Extração de óleo e compostos da casca de cacau com uso de dióxido de carbono supercrítico: uso de cossolventes e modelagem cinética da curva de extração

Abstract

This study investigated the extraction of bioactive compounds from cocoa shell waste using supercritical carbon dioxide (SCCO2), assessing: (i) the effect of co-solvents; (ii) chemical characterization of the extracts by GC/MS; and (iii) mathematical modeling of the kinetics using two models (Logistic and Splines). The residue was characterized for particle size (D = 5.70 mm) and density. Extractions were carried out in duplicate at 40 °C/200 bar and 60 °C/250 bar, with CO2 flow rate controlled at 3 mL/min in an extractor of 63 mL; mean yields were statistically similar: 3.014 ± 0.075% (40 °C/200 bar) and 3.046 ± 0.028% (60 °C/250 bar). In the co-solvent tests (5 mL of solvent per 7 g of residue, 40 °C/200 bar, 120 min) oil yields of 2.77% (hexane) and 2.80% (ethanol) were obtained. Kinetic modeling showed an excellent fit (R2 = 0.99), with reductions in tCER and tFER and an increase in the initial rate (coefficient b1) under the more severe conditions (60 °C/250 bar). GC/MS analysis indicated a predominance of oxygenated compounds — especially carboxylic acids — and the presence of long-chain esters; caffeine and theobromine were not detected under the analytical conditions employed. The results demonstrate technical-scientific feasibility for valorization of this residue, with operational robustness and co-solvent-tunable selectivity potential.