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.