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4861238 
Journal Article 
Green Tea Quality Evaluation Based on Its Catechins and Metals Composition in Combination with Chemometric Analysis 
Koch, W; Kukula-Koch, W; Komsta, Ł; Marzec, Z; Szwerc, W; Głowniak, K 
2018 
1 
Molecules
ISSN: 1420-3049 
MDPI AG 
23 
7 
1689 
English 
29997337 
WOS:000445301800192 
Green tea infusions are one of the most popular beverages consumed across the world, especially is Asian countries. Green tea quality is primarily based on catechin content, however, the concentration of elements could also significantly influence its biological properties and thus quality and safety. The main purpose of the present study was the evaluation of catechin, antioxidant activity and metal content (K, Na, Ca, Mg, Fe, Mn, Cu, Zn, Cr, Pb, Cd and Ni) in different green tea types cultivated in Japan, Sri Lanka, South Korea, India, China and Japan. The chemical analysis of samples was performed using LC-ESI-Q-TOF-MS for organic constituents and atomic absorption spectrometry (flame and electrothermal) method for inorganic ones. The obtained results were subjected to chemometric elaboration. EGC (213 mg/100 mL of the tea infusion in South Korean Jeoncha) and EGCG (124 mg/100 mL in Japanese Sencha) were the dominant catechins in all green tea samples. Chinese and Indian green tea samples contained the highest concentration of toxic heavy metals, however these values were far below appropriate limitations for green teas. PCA revealed significant similarities between Japanese samples and Korean Jeoncha. In general the latter one was evaluated to have the best quality based on the investigated parameters. 
Japan; Chemical analysis; Beverages; Magnesium; Spectrometry; Iron; Green tea; Catechins; Nickel; Copper; Metal concentrations; Biological properties; Tea; Evaluation; Cadmium; Infusion; Calcium; Atomic absorption analysis; Antioxidants; Quality assessment; Spectral analysis; Catechin; Organic chemistry; Zinc; Organic constituents; Chromium; Lead (metal); Heavy metals; Epigallocatechin-3-gallate; Manganese