# Dynamic Evolution of Aroma Characteristics in Ripened Pu-Erh Tea During Industrial Fermentation: Insights from GC-MS and Flavor Wheel Analysis

## TL;DR

This study tracks how the aroma of ripened Pu-erh tea changes during industrial fermentation, identifying key compounds that contribute to its unique scent.

## Contribution

The study provides a stage-resolved analysis of aroma compound evolution during Pu-erh tea fermentation using GC-MS and a flavor wheel.

## Key findings

- 134 volatile organic compounds were identified, with 13 key aroma-active compounds (rOAVs > 1) contributing to RPT's aroma.
- Early fermentation reduces fresh/green aromas (e.g., linalool) while increasing woody/minty aromas (e.g., methyl salicylate).
- A flavor wheel was developed to visualize dynamic aroma profile shifts during fermentation stages.

## Abstract

Ripened Pu-erh tea (RPT) experiences notable aroma transformations during industrial pile fermentation, yet the stage-dependent evolution of key aroma compounds remains poorly understood. This study analyzed two independent industrial batches of RPT across three fermentation stages: raw material (RM), intermediate fermentation (IF), and final fermentation (FF). Using HS-SPME/GC-MS coupled with multivariate statistical analysis and relative odor activity values (rOAVs), 134 volatile organic compounds (VOCs) were identified, with hydrocarbons, alcohols, and esters as predominant classes. In total, 13 key aroma-active compounds (rOAVs > 1) were found to be major contributors to RPT’s characteristic aroma. During early fermentation, relative levels of VOCs responsible for fresh and green aromas (e.g., linalool, D-limonene) diminished, while those for woody and minty aromas (e.g., isophorone, methyl salicylate) increased. A flavor wheel was developed to illustrate the dynamic shifts in aroma profiles. This stage-resolved analysis offers new mechanistic insights into aroma formation, aiding in the optimization of aroma quality control and process standardization for RPT production.