서리피해를 받은 잎으로 만든 홍차의 GC×GC-TOFMS 휘발성 화합물 분석

Abstract

Korea suffers from unusual droughts, heavy rain, or high temperatures due to the abnormal weather phenomenon worldwide. This climate change directly impacts the occurrence of frost in spring, which is causing serious damage to the buds and leaves of tea plants that mainly grow in spring. Frost damage delays the harvest time and decreases production, leading to a decline in the income of tea-producing farmers. Therefore, it is essential to develop ways of using discarded tea leaves. This study analyzed the volatile compounds in black tea prepared from the discarded tea leaves by two-dimensional gas chromatography-time of flight mass spectrometry (GC×GC-TOFMS). The total relative content of 481 compounds was approximately 1.8 times higher in frost-damaged black tea than in regular black tea. The ketone and ester levels in frost-damaged black tea were approximately twice as high as that in normal black tea. Two types of black tea samples were well distinguished by a dependable PLS-DA model, which presented satisfied variance and cross-validated predictive capability (R2Y=0.997, Q2=0.956) without overfitting phenomena (R2=0.953, Q2=-0.266). One hundred eighty compounds with variable importance in the projection (VIP) values >1.0 were applied. The result of HCA analysis, esters, and alkenes were concentrated in normal black tea, and the ketones and heterocyclic compounds were concentrated in frost-damaged black tea. These results provide basic data for improving the process of producing good products using discarded leaves caused by frost damage.