Abstract
Supercritical CO2 was studied for impregnation or encapsulation of essential oils in modified starches via Particle from Gas Saturated Solutions or Suspensions (PGSS). Modified starches were choose as function of its low cost. The advantage of this method over conventional encapsulation that use modified starch via spray drier refers to the low temperatures used and absence of water in the process. Modified starch presents hydrophobic elements and this molecules present amphiphilic character. Usually it is employed in the encapsulation of essences as wall material with excellent volatiles retention due to its polar and nonpolar interface. Considering its hydrophobic characteristics, interactions between the modified starch and supercritical CO2 occurred, resulting in two different structural interactions of the limonene and modified starch in the PGSS (50°C and 60°C at 100bar and 120bar). When hydrous ethanol was used in the suspension, impregnation occurred and, when anhydrous ethanol was used, encapsulation occurred. Analysis of particle morphology via scanning electron and confocal microscopy, thermo-oxidative characterization by differential scanning calorimetry and determination of microencapsulated limonene via gas chromatography coupled to mass spectrometry indicated limonene microencapsulation and impregnation occurred despite the highly solubility of limonene in supercritical CO2. The retention of limonene by Purity Gum Ultra® was 86% when encapsulated and, 53% when impregnated, similar values to those obtained in conventional microencapsulation methods via a spray drier or via PGSS-drying.
Published Version
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