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

Abstract

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, Plateau States). 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 industries. 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 > stearic >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 myristic acid were absent in oils. In addition, the magnitude of six Phospholipids (phosphatidylcholine > phosphatidylethanolamine> phosphatidylinositol > phosphatidylserine > phosphatidic acid > lysophosphatidylcholine) were also achieved, respectively. The iodine were below the FAO/WHO and the acid value was higher than the normal range.