Oil produced from Ghana cocoa bean for potential industrial applications

Abstract

Cocoa bean (Theobroma cacao L.) oil is a promising intermediate cocoa product with few research demonstrating its potential for the direct production of industrial cocoa products. This study highlights the extraction and characterisations of oil obtained from the Ghana cocoa bean crop to evaluate its suitability for industrial applications. A solvent extraction method was employed to extract the oil at variable extraction temperatures and times. Kinetic and thermodynamic models were adopted to study the oil’s extraction at varying temperatures and times. The maximum yield of the oil (21.62%) was reached at the highest temperature, 333 K (at 130 min), following first-order kinetics. The mass transfer (km) and regression coefficient (r2) were 0.0389 ± 0.0045 min−1 and 0.9993 ± 0.0005, respectively. The activation energy (Ea), entropy change (ΔS), equilibrium constant (K), and enthalpy change (ΔH) were 15.57 kJ mol−1, 276.13 J/(mol K)−1, 5.64, and 78.11 kJ mol−1, respectively. The activation enthalpy (ΔH*), entropy (ΔS*), and Gibb’s free energy (ΔG*) were 12.87 ± 0.05 kJ mol−1, − 258.88 ± 0.17 J/(mol K)−1 and 97.13 ± 1.67 kJ mol−1, respectively, favouring a forward, irreversible, endothermic, and spontaneous extraction. The major fatty acids identified in the oil were stearic acid (37%), oleic acid (34%), and palmitic acid (26%). The iodine value, peroxide value, saponification value, unsaponification value, and free fatty acids of the oil were below the recommended standards acceptable for industrial applications. Differential scanning calorimetry–thermal gravimetric studies showed that the oil was thermally stable at high temperatures until thermal decomposition occurred around 260 °C. The oil’s oxidation was monitored with computational modelling and Fourier infrared red spectroscopy, which found the oil highly stable despite the thermal extraction.