Bioaugmentation Of Lactic Acid Bacteria For Brewing Acidity-adjustment Chinese Rice Wine

With the rising health consciousness of consumers, the low-alcohol Chinese rice wine(CRW) with alcohol content of 8%~12%(v·v-1) occupies a large market and will become one of the mainstream trends of CRW industry. Low-alcohol CRW is usually produced by dilution of CRW with high alcohol content. Howerer, the acidity of diluted CRW is much too low, leading to weak flavor. In order to improve the taste, the rancidity rice wine is added to adjust the acidity, which will cause safety problem at same time. In this study, lactic acid bacteria(LAB) from CRW fermentation process was studied. Furthermore, LAB with high yield of lactic acid and low yield of biogenic amines was isolated from CRW fermentation. The LAB strain was applied to optimize CRW fermentation process for high lactic acid in CRW, which could substitute rancidity rice wines and then be used to produce low-alcohol CRW with no safety or taste problems.(1) The composition of organic acids and biogenic amines in commercial rice wine and rancidity rice wine was analyzed and compared by high performance liquid chromatography(HPLC). It showed that lactic acid was the main organic acid in CRW(averaged at 1807.8 mg·L-1, 31.4% of total organic acids); Acetic acid was the main organic acids in rancidity rice wine(27653.2 mg·L-1, 74.5%). However, the content of biogenic amines in rancidity rice wine was significantly higher than that in normal CRW. Therefore, the use of rancidity rice wine to blend with normal high-alcohol CRW to produce low-alcohol CRW could decrease CRW quality and cause safety problems.(2) 73 acid-producing strains were isolated from CRW fermentation and identified as Lactobacillus by 16 S rDNA sequence. All these strains belonged to heterofermentation lactic acid bacteria and yielded a large number of lactic acid, a little acetic acid. Among these strains, strain Lactobacillus sp B46, with high yield of lactic acid and low yield of biogenic amines, was selected to use in CRW fermentation for acid production.(3) Single factor experiments and Uniform Design were used to optimize Lactobacillus sp B46 fermentation parameters. The optimized conditions were fermentation temperature 24℃, inoculum rate 5.3%, ratio of rice to water 1: 2.5. With the optimal fermentation conditions, the total acid production by Lactobacillus sp B46 was 17.5 g·L-1,which was 326.8% higher than that by normal fermentation process. By Lactobacillus sp B46 bioaugmention, the content of alcohol, isoamyl alcohol and isobutyl alcohol decreased by 21.8%, 50.3%, 58.9%, while the content of lactic acid, ethyl lactate, ethyl acetate increased by 420.8%, 75.3%, 16.8% than normal CRW, indicating the improvement of the flavor of CRW.(4) The acidity-adjustment CRW by Lactobacillus sp B46 with high content of lactic acid and low content of biogenic amines could replace rancidity rice wine and be of great practical significance to blend with normal high-alcohol CRW to produce low-alcohol CRW.