The quality, antioxidant activity, and storage behavior of milk fermented with Ligularia fischeri extracts

Abstract

In this study, milk samples were fermented following the addition of Ligularia fischeri extracts. The aqueous extracts were obtained from L. fischer grown in the open field (OL) or in a greenhouse (GL). The quality related properties, and antioxidant activity of the fermented milk were evaluated, and the effects of storage on the fermented samples were assessed. The time required for the fermented milk to reach pH 4.6 was approximately four hours in all samples. The titratable acidity of the samples was in the range of 0.5-1%. The number of lactic acid bacteria in the fermented milks made with L. fischeri GL extract was slightly higher than it was in milks samples fermented with L. fischeri OL extract. The Hunter Lab color (L) and redness (a) values of the samples were lower after fermentation, but their yellowness (b) increased with increasing amounts of L. fischeri extracts. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity in milk fermented with 0.5%, 1%, 3%, and 8% L. fischeri OL extracts was higher than that in milk fermented with corresponding amounts of L. fischeri GL extract. However, the difference was not significant. DPPH activity in milk fermented with 5% L. fischeri GL extract was higher than it was in milk fermented with 5% L. fischeri OL extract. The pattern of 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonate) radical cation (ABTS˙+) scavenging activity in the samples was similar to that observed during the DPPH assay. The pH and, titratable acidity, of the fermented samples were not significantly affected by storage, and the number of lactic acid bacteria in the stored and freshly fermented samples was similar.