Influence of protein extraction techniques of different de-oiled residues from Jatropha curcas L. on protein recovery and techno-functional properties

As Jatropha curcas L. is a non-edible energy plant biodiesel production from J. curcas L. crude oil is an important field of interest in order to avoid the 'tank or table' discussion. As a by-product from oil extraction, high amounts of Jatropha meals are obtained requiring a concept for its sustainable utilization. Due to the high protein content (up to 40 %) in Jatropha seed cakes, added value can be generated by extraction of these proteins for further applications. The present study compared an aqueous and an enzyme-assisted process for protein extraction from screw-pressed and aqueous de-oiled Jatropha residue. Additionally, different methods for protein recovery were evaluated. Aqueous-extracted proteins were recovered by ultrafiltration, isoelectric precipitation and/or lyophilisation while the proteins from enzyme-assisted extraction were only lyophilized. Functionality of the obtained protein products was determined indicating good emulsifying properties as well as a good gelation behaviour for the aqueous-extracted proteins. In general, proteins from enzyme-assisted extraction had slightly lower functionality. The study indicates potential for the application of Jatropha proteins as emulsifiers in biodegradable bags or as antifoam agents.