Electrosprayed octenyl succinic anhydride starch capsules for rosemary essential oil encapsulation

Octenyl succinic anhydride starch (OSA-starch) is often used as an emulsifier to protect bioactive compounds such as essential oils. In this study, rosemary essential oil was encapsulated in OSA-starch capsules via electrospraying an emulsion. Creaming was observed in the emulsions with 40% ethanol (v/v) 2 h after preparation, and phase separation occurred after 4 days. The emulsion with 20% ethanol revealed smaller droplets and lower zeta potential, and remained stable for 7 days. The morphology, loading capacity (LC), and encapsulation efficiency (EE) of the capsules, electrosprayed from the emulsions, were evaluated. The capsules from 20 and 30% aqueous ethanol (v/v) were smooth and spherical in shape with few dimpled. EE values were higher in the emulsions with 20% ethanol (82%-98%) when compared to those with 30% ethanol (89%-96%), except when 30% oil content was used. Fourier-transform infrared spectrometry suggested interaction of essential oil with the wall material. In summary, OSA-starch produced a stable emulsion that was suitable for electrospraying into capsules.