Figure 1. Hydro-distillation of essential oils [23].
The turbo distillation process is the same as water distillation, except that in this method, the mixture is stirred continuously with a stainless steel stirrer at appropriate speed. This method is suitable for coarse raw materials and hard-to-extract (spices, woods). Turbo distillation reduces distillation times and energy consumption and prevents the degradation of volatile compounds compared to aqueous distillation. In fact, it is a kind of green extraction from water distillation (figure 2) [22, 27]. Among the essential oils that were extracted by turbo hydro-distillation method, the extraction of essential oils from Kaempferia galangal can be mentioned [28].