Data
show that different domestic heating methods provided different
chemical qualities of cold-pressed RBO (P < 0.05). Steaming, roasting,
hot air and microwave heating could retard the forming of AV,
FFA and PV compared with unstabilized rice bran. Cold- pressed RBO
of hot air and microwave heating had lower AV, FFA and PV than that
of roasting and steaming methods, respectively. However, therewas
no significant difference between the rice bran samples treated with
hot air and microwave heating (P<0.05). This may be due to the fact
that, in this condition, the heat could penetrate and effectively
destroy lipase and it combined with the prevention effect of rice
bran to retard the development of oxidation products in rice bran.
Stabilization of rice bran with hot air and microwave heating are
effective methods for controlling enzyme activity in rice bran. These
results indicate that the stabilization of rice bran by domestic
heating can be employed without concern as to deleterious changes
to major nutrient concentrations in the bran. Our result is in
agreement with Ramarathnam et al. (1989) who reported that fatty
acid and proximate compositions did not change drastically in
microwave-heated rice bran compared with raw samples kept
under similar storage conditions. Amarasinghe et al. (2009) studied
the effect of method stabilization on aqueous extraction of rice bran
oil. They found that steaming, microwave and hot air heating could
retard the lipolytic activity of rice bran resulting in the lower FFA
when compared with unstabilized rice bran.
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