Study On Aroma Quality And Main Organic Acids Of Persimmon Vinegar During Processing

In this experiment, we used conventional fermentation methodology and one-step fermentation methodology processing persimmon vinegar from persimmon as raw materials growing in Yangling, Shaanxi. The study of the aroma substances and seven organic acid changes in the two processes aimed to explore the origin and changes of the aroma substances and seven kinds of organic acids in the process of persimmon vinegar and provide theoretical clues to in-depth mechanism study. The results obtained are as follows:1、Study on the the changes of aroma qualitySeparated and identified the aroma substances of four samples of the original pulp, the end of alcoholic fermentation, the end of the acetic acid fermentation, aging end in conventional fermentation process and the three samples of the original pulp, the end of fermentation, aging end in one-step fermentation process using SPME/GC-MS technique. We sorted the results in accordance with hydrocarbons and their derivatives, phenols, ketones, aldehydes, alcohols, acids, esters and other types and analysed eight major categories of aroma substances and the changes of relative content.67,66,59and74substances were identified from the samples of four different stages of the conventional fermentation process, accounting for96.91%,99.85%,99.46%and99.91%of the total peak area respectively. The relative content and type of carbonyl substances took relatively high levels in the original pulp. After alcoholic fermentation, the relative content of the alcohols soaring, the number of its type also increased, the number of esters’type also augmented. After the end of the acetic acid fermentation, the relative content of the acids and esters has increased, the relative content of the alcohols decreased. After the end of the aging, the relative content of the acids and esters continue to rise but their types have not changed, and the relative content and type of the alcohols continue to reduce.70,72and73kinds of volatile substances were identified from the samples of three different stages of one-step fermentation process and accounted for99.86%,99.91%and99.77%of the total peak area respectively. Hydrocarbons and their derivatives take the highest relative content in the original pulp. After fermentation, the relative content and type of the alcohols, acids and esters significantly improved. The relative content and type of the hydrocarbons and their derivatives have declined. 2、Study on the changes of organic acidsUsing RP-HPLC to measure the content of7kinds of organic acid (oxalic acid, tartaric acid, malic acid, lactic acid, acetic acid, citric acid, succinic acid) which were got from four samples of the original pulp, the end of alcoholic fermentation, the end of the acetic acid fermentation, aging end in conventional fermentation process and the three samples of the original pulp, the end of fermentation, aging end in one-step fermentation process. Then analyze the results with statistical tools.During the processing of conventional fermentation methodology, the content of oxalic acid, tartaric acid, malic acid and succinic acid content has increased significantly (p<0.01) after the end of alcoholic fermentation; the content of malic acid, lactic acid, acetic acid and succinic acid has increased significantly (p<0.01), especially the acetic acid (p<0.01), followed by lactic acid, while the content of tartaric acid slightly reduced after the end of the acetic acid fermentation. After the end of the aging, the content of all the other acid decreased except acetic acid, malic acid and tartaric acid.During the processing of one-step fermentation methodology, the growth rate of the acetic acid (p<0.01) was the highest after fermentation, followed by lactic acid andsuccinic acid (p<0.05), while the tartaric acid and malic acid declined (p<0.01). The content of lactic acid and succinic acid decreased while the content of acetic acid increased significantly, and the content of tartaric acid stay the same after the end of the aging.