Enhanced delivery performance of apigenin microcapsules modulated by soy protein isolate/octenyl succinic anhydride-modified starch complexes and acetylated monoglycerides.

Although apigenin has anti-inflammatory, antioxidant, and other health-promoting benefits, its poor water solubility, chemical instability, and low bioavailability limit its potential utilization in functional foods. In this study, new microcapsules were prepared with soy protsein isolate (SPI)/octenyl succinic anhydride-modified (OSA) starch complexes as wall materials and acetylated monoglycerides (AMs) as lipophilic core to encapsulate apigenin. The effects of the ratio of SPI/OSA-starch (10:1-1:10) and AMs on the properties of the microcapsules were investigated. The result of zeta potential confirmed the formation mechanism of electrostatic attraction between SPI and OSA-starch. Apigenin was entrapped in the solid core of AMs by a solubilized solid-state or an amorphous form and covered by the complex wall materials. The SPI/OSA-starch complex with ratio of 1:1 had the best emulsifying capacity. AMs improved the encapsulation efficiency (EE) of apigenin, and microcapsules of SPI/OSA-starch 1:1 had the highest apigenin loading (1.06 ± 0.03%) and EE (94.1 ± 0.5%). In vitro digestion study demonstrated that apigenin microcapsules had a slow release in the stomach and a fast release in the intestine. Microcapsules prepared from SPI/OSA-starch 1:1 had the fastest release rate, and AMs delayed the release of apigenin. Finally, the stability study indicated that AMs protected apigenin in the microcapsules against oxidation and enhanced the antioxidant activity of apigenin. Microcapsules of SPI/OSA-starch 1:1 exhibited the highest stability.