Evolution of polyphenols and organic acids during the fermentation of apple cider.

Polyphenols and organic acids are important constitutes in the cider because they greatly contribute to organoleptic quality. The determination of their changes is important for monitoring the fermentation process for purposes of quality control. In this study, the evolution of polyphenols and organic acids was monitored throughout the cider fermentation process. The samples were taken periodically and the polyphenols and organic acids contents were determined using HPLC methods. The contents of polyphenols and organic acids were in constant change. After fermentation, the content of (+)-catechin, (-)-epicatechin, chlorogenic acid, cinnamic acid, p-coumaric acid, gallic acid, caffeic acid, ferulic acid, rutin and phloridzin decreased by different degrees, while protocatechuic acid increased after fermentation. The content of organic acids was also affected by fermentation. Malic acid, lactic acid, quinic acid, pyruvic acid and citric acid showed different levels of increase, but succinic acid content decreased. The contents of polyphenols and organic acids were affected by fermentation. Their changing profiles during fermentation process were dependent on the type of phenolic compounds and organic acids studied.