The objective of this study was to investigate the
effect of 2 plant leaf extracts on fermentation mechanisms
and health-promoting activities and their potential
as a nutraceutical prebiotics ingredient for application
in dairy products. The individual active phenolic
compounds in the plant extract-supplemented milk and
yogurts were also identified. Compared with control
fermentation, the plant extracts significantly increased
the growth and acidification rate of Streptococcus thermophilus
and Lactobacillus delbrueckii ssp. bulgaricus.
In particular, plant extract components, including
monosaccharides, formic acid, and hydroxycinnamic
acid, such as neo-chlorogenic, chlorogenic, and caffeic
acid, together play a stimulatory role and cause this
beneficial effect on the growth of yogurt culture bacteria
through fermentation. In addition, supplementation
with the plant extracts enhanced antioxidant activities
with increased total phenolic contents, especially the
highest antioxidant activity was observed in yogurt
supplemented with Cudrania tricuspidata leaf extract.