Kinetic, thermodynamic and optimization study of the corn germ oil extraction process

Abstract

Corn germ oil (CGO) was recovered from the ground corn germ by maceration using n-hexane at the ranges of the temperature and the solvent:germ ratio (SGR) of 20–70 °C and 3:1–10:1 mL/g, respectively. The obtained CGO contained mainly the unsaturated fatty acids (87.09 ± 0.37%) with linoleic and oleic acid as the most abundant while the main saturated fatty acid was palmitic acid. The CGO extraction yield was statistically analyzed, modeled and optimized combining the response surface methodology with the 33 full factorial design with replication. All individual process variables (maceration temperature, SGR and maceration time), the interaction of maceration temperature with SGR and the quadratic terms of maceration temperature and SGR had a statistically significant influence on the CGO yield. For the kinetic modeling of the CGO maceration, three models, namely the phenomenological model, the model that included instantaneous washing and diffusion and the diffusional model, were tested. Although all models successfully described the kinetics of CGO extraction (MRPD values ≤2%), the diffusional model was less accurate. The thermodynamic analysis of CGO extraction showed that the extraction process was spontaneous, endothermic and irreversible.