Thermal oxidation, heat, oxidation and reagents stability was examined as an index of fatty acid stability. Color determination and chemical test to indicate values such as those of anisidine and peroxide are usually conducted according to conventional methods for stability determination. In particular, color determination is usually done by methods such as the APHA and Gardner color methods.
Various color evaluation for determination of the thermal oxidation stability of fatty acids were studied and the results compared.
Since the APHA and Gardner color methods of ten gives results that vary according to the person and place for conducting the experiments, attention in the present study was focused on spectrophotometric method to determine the stability of fatty acid.
The photometric index (P.I.) calculated by the following equation was found useful for the color determination of fatty acids.
PI=100 log 100/A
where, A=0.0002 T400*+0.0093 T440+0.0842 T490+0.3491 T530+0.4029 T550+0.1543 T620
*T400 : Transmittance at 400 nm
A good relationship was also noted between the PI and APHA standards.
That is PI × 100 was identical with the color number of APHA standard solution.
