EFFECTS OF ENRICHMENT WITH POLYPHENOLIC EXTRACTS FROM SARDINIAN PLANTS ON PHYSICO-CHEMICAL, ANTIOXIDANT AND MICROBIOLOGICAL PROPERTIES OF YOGURT

摘要

The effect of adding artichoke (Cynara scolymus L.), strawberry-tree fruit (Arbutus unedo L.) and cherry (Prunus avium L.) extracts was evaluated on the physico-chemical, antioxidant and microbiological properties of home-made yogurts. Yogurts, enriched with artichoke or red ripe strawberry-tree fruit extract, demonstrated high in vitro antioxidant activity. Ten days after their preparation, no variations in the antioxidant components and antioxidant activity of the yogurts were observed. The enriched yogurts showed an increase in lactic acid and acetaldehyde. As regards microbial characteristics, there was a notable increase in the microbial count of Lactobacilli in yogurts with edible artichoke parts (4.5x10(9) cfu/g)and with strawberry-tree fruit extracts (1.8x10(9) cfu/g) during the three-week experimental period. During the same period persistence of Streptococci in yogurt with artichoke edible parts was observed until the end of the first week (5.2x10(7) cfu/g). Our results indicate that the enrichment of yogurts with Sardinian plant extracts can significantly improve the antioxidant activity of yogurt and in some cases the survival of its microbial flora.