Abstract
The characteristics of Algerian Nigella sativa (Ns) seeds were investigated after extraction with three aqueous ethanol concentrations (40, 60 and 80%) at three seed concentrations (2.5, 5 and 7.5%) referred as T, F and S, respectively. Aqueous ethanol extraction (40%) at 2.5 and 5% Ns seed concentration [T40% and F40%] had the highest total phenolic and total flavonoid contents. Higher seed (7.5%) and aqueous ethanol concentrations (60 and 80%) extracts [S60% and S80%] exhibited the maximum antioxidant activity. T80% and S40% extract exerted high antimicrobial activity against Escherichia coli and Staphylococcus aureus, respectively. Four stirred yogurts formulated with 0, 0.5, 1 and 2% of S60% extract were evaluated for physicochemical and sensory properties; two of these formulated yogurts were further investigated for stability under refrigerated storage (4 °C for 21 days). Yogurt formulated with 0.5% of S60% extract exhibited the highest antioxidant activity, high titratable acidity, low pH and increasing syneresis during storage. However, the control yogurt had higher syneresis than the fortified yogurt (60 vs 46% at 21 days storage).
Publisher
Universitatea Dunarea de Jos din Galati