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Abstract
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The aim of this work was to evaluate the effects of microwave treatment on hydrolytic and oxidative stability of Iranian
rice, barley, and oat brans. The bran samples were treated with different microwave powers (2, 4, 6, 8, and 10 kW) and
treatment durations (30, 60, 120, 180, and 240 s) and the moisture content, color values, total phenolic content (TPC),
lipase activity, free fatty acid (FFA), and antiradical activity were measured. The moisture decreased in microwave treated
samples as it was 10.2–11.5% for control and < 8% upon treatment by 4 ≤ kW power for 60 ≤ sec. The highest reduction
in the lipase activity was obtained at 10 kW/60sec for barley bran (53.7%), 10 kW/30sec for oat and rice bran (51.1%
and 47.66%, respectively). The lowest FFA of rice bran was 2.95% after treatment at 10 kW/240sec, for barley bran
it was 0.8% after treating at 10 kW/180 sec, and for oat bran the lowest FFA was 1.2% (treatment at 10 kW/240sec.
The highest TPC was found at 8 kW/240sec for barley bran (26.2% increase), 8 kW/180sec for oat (23.8%), and rice
bran (19.1%) compared to the controls. For oat, barley, and rice bran, treatment at 10 kW/120sec, 10 kW/60sec, and
8 kW/180sec, respectively, enhanced the scavenging activity to higher than 50%. According to the results, microwave
power at 8 kW/180sec for rice bran, 10 kW/120sec for oat bran, and 10 kW/60sec for barley bran increased oxidative and
hydrolytic stability of Iranian rice, barley, and oat bran samples with the least color variation.
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