Understanding the influence of encapsulating matrix on the physical and thermal properties of oregano essential oil powder

Abstract

In this study, the influence of blends of carbohydrates on the physical and thermal properties of oregano essential oil micro particles was evaluated. Powders were produced by spray drying using different wall materials: gum Arabic (GA), modified starch (MS) and maltodextrin (MD). The micro particles were characterized by morphology, moisture content, water activity, particle size distribution, particle mean diameter, poly dispersity index, glass transition temperature (Tg) and thermal stability. The partial replacement of GA by MS or a mixture of MS and MD resulted in micro particles with lower moisture content. The results showed that micro particles with GA had higher values of Tg (97.02 °C), indicating more physical stability. However, the use of MS and MD results in a slight reduction of Tg. TGA results showed that the nature of wall materials have considerable effect on the thermal degradation of micro particles. Thermal analysis revealed the potential of application of these carbohydrates for substitution of GA.