The experiments were carried out in Marrakech, Morocco. Untreated thyme was prepared by commercial Thymus satureioides dried under ambient conditions and packed under vacuum packaging. The samples were kept at ambient temperature until use. For the treated thyme, samples were pulverized by citric acid solution prepared at two concentrations C1 (2.5 g/L) or C2 (5 g/L). For witness thyme, plants were sprayed with distilled water without citric acid C0 (0 g/L). Two volumes were used either 25 ml or 50 ml to spray the plant.