Euterpe oleracea juice as functional pigment for yogurt

The juice of Euterpe oleracea Mart. fruit (Arecaceae), known as Açai in the Brazilian Amazon region, is dark purple with a high anthocyanin and phenolic content. The antioxidant and anti-radical properties of E. oleracea juice are well known; the chemical characterisation of its phenolic composition as well as its potential use as food ingredient and natural pigment have been previously studied. Cyanidin 3-O-glycoside, and various hydroxy-benzoic and hydroxy-cinnamic acids were detected in E. oleracea juice. The radical scavenging properties, measured as the mean of DPPH radical tests, were similar to those obtained by a common commercial bilberry juice. Therefore, novel natural colorants from E. oleracea juice could be considered as "functional" ingredients for their anti-oxidant and anti-radical activity. Yogurt is a typical fermented dairy product consumed all around the world; the yogurt flavouring is obtained both by means of natural ingredients like fruit juices and also by synthetic aromas. The aim of this work was to evaluate the use of E. oleracea fruit juice as a natural colorant for yogurt. The results obtained showed that yogurt enriched with Euterpe juice (10%, w/w) showed characteristics similar to those of typical commercial yogurt with bilberry juice. Aggregation of milk proteins in the E. oleracea containing yogurt was measured by SDS-PAGE. The protein profile of the E. oleracea containing yogurt was essentially identical to the untreated control yogurt. In conclusion, we suggest that E. oleracea juice could be used as a natural functional pigment for flavouring and colouring yogurt.