Encapsulation Efficiency and Functional Stability of Cinnamon Essential Oil in Modified β-cyclodextrins: In Vitro and In Silico Evidence

Essential oils (EOs) have good natural antioxidant and antimicrobial properties; however, their volatility, intense aroma, poor aqueous solubility, and chemical instability limit their applications in the food industry. The encapsulation of EOs in beta-cyclodextrins (beta-CDs) is a widely accepted strategy for enhancing EO applications. The complexation of cinnamon essential oil (CEO) with five types of beta-CDs, containing different substituent groups (beta-CD with primary hydroxyl, Mal-beta-CD with maltosyl, CM-beta-CD with carboxymethyl, HP-beta-CD with hydroxypropyl, and DM-beta-CD with methyl), inclusion process behaviors, volatile components, and antioxidant and antibacterial activities of the solid complexes were studied. The CEOs complexed with Mal-beta-CD, CM-beta-CD, and beta-CD were less soluble than those complexed with DM-beta-CD and HP-beta-CD. Molecular docking confirmed the insertion of the cinnamaldehyde benzene ring into various beta-CD cavities via hydrophobic interactions and hydrogen bonds. GC-MS analysis revealed that HP-beta-CD had the greatest adaptability to cinnamaldehyde. The CEO encapsulated in beta-, Mal-beta-, and CM-beta-CD showed lower solubility but better control-release characteristics than those encapsulated in DM- and HP-beta-CD, thereby increasing their antioxidant and antibacterial activities. This study demonstrated that beta-, Mal-beta-, and CM-beta-CD were suitable alternatives for the encapsulation of CEO to preserve its antioxidant and antibacterial activities for long-time use.