Successive deep-Frying impact on the physicochemical properties of Himalayan Cheura oil

Abstract

The seed oil derived from Diploknema butyracea (Roxb.) H. J. Lam has considerable significance in the Western Himalayan regions of India and Nepal. It serves as a vital resource for livelihoods and is widely employed for cooking and ethno-medicinal purposes. Reusing oil for frying is a common practice during cooking. Frying alters the composition and quality of oil. This study, for the first time, assesses the physicochemical properties of Cheura oil after three repeated frying cycles using potatoes and chicken meat. Various physicochemical parameters, including visual appearance, moisture, viscosity, Fourier transform infrared spectroscopy analysis, and chemical parameters (peroxide, acid, iodine, saponification, and ester values) were evaluated. Comparisons were made between unfried oil and three frying cycles of potatoes and chicken. Results revealed slight refractive index and viscosity changes, while spectral analysis showed significant functional group alterations. Also, colour intensity, moisture, saponification (12.06-14.025 mg KOH/g), acid (2.29-3.87 mg KOH/g), peroxide (6.45-16.45 meqO₂/kg), and ester values (8.85–13.65 mg KOH/g) increased, while iodine (22.32 to -11.62 g/100g) decreased, indicating progressive quality deterioration over frying cycles. Overall, Cheura oil is suitable for frying; however, repeated use degrades its quality.