethyl ester, ethyl caprylate are higher. Fermenting without SO2is a feasible way to explore, and the wine will have more types of flavor substance.