Abstract
Soybean curd or Tofu and doughnuts were fried and the temperatures of the inside of these foods and of the foams were measured by thermocouple. The temperature of the foams was the same with that of frying oil. Soybean oil were heated for 2, 3 and 4 hours at 240°C in the presence of air. Thus soybean oils of slightly foaming and strongly foaming tendencies were obtained. Their surface tension, oil-water interfacial tension, surface viscosity and viscosity were measured at various temperatures.
To measure their surface tension, the Sugden's apparatus based on the bubble pressure method was used. The oil-water interfacial tension was measured with the stalagmometer based on Traube's drop method. The viscosity was measured with BL-viscometer made by Tokyo-Keiki Co. and the surface viscosity was measured with FT rheometer made by Odawara-Tekkojo Co. with a platinum ring in place of the inner tube. Through the above experiments, it seemed that surface tension had no relation with foaming of oil, but surface viscosity and viscosity had a great concern with it.
