Stabilisation of lavender essential oil extracted by microwave-assisted hydrodistillation: Characteristics of starch and soy protein-based microemulsions

Abstract

In this work, microwave-assisted hydrodistillation (MAHD) technique was used to obtain lavender essential oil (LEO) with a yield of 5.5 %. Oil in water microemulsions of LEO were prepared with starch and soy protein by ultrasonic emulsification. Total phenolic content and antioxidant capacity of the samples were evaluated. Microemulsions exhibited antimicrobial effect against S. aureus and B. cereus. The major volatiles of LEO were linalool L (29.0 %), 1,8-cineole (13.9 %), camphor (12.3 %) and linalyl acetate (11.9 %). Camphene, 1,8-cineole, (Z)-ocimene, linalool, and 2,6-nonadienal were determined as aroma-active compounds by gas chromatography-olfactometry. The stability of emulsions at different pH (3, 6 and 9) and temperatures (4 and 25 °C) were evaluated by measuring their size distribution, zeta potential, viscosity and color during storage. The stable droplets of LEO microemulsion that ranged between 392 and 732 nm were obtained with starch at pH 6. The formulated starch-based emulsions of LEO at pH 6 revealed the highest stability at 25 °C.