Crude rice bran oil has an OSI of over 37 hours, over four times
longer than soybean oil. The high resistance of rice bran oil to oxidation
is usually attributed to γ-oryzanol [5]. Thus, products derived
from rice bran oil that retain γ-oryzanol should also have increased
resistance to oxidation. OSI of the rice bran oil spreads was
difficult to determine directly, as the rigid texture of the spreads did
not allow air to be bubbled uniformly through the samples, making
the measurement impossible for all samples except the crude rice
bran oil. Instead, the rice bran oil spreads were dissolved at 1, 2,
and 3 wt% in refined soybean oil and the oxidative stabilities of the
mixtures were measured. Alone, soybean oil had an OSI of 8.44
hours. At 1 wt%, the OSI of all rice bran oil spreads was extended
to approximately 12 hours, and at 2 wt% the OSI was extended to
approximately 13 hours. Thus, the rice bran oil spreads impart up
to a 50% increase in induction time, depending on the concentration.