The stabilization of Monascus pigment by formation of Monascus pigment-sodium caseinate complex

Abstract

This study aimed to evaluate the effect of sodium caseinate (SC) on the thermal stability of Monascus pigments (MPs) under acidic conditions (pH 3.0) during heating at 100 °C at different time (0, 30, 60, 90 and 120 min). The MPs solution was precipitated after heating in an acidic condition, while it was stable in the presence of SC. Particle size results indicated the formation of MP-SC complex nanoparticles. Their values (141) were much smaller than MP and significantly improved the solubility and stability of MP in acidic conditions. The formation of covalent interactions (CC at peak 1643–1654 and NO stretching at peak (1537–1539) and hydrogen bonds (CH binding at peak 1452–1454) between MPs and SC were clear. Overall, the formation of the MP-SC complex was attributed to the covalent interactions and hydrogen bonds between MPs and SC, leading to the inhibition of MPs aggregation and improved stability in acidic solution.