Grape seed oil deacidification by molecular distillation: Analysis of operative variables influence using the response surface methodology

The purpose of this paper is to study the physical refining process of grape seed oil using molecular distillation. Crude oil was submitted to three preliminary steps: water degumming, dewaxing and bleaching and to a final deacidification step that was accomplished by molecular distillation. The influence of two operative conditions in molecular distillation step was considered: feed flow (0.5–1.5 ml/min) and evaporation temperature (200–220 °C), in relation to free fatty acids content and tocopherols recovery in the refined oil.It was found that the target free fatty acids content (less than 0.1%) could be obtained at high evaporation temperatures, for all the studied feed flows. High tocopherol recovery was obtained in two regions of the domain: the region of low feed flows and low temperatures; and the region of high feed flows and high temperatures. So, it was found that it is possible to employ high feed flows (1.5 ml/min), that allow high outputs, and high temperatures (220 °C) to obtain refined oils with low enough free fatty acid content and high tocopherol recovery (in the order of 100%).