Selective Breeding Of Acetic Acid Bacteria And Study Of Brewage Technology Of Shanxi Overmature Vinegar

Vinegar is commonly used as flavoring material. However, it is good tohuman's health also. It can prevent and cure many kinds of diseases. Shanxiovermature vinegar is one of the four famous vinegar in China. With theimprovement of the People's living level, the demand of the Shanxiovermature vinegar was increasing. In order to improve the output ofvinegar and optimize its production technology, the following researcheswere carried out.First, Acetobacter pasteurianus S12 was isolated. The strain wasmutagenized by ultraviolet ray-lithium chloride and N⁺ ion implantation.After lots of screen tests, a strain SM12-87 was obtained, the transformationrate from alcohol to acetic acid was raised 22.36% than the original strain,and its genetic character was stable.Second, the optimum medium and culture condition were determinedby orthogonal tests. The optimal medium was glucose 10%, yeast extractpowder 10%, alcohol 10% (v/v), medium capacity 50mL/500 mL, pH5.5and 30℃quiescently cultured for 5d.The yield of total acid and thetransformation rate from alcohol to acetic acid was 91.67g/L and 88.98%respectively.Third, the liquid batch fermentation was performed in a 10-L autocontrolled fermentor based on the optimum condition. Experimental resultsindicated that the strain had many excellent productive traits such as fasterproductive vinegar rate (1.369g L^-1 h^-1), shorter cycle of thefermentation (35.5h) and higher yield of acetic acid (48.6g/L).Fourth, the liquid state seed of SM12-87 was inoculated into the solidfermentation substrate of Shanxi overmature vinegar by 3% inoculums size.The result showed that the yield of acetic acid and ethyl acetate hadincreased by 20.52% and 41.53% respectively. The transformation rate from alcohol to acetic acid was raised 15.17%, and taste is good. So, this is afeasible way to improve traditional brewing process.Fifth, in the research the variation of flavor components in Shanxiovermature vinegar during smoking solid fermentative substrate of vinegar,we find maillard reaction was taken place during smoking solid fermentativesubstrate of vinegar, and furfural was generated. The content of propylacetate was increased at first, and then decreased; the content of ethanol andethyl acetate has decreased obviously; the change of acetic aldehyde,3-hydroxy-2-butanone and acetic acid was little. So, we can draw aconclusion: the traditional technology is reasonable. In traditionaltechnology, half of solid fermentative substrate of vinegar was smoked andthe others were not, then extracted and mixed. It not only generates the newflavor ingredients, but also contains the intrinsic nutritive ingredients in thegreatest degree.