Retention of aroma compounds by corn, sorghum and amaranth starches

The presented study addressed assays of odorant retention from an essential oil mixture by native corn, sorghum and amaranth starches using capillary gas chromatography (GC) and differential scanning calorimetry (DSC). The essential oil mixture consisted of 30 main compounds, including monoterpene and sesquiterpene hydrocarbons, alcohols, ketone, phenols and ester. The native starches were characterized for their chemical composition (amylose, protein, and surface lipids content), surface properties (surface area, pore diameter), and microstructure (SEM). The starches were mixed with odorants, stirred intensively, and stored at room temperature in the dark for 2 days (reference sample), 3 and 7 months. The chemical properties of odorants, their composition in the mixture as well as starch surface properties were observed to affect the retention of aroma compounds upon storage. Irrespective of starch botanical origin, a significant loss was noticed in monoterpene hydrocarbons throughout the storage period. Alcohols, ketone, phenols and sesquiterpene hydrocarbons were highly retained on amaranth and sorghum starches upon 3 months of storage. However, after prolonged storage their retention diminished, especially in the case of amaranth starch. The DSC results obtained for stored corn and sorghum starches with odorants demonstrated an extra endothermic contribution, which indicated that the aroma compounds were highly retained by the gelatinized starch matrixes. Furthermore, the odorants showed ability to interact with the solubilized amylose.