Detoxification of jatropha kernel meal to utilize it as aqua-feed

Jatropha is an oilseed crop with high kernel oil (55-58%) and protein (26-29%) contents, which makes it a good source of biodiesel and animal/aqua-feed. However, the presence of anti-nutritional toxins, such as phorbol esters, lectins, trypsin inhibitor, phytate, and saponins, restricts its use as feed. This paper describes chemical, ultraviolet (UV) radiation, and biological treatments for detoxification of jatropha kernel meal. Raw, defatted, and one-time and two-times mechanically expressed oil samples were analyzed for toxins. Chemical treatment involved heating with 90% methanol and 4% sodium hydroxide. UV treatment was carried out at UV light intensity of 53.4 mW cm^-2 for 30 min. For biological treatment, cell-free extract from Pseudomonas aeruginosa (strain PAO1) was mixed with kernel meal for detoxification.

Among treatments, chemical treatment was most effective in reducing all toxins, with phorbol esters in the range 0.034-0.052 mg g^-1 , lectin 0.082-10.766 mg g^-1 , trypsin inhibitor 10.499-11.350 mg g^-1 , phytate 2.475-5.769 mg g^-1 , and saponins 0.044-0.098 mg g^-1 . Biological treatment reduced all toxins except phytate, whereas UV treatment could not reduce any of toxins and, hence, cannot be used for aqua-feed preparation. Pellets prepared from chemically detoxified kernel meal with the least oil content (defatted) resulted in the highest strength (70.93 N).

Chemically treated jatropha kernel meal can be used for aqua-feed pellet preparation because of its low toxin content. The highest compressive strength was obtained for pellets with the least oil content (defatted). Biological treatment time must have been extended for many hours instead of 24 h. Jatropha kernel meal treated chemically can be recommended for aqua-feed manufacturing. © 2021 Society of Chemical Industry.