Application of anthocyanins from black goji berry in fermented dairy model food systems: An alternate natural purple color

Abstract

The application of anthocyanin extracts from black goji berry (Lycium ruthenicum Murray) in yoghurt and fermented milk at 1 and 2 g/100 mL concentrations was investigated and compared to a commercial colorant, purple sweet potato. The total anthocyanin content, antioxidant activity, pH, titratable acidity, syneresis, color, and viable cell count were measured during storage at 4 °C. The total anthocyanin content of yoghurt with black goji berry anthocyanin extract demonstrated high stability during storage. The yoghurt and fermented milk with black goji berry anthocyanin extract demonstrated higher antioxidant activity than the negative control and samples containing purple sweet potato colorant. The total color change of the yoghurt and fermented milk with black goji berry anthocyanin extract was less than samples containing purple sweet potato colorant during storage. All samples retained a viable cell count of more than 7 log CFU/g at the end of storage. The average color acceptability of yoghurt and fermented milk containing black goji berry anthocyanin extract did not significantly differ from those containing purple sweet potato colorant. Therefore, an anthocyanin extract from black goji berry at 2 g/100 mL concentration was a better natural purple colorant than purple sweet potato in yoghurt and fermented milk systems.