Utilization of green tea (Camellia Sinensis) extract for the production of antioxidant rich functional drinking yoghurt
N Thomas, MAJ Wansapala
Aqueous extract was prepared from dried green tea leaves, and its antioxidant activities, DPPH radical scavenging and total phenolic content (TPC) was determined. Folin-Ciocalteu’s reagent was used to determine the total phenolic content spectrophotometrically and Gallic acid was used as the calibrant. The yield was 162 mg GAE/g extract. This was obtained at extraction temperature 100 °C and extraction time 40 minutes. Drinking yoghurt was prepared with standardized & homogenized pasteurized milk fortified with 5%, 10% and 15% of the green tea extract after the incubation period of the yoghurt. The physico-chemical, microbial and sensory analysis was determined to ascertain the quality attributes of the product. A sensory analysis was carried out to determine the best ratio of yoghurt mix and green tea extract. The best ratio selected was the drinking yoghurt which consists of 15% (v/v %) GTE. The antioxidant activity of the drinking yoghurt was determined for three weeks. The highest antioxidant activity was obtained just after the green tea extract was incorporated into the drinking yoghurt and the lowest activity was recorded after 21 days. The antioxidant activity decreased at a higher rate in the first week compared to the second and third week. Addition of GTE had no significant effects on the sensory attributes (appearance, overall flavor, after taste, aroma and overall acceptability) as compared to the control sample. The results of physico-chemical analysis obtained showed increase in values for pH (4.37-4.40), soluble solids (13.9-14.7). There were also remarkable increase in the proximate values for moisture (79.7-82.99) and ash (0.34-0.42). A reverse trend was observed for acidity (0.741-0.738), total solids (20.30-17.01), protein (6.12-5.98) and fat (2.50-2.20) values in GTE enriched drinking yoghurts. The microbial analysis showed no presence of E. coli bacteria. Yeast and the mold growth was less in the green tea drinking yoghurt. Yeast count was recorded for the control sample after 21 days and in the selected sample after 26 days.