| Summary: | 碩士 === 國立中興大學 === 食品暨應用生物科技學系所 === 103 === Beer was one of the ancient beverages that could be dated back to Mesopotamia. The beer kinds were various due to the development of crafts and the usage of different material. The flavor and taste of the beer would influence the acceptability of customers toward a new kind of beer, and astringency might be one of this unfavorable taste.
This research indicated that the content of tyrosine and tryptophan seemed to be unchanged during brewing. The variation of the phenolic compounds just coincided with the mode of the alcohol production, sugar and amino acid utilization. The content of p-coumaric acid, trans-ferulic acid and vanillic acid compared to other phenolic compounds varied during main fermentation, and the content of phenolic compounds were primarily determined in this stage. Vanillic acid , trans-ferulic acid and p-coumaric acid were related with the formation of volatile phenolic flavor. There was a highly positive correlation between trans-ferulic acid and p-coumaric acid , and it might attribute to the similar metabolic pathway of yeast.
There was a moderately positive correlation between astringency and tannin content, its correlation coefficient fell between 0.618 and 0.730. The relationship could be observed in the sample with higher alcohol content (5.0-5.7%), lower sugar content, and tannin content above 0.40 g/L.
In general, there was a moderately positive correlation between astringency and lingering bitterness. According to the principal component analysis chart, procyanidin B2 in beer have positive effect on beer body and enrich the beer.
We observed that total acidity of beer also influenced the astringency perception of beer. Rutin, an important astringency substance found in wine, was also correlated with astringency perception in beer. The astringency caused by this compound was primarily observed in the sample with lingering bitterness, lower alcohol and sugar content.
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