Tao Xin-liang, Yan Peng, Hao Jun-guang, Yin Hua, Dong Jian-jun, Li Qi
A method developed by our lab based on gas chromatography–mass spectrometry(GC/MS) coupled with headspace solid-phase micro-extraction was used to track the content changes of 5 terpenols derived from hops,aiming at finding out their dynamic changes during the fermentation of commercial beer.Firstly,the influence of different hop formulations,boiling system and hopping regimes were evaluated during the mash process.The results showed that the terpenols in the cold wort were mainly attributed to the last addition of hops.Compared to the traditional boiling system,the use of Stromboli system was conductive to the remaining of terpenols in the cold wort.In the case of last hop addition,it was suggested that adding hops at the end of boiling was of great meanings for the remaining terpenols in the cold wort,where the linalool content in experiment C was 209.4% higher than experiment A,while α-terpineol was 91.2%,geraniol was 31.4% and nerol was 175.0%.Secondly,the content change of 5 terpenols in the fermentation process were tracked,and it was observed that the content of terpenols in beer were higher than those in cold wort,which can be explained by an occurrence of glycosidically bound flavor precursor and a glucoside hydrolase activity secreted from our lager yeast.Citronellol was almost absent in the cold wort but sharply increased during the first 3days,corresponding to the fast decrease of geraniol,which indicated that geraniol can be converted into citronellol in the first 3 days.
