Tea Aroma Analysis Based on Solvent-Assisted Flavor Evaporation Enrichment

Summary

Presented here is a method for enriching and analyzing the volatile components of tea extracts using solvent-assisted flavor evaporation and solvent extraction followed by gas chromatography-mass spectrometry, which can be applied to all types of tea samples.

Abstract

Tea aroma is an important factor in tea quality, but it is challenging to analyze due to the complexity, low concentration, diversity, and lability of the volatile components of tea extract. This study presents a method for obtaining and analyzing the volatile components of tea extract with odor preservation using solvent-assisted flavor evaporation (SAFE) and solvent extraction followed by gas chromatography-mass spectrometry (GC-MS). SAFE is a high-vacuum distillation technique that can isolate volatile compounds from complex food matrices without any non-volatile interference. A complete step-by-step procedure for tea aroma analysis is presented in this article, including the tea infusion preparation, solvent extraction, SAFE distillation, extract concentration, and analysis by GC-MS. This procedure was applied to two tea samples (green tea and black tea), and qualitative as well as quantitative results on the volatile composition of the tea samples were obtained. This method can not only be used for the aroma analysis of various types of tea samples but also for molecular sensory studies on them.

Introduction

Tea is a preferred beverage of many people all over the world^1,2. The aroma of the tea is a quality criterion as well as a price-determining factor for tea leaves^3,4. Thus, the analysis of the aroma composition and content of tea is of great significance for molecular sensory studies and the quality control of tea. As a result, aroma composition analysis has been an important topic in tea research in recent years^5,6,7.

The content o....

Protocol

1. Preparation of the internal standard and tea infusion

1. Stock solution: Dissolve 10.0 mg of paraxylene-d10 (see Table of Materials) in 10.0 mL of anhydrous ethanol to prepare a 1,000 ppm stock solution of the internal standard.
2. Working solution: Dilute 1 mL of the stock solution (step 1.1) to 100 mL with pure water to prepare a 10 ppm working solution of the internal standard.
   NOTE: The working solution must be prepared on the same day as the analysis.
.......

Discussion

This article describes an efficient method for analyzing volatile compounds in tea infusions using SAFE and GC-MS analysis.

Tea infusions have a complex matrix with a high content of non-volatile components. Several methods have been described in the literature for isolating the volatile components from tea infusions. A common method is simultaneous distillation extraction (SDE)^15,16. However, it is not suitable for the analysis of tea.......

Materials

Name	Company	Catalog Number	Comments
Alkane mix (C10-C25)	ANPEL	CDAA-M-690035
Alkane mix (C5-C10)	ANPEL	CDAA-M-690037
AMDIS	National Institute of Standards and Technology	version 2.72	Gaithersburg, MD
Analytical balance	OHAUS	EX125DH
Anhydrous ethanol	Sinopharm
Anhydrous sodium sulfate	aladdin
Black tea	Qianhe Tea		Huangshan, Anhui province, China
Concentrator	Biotage	TurboVap
Data processor	Agilent	MassHunter
Dichloromethane	TEDIA
GC	Agilent	7890B
GC column	Agilent	DB-5MS
Green tea	Qianhe Tea		Huangshan, Anhui province, China
MS	Agilent	5977B
p-Xylene-d10	Sigma-Aldrich
SAFE	Glasbläserei Bahr
Ultra-pure deionized water	Milipore	Milli-Q
Vacuum pump	Edwards	T-Station 85H