Investigating the frying stability of African oil bean seed (Pentaclethra macrophylla) and refined palm olein oil blends

Abstract

The present study evaluated the frying stability of African oil bean seed oil (AB) and refined palm olein (RPO) and their blends. African oil bean seed oil was extracted via the Soxhlet method, yielding a high oil content of 47.95%. AB was then blended with RPO in seven proportions: 100: 0 (AB100), 0: 100 (RPO100), 90:10 (AB90:RPO10), 80:20 (AB80:RPO20), 70:30 (AB70:RPO30), 60:40 (AB60:RPO40) and 50:50 (AB50: RPO50). Unmixed and blended oils were used to fry potato strips (175 + 5oC) over four consecutive days without oil replenishment. After each daily cycle, oil samples were analyzed for smoke point, iodine value, moisture content, peroxide value (PV), free fatty acid (FFA) value, and thiobarbituric acid (TBA) value. Frying stability studies showed that smoke points and iodine values significantly decreased (p < 0.05) as frying cycles increased, while moisture content, PV, FFA, and TBA values increased. The 100% African oil bean seed oil (AB100) showed the highest degradation, with moisture content increasing from 1.90% to 3.24% and the highest final PV, FFA, and TBA values across all cycles. Conversely, blending AB with RPO steadily reduced the increases in these degradation products, with reductions observed from the 10% RPO blend up to the 50% RPO blend. Oil blends containing up to 50% refined palm olein (AB50:RPO50) demonstrated the highest overall frying stability. Conclusively, oil blends containing up to 50% refined palm olein had the highest frying stability, hence, blending African oil bean seed oil and refined palm olein reduced the incidence of hydroperoxide formation, FFA and secondary oxidation products during frying.