The application of Plackett and Burman design in screening the parameters acting on the hydrodistillation process of Moroccan rosemary (Rosmarinus officinalis L.)

Rosemary, Rosmarinus officinalis L., is an herb widely used throughout the world. It is, without doubt, one of the most popular plants in Morocco. For the purpose of examining, the factors affecting the extraction of the essential oil of this plant by hydrodistillation, a screening study by Hadamard matrix type Plackett and Burman was conducted. After an appropriate choice of seven variables, sixteen experiments lead to a mathematical model of first degree connecting the response function to factors. Later than the realization of the experiments and data analysis, the researchers concluded that six factors have a significant effect on the hydrodistillation process, namely: the extracting time, the individuality effect, the harvest period, the mass plant/water ratio, the drying of plant material and the temperature of heating. As for the cutting of plants, it presents a statistically negligible effect. This study proved the great efficiency to applying the experiments design methodology for characterizing the operational parameters that affect the hydrodistillation.