Rheological, Physicochemical, and GC-MS of Fatty acid Composition of Palm Oil from Cross River State, Nigeria

Palm oil is a ubiquitous ingredient in numerous products and is a significant global commodity. This study presents a comparative analysis of the rheological, physicochemical properties and fatty acid composition of palm oil from Cross River State, Nigeria. Palm oil samples were selected at random from the open market in the eighteen local government areas of Cross River State, Nigeria. The samples were tested for their quality, nutritional values and suitability for human consumption. Physicochemical tests were conducted on the palm oil samples. Gas chromatography-mass spectrometry (GC-MS) was performed to examine the fatty acids in the samples. Rheological analysis of the samples was performed at 27 °C. The physicochemical analysis results obtained revealed the composition of free fatty acid as (3.52±0.02 to 56.00±0.00%), Iodine value (42.85±0.02 to 54.10±0.02 wij.s), total cholesterol (318.43±1.61 to 3308.16±0.13 mg/kg), Peroxide value (3.16±0.12 to 30.50±0.06 meg/kg), P-ansidine value (7.37±0.11 to 11.08±0.01 Av), saponification value (98.95±4.71 to244.49±0.42 mg/KOH/G) and moisture content of (0.25±0.02 to 1.97±0.07). GC-MS analysis revealed sixteen compounds: thiazole 5-methyl, octanoic acid, dodecanoic acid, methyl tertadecanoic acid, dodecanoic acid methyl ester, hexadecanoic acid methyl ester, 9, 12-Octadecadienoic acid methyl ester, octadecenoic acid methyl ester, 9-Octadecenoic acid methyl ester, and n-hexadecanoic acid. Others include tetradecanoic acid, dodecanedioic acid, oleic acid, arachidonic acid, Squalene, and Eicosanoic acid methyl ester. The rheological signatures of the samples ranged from near—Newtonian and Newtonian to pseudeoplastic behaviour. Two rheological models, the Ostwald-de Waele Power Law and the Carreau-Yasuda models, were applied to extract rheological data from the palm oil samples. It was observed that the recently prepared palm oil samples exhibited Newtonian or near-Newtonian behaviour with minimal concentration of FFA. The accumulation of FFA in the samples induced by long storage drags the properties of the samples to shear pseudoplastic behavior. The results show