Colorant and antioxidant properties of freeze-dried extracts from wild berries: use of ultrasound-assisted extraction method and drivers of liking of colored yogurts

This work aimed at developing powders rich in antioxidants and pigments from two wild berries: maqui ( Aristotelia chilensis ) and murra ( Rubus ulmifolius ). Fruits were subjected to successive ultrasound-assisted extractions (UAE) and then freeze-dried. Physical properties, anthocyanin stability of powders, and their performance as natural colorants in yogurts were evaluated. The optimum extraction methods were: UAE for 10 min in murra, and without UAE (control) in maqui, with juice extraction yields ranging between 80 and 82%. Maqui powder exhibited ≈ 2.8 times more polyphenol and anthocyanin content than murra. However, murra powder showed better stability characteristics as powder colorant since it exhibited greater protection of anthocyanins by means of copigmentation phenomena. Regarding consumer's perception of colored yogurt, samples with 4% and 8% maqui powder could be considered as future prototypes to be launched into the market. The obtained powders may be used in different industrial food applications.