Effect of drying on the extraction yield of Luma chequen (Molina) A. Gray essential oil

This work studies the effect of drying at 40 °C of the leaves and stems of the species Luma chequen (Molina) A. Gray on the extraction yield of its essential oil by steam distillation at a pilot scale. From the micromorphological evaluation at the moisture levels fresh state (72±1%), critical moisture (24±1%) and equilibrium moisture (8.2±0.5%), it is found that the tissues fold, the secretory cavities thin out, according to the lacunarity, the microstructure of the plant material exhibits greater uniformity at the critical moisture. For the extraction tests 18 levels of moisture were considered, keeping the packing factor at 54 Kg/m³. The maximum yield of 0.52 ± 0.01% (v/w) was reached when the moisture of the material was 22±1%, very close to the critical moisture. A first-order model provided a suitable fit to the extraction kinetic data for samples with different humidity levels. Based on the evaporation rate equation, a description of the microstructure of the material and the drying conditions, a model was developed which shows the evaporation mechanism to be dominant in both the drying process and in the extraction of essential oil.

Keywords: drying, Luma chequen, micromorphology, oil essential, yield.