Enzyme-Assisted Extraction and Preparation of Saponin Microcapsules and Gelatin Gummies: Characterization and In Vitro Digestion

Saponins, the primary bioactive constituents with immunomodulatory activities in Baoyuan decoction—a traditional Chinese medicine formula composed of ginseng, astragalus, licorice, and cinnamon—are limited by low extraction yield, poor stability, and easy degradation. In this study, cellulase and pectinase were used for the extraction of saponins from Baoyuan decoction and optimized by response surface methodology. Subsequently, the optimal extracts were microencapsulated by spray drying with soy protein isolate (SPI) or high-oleic acid soy protein isolate (HOSPI) and pectin (PE) as composite wall materials, followed by application evaluation in gummies and in vitro digestion. After optimization, the total saponin yield was 63.68 ± 0.15 mg/g. HOSPI-PE microcapsules (HBP) had a higher encapsulation efficiency (90.38%), smaller particle size, and lower hygroscopicity than SPI-PE ones (SBP). Furthermore, both microcapsules showed good stability during storage and controlled release, with 60.9% of saponins in SBP and 65.8% in HBP being delivered to the intestinal phase during in vitro digestion of microparticles. When applied in gummies, microcapsule gummies retained satisfactory sustained-release in vitro digestion (23.0% released in the stomach and 66.2% in the small intestine). In contrast, the unencapsulated gummies exhibited a burst release (74.4%) at 30 min in gastric digestion. This study provides theoretical and technical insights into the development of plant-derived functional foods and promotes the practical application of microencapsulation in functional gummy candies.