Evaluation of Techniques for Intensifying the Process of the Alcoholic Extraction of Coffee Ground Oil Using Ultrasound and a Pressurized Solvent

Abstract

Ultrasound-assisted extraction (UAE) and pressurized liquid extraction (PLE) techniques were evaluated and compared with conventional extraction for obtaining spent coffee ground oil (SCGO). The use of absolute ethanol (ET0) and hydrated ethanol (ET6) as solvents, two levels of SCG mass ratio:solvent, 1:4 (U4) and 1:15 (U15), and ultrasound powers of 0, 200, 400, and 600 W were tested. ET0 and U15 resulted in higher extraction yields of SCGO (YSCGO, 82%). A positive effect of sonication on YSCGO was observed only for condition U4. UAE resulted in defatted solids (DS) with higher apparent density values, corroborating the increase in the amount of smaller diameter particles due to sonication. The micrographs showed changes in the surfaces of the solids from the UAE and PLE, although the crystalline structures of the DS were not altered. UAE and PLE, compared to conventional extraction, did not allow significant gains in terms of YSCGO and, consequently, in the number of contact stages in an extractor configured in cross-currents.

Experimental Comparison between Ethanol and Hexane as Solvents for Oil Extraction from Peanut Press Cake

“…The aim of the multistage experiments was to evaluate the number of solid/solvent contact stages required to achieve a given oil extraction yield. In this type of operation and configuration, after the first stage of contact between PPC and solvent, the solid partially defatted from the first stage became the feedstock for the subsequent stage, contacting the new solvent, as demonstrated by Toda et al [42]. In the sequential extraction experiments performed with Et, a solid/solvent mass ratio of 1/5, a contact stage number of 5, a constant agitation speed of 180 rpm and an extraction time of 1 h at each stage were adopted.…”

Multiple Solid–Liquid Extraction: Determination of Extraction Yield through UV–Vis Spectroscopy

“…The industrial unit operation defined as solid–liquid extraction can be conducted in two ways, defined as “countercurrent” and “cross-currents”. , The multistage countercurrent extraction consists of contacting the solid to be extracted (R or F) with the extract (E) from a later stage (Figure ).…”