Current Applied Science and Technology

Abstract

Rice bran samples from dough and mature grain stages of rice were stabilized by heating in a hot air oven at 70ºC for 3h (or moisture <5.0%). Unstabilized and stabilized rice bran samples were subsequently pressed for oil extraction using a screw press machine. The γ-oryzanol, physicochemical, and antioxidant properties of both the unstabilized and stabilized rice bran oil (RBO) were determined. The fat content of fresh rice bran (unstabilized) from dough stage (19.19 %w.b.) was higher than that of the mature stage (13.22 %w.b.). Unstabilized RBO from mature stage (URBO-MS) had the lowest L* (35.70) and the highest a* (4.28) values. The γ-oryzanol content detected by UV-Vis spectophotometer was not significantly different among URBO-MS, stabilized RBO from the dough stage (SRBO-DS), and crude commercial RBO (CRBO). While the γ-oryzanol content of SRBO-DS detected by reversed-phase HPLC with diode array detector (DAD) was the highest, with a value of 1.00 g/100 g oil. The DPPH scavenging activity of SRBO-DS was the highest while that of CRBO was the lowest. The ABTS radical scavenging activity of unstabilized RBO from the dough stage (URBO-DS), SRBO-DS, and URBO-MS were not significantly different and were higher than that of stabilized RBO from the mature stage (SRBO-MS) and CRBO. The peroxide and free fatty acid (FFA) contents of SRBO-DS were the lowest with values of 1.19 meg/kg and 4.84% (as oleic acid), respectively. This finding suggests that stabalizing rice bran at the dough stage can increase the color values (as L* and b* values), γ-oryzanol, and DPPH scavenging activity, and decrease peroxide and FFA values of RBO. Thus, stabilized RBO from the dough stage grain may be a functional food with antioxidant activity.

References

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Author Information

Boonyabhorn Duangsa

Faculty of Business Administration and Information Technology, Rajamangala University of Technology Isan , Khon Kaen, Thailand

Porntip Rodpon

Faculty of Business Administration, Rajamangala University of Technology Isan , Nakhon Ratchasima, Thailand