Abstract
The length of time by which any frying oil may become to show the strong foaming during the deep fat frying is presumed to depend on several factors, principally temperature of frying, surface area of oil exposed to air and degree of contamination of oil by the fried foods.
This paper deals factors that affect the rate of oil deterioration during the deep fat frying, such as degree of heating, amount of steam blown into oils, kind of gases passed in oils, kind of metals used as frying pans and so on.
To compare the effects of defference in amount of steams blown into oils, 700 gr or 1, 000 gr of soybean oil placed in iron frying pan was heated for 2.5 hrs at 240°C, blowing the steam through a glass plate filter, then the chemical and physical properties of oils thus obtained were measured. The more the steam blown, the more the oil deteriorates.
Blowing of air and oxygen into oil affected much the rate of deterioration of oil, while blowing of steam or heating in absence of air seemed to prevent oil deterioration.
With regard to the factors resulting from contamination of the oil by the fried soybean curd, “Tofu” didnot affect on the deterioration except the colour. The kind of metals used for vessels such as iron, stainless steel, coppor and aluminium didnot show any significant difference of effect on oil deterioration except the changes in colour and flavor in the case of copper.
