Assessment of Physicochemical Characteristics and Sensory Quality of Palm Oil Commercially Available in Nasarawa State Markets, Nigeria

Abstract

This study evaluated the physicochemical and sensory quality of palm oil obtained from major markets in Nasarawa State, Nigeria. Nine palm oil samples were systematically collected from three markets in each of the Northern, Southern, and Western Senatorial Districts. Physical properties (moisture content, specific gravity, viscosity, refractive index, smoke point, fire point) and chemical properties (acid value, iodine value, peroxide value, free fatty acid, saponification value, unsaponifiable matter, beta-carotene) were analysed using standard AOAC and AOCS methods. Sensory evaluation was conducted using a 9-point hedonic scale by twenty semi-trained assessors. Data were analysed using ANOVA (p < 0.05). Moisture content ranged from 0.21% to 0.67%, and all nine samples exceeded the ≤0.2% limit. Specific gravity (0.91–0.94) exceeded SON/NIS standards (0.897–0.907). Peroxide values (0.84–4.23 meq/kg) and acid values (0.33–0.94 mg KOH/g) were within permissible limits. Free fatty acid values recalculated from the reported acid values using the stated equation ranged from 0.151% to 0.429% and were below the 3.5% limit stated in Table 2. Iodine values (44.85–63.30 I₂/100 g) were outside the recommended 45–53 I₂/100 g range in all samples: eight were above the upper limit and Keffi (44.85 I₂/100 g) was below the lower limit. Reported beta-carotene values ranged from 0.62 to 59.40 mg/kg and were below the stated 500–700 mg/kg range; however, the exceptionally low values require verification against the original analytical records before definitive interpretation. Sensory acceptability scores ranged from 6.45 to 7.60. Significant variations (p < 0.05) were observed across locations. Palm oil quality in Nasarawa State showed considerable variation in several measured properties, while the beta-carotene results require analytical verification. Improved processing practices, quality monitoring, and verification of the beta-carotene calculations are recommended.