Preparation, Characterization and Stability Evaluation of Gum Arabic- and Maltodextrin-loaded Anthocyanin Microcapsules Prepared from Grape-skin Pomace

In this study, the process of preparing microcapsules using a vacuum freeze-drying technique, with gum arabic/maltodextrin as the wall and anthocyanins derived from grape-skin pomace as the core materials, was optimized. The stability of the microcapsules under various temperature, light, and oxygen conditions was investigated before and after encapsulation. Single-factor experiments were conducted using the encapsulation rate as the indicator to evaluate the effect of the core-to-wall ratio, gum arabic-to-maltodextrin ratio, embedding temperature, and embedding time on the encapsulation performance of anthocyanins. The optimal encapsulation process was refined using the response surface methodology. The results indicated that the optimal process parameters were a core-to-wall ratio of 1:3.3, a gum arabic-to-maltodextrin ratio of 1:3.3, an embedding temperature of 41 ℃, and an embedding duration of 30 min. The encapsulation efficiency of the microcapsules was 98.48%±0.03% under this process. The surface of the anthocyanin microcapsules exhibited amorphous, concave-convex, and wrinkled structures. Fourier-transform infrared spectroscopy and X-ray diffraction revealed that the anthocyanins could be encapsulated by gum arabic and maltodextrin, with an average encapsulated particle size of 1.0213 μm, a distribution index of 0.456, and an average potential of −13.70 mV. Investigating the effect of natural light, temperature, and oxygen on the stability of anthocyanins showed that the microencapsulated anthocyanins were more stable than their unencapsulated counterparts. In conclusion, the microcapsule preparation process is feasible and exhibits high encapsulation efficiency, which can effectively enhance the stability of anthocyanins. This study provides a theoretical basis and technical reference for the high-value utilization of grape-skin pomace by-products and the stabilization application of anthocyanins in the food industry.