| Popis: |
Seasonal variation of total phenolics, antioxidant activity and minerals in fresh tea shoots, consisting of one apical bud and two adjoining leaves sampled from Muradiye, Tuglali, Gundogdu, Enstitu 9, Hamzabey, Hayrat and Pazar 20 clones grown in Eastern Black Sea region in Turkey was investigated during three harvest season (May, July and September) in both 2006 and 2007 years. The total phenolics of all clones were lower in cool months of May in both years (average 33.00-90.27 mg GAE/g dry weight basis). Thereafter, the levels of total phenolics increased throughout the warmer months from July to September. Antioxidant activity determined by beta-carotene bleaching assay showed similar trends which increased from 1st harvest (May) to 3rd harvest (September). All clones showed nearly 100% antioxidant activity at 2nd and 3rd harvest season which higher than standard synthetic antioxidant BHA (butylated hydroxyanisole). However, seasonal variation of minerals (N, P, K, Ca, Mg, Na, Fe, Cu, Mn, Zn) showed different results according to clones used. These results seem to suggest that the harvest time is crucial to determining the antioxidant potential of fresh tea shoots. |
