Analysis of aroma-active compounds in hop by GC-O-MS

Head space-solid phase microextraction-gas chromatography-olfactometry-mass spectrometry(HSSPME-GC-O-MS) was used to analyze the aroma-active compositions and flavours in hops.The identification of volatile compounds was performed using mass spectral library searching based on Kovats retention index(KI).Greatly different results of the aroma-active compounds were separately obtained from the HS-SPME,simultaneous distillation extraction(SDE) and conventional steam distillation(SD) methods.After HS-SPME extraction,71 kinds of volatile compounds were found in NO.1 hops,and accounted for 97.93% of the total pear area,among which the terpenes,mainly humulene and β-caryophyllen,together accounting for 88.73% of the total amount of volatile compounds.While alcohols and esters were 1.98% and 3.42%,respectively.Results showed that the most suitable extraction method for kinds of hop cultivars was SPME.In total,34 volatile aroma-active compounds were identified including 7 kinds of hydrocarbons(contain tepenes),11 kinds of alcohols(contain terpenols),10 kinds of esters,2 kinds of ketones and 4 kinds of unkonwn compounds.26,23 and 16 kinds of odor-active compounds were identified by GC-O-MS,from three different hops,respectively.The main contributors of hop flavor are β-mycrene,β-caryophyllene,linaool,geraniol,α-terpined,β-citronellol,nerol,nerolidol,methyl,geranate,octanoic acid,methyl ester,geranyl acetate,et al.