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

ABSTRACT 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 (K 232 ) and trienes (K 270 ), 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.