| Summary: | 碩士 === 國立臺灣大學 === 園藝學研究所 === 93 === The objectives of this study are to investigate the effect of growth factors on the acetic acid fermentation of the diluted pineapple wine, and to analyze changes of flavor volatiles of pineapple vinegar during acetic acid fermentation and aging periods.
Acetic acid fermentation of diluted pineapple wines with 3% and 4% alcohol content resulted in the highest conversion rate of alcohol to acetic acid, however, the acetic acids produced in these two samples were too low to meet the vinegar standard (>4.2% acetic acid) of Chinese National Standard (CNS). Although fermentation of diluted pineapple wines with 5% alcohol content has lower acetic acid conversion rate, the acetic acids produced in this sample was above 4.2% acetic acid, which matched the CNS vinegar standard. Conversion rates of alcohol to acetic acid were very slow in the acetic acid fermentation of diluted pineapple wines with 6% and 7% alcohol content. The activity of Acetobactor may be inhibited in the fermentation process at diluted pineapple wine samples with alcohol content higher than 5%.
Acetic acid productions by Acetobacter in 5% alcohol vol. diluted pineapple wine were faster in 30oC then the fermentation processes at 25oC and 35oC. Aeration of oxygen at 3mg/L/min in same fermentation broth at 30oC resulted in the highest acetic acid production rate as compared to oxygen aeration of 1mg/L/min and 5mg/L/min.
A total of 12 alcohols, 6 acids, 11esters, 2 lactones, 8 carbonyl compounds were identified in the volatile flavor pineapple vinegars in this study. The key flavor volatile compounds were identified as ethyl acetate, ethyl lactate, 2,3-butanediol, ethyl-3-(methylthio)propanoate, 2-methyl-1-butanol, ethyl 4-hydroxybutanoate. Flavor volatiles changes significantly during fermentation process and decreased as aging time increased.
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