Stability, kinetics, and application study of phycobiliprotein pigments extracted from red algae Gracilaria gracilis

Phycobiliprotein (PBP) pigments were extracted from red algae Gracilaria gracilis through maceration in phosphate buffer using previously optimized conditions. The stability of PBPs in the extracts was assessed by monitoring the extracts at different pHs and temperatures for 10 days. Since phycoerythrin (PE) is the main PBP present in G. gracilis, PE content was spectroscopically determined and used as a response factor. Kinetic modeling was used to describe PE degradation under different ranges of T and pH. The pigment extracts presented higher stability at pH 6.9 and −20 °C. PE was semipurified by precipitation with ammonium sulphate 65% followed by dialysis against water until a purity index of 0.7. The pigment was successfully applied as colorant in pancakes and yogurts with a pigment concentration of 0.15%. This study highlights the potential of PE pigments extracted from G. gracilis for applications in food products.