Case study: Quality control of Camellia sinensis and Ilex paraguariensis teas marketed in Brazil based on total phenolics, flavonoids and free-radical scavenging activity using chemometrics

This study aimed at monitoring the quality of Brazilian ready-to-drink teas and teas marketed in bags from Camellia sinensis and Ilex paraguariensis based on chemical composition and antioxidant activity by using chemometrics. Tea samples could be clustered into three distinct groups: Cluster 1, composed of 50% green tea samples, presented the highest content of antioxidant polyphenols, while Cluster 3, composed of 62.5% yerba mate teas, presented intermediate content of flavonoids, total phenolics and antioxidant capacity, and Cluster 2, which contained a mixture of black, red and white teas, presented the lowest antioxidant capacity and contents of phenolics and flavonoids. The total content of phenolic compounds, flavonoids, and antioxidant activity of teas marketed in bags were up to 1.5, 3.85, and 3.21 times higher than ready-to-drink samples. Data indicated that the use of chemometrics, especially cluster analysis, is suitable to monitor the quality of teas based on the content of bioactive compounds.