In the previous papers, the authors previously reported on the results of collaborative tests with regard to a standardization of the fat stability test on the autoxidation by using soybean oil. In this paper, the authors report on investigations concerning the stability test made on the autoxidation by using refined lard as follows :
1. Results of AOM test
Average AOM value of 6 laboratories was 16.2h, showing that deviations among them were small except for a specific laboratory.
2. Results of Oven test
The peroxide value (POV) measured by these laboratories were varied widely especially at the long standing period. A reason of this was considered as the differences of the inconsistencies on the thermostat specifications, not that the differences of the POV determination method and the sampling conditions.
3. Results of organoleptic evaluation
The results of organoleptic evaluation were comparatively consistent among collaborators. The correlation between the organoleptic evaluation and the POV was as given hereunder :
POV (meq/kg) Flavor score Response
01.3 5 Odorless, Fresh oil
1.32.0 4 Slightly grassy, Flavor reversion, Nutty
2.35.0 3 Slightly rancid, Heavy flavor reversion
5.38.0 2 Rancid, Viscous taste
8.0> 1 Strong rancid, Pungent smell
4. Results of test on weighing method
When the collaborators followed different specifications of thermostat, the deviations on the results obtained were very big. The greatest cause of deviations on the test by weighing method certainly consisted in various and uneven specifications of thermostat and difference of heat capacity. In the case of using the same thermostat, the deviation lessened. Therefore, if the specifications of the thermostat is unified, the standardization will be realized.
