Minimization of the soluble coffee processing waste through the reutilization of the grounds in oil extraction using renewable solvent

Abstract

Coffee is one of the most consumed world commodity, consequently, the generation of waste from the processing of soluble coffee is quite high. The coffee grounds, a major waste of the grain processing industry, can contain 15-17% fat, and of these 75% are triacylglycerols, 18% are diterpene esters and the remaining 7% are distributed in free and esterified sterols.Vegetable oils are widely used in the food industry with various applications such as emulsifiers, viscosity modifiers, dispersants, and other important functions. The oil contained in coffee grounds, if extracted through proper methodology, can become a raw material for the food industry and not being considered as a mere residue.This proposal of master's dissertation suggest the study of the technical feasibility of using less aggressive solvents, ethanol and isopropanol, absolute or hydrated, as a substitute for hexane in the extraction process of the coffee grounds oil.The suggested alcoholic solvents have advantages in relation to the solvent traditionally used by the vegetable oils industry, hexane, since they do not generate toxic residues, may be produced by biotechnological processes, have lower degree of flammability, and are considered safe for human health (GRAS).Although some advantages of changing the hexane for alcoholic solvents are evident, there are gaps that must be answered through a systematic study of the liquid-solid extraction process. In research projects (FAPESP 2006/00565-4 and 2009/17855-3) recently finalized by the research group led by the advisor of this proposal, efforts were put towards to facilitate the use of ethanol as an extractant of solid matrices vegetable oils. In these projects, the study of the solid-liquid equilibrium was performed in thermo-static equipment monitoring the extraction of free fatty acids and antioxidants and vitamin compounds. Excellent conditions of the contact between the solid and the solvent were investigated, such as: solid:solvent ratio, extraction temperature, contact time, solvent recovery, among others.In this master's dissertation project it is suggested a refinement of the study of this alternative extraction method of vegetable oils. Experiments of solid-liquid equilibrium are proposed aiming the monitoring of the quality oil index (fatty acid composition and content of chlorogenic acids) and protein fraction present in the defatted bran.In fact, the objective through the development of this project not only the technical feasibility of the use of alternative solvents in the vegetable oil industry, but also the minimization of waste from coffee processing industry by adding value to the ground generated in the production of soluble coffee .It is important to emphasize that this research project is embedded in the thematic project BIOEN (FAPESP 2008/56258-8) in which the advisor acts as the researcher responsible for the alcoholic extraction line of vegetable oils.