1h Hr-Mas Nmr Chemical Profile and Chemometric Analysis as a Tool for Quality Control of Different Cultivars of Green Tea (C. Sinensis)

The influence of climatic parameters on the chemical composition of green tea cultivars ('Yabukita' and 'Yutakamidori) over the harvest was evaluated using HR-MAS NMR. The main changes in the metabolic profile of green teas were discussed based on the presence and amount of linolenic acid, theanine, epicatechin, and caffeine. Cultivar 'Yabukita' showed higher concentrations of epicatechin while higher amounts of theanine and caffeine were found in 'Yutakamidori'. The decline of theanine was associated with high average maximum temperature and solar radiation indexes, this latter also seemed to be responsible for relevant changes in epicatechin concentrations. On the other hand, fluctuations in linolenic acid concentration were monitored during the harvest period and were associated with the plant's defense mechanism at high values of relative humidity and rainfall rate. Monitoring the chemical composition of green tea over seasons might become an efficient strategy for establishing quality standards for green teas.