Improving the color stability of red Monascus pigments by direct protein microgelation

The application of red Monascus pigments (RMPs) in food storage as well as food processing usually endures harsh environmental conditions. Here, we presented a new encapsulation strategy to improve the stability of RMPs. At first, we managed to realize the azaphilic substitution reaction between orange Monascus pigments (OMPs) and soy protein to produce water-soluble RMPs, i.e., soy protein chemically modified by OMPs. Then, the as-prepared RMPs as a kind of protein were directly utilized to fabricate microgels where microgel efficiency > 60 % (encapsulation of RMPs in microgels > 60 %) was achieved after optimization of Ca²⁺ and RMP concentrations. The microgels with particle sizes < 10 μm dispersed very well in water. The stability of encapsulated RMPs in microgels under harsh environmental conditions, such as heating, acidic pH, and sunlight irradiation, had improved approximately 10-20 % compared with that of free RMPs under the same condition.