Characterization of 3-Methylindole as a Source of a "Mud"-like Off-Odor in Strong-Aroma Types of Base Baijiu.
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2018;
66:12765-12772. [PMID:
30392373 DOI:
10.1021/acs.jafc.8b04734]
[Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The "mud"-like off-odor, which is an odor reminiscent of musty and strong animal fecal odors, affects the quality classification of the strong-aroma types of baijiu (SAB), but little is known about which compounds are responsible for this aroma, except for certain phenolic compounds. However, not all mud-like off-odor expressions in SAB can be attributed to those phenolic compounds. In this work, volatile compounds in pit mud and SAB samples were isolated by headspace solid-phase microextraction and liquid-liquid extraction. An odoriferous zone was detected by GC-MS/olfactometer and GC-MS and was attributed to 3-methylindole rather than ethyl oleate on the basis of their odor characteristics, MS data, and retention indices. Combined with the detection threshold of 3-methylindole determined by a three-alternative forced-choice (6.09 μg/L) procedure, odor activity values in the tested base SAB were from 1 to 23. Sensory studies and the prepared heat map highlighted the contribution of this compound to the odor characteristics for the first time.
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