Evaluation of Deterioration Parameters of Hazelnut Oil, Palm Olein and Their Blends During Repeated Deep-Frying of Potatoes.

This study investigated the deterioration behavior of hazelnut oil (HO), palm olein (PO), their blends (B-1: 34% PO + 66% HO; B-2: 66% PO + 34% HO), and shortening (S) during 12 consecutive deep-frying cycles of potato slices at 180°C. Changes in free fatty acids (FFA), peroxide value (PV), p-anisidine value (p-AV), total oxidation value (TOTOX), conjugated dienes (K232) and trienes (K270), color (L*, a*, b*), viscosity, total polar compounds (TPC), fatty acid profile, and heat-induced contaminants 3-monochloropropane-1,2-diol esters (3-MCPD) and glycidyl esters (GE) were monitored to assess oxidative and physicochemical stability. HO, despite its high oleic acid content, exhibited the fastest deterioration, showing substantial increases in PV, p-AV, TOTOX, and spectrophotometric indices. PO demonstrated superior thermal stability due to its higher palmitic and oleic acid levels, while S showed the lowest overall deterioration but accumulated the highest levels of 3-MCPD and GE. Blends exhibited intermediate performance, with B-2 outperforming B-1, indicating the positive contribution of PO to oxidative resistance. TPC values in all samples remained below the regulatory limit of 25%, although progressive viscosity increases reflected polymerization during frying. The formation of 3-MCPD and GE intensified with frying cycles, particularly in PO and S, underscoring the importance of contaminant control in high-temperature applications. Overall, blending HO with PO improved oxidative stability and frying performance while maintaining acceptable quality indices. These findings support the potential of optimized HO-PO blends as economically and technologically viable frying oils.