单萜醇类在啤酒发酵过程中的变化及对酒花香气的贡献

啤酒中的里那醇、香叶醇和β-香茅醇等单萜醇类物质是贡献啤酒酒花香气的重要成分,其在发酵过程中的变化对啤酒香气质量产生直接影响。结合感官品评和数理统计手段,发现在4%(v/v)乙醇溶液中,不同浓度的里那醇、香叶醇和β-香茅醇的单一物质香气及其协同作用香气呈现出的特性均不同。当含量不高于50μg/L时,混合不同浓度的3种物质,发现并非3者的浓度越高啤酒获得的香气强度就越大,且当里那醇浓度为12.5μg/L,香叶醇浓度为12.5μg/L,β-香茅醇浓度为25μg/L时,3者的协同作用可促使啤酒获得最突出的酒花香气。此外,里那醇、香叶醇和β-香茅醇在发酵过程中发生了生物化学变化,其中里那醇主要转化为α-萜品醇;香叶醇主要转化为β-香茅醇;β-香茅醇主要转化为乙酸香茅酯。3者总体损失率分别为36.6%、45.1%和38.1%。结合上述两方面研究,在采用发酵罐添加酒花的方式进行酿造时,控制好酒花的添加量,促使啤酒中里那醇、香叶醇和β-香茅醇的最终含量在12.5μg/L,12.5μg/L和25μg/L即可达到合理利用酒花香气资源的目的。

The change of monoterpenoids during fermentation and their contribution to hop aroma of beer

Monoterpenoids,such as linalool,geraniol and β-citronellol,are important compounds in beer and their changes during fermentation have effect on the beer aroma directly.In 4%(v/v) ethanol solution,it was found that single compound and mixture with linalool,geraniol and β-citronellol in different concentration both have different characteristics by sensory evaluation and statistics.When their concentration were no more than 50 μg/L,it's not necessarily that there was stronger hop aroma in beer with their higher concentration,and the synergy of three compounds had the strongest hop aroma with 12.5 μg/L of linalool,12.5 μg/L of geraniol and 25 μg/L of β-citronellol.In addition,biochemical changes happened during fermentation,and linalool was converted into α-terpineol,geraniol was converted into β-citronellol rapidly and β-Citronellol was converted into citronellyethanoate.Generally,the loss rates of them were 36.6%,45.1% and 38.1% respectively.Sum up,it was probable to get the outstanding hop aroma in beer by adding appropriate amount of hop during brewing and controlling the final concentration in beer with 12.5 μg/L of linalool,12.5 μg/L of geraniol and 25 μg/L of β-citronellol.