Detoxification of Jatropha curcas seed cake using chemical treatment: Analysis with a central composite rotatable design

•Jatropha curcas seed cake has a high nutritional value and can be used in animal feed.•Phorbol esters are the main toxic components of Jatropha curcas seed cake.•Chemical treatment using ethanol and methanol is able to detoxify the seed cake.•Protein value in the Jatropha cake did not change with the detoxification treatment.•Statistical analysis could be a useful tool to evaluate the phorbol esters extraction.

Jatropha curcas is a plant whose seeds are rich in oil that can be used for biofuel production, and the seed cake has a high nutritional value. The presence of phorbol ester (PE), a toxic constituent, restricts the cake use in animal food. The detoxification of this by-product is the aim of this work and the seed cake was extracted using Soxhlet for PE removal. A statistical analysis was used to evaluate the PE extraction as function of extraction time, mixture of methanol and ethanol and solute/solvent ratio. The detoxification was reached, reducing the PE content in 97.30% (0.10 mg/g) using a mixture of 50% of methanol, extraction time of 8 h and solute/solvent ratio of 1:10 (w/v). The treatments had a positive effect on protein content and the dry matter, ash and dietary fiber content ranged from 88.47 to 90.70%, 4.89–6.16% and 33.09–38.23%, respectively.