The chemical changes (iodine value and peroxide value) of olive oil, corn oil and soybean oil by surfactant were investigated under the next conditions: (1)The leaving alone at 30±0.5°C for 52 days. (2)The slightly heating at 75, 100, 125 and 150°C for 30 minutes. (3)The irradiation by a 20-watt lamp of ultraviolet rays for 23 and 46 hours.
The results were as follows.
(1)Iodine value showed a rate of remarkable decrease on the test section only corn oil. The other were comparatively the same rates of decrease on each sections.
Peroxide value showed unilateral increases on each sections of all oils. Generally the increases were large on the test section, especially corn oil.
(2)Iodine value on each sections generally decreased than the raw materials, and on an average, corn oil and soybean oil showed a large rate of decrease on the test section. Especially corn oil was large.
Peroxide value increased than the raw materials on each sections of all oils and showed generally a large rate of increase at 100 and 125°C. Especially corn oil showed the largest rate of increase of all oils. Generally corn oil and olive oil were the little rates of increase on the test sections, but soybean oil was a large.
(3)The raw materials leaved alone at room temperature for 111 days in the height of summer were irradiated by a 20-watt lamp of ultraviolet rays for 23 and 46 hours with 21cm in height.
Jodine value showed on an average generally a little rate of decrease on the test section, especially corn oil was little.
Peroxide value showed unilateral increases on each sections of all oils. Olive oil and corn oil were the large rates of increase on the test section on an average, especially olive oil was remarkable and soybean oil was a little.
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