Research on detection and the change of terpene alcohols steroisomer in hop during brewing in beer

In this study,a method developed by our lab based on gas chromatography – mass spectrometry( GC/MS) coupled with headspace solid-phase micro-extraction was used to trace the content changes of( R)-(-)-linaloo,( S)-( +)-linaloo,S-(-)-β- citronellol,R-( +)-β-citronellol,( +)-α-terpineol,(-)-α-terpineol,geraniol and nerolidol derived from hops. The influences of different hopping regimes were evaluated during the mash process. As a result,compared to the before the end of boiling 10 min- hopping,the late-hopping,whirlpool tankhopping and fermetation end-hopping could significantly enhanced the remaining content of terpenols in the beer. The contents of( R)-(-)-linaloo,geraniol,R-( +)-β-citronellol,and nerolidol were 1. 94 ~ 14. 39 μg /L,9. 83 ~12. 10 μg /L,2. 91 ~ 6. 79 μg /L,and 5. 34 ~ 6. 81 μg /L,respectively. Their OAV were found to be in the range of0. 29 ~ 6. 54. So,we further investigated the biotransformation of four alcohols during fermentation of hopping regimes. Combined with the sensory evaluation of 4 hopping regimes for flavor in beer,it showed that whirlpool tankhopping produced better hoppy aroma than others.