title: Characterization of volatile aroma compounds in different brewing barley cultivars.
abstract: BACKGROUND
  Beer is a popular alcoholic malt beverage resulting from fermentation of the aqueous extract of malted barley with hops. The aroma of brewing barley impacts the flavor of beer indirectly, because some flavor compounds or their precursors in beer come from the barley. The objectives of this research were to study volatile profiles and to characterize odor-active compounds of brewing barley in order to determine the variability of the aroma composition among different brewing barley cultivars.
  
  
  RESULTS
  Forty-one volatiles comprising aldehydes, ketones, alcohols, organic acids, aromatic compounds and furans were identified using solid phase microextraction combined with gas chromatography/mass spectrometry, among which aldehydes, alcohols and ketones were quantitatively in greatest abundance. Quantitative measurements performed by means of solvent extraction and calculation of odor activity values revealed that acetaldehyde, 2-methylpropanal, 3-methylbutanal, 2-methylbutanal, hexanal, heptanal, octanal, nonanal, 3-methyl-1-butanol, cyclopentanol, 2,3-butanedione, 2,3-pentanedione, 2-heptanone, acetic acid, ethyl acetate, 2-pentylfuran and benzeneacetaldehyde, whose concentrations exceeded their odor thresholds, could be considered as odor-active compounds of brewing barley.
  
  
  CONCLUSIONS
  Principal component analysis was employed to evaluate the differences among cultivars. The results demonstrated that the volatile profile based on the concentrations of aroma compounds enabled good differentiation of most barley cultivars.
authors.affiliation: Key Laboratory of Fermentation Technology, School of Bioengineering, Dalian Polytechnic University, Dalian, 116034 Liaoning, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Dong
authors.forename: Yingmin
authors.initials: Y
authors.lastname: Hou
authors.forename: Feng
authors.initials: F
authors.lastname: Li
authors.forename: Yongzhe
authors.initials: Y
authors.lastname: Piao
authors.forename: Xiao
authors.initials: X
authors.lastname: Zhang
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Zhang
authors.forename: Cheng
authors.initials: C
authors.lastname: Li
authors.forename: Changxin
authors.initials: C
authors.lastname: Zhao
mesh_terms: D000438:Alcohols / Q000032:analysis; D000447:Aldehydes / Q000032:analysis; D001515:Beer / Q000032:analysis / Q000382:microbiology; D018556:Crops, Agricultural / Q000737:chemistry*; D005285:Fermentation; D008401:Gas Chromatography-Mass Spectrometry; D001467:Hordeum / Q000737:chemistry*; D007659:Ketones / Q000032:analysis; D015999:Multivariate Analysis; D009812:Odorants; D025341:Principal Component Analysis; D015203:Reproducibility of Results; D036226:Seedlings / Q000737:chemistry; D012639:Seeds / Q000737:chemistry*; D012684:Sensory Thresholds; D052617:Solid Phase Microextraction; D013045:Species Specificity; D055549:Volatile Organic Compounds / Q000032:analysis*
chemical_list: D000438:Alcohols; D000447:Aldehydes; D007659:Ketones; D055549:Volatile Organic Compounds
keywords: GC/MS; PCA; aroma; barley; brewing; solid phase microextraction; volatile compounds