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

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 homemade
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 (4.5x109
cfu/g) and with strawberry-tree fruit extracts
(1.8x109 cfu/g) during the threeweek
experimental period. During the
same period persistence of Streptococci
in yogurt with artichoke edible parts
was observed until the end of the first
week (5.2x107 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.