III. Correlation between Standard and Rapid Methods
Table 3 shows the measurements from all test methods
were significantly correlated (p < 0.05). The standard
methods moderately correlated with other methods (r = 0.51
- 0.64). The 3M Shortening Monitor had better correlations
with the total polar compounds test methods (r = 0.801 -
0.888). In some studies
(10,14,31,39)
, a poor relationship was
observed between the acid value and the content of total
polar compounds in used oil. However, Lee(12)
pointed that
the correlation between the content of total polar compounds
and acid value exist only under the same oil, food and frying
operation.
In this study, it was observed the discontinuous reading
of the 3M Shortening Monitor. In addition, the color change
in the bands of the 3M Shortening Monitor from blue to green
or yellow was difficult to determine. Occasionally, it showed
the color of blue-green or green-yellow, or showed the color