# Optimization of the sealed yellowing parameters and suitability evaluation of the different cultivars for manufacturing the Pingyang Huangtang tea

## TL;DR

This study identifies optimal sealed yellowing conditions and suitable tea cultivars to improve the quality of Pingyang Huangtang tea.

## Contribution

The study provides optimized sealed yellowing parameters and recommends new tea cultivars for Pingyang Huangtang tea production.

## Key findings

- Optimal sealed yellowing occurs at 60°C, 70% RH for 10 hours with two ventilation operations.
- Cultivars 'Zhenong 801', 'Zhongcha 108', 'Jiukengzao', and '5–21' produce higher quality Pingyang Huangtang tea.
- Quality is influenced by chlorophyll degradation, volatile compounds, and polyphenol-to-amino acid ratios.

## Abstract

Lack of optimal sealed yellowing (SY) technique and suitable tea cultivars limits the yield and quality improvement of the Pingyang Huangtang (PYHT) tea. In this study, the effect of SY temperature, relative humidity (RH) and ventilation operation on the PYHT quality had been investigated. Results showed total sensory score was significantly influenced by SY temperature and RH, and optimal PYHT quality could be achieved when SY was performed at 60 °C, 70 % RH for 10 h with 2 ventilation operation. Quality formation of PYHT was mainly associated with degradation of chlorophylls, fluctuation of volatile with different odor notes, and decrease in level of galloylated catechins and the ratio of total polyphenols to amino acids. The quality of tea made from the shoots of ‘Zhenong 801’, ‘Zhongcha 108’, ‘Jiukengzao’ and ‘5–21’ was higher than that of the commonly used cultivar ‘Pingyang Tezao’, therefore, these cultivars were recommended to apply in PYHT industry.

Unlabelled Image

•Temperature and RH of yellowing will significantly influence the PYHT quality.•Yellowing should be performed at 60 °C, 70 % RH for 10 h with ventilation 2 times.•Cultivar ZN801, ZC108, 5-21 and JKZ are much suitable to manufacture the PYHT.•Technique defines the lower limit of PYHT quality and cultivar does the upper one.

Temperature and RH of yellowing will significantly influence the PYHT quality.

Yellowing should be performed at 60 °C, 70 % RH for 10 h with ventilation 2 times.

Cultivar ZN801, ZC108, 5-21 and JKZ are much suitable to manufacture the PYHT.

Technique defines the lower limit of PYHT quality and cultivar does the upper one.