However,
for the accuracy of determination, SIMCA was also performed to
detect the classification limit of soybean oil in walnut oil. Walnut
oil and walnut oil–soybean oil mixtures were clearly divided into
two groups, and walnut oil was found to be vastly differentiable
from the adulterations (Fig. 4). The SIMCA classification limit of
soybean oil in walnut oil was less than 5%. Therefore, fluorescence
spectroscopy was a better choice than FTIR spectroscopy in determining
walnut oil adulteration because of the lower detection limit.