Effect of Extraction Solvent on Oil and Bioactives Composition of Commercial Indian Niger (Guizotia abyssinica (L.f.) Cass.) Seed.

Commercially available niger (Guizotia abyssinica
(L.f.) Cass.) seed was investigated to evaluate the effect
of extraction solvent on oil and bioactives composition. For
this purpose, niger seeds were subjected to solvent extraction
using solvents of different polarity, viz., hexane, petroleum
ether, chloroform, acetone, methanol and ethanol. The oil
content of niger seeds obtained after extraction with solvents
of different polarities was in the range of 31.8–41.3 g/100 g.
The extracted oil was characterized by the following
parameters: color (40.0–95.0 Lovibond units), free fatty
acids (3.6–12.3 g/100 g), peroxide value (3.2–7.8 mequiv
O2/kg), iodine value (137.6–140.3 cg I2/g), saponification
value (177.3–185.9 mg KOH/g) and unsaponifiable matter
(1.3–4.3 g/100 g). Among fatty acids, linoleic acid
(69.4–73.2 %) was the major fatty acid and trilinolein
(31.2–33.4 %) was the major triacylglycerol. The composition
of bioactive molecules was 171.9–345.8 ppm of total
tocopherols; 247.1–2,647.7 ppm of total phenolics;
1,249.6–6,309.3 ppmof total sterols and 18.9–181.0 ppm of
total carotenoids. Among the tocopherols, a-tocopherol was
the major component with 154–276 ppm. Of the total
phenolics, vanillic acid with 176–1,709 ppm was the major
phenolic compound in the oil extracted using different solvents.
Ethanol-extracted oil showed a 13.9-fold better oxidative
stability and a higher radical scavenging activity (IC50
value of 9.2 mg/mL) compared to hexane-extracted oil (IC50
value of 40.3 mg/mL). This is probably the first report of its
kind on solvent extractability of bioactives of niger seed.