Development of Alginate–Inulin Beads for Loading and Controlled Release of Bioactive Compounds from Spent Sour Cherry Pomace

Sour cherry pomace is a valuable by-product of Maraschino liqueur production in Italy, rich in phenolic compounds (PCs). This by-product is often discarded despite its high content of bioactive compounds with potential health benefits. To improve their stability, control their release, and enhance their functional food application, this study aimed to load phenolic extracts from post-fermented sour cherry pomace into sodium alginate beads, with and without the addition of inulin. Beads were prepared using 1.5% (w/v) sodium alginate and 50% (v/v) phenolic extract, while inulin was added at concentrations of 0, 0.5, 1, 1.5, 2, and 3 g. The beads were formed through ionic gelation and then freeze-dried before release studies. The extract contained a total phenolic content (TPC) of 249.11 ± 3.65 mg gallic acid equivalent/L and a total monomeric anthocyanin content (TMAC) of 18.53 ± 0.23 mg/L. The physical properties of the hydrogel beads, including hardness, cohesiveness, elasticity, gumminess, and resilience, were evaluated before freeze drying using a texture profile analyser. Loading efficiency (LE) and antioxidant release were also assessed. The release kinetics of TPC and TMAC were fitted to five models, including zero-order, first-order, Higuchi, Hixson-Crowell, and Korsmeyer-Peppas models. The Korsmeyer-Peppas model provided the best fit (R² > 0.9), with n values indicating that Fickian diffusion was the primary release mechanism. The presence of inulin increased the initial burst release and contributed to more sustained release thereafter. These results suggest that inulin influences both the mechanical strength and release behaviour of alginate beads. Overall, sodium alginate beads, with optimized inulin content, may serve as a protective and functional delivery system for PCs in functional food formulations.