Colour stability and antioxidant activity of C-phycocyanin-added ice creams after in vitro digestion.

C-phycocyanin (C-PC) is a protein with bioactive properties, which is found mainly in cyanobacteria and that is used as a natural food dye. Even though it is extensively studied, few authors have reported C-PC's colour stability and antioxidant activity when applied to food matrices. Therefore, the aim of this research was to evaluate the colour stability over time and the antioxidant capacity of a food grade C-PC extract applied to milk-based ice creams. The C-PC-added ice creams showed insignificant colour loss during 182 d. Regarding antioxidant activity, the C-PC-added ice creams presented low ABTS and peroxyl radicals scavenging capacities before in vitro simulated digestion. However, after in vitro digestion, the ice creams with C-PC extract addition showed antioxidant capacities of 134.63 ± 15.68 and 1425.19 ± 54.93 μmol.g by the ORAC and ABTS methods, values 2- and 13-fold higher than the achieved by the controls, respectively. Thus, the results demonstrate that C-PC extract can be applied as a stable blue dye in ice creams and highlight the increased antioxidant activity of the C-PC-added products after in vitro simulated digestion, which can encourage the formulation of food products that attract consumers' attention for both their colour and biological activities.