Aroma Comparison of Tibetan “Qingke” Liquor with Other Chinese Baijiu

The aroma composition of a Tibetan Qingke (QK) liquor, which is made from highland barley exclusively grown at an altitude greater than 4000 m, was compared with 16 other Chinese baijiu of varying aroma styles. A total of 63 aroma compounds were quantified. Results showed that strong-aroma baijiu has much higher concentrations of ethyl hexanoate, ethyl heptanoate, ethyl octanoate, and hexanoic acid than those of QK liquor and the remaining baijiu. In contrast, QK liquor, along with other light-aroma baijiu and Mao Tai (MT), Si Te Jiu (STJ), and Heng Shui Lao Bai Gan (HS), have higher levels of ethyl acetate and ethyl lactate. QK liquor has the highest concentrations of linalool, β-damascenone, and β-ionone. Dimethyl trisulfide (DMTS) is the most important sulfur-containing compound in Chinese baijiu. Strong-aroma baijiu, along with MT, STJ, and Bai Yun Bian (BYB), have a higher amount of DMTS than the other baijiu. Odor activity values (OAVs) were calculated to illustrate the potency of aroma compounds. Strong-aroma baijiu, along with BYB, STJ, and Gu Jing G6 (GJG6), have OAVs of ethyl butanoate, ethyl hexanoate, ethyl pentanoate, ethyl octanoate, and hexanoic acid that are greater than 100, indicating that they were the key aroma compounds. For light-aroma baijiu, alog with MT, Hong Xing Er Guo Tou (HX), Gui Lin San Hua (GL), and Guang Dong Jiu Jiang (GDJJ), isoamyl acetate was the most important aroma compound, contributing fruity and floral notes. A principal component analysis (OAV of at least 1) illustrated that QK liquor has a similar aroma composition to other light-aroma baijiu (CYW, C20) and HS, but each individual baijiu has its own aroma profile. Strong-aroma baijiu were well separated from light-aroma due to their high concentrations of ethyl hexanoate, ethyl heptanoate, hexanoic acid, and octanoic acid. MT, as the only soy-sauce aroma baijiu, stands alone with its unique aroma profile.