Detoxification of Jatropha Biomass Mediated by Application of Microbubble and Plasma Microreactor Technology

Food security and alternative fuel production are a poignant concern for sustainable development. It is desirable to attain high nutritional value without comprising on the supply of raw materials for biofuel production. The residual biomass in biofuel processing of Jatropha curcas Linn is called Jatropha meal. Its utilisation is limited due to a constituent, a natural carcinogen: phorbol ester, although it also contains a high level of nutrients, potentially useful as feed stock or fertiliser. This research aims to develop technology for detoxifying phorbol esters in jatropha meal while maintaining the protein content. Experiment was conducted by passing air through a plasma microreactor to produce ozone while a ceramic diffuser was used to generate microbubble. The air flow rate was set to 2 L/min before the sample was loaded into the reactor. The ignition voltage of plasma was 4 kV while the working voltage was 3.8 kV. The mixture was treated with ozone for 1 to 5 hours. Indonesian variety of Jatropha meal was used as sample. HPLC technique was used to determine phorbol ester content and Bradford Assay was used for protein quantification. It was observed that only 40% reduction of synthetic phorbol ester was achieved after 30 minutes of aeration (without ozone activation) while 64% of degradation was detected after 5 minutes of ozonolysis (with ozone activation). A 97% reduction of natural phorbol ester (obtained from Indonesian Jatropha meal) content after 5 hours of ozonolysis resulted in a final phorbol ester concentration of 0.11 mg/g in jatropha meal sample. This value is also phorbol ester concentration found in the non-toxic Mexican variety which has become the limiting level for of jatropha edibility. Further, it is observed that the protein content remains stable after 5 hours of ozonolysis. It was reported that total protein concentration ranged from 18-32% which meets the requirements for sufficient nutritional content. Various benefits offered by developed technology in this research promise to overcome the conflict between oil and food supply. A higher economic value of jatropha meal as biofuel processing residual can be achieved.