Enhancement of antioxidant activity of C-phycocyanin of Spirulina powder treated with supercritical fluid carbon dioxide

Abstract

The functionality and activity of proteins can be modified by supercritical fluid CO₂ (SCFCO₂). The objectives of this study were to investigate the possibility of enhanced antioxidant activity of C-phycocyanin (C-PC) proteins from light-harvested Spirulina maxima powder using the SCFCO₂ pretreatment and to optimize the SCFCO₂ pretreatment conditions enhancing the antioxidant activity of C-PC. The Taguchi method was used to determine the optimum conditions for the SCFCO₂ pretreatment. The experimental factors were the pretreatment temperature, pressure, pretreatment mode (static, dynamic and conjugated) and duration. The optimal conditions of SCFCO₂ pretreatment were: 60 ^oC, 24.13 MPa and 60 min in static batch mode. Using these pretreatment conditions, the maximum antioxidant activity of C-PC from the treated residual biomass was 410.1 mmole trolox/mg, which was 1.7-fold higher than the untreated biomass (control). The factor that most affected the antioxidant activity of C-PC was temperature (59%). A high pretreatment temperature could damage C-PC, but promoted antioxidant activity. Of note is that this work was the first to explore SCFCO₂ treatment enhancing the antioxidant activity of C-PC in Spirulina sp. powder.