Effect of Subcritical Solvent Extraction Conditions on Amount of G-Oryzanol and G-Tocopherol in Dawk Pa-Yom Rice Bran Oil

This research focused on the subcritical solvent extraction of phytochemicals -oryzanol and -tocopherol from upland rice bran (Dawk Pa-yom variety, DY). Subcritical solvent extraction was conducted using a batch reactor. The temperature was varied in range from 80 to 120°C for 20 to 60 min. The solvents in use were ethanol, methanol, and water. -Oryzanol and -tocopherol were simultaneously analyzed by HPLC. Antioxidant activity was determined by a DPPH radical assay. Methanol was able to extract a higher level of -tocopherol than ethanol and water. Extraction by methanol gave higher antioxidant activity than ethanol. Even though water could not extract -oryzanol, it was able to extract substances with higher yield of antioxidant activity than either methanol and ethanol. Increasing the extraction temperature increased the oil yield, -oryzanol and -tocopherol in parallel with an increased antioxidant activity. During the extraction process, some degradation of antioxidants was observed, and this showed the importance of  kinetics parameters in this research.

Keywords: extraction; kinetics; oil recovery; solvent extraction; -oryzanol; -tocopherol; rice bran

*Corresponding author:  E-mail: duangkamolruen@gmail.com, duangkamol.ru@kmitl.ac.th,   

                                              duangkamol.rue@rmutr.ac.th