Effects of Hydroxycinnamates and Exogenous Yeast Assimilable Nitrogen on Cider Aroma and Fermentation Performance

Cider apple cultivars typically contain high concentrations of tannins (phenolic compounds) and/or acids. The phenolic content of some cider apples far exceeds that of white wine grapes, yet modern global cider styles are often fermented using yeast strains originally selected and commercialized for white wine production. The potential for phenolic compounds in cider apple juice to influence fermentation rate or aromas generated during cider fermentation is not typically considered in yeast strain selection. The objective of this study was to determine the impact of ferulic acid, p-coumaric acid, and chlorogenic acid (at concentrations reported in apples) on fermentation kinetics and cider aroma, and the interactive effects of yeast assimilable nitrogen (YAN) on these outcomes. Our hypothesis was that phenolic compounds present in high-tannin cider apples would slow down fermentation, but not alter aroma, and that added YAN would moderate these effects. Ferulic acid negatively affected fermentation performance (p<0.05), but p-coumaric and chlorogenic acids did not. A sensory sorting task showed that p-coumaric acid led to distinct differences in grouping by aroma, while ferulic acid resulted in distinct aroma descriptors. Finally, addition of YAN improved fermentation performance for low concentrations of ferulic acid, and it affected the aroma of cider amended with p-coumaric acid. Supplemental data for this article is available online at at [publisher’s weblink].苹果酒专用苹果品种通常含有高浓度的单宁（tannins）和/或有机酸。部分苹果酒专用苹果的酚类化合物（phenolic compounds）含量远高于白葡萄品种，但当前全球主流的苹果酒酿造风格，往往采用最初为白葡萄酒生产筛选并商业化的酵母菌株进行发酵。在酵母菌株筛选环节中，苹果酒苹果汁中的酚类化合物对发酵速率或苹果酒发酵过程中产生的香气的影响，通常未被纳入考量范畴。本研究的目标为：明确阿魏酸（ferulic acid）、对香豆酸（p-coumaric acid）与绿原酸（chlorogenic acid）（按苹果中已报道的浓度设置）对发酵动力学及苹果酒香气的影响，以及酵母可同化氮（yeast assimilable nitrogen，YAN）对上述结果的交互效应。本研究的假设为：高单宁苹果酒专用苹果中存在的酚类化合物会延缓发酵进程，但不会改变香气；而添加酵母可同化氮可缓解这些影响。实验结果显示，阿魏酸会对发酵性能产生负面影响（p<0.05），但对香豆酸与绿原酸则无此效应。一项感官分类任务表明，对香豆酸会导致香气分组出现显著差异，而阿魏酸则会产生独特的香气描述词。最终，添加酵母可同化氮可改善低浓度阿魏酸条件下的发酵性能，同时会影响添加对香豆酸的苹果酒的香气。本文的补充数据可于[出版商官网链接]在线获取。