Identification of coumarin-enriched Japanese green teas and their particular flavor using electronic nose

Abstract

a b s t r a c tConventionally, tea flavor is analyzed through the use of a combination of gas chromatography-mass spectrometry and human taste panel. These methods present time-consuming or inaccurate factor. In this work, a rapid, accurate and nondestructive approach was put forward to identify coumarin-enriched Japanese green teas and evaluate their particular flavor using electronic nose (E-nose) technique. The multivariable analyses including principal component analysis and cluster analysis were applied to distinguish the tea samples and evaluate the particular (coumarin-like) flavor of coumarin-enriched tea under different infusion conditions. A correct classification was achieved for the seven tea samples with different content of coumarin. The E-nose successfully characterized the drying temperature-dependently trend of coumarin content during the manufacture process of coumarin-enriched green tea. It also revealed that the comparatively low-infusion temperature and long-infusion time were favorable for the emission of coumarin-like flavor of the tea infusion. In addition, a comparatively newly developed ''absolute value expression" (AVE) method was employed to divide the tea flavors into quality and express them numerically. Using AVE, the role of coumarin in the total flavor of coumarin-enriched green tea was elucidated. These results suggest that E-nose could be employed to identify the green teas with particular flavor and evaluate the tea flavor.

Sample handling for electronic nose technology: State of the art and future trends

“…Its authors prove that the approaches using traditional sample handling procedures do not give adequate results in that case. Similar conclusions have been made by the authors of [54] and [55] dealing with identification of teas and analysis of human expired air: application of a gas trap and preconcentration using adsorbents to remove water vapor made it possible to improve analysis efficiency in the both cases.…”

Recent Developments in Smart Drying Technology

“…It was demonstrated that the e-nose successfully characterized the drying temperature-dependent trend of coumarin content during the manufacturing process, and could be employed to identify green teas with particular flavor and evaluate the tea flavor. [25] A novel electronic nose based on miniaturized surface acoustic wave (SAW) sensor arrays coupled with solid phase micro extraction process(SPME) enhanced headspace-analysis was studied by Bari´e et al [26] . With the SPME technique this system was used for rapid determination of the volatile organic compounds for food quality monitoring.…”

Potentiometric Sensors Based on Polyaniline and Thiacalixarenes for Green Tea Discrimination

“…The total antioxidant capacity was determined coulometrically with electrogenerated bromine in accordance with [28,29]. The amount of antioxidant was expressed by the charge required for generation of equivalent quantity of bromine, coulombs per 100 mL of undiluted sample.…”