Isolation of volatils from maritime pine sawdust waste by different processes: Ultrasound, microwave, turbohydrodistillation, and hydrodistillation

This study concerns the transformation of maritime pine (Pinus pinaster) sawdust waste into potentially novel products through isolation of volatile compounds in the form of valuable oil. Different techniques, namely, turbohydrodistillation (THD), solvent-free microwave extraction (SFME), microwave hydrodiffusion and gravity (MHG), and ultrasound-assisted extraction (UAE) were tested. These different processes were compared to conventional hydrodistillation (HD) and allowed to extract almost similar yields of isolated oils. THD which consists in a permanent agitation during extraction and UAE improve the kinetics of extraction, but MHG and SFME required the shortest extraction times, 60 min to reach a maximal yield of 0.272 and 0.266% (w/w), respectively. The compositions of isolated oils are almost similar with a high proportion of oxygenated compounds for MHG and SFME, respectively, 56.9% and 54.5% compared with 37.7%, 44.1% and 34.1%, respectively, for THD, UAE, and for the conventional HD method.