Abstract
A comprehensive study on the composition and antioxidant properties of black tea samples with a chemometric approach was performed via LC-ESI-Q-TOF-MS, DPPH radical scavenging assay, and Folin–Ciocalteu assay (TPC). Marked differences between the teas from seven different countries (China, India, Iran, Japan, Kenya, Nepal, Sri Lanka) were shown. The Indian samples demonstrated the highest total catechin content (184.8 mg/100 mL), the largest TPC and DPPH scavenging potential (58.2 mg/100 mL and 84.5%, respectively). The applied principal component analysis (PCA) and ANOVA revealed several correlations between the level of catechins in tea infusions. EC (epicatechin), ECG (epicatechin gallate), EGC (epigallocatechin), and EGCG (epigallocatechin-3-gallate) content was not correlated with DPPH, gallic acid, and TPC; however, a strong correlation of EC and ECG between themselves and a negative correlation of these two catechins with EGCG and EGC was noted. Interestingly, simple catechins were not found to be responsible for antioxidant properties of the black teas. The samples collected in the higher altitudes were similar.
Highlights
Tea is the most widely consumed drink across the world after water [1]
Samples from China, Japan, and Iran used in this study were characterized by low antioxidant activity, which was well correlated with total phenolic content (TPC) and catechin content, which were significantly lower compared to other teas
This study shows a detailed analysis of catechins content, TPC analysis, and radical scavenging activity assessment of black tea samples from different cultivation areas: China, Japan, Kenya, Iran, Nepal, India, and Sri Lanka
Summary
Tea is the most widely consumed drink across the world after water [1]. Every day almost 2/3 of the world’s population drinks 18–20 billion cups of tea, and its annual production is estimated to be around 2.9 million tons [2]. Tea ((Camellia sinensis (L.) Kuntze)) belongs to the family Theaceae and is cultivated in over 45 countries across all continents except North America and Antarctica. Based on the type of production process, C. sinensis-based teas can be divided into black, green, Pu-erh, oolong, yellow, and white teas [4,5]. Recent research demonstrated that C. sinensis can be divided into seven types, namely green, yellow, white, oolong, black, aged pu-erh and ripened pu-erh [6]
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