Evaluation of Aqueous Enzymatic Extraction for Obtaining Oil from Thevetia peruviana Seeds

The aqueous enzymatic extraction (AEE) of oil from Thevetia peruviana seeds was studied. The oil extraction yields obtained by treatment with cellulase, Alcalase, and Viscozyme L were compared, finding that the treatment with Alcalase at pH 6 and 50 °C gave the highest yield (63.07%), so it was selected for the optimization of the oil extraction process through a central composite design and a response surface methodology. An oil extraction yield of 78.22% was achieved under the optimum conditions (2% of Alcalase, 4 h of incubation, 250 rpm, and a solid-to-liquid ratio of 1:4.5). The predominant fatty acids in the oil obtained by both AEE and standard solvent extraction (SE) were oleic, linoleic, stearic, and palmitic acids. However, AEE produced an oil presenting lower acidity and peroxide values and greater oxidative stability, indicating that this method produces an oil with better quality. Scanning electron microscopy images of Thevetia peruviana seeds showed a structural alteration of their cell wall caused by AEE, which allowed the release of oil from this seed in the aqueous medium. The results suggest that AEE could be an excellent alternative in terms of efficiency, oil quality, and environmental friendliness for the extraction of this oil.