Encapsulation of Bee Pollen Phenolics with β-Cyclodextrin: Effects on Antioxidant Activity, Antimicrobial Properties, and Digestive Stability

Bee pollen is a natural product with multifunctional properties, containing abundant bioactive compounds, especially phenolic acids and flavonoids, which are largely responsible for its antioxidant and antimicrobial activities. In this study, the bioactive composition, antioxidant capacity, encapsulation efficiency, antimicrobial activity, and gastrointestinal stability of bee pollen extract (PE) were investigated. The pollen extract exhibited high total phenolic (2817 mg GAE/100 g) and flavonoid contents (5255 mg QE/100 g), along with strong antioxidant activity (DPPH: 4305 mg TE/100 g; CUPRAC: 3685 mg TE/100 g). To improve the stability and bioaccessibility of phenolic compounds, PE was encapsulated using β-cyclodextrin (BCD) at different weight ratios. Among the formulations, the PE:BCD ratio of 1:2 showed the highest encapsulation efficiency (64%) and favorable physicochemical properties, including higher particle size and more negative zeta potential values, indicating good colloidal stability. Antimicrobial activity was evaluated for PE, BCD-only, and the selected PE-loaded formulation (1:2, <i>w</i>:<i>w</i>). Encapsulation led to a modest reduction in antimicrobial activity compared to free PE (6.25-50 mg/mL); however, the encapsulated formulation still exhibited considerable antibacterial effects against both Gram-positive and Gram-negative strains (25-50 mg/mL). Furthermore, in vitro gastrointestinal digestion indicated that BCD encapsulation substantially enhanced the bioaccessibility of total phenolics (81%) and antioxidant capacity (DPPH: 48%; CUPRAC: 76%), particularly during the intestinal stage. Phenolic profiling showed that chlorogenic acid and quercetin derivatives remained relatively stable throughout digestion. Overall, encapsulation with BCD effectively safeguarded pollen phenolics, improved their gastrointestinal stability, and increased bioaccessibility, highlighting the potential of encapsulated bee pollen as a functional food ingredient or nutraceutical.