A study on development of yogurt rich in antioxidants and pjenolic compounds by fortification with moringa oleifera

Abstract

The aim of this study was to develop an yogurt product which is rich in antioxidants and phenolic compounds by incorporating Moringa oleifera leaf powder without affecting the sensory attributes as well as yogurt starter culture. Total phenolic content, antioxidant activity, pH and number viable cells count of the products at three different concentrations of Moringa oleifera leaf powder added into yogurt: 2, 5 and 8% weight/dry weight of yogurt were determined during different storage times namely 0, 3, 6, 15 days for total phenolic content, antioxidant activity, pH and 0, 5, 10, 15 days for total viable cell count at the storage temperature 4 oC. The Moringa oleifera leaf powder increased the total phenolic content, antioxidant activity and total viable cell count significantly while the pH decreased significantly for 8% concentration. The 8% Moringa oleifera yogurt had highest total phenolic content (10.35 ± 0,23 mgGAE/g dry weight) and antioxidant activity (64.24 ± 1.01%) on day 15 compared to plain yogurt (4.27 ± 0.09 mgGAE/g dry weight and 27.75 ± 1.04%, respectively). The 8% Moringa oleifera yogurt had significant enhancement growth effect on yogurt bacteria so it had highest total viable cell count (2.89± 0.116 x 107 CFU/ml) on day 15 compared to plain yogurt (1.22 ± 0.122 x 107 CFU/ml). The pH value (3.82 ± 0.02) of the 8% Moringa oleifera yogurt in day 15 is lowest and significantly lower than that of the plain yogurt (3.97 ± 0.02) due to the strongly growth of yogurt bacteria. The sensory evaluation was performed, the result shows that 5% Moringa oleifera leaf powder added into yogurt resulted in good overall acceptability while the other concentrations had undesirable effects on the overall acceptability of the product. The proximate analysis were performed to the 5% Moringa oleifera leaf powder yogurt in order to make the nutritional values for the final product which has big potential in the future market. Keywords: Antioxidant activity, Moringa oleifera, total phenolic content, yogurt.