Study Of Changes In Several Kind Of Organic Acid And Enzyme Activity During Saccharomyces Cerevisiae Aging

Saccharomyces cerevisiae play a decisive role in the wine brewing process, a good Saccharomyces cerevisiae can give the wine with pure flavor and taste, Saccharomyces cerevisiae changes it’s structure during aging, function of cell metabolism, adaptation, compensatory etc is low, and Saccharomyces cerevisiae is lack of ability to recover. In the brewing process, using the aging of Saccharomyces cerevisiae can cause serious problems such as fermentation rate is slow, reducing sugar dose not drop down etc, and have a direct affect on the quality of the alcohol. The present study combine the approach of organic acids and intracellular enzyme activity changes in the fermentation broth of yeast aging process to provide a strong theoretical basis for the identification of yeast aging, and have far-reaching significance for wine brewing industry.The fermentation broth of different generation saccharomyces cerevisiae were compared by high performance liquid chromatography and found that six kinds of organic acids in different generation have significant differences and regularity. Malic acid concentration in the fermentation broth of Saccharomyces cerevisiae aging process is roughly the same, it begins to increase before48h then begin to decline, the concentration of malic acid decreases as the generation increases, The highest point of the first generation of yeast producing malic acid concentration is445.55mg/L, the highest point of the third generation of yeast producing malic acid concentration is410.11mg/L, the highest point of the5th generation of yeast is380.15mg/L, the highest point of the7th generation of yeast is345.25mg/L. The1st,3rd, and5th generation of yeast producing citric acid concentration has been a downward trend, only a slight increase after60h, the citric acid concentration of the7th generation yeast first increase and reache its highest point at36h, and decrease to60h then have a slight upward trend. Oxalic acid concentration of lst,3rd,5th generation yeast appears to grow first and then decline, in the final it approaches to steady trend, but oxalic acid concentration of the7th generation yeast always show a downward trend. Succinic acid concentration of different generation yeast have the same trend, they all gradually increase before60h,and rapid decline after60h. a-ketoglutaric acid concentration of different generation yeast appear to grow first and then decline to reached its lowest point at72h. Propionic acid concentration of different generation yeast have a increasing trend, the1st,3rd, and5th generation yeast have a stable growth trend, but the7th generation of yeast have a rapid growth trend between48h and62h.The experiment to measure the changed in enzyme activity during different generation of Saccharomyces Cerevisiae aging, we fund that the protease activity increased gradually in the yeast aging process, from50.25U of the first generation increased to82.16U of the15th generation, increased by approximately65%. Sucrase activity decreased gradually with the yeast generation increased, from5.93U of the first generation decreased to1.55U of the15th generation. Lipase activity decreased gradually with the increasing generation, from3.67U of the first generation reduced to1.03U of thel5th generations, a-amylase activity was decreased gradually, it was reduced from3.362U of the first generation to1.100U of the15th generation. Lactase activity was decreased gradually, it was reduced from4.286Uof the first generation to1.261U of the15th generation, decreased by approximately70.1%. Nuclease activity were decreased gradually, decreased from31.4U of the first generation to7.8U of the15th generation, decreased by approximately75%.