We investigated the quality of frying and fats used by frying manufacturers (10 groups, 85 samples). Although there is no line of demarcation for usage in our country, we attempted to estimate the quality of frying oils and fats by reference to the limit in the Federal Republic of Germany (petroleum ether insoluble oxidized fatty acid content, <0.7%, acid value, <2.5).
It is noteworthy that the usage of solid fats (saturated glyceride rich) have a tendency to rise acid values extremely, while the frying fats are not always spoiled. Referring to the contents of oxidized fatty acid, 9 samples are higher than 0.7%, and it is remarkable that in all these cases carbonyl values are higher than 50 meq/kg. the colouration of frying oils and tats are not always correspond to various indices.
Carbonyl values are seemed to be more reasonable index for the quality of frying fats than peroxide values or acid values.