Infusions
prepared from raw pu-erh tea (RAPT) and ripened pu-erh
tea (RIPT) showed remarkable aroma differences. Predominant odorants
in RAPT and RIPT infusions were identified and compared by the combined
use of gas chromatography–olfactometry, aroma extract dilution
analysis, odor activity values (OAVs), and multivariate analysis.
A total of 35 and 19 odorants (OAV > 1) were detected in RIPT and
RAPT, respectively. Odorants in RAPT and RIPT are significantly different
in both odor properties and aroma compound intensities. Overall, RAPT
contained a complex variety of chemical classes with diverse odors
and moderate odor intensities, while RIPT is dominated by structurally
and organoleptically similar compounds with high potency. Specifically,
stale and musty smelling methoxybenzenes contributed the most to RIPT,
while floral-, sweet-, and woody-smelling terpene alcohols, terpene
ketones, and phenolic compounds were the predominant odorants in RAPT.
Orthogonal partial least squares discriminant analysis revealed that
linalool, α-ionone, 1,2,4-trimethoxybenzene, 1,2,3-trimethoxy-5-methylbenzene,
1,2,3,4-tetramethoxybenzene, and 1,2,3-trimethoxybenzene underwent
remarkable changes during pile fermentation and could be used as potential
odor-active markers for RIPT and RAPT discrimination. The comprehensive
aroma characterization of pu-erh tea and determination of the effect
of pile fermentation on odorant alteration herein will provide guidance
for pu-erh tea flavor quality control and evaluation.
