Polymeric Encapsulation of Mint Oil: Effect of Oil Load on the Physical Properties

Abstract

Mint oil has many applications including foods, perfumes and fragrances, pharmaceuticals, cosmetics and pest control. This essential oil is easily damaged because of its high sensitivity to environmental conditions such as heat, oxygen, light and reactions with other compounds. Encapsulation provides protection of the oil against these undesirable conditions. This study was aimed at evaluating the characteristics of mint oil encapsulated in polyethylene glycol (PEG 6000) as influenced by mint oil load. Mint oil was encapsulated in polyethylene glycol at four different percentages (5.0, 7.5, 10 and 12.5%) using a melt dispersion technique. The experiment was done in two replicates. The encapsulates were characterized for their morphology, size attributes and thermal properties. Particulate sizes ranged from 281.4-569.5 nm and tended to increase with the increase in oil load. Microstructure of the particles examined under scanning electron microscope showed irregular flakes with sizes around 10 µm. These particles contained oil droplets in the sizes of about 200-500 nm as confirmed by observation with a transmission electron microscope. The enthalpy of melting of encapsulates were higher than that of mint oil, describing the enhancement of oil stability under thermal conditions. This study provides useful information in developing essential oil encapsulation for use in wider applications.