Effects of enrichment with polyphenolic extracts from Sardinian plants on physico-chemical, antioxidant and microbiological properties of yogurt

The effect of adding artichoke (Cynara scolymusL.), strawberry-tree fruit (Arbutus unedoL.) and cherry (Prunus aviumL.) extracts was evaluated on the physico-chemical, antioxidant and microbiological properties of homemade yogurts. Yogurts, enriched with artichoke or red ripe strawberry-tree fruit extract, demonstrated highin vitroantioxidant 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 ofLactobacilliin yogurts with edible artichoke parts (4.5x109 cfu/g) and with strawberry-tree fruit extracts (1.8x109 cfu/g) during the threeweek experimental period. During the same period persistence ofStreptococciin yogurt with artichoke edible parts was observed until the end of the first week (5.2x107cfu/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.