The current procedure of rapeseed oil extraction is based on a first extraction step by pressing followed by a second extraction step with hexane. This solvent being toxic for the users, the consumers and the environment, its use could be forbidden within the coming years. Stimulated by a stringent regulation, the research activity for the replacement of toxic solvents shows a significant development. The aim of this study was to select alternative solvent to hexane such as ethanol or isopropanol, and, to adjust the oil extraction process by developing an ultrasound assisted method. The objective was to reach a comparable efficiency but also to enhance the oil quality. When applied to isopropanol, the ultrasound assisted extraction method has shown promising results, and comparable to those obtained with hexane (oil yield of 80% for hexane and 79% for isopropanol at optimum extraction conditions (20min of ultrasound pretreatment followed by 2h of additional solid/liquid extraction)). Conversely, in studied conditions, ethanol did not seem to be an appropriate alternative solvent to hexane as the extraction yields obtained by using this solvent were quite low.
The treatment of Cabernet Sauvignon red grapes by Pulsed Electric Fields (PEF) is performed prior to vinification in order to enhance the extraction of polyphenols. PEF treatments of the longest duration and of the highest energy (E = 0.7 kV/cm, tPEF = 200 ms, W = 31 Wh/kg) changed the structure of grape skins and produced a wine that was richer in tannins (34%), while treatment of the highest strength (E = 4kV/cm, tPEF = 1 ms, W = 4 Wh/kg) altered the visual appearance of phenolic compounds in the skins and led to greater extraction of the anthocyanins (19%). The PEF treatments caused the depolymerization of skin tannins, improving the diffusion of these decondensed tannins which are smaller. The PEF treatment of longest duration and of the highest energy had more impact on the parietal tannins and the cell walls of the skins while treatment of the highest strength modified more the vacuolar tannins. Changes in the operating parameters of the PEF treatment (E = 0.7 to 4 kV/cm, tPEF = 1 to 200 ms, W = 4 to 31 Wh/kg) did not affect alcohol content, total acidity, nor volatile acidity in finished wines compared to the values of the control wine but seemed to cause a slight increase in pH (1-2%).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.