Detection of Volatile Organic Compounds in Adulterated Tea Using Fourier Transform Infrared Spectroscopy and Proton-Transfer-Reaction Mass Spectrometry

Abstract

Aroma is a key factor used to evaluate tea quality. Expired or substandard tea can be adulterated with essence to improve its aroma and increase profits. Traditional tea quality testing methods by physical and chemical analysis are complex, time-consuming, and expensive. Rapid detection techniques, such as near-infrared spectroscopy and machine vision, can be used to detect powdered solid essences but cannot be used to detect liquid essences. In this study, we investigated proton-transfer-reaction mass spectrometry and Fourier transform infrared spectroscopy for accurate and rapid identification of liquid essences in adulterated tea. These techniques were used to measure the volatile organic compounds in the tea and essence. Proton-transfer-reaction mass spectrometry had a prediction accuracy of more than 0.951. With Fourier transform infrared spectroscopy, the prediction accuracy was more than 0.968. These techniques meet practical use requirements and could be used for rapid detection of liquid essence in adulterated tea.

Keywords: Aroma, Tea, Proton-transfer-reaction mass spectrometry, Fourier transform infrared spectroscopy, Essence