The Effects of Adding Milk on Antioxidant Activities of Green and Black Tea

The aim of present study, eleven different types of commercial tea samples were assayed to phenolic contents and antioxidant activities. For tea infusion , 2 g of green and black tea were infused in 1000 ml of boiling water in a flask for 30 min, and for preparation of milk with tea , 50 ml of prepared tea was mixed with 50 ml of pre-warmed fresh cow milk with 4.2% fat . After 30 min, the infusions were filtered through a filter paper. Total phenolic and flavonoids content was measured according to the Folin-ciocalteus and aluminum chloride methods respectively. Total antioxidant activity was estimated by different assays such as 2,2-diphenyl-1-picrylhydrazyl radical DPPH ,Trolox equivalent antioxidant capacity (TEAC). Total polyphenols, and antioxidant activity were significantly (P<0.05) different in the commercial tea samples. Green tea had the maximum amount of total phenols, Flavonoids, and antioxidant activity. The addition of cow's milk increased the antioxidant activity of green and black tea preparations. Generally, antioxidant activities of tea+ milk infusion approximately 2 .1 fold greater than black and green tea. Both green and black tea infusions released high level of total phenols and antioxidants into the boiling water within 30 min compare to boiling water in duration of 10 min. For acquires of the highest antioxidant activity and therefore greatest health value, infusion with water at boiling point for up to 30 min ina flask was recommended .