Stability mechanism of Monascus pigment‐soy protein isolate‐maltodextrin complex

Abstract Background Monascus pigment (MP) is a natural food coloring with vital physiological functions but prone to degradation and color fading under light conditions. Results This study investigated the effect of complex formation of soybean protein isolate (SPI), maltodextrin (MD), and MP on the photostability of MP. Light stability was assessed through retention rate and color difference. Fluorescence spectroscopy (FS), circular dichroism (CD), Fourier transform infrared spectroscopy (FTIR), and X‐ray diffraction (XRD) explored MP, SPI, and MD interactions, clarifying the MP‐SPI‐MD complex mechanism on MP's light stability. Microstructure and Differential Scanning Calorimetry (DSC) analyzed the morphology and thermal properties. The retention rate of MP increased to approximately 80%, and minimal color difference was observed when adding SPI and MD simultaneously. FS revealed hydrophobic interaction between MP and SPI. FTIR showed intensity changes and peak shifts in admin I band and admin II band, which proved the hydrophobic interaction. CD showed a decrease in α‐helix content and an increase in β‐sheet content after complex formation, indicating strengthened hydrogen bonding interactions. SEM analysis demonstrated that MP was attached to the surface and interior of complexes. XRD showed MP as crystalline, while SPI and MD were amorphous, complexes exhibited weakened or absent peaks, suggesting MP encapsulation. The results of DSC were consistent with XRD. Conclusion SPI and MD enveloped MP through hydrogen bonding and hydrophobic interaction, ultimately enhancing its light stability and providing insights for pigment‐protein‐polysaccharide interactions and improving pigment stability in the food industry. This article is protected by copyright. All rights reserved.