Comparative analysis of groundnut oil quality in the north-central zone of Nigeria: Determination and evaluation of heavy metals, fatty acids, Phospholipids, and iodine values in groundnut oil

The research presents a comparative analysis of the quality of locally produced groundnut oil (Arachis hypogaea) sold in the north-central zone of Nigeria markets (Benue, Nasarawa, Kogi, Kwara, Niger and Plateau S tates). The aim was to assess and compare the qualities of the oils and to know the safety of human consumption. The groundnut oil produced biodiesel, shampoo lubricants, and soap-making indus tries. The concentrations of the heavy metals were analyzed with atomic absorption spectrometry (AAS). It showed that the lead, zinc, and copper (Pb, Zn, Cu) were within the FAO/WHO recommended limit, while Cd (0.201-0.331 mg kg-1) was above the limit (0.07 mg kg-1). Also, the gas chromatography (GC-FID) results indicated that twelve fatty acids (linoleic > oleic > palmitic > s tearic > lignoceric > arachidic acid > behenic > erucic > arachidonic > margaric > linolenic > palmitoleic) were obtained in the groundnut oils in all markets and fatty acids include caprylic acid, capric acid, lauric acid, and myris tic acid were absent in oils. In addition, the magnitude of six phospholipids (phosphatidylcholine > phosphatidylethanolamine > phosphatidylinositol > phosphatidylserine > phosphatidic acid > lysophosphatidylcholine) were also achieved, respectively. The results showed that iodine, peroxide, saponification value and refractive index were below the FAO/WHO recommended level, and the acid value was higher than the normal range.