Fındık Zarı Ekstraktının Fındık Yağı Oleojellerinin Stabilitesine Etkisi

This study investigated the effects of hazelnut husk extract (HHE) on the oxidative stability, physicochemical properties, and rheological behavior of hazelnut oil-based oleogels structured with glyceryl monostearate (GMS). Oleogels were prepared as a control, with a synthetic antioxidant (BHA), and with HHE at concentrations of 0.20%, 0.40%, and 0.60%. Samples were stored for 30 days and analyzed periodically for acidity, peroxide value, TBARS, Rancimat induction time, color, oil holding and release capacity, rheological properties, and FTIR. All samples showed increased oxidation during storage; however, this increase was more limited in HHE-containing oleogels. The 0.60% HHE sample exhibited lower peroxide and TBARS values and approximately 20–30% higher Rancimat induction time compared to the control. Oil holding capacity improved with extract addition, reaching 10–15% higher values in the 0.60% sample. FTIR results indicated interactions between extract components and the oleogel matrix, particularly in fingerprint and aromatic regions. Rheological analysis showed that all samples exhibited pseudoplastic flow behavior, with viscosity decreasing as shear rate increased. Viscosity ranged between 10³–10⁴ Pa·s at low shear rates, and HHE addition, especially at 0.40% and 0.60%, significantly increased viscosity, indicating a stronger gel network. Overall, hazelnut husk extract demonstrates strong potential as a natural additive to enhance oxidative stability and improve the structural properties of oleogels.