科研之友
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摘要
Ultrasound-assisted extraction (UAE) of phorbol esters (PEs) from Jatropha curcas L. (JC) seed oil using methanol as the extraction solvent was optimized by response surface methodology (RSM).Jatropha curcas L. seed oil is an excellent feedstock for biodiesel production, in which the presence of major toxic factor (phorbol esters) has limited its industrial applications. The aim of this work is to prepare the nontoxic oil from Jatropha curcas L. whole seeds with the first phorbol esters removal step and the second oil extraction step. The Box-Behnken design was applied to optimize three key parameters in the first phorbol esters removal step including temperature (X-1,degrees C), extraction time (X-2, min) and liquid-to-solid ratio (X-3, mL:g) for achieving a high extraction efficiency and minimal energy consumption. Ultimately, the optimized conditions were as follows: extraction temperature 36 degrees C, extraction time 52 min and liquid-to solid ratio 5.78:1. Among these three parameters, temperature had the most significant effect on phorbol esters extraction efficiency followed by extraction time and liquid-to-solid ratio. Maximum content of phorbol esters obtained were 0.33 mg/gJatropha curcas L seed in the first step and 89.20 +/- 2.96% of seed oil could be recovered by n-hexane in the second step. A sensitive ultra-performance liquid chromatography method was also established to determine the phorbol esters content within 5 min, with a limit of detection (LOD) of 0.04 mu g/g. Since the concentrations of phorbol esters were all below the limit of detection, most of the virtually phorbol ester-free (PE-free) oil was produced to extend the Jatropha biodiesel production chain for household chemicals, cosmetic or jet fuel preparation. Meanwhile, the phorbol esters enriched fraction (PEEF, 71.9 +/- 0.3 mg/g) obtained from the first step can be utilized as value-added by-products in pharmaceutical and agro-pharmaceutical fields.
