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Antioxidant and anti-microbial properties of Camellia sinensis products

Products based on Camellia sinensis plant include white, green, yellow, oolong and black tea. White and green tea present completely unfermented products, due to enzyme inactivation during production. Oolong and black tea are products in which deliberate oxidation of polyphenols is induced, while yellow tea presents the rarest and least investigated type of teas in which a slight oxidation might occur due to the lack of enzyme inactivation phase during production. All of these products present a very rich source of bioactive compounds, especially polyphenols, which impart positive health effects but there is a lack of data on their anti-microbial properties. Bioactive composition (total phenols and flavonoids) of tested teas was determined spectrophotometrically. Additionally, antioxidant capacity was determined using three different assays (DPPH, ABTS, FRAP). Antimicrobial activity was tested on following test microorganisms: Escherichia coli 3014, Staphylococcus aureus 3048, Candida albicans 11 and Salmonella sp. 3064, by disc-diffusion and turbidimetric method on microtiter plates. In total, nine different teas were tested in this study (white tea – Pai Mu Tan superior ; yellow tea – Yin zhen ; green tea – Matcha, Twinings, Gyokuro, Long Jing ; oolong – Formosa Fine oolong ; black tea – Twinings English breakfast, Pu erh). Among tested teas, Twinings green tea possessed the highest content of total phenols (2560, 23 mg/L GAE) and flavonoids (1920, 20 mg/L GAE), while Pu-erh showed the lowest contents (675, 36 and 185, 76 mg/L GAE, respectively). Antioxidant capacity was in compliance with total phenol and flavonoid content. Bacteriostatic activity of Twinings English breakfast black tea against Salmonella sp. 3064 and Gyokuro green tea against S. aureus 3048 was detected. The obtained results confirmed high polyphenolic content and antioxidant capacity of tested teas. Despite the high content of bioactive compounds in all samples, only the Twinings English breakfast (black tea) and Gyokuro (green tea) showed bacteriostatic properties.

Camellia sinensis; polyphenols; antioxidant capacity; anti-microbial properties

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