Isolation of Volatiles from Oak Wood (Quercus alba) by a Thermomechanical Process: Screening of some Processing Parameters

Abstract

Experiments were performed to evaluate an extraction process developed in our laboratory called the instantaneous controlled pressure drop process (“Détente Instantanée Contrôlée” or (DIC)) for extracting volatile compounds from oak wood. This process involves subjecting oak chips for a short time (10 s to 12 min) under a steam pressure (1 to 6 bars or from 100 to 165°C). This first step is followed by a rapid decompression toward vacuum (up to 50 mbar). Some parameters were evaluated: steam pressure level, processing time, initial moisture content, chips thickness and velocity of the rapid decompression. A preliminary experimental design allowed optimizing the processing pressure and processing time: 6 bar and 5 minutes. Under these conditions, the optimal conditions were as follows: 20% for initial moisture content, 0.5 mm for the chips thickness. The number of decompressions towards vacuum was also investigated and it appeared that extraction yield can be enhanced by repeating the decompressions cycles for a same processing time. Moreover, GC-MS analysis indicated that DIC extract included the same molecules that obtained by steam distillation with almost the same percentages.