1967 Volume 16 Issue 7 Pages 410-412
Chemical and physical changes of soybean oil were determined after treated in the continuous water-spraying and heating system reported in previous paper and in the continuous heating without water, and the type of deterioration were compared between the both systems (Table-1, Fig.-15).
In the presence of water, remarkable changes were observed in the increase of acid value, monoglyceride content and hydroxyl value. In parallel with this, a noticeable colour development were also observed. In the absence of water, however, these changes were very small. These facts indicate that the hydrolysis should not be disregarded in heating of frying oil in the existence of water. On the other hand, thermal oxidative changes in the presence of water about two times greater than without water. However, the effect on promotion of the thermal oxidation was considered as the increase of fat surface exposed in air by the physical agitation of oil during the boiling of discharged water.
Accordingly, it was concluded that the major difference of deterioration of frying oil between continuous water-spraying and heating system and continuous heating system without water was the hydrolytic deterioration.
