The effect of Myrtus Communis fruits on physicochemical and antioxidant activity of yogurt

Abstract

Yogurt is a coagulated milk product obtained frome the lactic acid fermentation by the action of Lactobacillus bulgaricusand Streptococcus thermophilus. The additions of fruits in to milk may enhance the taste and the therapeutical values of milk products. However fruits also may change the fermentation behaviour. In this present study, the changes in physicochemical, total phenolics content and the antioxidant potential of yogurt upon the addition of Myrtus communis fruits were investigated. Fruits enriched yogurt (0.2%, 0.4%, 0.6% and 0.8 % w/w) were prepared and the pH, TTA, syneresis measurement, total phenolic content DPPH antioxidant inhibition percentage, iron reducing power and ABT test were determined. Myrtuscommunis fruit enriched yogurts generally showed lower pH readings (pH 4.02–5.04) compared to plain yogurt (pH 3.01). Fruit yogurt showed a higher lactic acid percentage (1.83%). Significantly higher syneresis percentage (83, 55%) compared to plain yogurt (6.48%) were seen in all fruit enriched yogurts. The DPPH antioxidant activity of plain yogurt (25.60%) was enhanced by the presence of myrtle fruit (28.72-43.21). fruit enriched yogurt showed an increment in total phenolic content (32.25 - 43.42mg/ml) compared to plain yogurt (25.59mg/ml). Therefore, it could be concluded that the addition of Myrtus communis fruit in to yogurt enhanced syneresis percentage, total phenolics content and antioxidant activity in yogurt.