High-temperature stability of refined perilla oil and effects of adding some food components

We have investigated the heat stability refined perilla oil (PO) without additives during continuous heating in a test tube for 10 h at 180 degrees C by measuring the acid value (AV), carbonyl value (CV), p-anisidine value (p-An.V), percentages of residual tocopherols and those of residual fatty acids. Prolonged heating brought about greater deterioration of PO than soy-bean oil. With 10 h heating of PO, CV and A-An.V increased to 131.0 and 242.4, respectively, in spite of the low value of 0.20 for AV. By 70 min of heating, although deterioration of PO was somewhat greater than that of SO, 93.6% residual alpha-linolenic acid and 87.0% residual total tocopherol remained in the former. The effect of water on the heat-induced deterioration of oils was compared between PO and SO following deep-frying of cotton balls containing certain amounts of distilled water successively in the both oils at 182 +- 2 degrees C, for 60 min. The increase of AV of PO after adding the water was somewhat greater than that of SO, while the CV, p-An.V and POV increased to a similar extent in either oil. Greater deterioration of PO occurred upon addition of FeCl3, glucose and water to the oil, but addition of glycine inhibited the deterioration considerably