Preparing bright Monascus yellow pigments by loading quercetin-Sn(II)- albumin –chitosan: Enhanced stability and bioactivity

Natural Monascus yellow pigments (MYPs) have received considerable attention due to their great safety and biological activities, but their unsatisfactory color tonality and stability limit their applications. A novel encapsulate system for hydrophilic yellow pigments (HYPs) were investigated through stable ternary nanocomplexes using quercetin-Sn (II), bovine serum albumin (BSA), and chitosan (CS) in this work. Layer-by-layer assembly preparation of HYPs-loaded quercetin-Sn (II)-BSA-CS nanocomplexes were verified by fluorescence spectroscopy, fourier transform infrared spectroscopy, X-ray photoelectron spectra, and 1H nuclear magnetic resonance. A hyperchromic effect on HYPs was obtained since their maximum ultraviolet absorption wavelength redshifted from 352 nm to 364 nm first due to the interaction with quercetin-Sn (II) and further redshifted to 408 nm due to ternary conjugation, greatly improved the color tonality and dye-uptake. The HYPs-loaded nanocomplexes showed irregular glomerate nanosphere with 252–382 nm of particle size. Their conjugation remitted HYPs degradation under various environmental stresses (thermal, light, and ascorbic acid treatment), and had a great color stability response to pH change. Higher lipid-lowering and antioxidant activities were detected in the nanocomplexes than free HYPs. This study provides a new way for fabricating novel MYPs with great physicochemical stability, bright color and hypolipidemic activities.