DETOXIFICATION OF JATROPHA KERNEL MEAL TO UTILIZE AS AQUA-FEED
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Date
2018
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Acharya N.G. Ranga Agricultural University
Abstract
Detoxification of jatropha (Jatropha curcas) kernel meal is of major interest for
the biodiesel industry to add economic value to this residue and also to reduce the
environmental damage caused by its inappropriate disposal. Jatropha kernel meal has
high protein content (26-29%) and, hence, has a great potential to be utilized as animal
feed. But, because of the presence of anti-nutritional factors, its use in preparation of
highly nutritious animal feed is restricted. Anti-nutritional factors present in jatropha
kernel meal are phorbol esters, lectins, trypsin inhibitor, phytate and saponins. Toxicity
of meal is mainly due to the presence of phorbol esters. Severalmethods have been tried
for detoxifying kernel meal that includes physical, chemical, biological and radiation
methods. Trypsin inhibitor and lectins are heat liable and, hence, can be inactivated by
physical methods like, moist heating. Phorbol ester content can be decreased by
chemical treatments such as, ethanol extraction or sodium hydrogen carbonate
treatment; but, complete inactivation is not achieved by these methods. Biological
treatment using bacteria and fungi can also decrease phorbol ester content to a limited
extent. Very less literature is found on detoxification of jatropha kernel meal using UV
radiation.
Four different samples, i.e., raw, defatted, one-time mechanically oil expressed
and two-times mechanically oil expressed samples were prepared from jatropha kernels.
These samples were subjected to three treatments, namely, chemical, UV radiation and
biological treatment for detoxification. Chemical treatment involved heating the
samples with 90% methanol and 4% NaOH twice. UV treatment was done by subjecting
the samples to UV radiation for 30 min in a closed chamber with UV light intensity of
53.4 mW/cm2. For biological treatment, strain Pseudomonas aeruginosawas used. Cellfree
extract obtained from growing strains in a specific media was mixed with kernel
meal samples to carry out detoxification.
Five toxins, particularly, phorbol esters, lectins, trypsin inhibitor, phytate and
saponins were estimated using standard analytical procedures before and after the three
treatments. Toxins content were compared with values that are reported to be safe for
aqua-feed to determine the effectiveness of these three treatments. Finally, chemically
detoxified kernel meal was used for preparation of aqua-feed pellets and compressive
strength of pellets was determined using force gauge.
Chemical treatment was found to be most effective in reduction of toxins and all
the toxins were found within acceptable limits to be utilized as aqua-feed. In chemically
treated kernel meal, phorbol esters were found to be in range of 0.034-0.052 mg/g,
lectin in the range of 0.082-10.766 mg/g, trypsin inhibitor in the range of 10.100-11.350
mg/g, phytate in the range of 0.248-0.577% and saponins in the range of 0.004-0.010%.
Biological treatment was also effective in reduction of all toxins, except phytate and
hence, biologically treated samples were not used in aqua-feed preparation. In
biologically treated kernel meal, phorbol esters were found to be in range of 0.051-
0.102 mg/g, lectin in the range of 0.497-14.815 mg/g, trypsin inhibitor in the range of
9.194-12.657 mg/g, phytate in the range of 1.097-2.994% and saponins in the range of
0.005-0.011%. UV treatment was found to be ineffective in reduction of toxins and
hence, was unsuitable for aqua-feed. It was also observed that temperature during
solvent extraction and mechanical oil expression had an effect in reducing lectin, trypsin
inhibitor and phytate content. Contents of these toxins were found inversely
proportional to temperature. Pellets prepared from chemically detoxified kernel meal
having lowest oil content resulted in highest strength of 70.93 N, i.e. defatted sample.
Keywords: Chemical treatment; UV treatment; Biological treatment; Phorbol esters; Lectins;
Trypsin inhibitor activity; Phytate; Saponins
Description
D5556
Keywords
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