# Process Optimization and Flavor Analysis of Lespedeza juncea Tea Based on HS-SPME-GC-O-MS, LC-MS, and Sensory Evaluation

## TL;DR

This study optimizes the processing of Lespedeza juncea tea to enhance its flavor and health benefits using advanced analytical techniques.

## Contribution

The study introduces optimized tea processing parameters and identifies key flavor compounds in Lespedeza juncea.

## Key findings

- Optimal processing conditions were 150 g leaf loading, 200 °C roasting temperature, and 180 s roasting time.
- The tea achieved a sensory score of 90.9 and 4.11% flavonoid content with strong antioxidant activity.
- Key aroma compounds identified were 1-octen-3-ol and β-ionone.

## Abstract

Based on ancient records of “Marching tea” and the flavonoid-rich properties of Lespedeza juncea, this study optimized green tea processing parameters for Lespedeza juncea tea. By adjusting leaf loading, roasting temperature, and time and employing precise methods such as gas chromatography–olfactory–mass spectrometry (GC-O-MS), liquid chromatography–mass spectrometry (LC-MS), and electronic tongues to determine key indicators, including metabolites, volatile compounds, and flavor profiles, the optimal processing conditions were determined through comprehensive analysis as 150 g, 200 °C, and 180 s. These conditions resulted in superior sensory quality (score: 90.9), the highest flavonoid content (4.11%), strong antioxidant activity (DPPH: 66.0% at 20 mg/mL; ABTS: >95% at 2.5 mg/mL), and key aroma compounds 1-octen-3-ol and β-ionone. This work revives an ancient tea tradition and provides a scientific basis for developing novel functional teas from grassland resources.