摘要：Factors affecting the oxidation of a substrate were investigated in the oven test at 60°C, as a stability test for oils and fats against oxidation. The test was carried out by using 4 methods and by using lard with a 0.02% addition of a mixed tocopherols concentrate (m-Toc) or not, as the substrate: putting 1g of the substrate into each of several small beakers (A), as samples for periodical measurement of the peroxide value (POV), prior to storage at 60°C; putting respective 50g (B), 100g (C) and 150g (D) of the substrate into individual 200ml beaker, and periodically sampling from them for POV during storage. 1) In the oven test for lard with no m-Toc addition, the increase in POV by the B method was similar to that by the A method, but the increase became clearly slower using the C method, becoming further slower by the D method. Such differences were observed in the test for lard with the m-Toc addition, but in this case, both differences in the oxidation rates by the C and D methods from the A method were smaller than those in the above case. 2) Although the surface area/weight ratio of substrate was not changed in the A method but in the B, C and D methods during the oven test, the ratio became higher in order by the A method≈the B method>the C method>the D method. The coefficient of variation for POV repeated 5 measurements was less than 5% in almost all cases, while the coefficient of cases by the A method, in general, was slightly smaller than that by the other methods. 3) From above results, it was concluded that the surface area/weight ratio of substrate is a factor affecting the oxidation of substrate by the oven test, and the test by the A method using small beakers is suitable for evaluating stability of oils and fats against oxidation.
