Analysis of organic acids in Chinese raisin tree (Hovenia dulcis) peduncle and their changes in liquid fermentation process

Chinese raisin tree (Hovenia dulcis) peduncle is a wonderful food material for fermented food for high contents of sugars and a variety of organic acids. The organic acids in the fresh peduncle, fermented wine, and vinegar were identified and quantified by HPLC, and changes in biochemical parameters and organic acids in the fermentation process were studied. Skin-on fermentation was carried out in the alcoholic fermentation, and 9 identified organic acids fluctuated by physical or biochemical reactions during the alcoholic fermentation. Submerged fermentation was carried out in the acetic fermentation. It took 72 h to finish the 1(st) cycle of acetification with the titratable acidity 5.42%(w/v), and 30 h to finish the 2(nd) cycle. The contents of acetic acid, formic acid, and alpha-ketoglutaric acid increased, while the rest identified organic acids decreased in the acetification process. The fermentation developed in this study appeared to be a practical processing method for Chinese raisin tree peduncles.