Characterization of rosemary essential oil for biodegradable emulsions

The characterization of rosemary essential oil (EO) for its formulation in biodegradable emulsions has been carried out. Firstly, the required HLB (hydrophile–lipophile balance) value of the oil was determined to be 15 based on droplet size analysis and the stability of emulsions with synthetic surfactants. Moreover the emulsion resulted to be stable after 50 days of storage in ambient conditions. Secondly, four biodegradable and non-toxic surfactants derived from starch were tested. The effect of these surfactants was analyzed by measuring interfacial tension between the oil and the aqueous phase.

► Required HLB (hydrophile–lipophile balance) value of rosemary essential oil is 15.
► n-Octenyl succinic anhydride (OSA) modified starches from maize and tapioca show adequate interfacial tension between oil and aqueous phases.
► Minimum concentration of OSA-modified starches surfactants is 25 g/L.