Comparison of Aroma Profiles of Whiskeys Fermented from Different Grain Ingredients

Different grain sources of whiskey have great potential for aroma expression. In this pa- per, four whiskeys fermented from different raw materials (barley, wheat, highland barley, and sor- ghum) were compared. Gas chromatography–mass spectrometry (GC-MS) and sensory evaluation were used to determine the composition of the aromatic compounds. A correlation analysis was further conducted between the aromatic compounds and sensory evaluations. Barley whiskey and wheat whiskey had more pronounced fruity, floral, and grain aromas, attributed to esters and ter- penes. Barley whiskey had the most compounds (55), followed by highland barley whiskey (54). Highland barley whiskey had the greatest number of unique aroma compounds (seven). It exhibited a unique cocoa aroma related to concentrations of trans-2-nonenal, γ-nonanolactone, 1-nonanol, iso- amyl lactate, 2-butanol, and 6-methyl-5-hepten-2-one. Sorghum whiskey had a specific leather and mushroom aroma attributed to 6-methyl-5-hepten-2-one, ethyl lactate, ethyl caprate, phenethyl oc- tanoate, farnesol, α-terpineol, 3-methyl-1-pentanol, and methyleugenol. Alcohols were the main aroma components of grain whiskeys. Isoamyl alcohol (231.59~281.39 mg/L), phenylethyl alcohol (5.755~9.158 mg/L), citronellol (0.224~4.103 mg/L), β-damascenone (0.021~2.431 mg/L), geraniol (0.286~1.416 mg/L), isoamyl acetate (0.157~0.918 mg/L), phenylacetaldehyde (0.162~0.470 mg/L), lin- alool (0.024~0.148 mg/L), 1-octen-3-ol (0.016~0.145 mg/L), trans-2-nonenal (0.027~0.105 mg/L), and trans-2-octen-1-ol (0.011~0.054 mg/L) were all important aroma compounds in the whiskeys. Keywords: whiskey; aromatic evaluation; barley; wheat; highland barley; sorghum