Reduction of phorbol esters in Jatropha curcas L. pressed meal by surfactant solutions extraction

Phorbol esters (PEs), a compound group found in Jatropha curcas seeds, are toxic and thermal-resistant compounds; thus, the further application of Jatropha pressed seed is limited to use only as soil amendment, even though the meal has high protein content, similarly to that of soy bean meal. This study introduces a technique to remove PEs from Jatropha meal using a surfactant aqueous-based solution. Both single and mixed surfactant systems were evaluated. The Hydrophile–lipophile Balance (HLB) of a nonionic surfactant was found to be related to its PEs removal efficiency. The average initial level of PEs in the mechanically-pressed meals was 1.45 mg g−1. The five systems used to reduce the mass fraction of PEs were as follows: water; 40 mmol L−1 polyoxyethylene (20) sorbitan monooleate (Tween 80); mixed of 40 mmol L−1 Tween 80, 5 mmol L−1 sodium bis (ethylhexyl) sulfosuccinate (AOT), and 100 mmol L−1 NaCl; 40 mmol L−1 fatty alcohol C12–14 extended with 9 ethoxylates (Dehydol LS9); and mixed of 40 mmol L−1 Dehydol LS9, 5 mmol L−1 AOT, and 100 mmol L−1 NaCl; these systems removed 22.49%, 81.43%, 81.23%, 81.87%, and 78.85% from the initial meal, respectively. The optimal extraction time was 15 min, and the removal of PEs was enhanced by the application of a double extraction procedure. This technique is promising because mass fraction of the PEs was reduced from the initial meal almost 90%; this approaches the level of PEs found almost as low as those found in a non-toxic variety of Jatropha seed.