Abstract

STUDIES ON PHYSICOCHEMICAL PROPERTIES AND FATTY ACID PROFILE OF SEED OIL FROM TWO HIBISCUS SPECIES

Rashmi Gadwal and G.R. Naik*

Abstract

A study on the seed oil of two Hibiscus species- Hibiscus cannabinus and Hibiscus sabdariffa were analyzed to establish their physicochemical properties and fatty acid using standard methods. The oil was extracted using hexane (40-45°) by Soxhlet apparatus and fatty acid profile was determined using Gas chromatography (GC) analyser. The present study shows that, Kenaf and roselle had golden yellowish oil color and oil content was found to be 24% (Kenaf) and 22% (Roselle). The acid value (3.02: 2.80 mg KOH/g), specific gravity (0.88:0.86), refractive index (1.46: 1.45), moisture content (1.88: 1.46%), viscosity (53.00:52.70mPas), FFA (0.77: 0.65%) and saponification values (172:170mgKOH/g) were higher in Hibiscus cannabinus when compared to that of Hibiscus sabdariffa whereas iodine value (133:177gI/100g), peroxide value (13.3: 26.6meq/kg) and Unsaponifiable matter (0.052: 0.85%) were lower in Hibiscus cannabinus when compared to that of Hibiscus sabdariffa. Both plant seed oils were rich in oleic and linoleic acids. The seed oil with highest amount of polyunsaturated fatty acids can find an application in surface coating industries biolubricant base oil applications, whereas the high amount of monosaturated fatty acid can find an application as a biodiesel feedstock. The evaluation of fatty acid composition using gas chromatography revealed that, Hibiscus cannabinus contained higher amounts of oleic acid (28.91%) and linoleic acid (38.49%) and significantly lower amounts of stearic (3.96%) and palmitic acid (20.75%) than Hibiscus sabdariffa seeds (25.16%, 44.72%, 18.52% and 4.31%, respectively).Hence, two plants of Hibiscus species seed oil has a great potential for industrial applications such as in paint and surface coatings, biolubricant and production of biodiesel. Therefore, it is crucial to have more research on these two plants seed oil in the future to explore its potential as a future biodiesel oilseed crops.

Keywords: Hibiscus cannabinus, Hibiscus sabdariffa, physicochemical properties, fatty acids, oil and seed characterization.