Chemical compounds that are naturally occurringdietary components and their influence on human body are more and more interesting for scientists. Polyphenols, bio-logically active compounds of plant origin, are classified as non–nutrients. An average daily intake of polyphenols with the diet is approximatively 1 gram, which can be important in fighting free radicals activity in human body [Scalbert & Williamson, 2000]. Recent research have shown the antiox-idant potential of food constituents. Numerous epidemio-logical studies have indicated that food and beverages richin polyphenols are an important factor in preventing dis-eases, decreasing mortality from cardiovascular and meo-plastic diseases, and slowing down the aging processes [DiCarlo et al., 1999]. Green tea contains relatively large amounts of polyphenols, mainly catechins and their deriva-tives, considered to exert a protective effect against cancerand cardiovascular diseases. As tea is one of the most pop-ular beverages, it could be a tremendously important source of polyphenolic constituents.