چكيده لاتين :
Residue of methanolic extract of Egyptian Jatropha curcas contains bioactive substances such as
phenolic compounds, which succeeded to be used as natural antioxidants for the protection of oils and their corresponding
biodiesel against oxidative deterioration. In the present work, the residue of Jatropha roots were extracted with methanol
and resulting residues, were investigated regarding their content of total phenolic compounds by folin-Cioalteau assay.
Further, the antioxidant activities of the extracts were characterized by the 2,2-diphenyl-1-picrylhydrazyl radical
method and proved remarkable results. Oxidation stability of Jatropha oil, used fried oil and olive oil and their corresponding
biodiesel obtained by conventional transesterification were tested using thermal oxidation. Natural antioxidants such as
(ل-trocopherol), synthetic antioxidants as butylated hydroxytoluene and natural Jatropha root extract were used in the
present study in comparison to investigate their addition effect on the oxidative stability of oils and their corresponding
biodiesel. In the rapied thermal treatment test, results showed that addition of butylated hydroxytoluene 0.25 % was
able to stabilize Jatropha oil 6 h, but poorly stabiliz biodiesel. Addition of 0.25 % ل-trocopherol to Jatropha oil showed
less oxidation stability after 2 h thermal treatment. Crude root extract addition at 0.25% to Jatropha oil showed good
stability up to 4 h thermal treatment while addition of root extract at 0.25 % to biodiesel showed better stability up to
6 h thermal treatment. Besides addition of 220 ppm crude root extract to biodiesel was enough sufficient to occure
oxidative stabilization. Also Jatropha root residue addition at 400 ppm was effective antioxidant for fresh Jatropha oil.
