Microcapsule Preparation and Properties of Flavonoid Extract from Immature Citrus reticulata ‘Chachiensis’ Peel

Citrus reticulata ‘Chachiensis’ is a citrus cultivar in the Rutaceae family, and its peel is commonly utilized as a raw material for Guangchenpi. This study used flavonoid extract from the peel of immature Citrus reticulata ‘Chachiensis’ (CCE) as the raw material to investigate the encapsulation ability of different wall materials (plant-based proteins, including soybean protein isolation (SPI), pea protein (PP), and zein; carbohydrates, including maltodextrin (MD), Momordica charantia polysaccharide (MCP), and gum acacia (GA); and composite wall materials of both types) on CCE. The wall material with the highest encapsulation rate was selected for the preparation of CCE microcapsules. Furthermore, the physicochemical characteristics, antioxidant capacity, bioavailability, and storage stability of the CCE microcapsules were explored. The results indicated that among all wall materials, the composite wall material PPMD had the highest encapsulation rate, which was 84.44 ± 0.34%. After encapsulation, the microcapsules tended to have a yellow color and exhibited characteristics such as system stability, low moisture content, and low hygroscopicity. In vitro antioxidant assays revealed that the encapsulation of CCE significantly increased the scavenging rates of DPPH and ABTS free radicals. In vitro gastrointestinal digestion experiments indicated that the release rate of PPMD-CCE in intestinal fluid was significantly greater than that of free CCE, ultimately reaching 85.89 ± 1.53%. Storage experiments demonstrated that after 45 days under various temperature and light conditions, the retention rate of CCE in the microcapsules was significantly greater than that of free CCE. The above findings provide new possibilities for the application of PP and plant proteins and lay a foundation for the future industrial application of CCE.