Development of a process of vegetable oil extraction using alcoholic solvents: evaluation of oil composition and changes in the protein fraction

Abstract

The present research project has the aim of analyzing the technical viability of replacing hexane, a commonly used solvent in vegetable oil extraction, by short chain alcohols. The solvents proposed in this study, ethanol and isopropanol, are generally regarded as safe (GRAS), and this characteristic is a marked advantage in relation to the high toxicity and inflammability of hexane. Besides, these solvents are replacements that may be more easily recovered after the extraction process, as they are partially miscible in oil at room temperature. Although some advantages of replacing hexane by alcoholic solvents are evident, there are gaps to be filled by the systematic study of the process. In other research projects supported by FAPESP (06/00565-4, 09/17855-3, 10/03058-1, 10/13285-5), the adequate conditions to make the use of alcoholic solvents viable in the extraction of soybean and rice bran oil, and the influence of the process variables were evaluated in the composition of the extract and quality indices of the protein fraction found in the defatted meal were analyzed. In the present research project, the study of these issues will be expanded to the use of different oleaginous materials, such as sesame seed, baru almonds and spent coffee. The project will be conducted in three different arms: a) Evaluation of the quality indices of the different protein fractions found in defatted meals, based on analyses that characterize the protein fraction and the functional properties of the protein in greater detail; b) Evaluation of the physical-chemical properties of the vegetable oils obtained from different raw materials using different alcoholic solvents (ethanol or isopropanol, hydrated or not), with emphasis on the behavior of minority compounds of interest (for example, sesamin in sesame oil, and chlorogenic acids in spent coffee oil); c) Study of the liquid-liquid equilibrium as a function of the temperature for systems composed by vegetable oils (sesame seed or baru almond) and solvent. This stage of the project has the aim of evaluating the partial recovery of the alcoholic solvent in the extract, besides studying the fractioning of minority compounds of nutritional interest found in the oils. (AU)