Statistical Approaches to Assess the Association between Phenolic Compounds and the in vitro Antioxidant Activity ofCamellia sinensisandIlex paraguariensisTeas

Abstract

Tea presents a diverse phenolic composition which is responsible for its alleged biological activities, including the in vivo and in vitro antioxidant capacity. It is very usual to find researches applying statistical methods, such as analysis of variances (ANOVA) and linear Pearson correlation coefficients to analyze the strength of correlation between phenolic composition and the in vitro antioxidant activity of teas from Camellia sinensis (green, black, white, oolong, red, and yellow teas) and Ilex paraguariensis (Yerba-mate), which are the most produced and consumed types of teas. However, evidence has shown that these approaches are not as suitable as multivariate statistical methods once they do not depict nor show association among all results and variables simultaneously, making it difficult to understand clearly the data structure and patterns. Then, the objective of this work is to review and explain some univariate/bivariate and multivariate statistical techniques used to assess the association between phenolic compounds and the in vitro antioxidant activity of green, white, black, red, yellow, oolong and Yerba-mate teas. Moreover, this paper provides an overview on some assays used to estimate the in vitro antioxidant capacity of teas.

Chemical profile and antioxidant potential of extractable and non‐extractable polyphenols in commercial teas at different fermentation degrees

“…Tea is especially rich in polyphenolic compounds such as catechins and theaflavins which are derivatives of flavan‐3‐ol. Generally, during fermentation catechin amount shows a significant reduction from 30%–42% in green tea to 10%–30% in black tea (De Oliveira, Araujo Calado, Ares, & Granato, 2015; Stewart, Mullen, & Crozier, 2005; Yang & Liu, 2013). The content of catechins in dark tea was much less than those of the non‐fermented and semi‐fermented teas whereas the more stable theaflavins formed from the condensation of catechins are increased to some of the degrees in oolong, dark, and black teas (Roy et al, 2010; Yao et al, 2017; Zhang, Zhang, Zhou, Ling, & Wan, 2013).…”

Health Benefits of Bioactive Compounds from the Genus Ilex, a Source of Traditional Caffeinated Beverages

“…It is widely accepted that the counteraction on oxidative stress is mainly attributable to the existing phenolic compounds, especially chlorogenic acids (like mono- and dicaffeoylquinic acids) as well as flavonols [ 49 , 50 ], since in vitro antioxidant capacity has been confirmed to be positively correlated with their concentrations [ 13 , 51 ]. In order to better retain the contents and stability of health-beneficial antioxidants in Ilex teas, more attention should be paid to the adjustment of industrial processing methods and the improvement of packaging methods [ 22 , 52 ].…”

Effect of Extraction Conditions of Green Tea on Antioxidant Activity and EGCG Content: Optimization using Response Surface Methodology

“…[8][9] Therefore, consumption of antioxidant-rich fruits or botanical extract are thought to enhance health and minimize the senescence and chronic diseases. [10][11][12] Green tea also has been reported to exert beneficial effect against various diseases, in parts, via antioxidant effects.…”