Conventional and pressurized ethanolic extraction of oil from spent coffee grounds: Kinetics study and evaluation of lipid and defatted solid fractions

Extraction kinetics of spent coffee grounds (SCG) soluble in absolute (ET0) and hydrous ethanol (ET6) in the temperature range of 60–150 ℃, under atmospheric and pressurized conditions, are discussed in this work. Solvent hydration negatively impacted oil extraction, while an increase in temperature...

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Bibliographic Details
Published in:The Journal of supercritical fluids 2021-11, Vol.177, p.105332, Article 105332
Main Authors: Toda, Tatiane Akemi, Franco Visioli, Paola de Cássia, de Oliveira, Alessandra Lopes, da Costa Rodrigues, Christianne Elisabete
Format: Article
Language:English
Subjects:
Accelerated solvent extraction
Carbohydrates
Coffee byproduct
Diffusion coefficient
Green solvent
Instant-coffee residue
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Summary:Extraction kinetics of spent coffee grounds (SCG) soluble in absolute (ET0) and hydrous ethanol (ET6) in the temperature range of 60–150 ℃, under atmospheric and pressurized conditions, are discussed in this work. Solvent hydration negatively impacted oil extraction, while an increase in temperature led to higher relative yields (≤ 96.8%) during SCG oil (SCGO) extraction. At 150 °C, ET0 and ET6 exhibited similar SCGO extraction efficiencies. Free fatty acids and chlorogenic acid were extracted in less amounts. Thus, a change in the physicochemical characteristics of ET6 was observed at high temperatures. The solvent became less polar. Low (≤ 3.49%) average relative deviation values were obtained via mathematical modeling considering washing and diffusion steps. This helped in the estimation of SCGO diffusion coefficients. The values of the diffusion coefficients increased with temperature. The values were comparable to the values obtained when hexane was used as the extraction solvent. These findings reveal the SCGO extraction efficiency of ethanol, mainly under conditions of high pressure. [Display omitted] •Oil extraction yields up to 96.8% were obtained using absolute and hydrous ethanol.•At 150 °C, the use of pressurized alcoholic solvents yielded low amounts of FFA.•Maximum yield of chlorogenic acid was obtained when hydrous ethanol was used.•The estimated diffusion coefficient values were comparable to the hexane ones.
ISSN:0896-8446
1872-8162
DOI:10.1016/j.supflu.2021.105332