Chemical Constituents, Proximate Composition, and Heavy Metals of the Oil Seed of <i>Guizotia scabra</i> Consumed in Plateau State-Nigeria

Abstract

<i>Guizotia scabra</i> (L. F cass. composite) is an oil seed crop found wildly and in some areas cultivated at middle and higher geographical locations in Nigeria and other African countries. The objectives of this research were to among other things determine the physicochemical properties, proximate composition, and chemical constituents. Standard methods for physicochemical properties, proximate analysis and GC/MS was used to determine the chemical constituents. The physicochemical properties revealed acid value 0.455 mg/KOH/g. The percentage yield was 21.34%. The saponification value was 33.10 mg of KOH/kg. Peroxide value revealed 16.35 meq/KOH/kg. The iodine value was 66.83g/100g. The Specific gravity was 0.9246 and the viscosity was 25.3 mPa.s. A proximate composition 6.95% of moisture content, ash content was 3.05%, crude protein was 21.72%, crude fat was 24.4%, crude fibre was 29.5%, dry matter content was 93.50% and organic matter content was 96.95%. The chemical constituents revealed 9, 12-Octadecadienoic acid (31.80%) as the predominant unsaturated fatty acid in the seed oil while Dodecanoic acid (Lauric acid) (3.46%) is the predominant saturated fatty acid. The concentration of Zn in the samples was (1.146±0.00 µg/g), is higher than the other metals (Cu, Fe, Ni, and Pb), Ni and Pb were not detected in the sample. <i>Guizotia scabra</i> seed oil from Plateau state is therefore good for consumption due to it low acid value, good protein content, good amount of unsaturated fatty acid, low concentration of heavy metals and some phytochemicals.