Influence of Milk on Phenolic Composition and Antioxidant Power of Black Tea

Introduction: Tea leaves are rich in several polyphenolics and flavonoidal compounds that could potentially have health-promoting properties. The objective of the present study was to analyze the antioxidant capacity of black tea and to study the effect of addition of fresh milk and packed milk on the phenolics concentrations and antioxidant efficacy. Methods: The black tea infusion (BT), black tea infusion with fresh milk (BTFM) & black tea infusion with packed milk (BTPM) samples were comparatively analyzed for total phenolics, flavonoids and HPLC profiling of major phenolic content. All samples were investigated for their total antioxidant capacity and glutathione level in different organs (brain, liver, kidney and heart). Results: The results shown that BT(black tea infusion) had higher total phenolics and flavonoids followed by BTPM (black tea infusion with packed milk) and then the BTFM (black tea infusion with fresh milk). The analytical HPLC results obtained also indicated that BT contained higher amount of catechins and garlic acid derivatives than BTFM, and BTPM may be due to chelation of free phenolics with some fats and protein in the tested milk samples, which reduces the levels of free phenolics significantly. Concerning antioxidants capacity both tested milk samples reduced antioxidant capacity to more than 50% in different tested tissues. Conclusion: We conclude that black tea is a valuable source of antioxidants and that the inhibitory effect of milk on the total antioxidant capacity may be related to complex formation of the fat & protein content of the milk with major phenolics in the black tea.