Comparison of two protein extraction techniques utilizing aqueous de-oiled residue from Jatropha curcas L

As a by-product from oil extraction, high amounts of Jatropha meal with high protein contents are obtained. These are not suitable for feed and food applications. As a consequence, concepts concerning the integrated and sustainable usage of Jatropha curcas seeds are extremely important. To this end protein extraction from the meal is an important process. In this study, the efficiency of an aqueous extraction process in comparison to an enzyme-assisted process for the extraction of denatured proteins were studied systematically. The aqueous extraction process had a protein yield of 76 %. Best parameters for protein extraction are pH 11, 60 °C, while stirring the suspension for 30 min with 200 rpm. To perform the enzymatic protein extraction a screening of commercially available proteases was conducted with 7 exo- and endoprotease preparations. Protease A01 turned out to be most effective in supporting protein solubilization. Optimum conditions for the enzyme assisted extraction process are 0.5 % (w/w) of Protease A01 preparation, pH 8, 55 °C and a reaction time of 60 min. Here a protein yield of 76 % is reached. The degree of hydrolysis was 13 % compared to 1 % for the aqueous process. Protein yields of both processes were comparable.