THE RELATION BETWEEN THE COLORATION OF FRYING OIL AND THE DETERIORATION USING FRIED MODEL-MATERIALS

To study the relationships between the coloration and the deterioratio n of frying oils, the following model-materials were applied. Namely, a series of 10 mm square filter papers, made of glass-fiber, were soak ed in the following various solutions, i.e. sodium chloride, glucose, sucrose, albumin, glycine, alanine, leucine and lysine. The dripping s olution of the model-surface were removed. A series of the models were fried with rapeseed oil in 180 degrees C, and obtained oil were measu red by coloration, acid value (AV), carbonyl value (COV), anisidine va lue (An.V), conjugated diene content and viscosity. The following resu lts were obtained. A series of the models soaked in amino-acid solutio ns, except lysine, show the vigorous coloration comparing to other mod els, and make the frying oil characteristically to red, and also make COV and An.V lower than even the fresh oil. For this reason, it is ass umed that the carbonyl compounds, formed by deteriorated frying oil, c hanged to the browning pigments formed by the amino-carbonyl reactions with the amino acids from fried materials. And that there were not re lating to the measurements of COV and An.V.