THERMO-OXIDATIVE STABILITY OF COLD-PRESSED WALNUT OIL

Abstract

Walnut oil has many health benefits due to uniqe chemical composition: the desirable ratio of ω-3:ω-6 fatty acids and many compound present in a small amount. But, polyunsaturated fatty acids cause the weak oil stability. The aim of this research was to examine the thermo-oxidative stability of cold-pressed walnut oil at 180°C during 2 h. Significant sensory and chemical changes were observed. Specific absorbances at 232 nm and 270 nm increased during thermal treatment. Refractive index and peroxide value increased also. An acceleration of secondary oxidation products formation increase was recorded during 2 h of heating. After 2 h at 180°C a peroxide value indicated that the oil was no longer edible.