Rice bran oil was extracted using environmentally-friendly supercritical carbon dioxide at varying conditions. Experimental treatments included pressure (27.6, 41.4 and 55.2 MPa), temperature (40 and 60 oC) and flow rates (25, 45 and 65 g/min) of supercritical carbon dioxide. Extracts collected at different time intervals during 4-hour extraction runs in a 3-L extractor were analyzed for oil yield and antioxidants. Normal-phase HPLC was used for analyzing the extract for important antioxidant compounds of oryzanol, tocopherols, tocotrienols. Silica rich rice hull ash adsorbent was also incorporated in combined extraction-adsorption experiments under similar supercritical fluid conditions. Supercritical extraction yields of rice bran oil and antioxidants were compared with 6 -hour Soxhlet extraction using petroleum ether solvent. Total oil extract yields for SFE (17.26-18.52 %) and experiments conducted with ash (17.35-18.99 %) for the extraction conditions of higher pressure (55.2 MPa) and flow rates (65 g/min) were comparable to the ether extractable oil yield (17.88 %). Extract yield significantly increased (p<0.05) with an increase in pressure and flow rate. However, the temperature effect on extract yield was not significant. Antioxidant extraction significantly increased with increased pressure, but not with increased flow and temperature. These behaviors with pressure, flow and temperature were similar for oryzanol, tocopherols and tocotrienols. Rice hull ash adsorbent did not significantly affect oil yields, but did influence the antioxidants in the extract. A much greater ash adsorption effect for noted for oryzanol, which was different from the effect that was seen for of vitamin E components. A separate batch adsorption study carried out at different temperature (20, 30, 40 oC) for varied time intervals also showed similar adsorption behavior. Freundlich isotherms successfully described adsorption behavior of the antioxidant compounds in the batch study using rice bran oil-hexane miscella. Freundlich fitting parameters (k and 1/n) were used to plot Vanât Hoff- Arrhenius equations and calculate the change in enthalpy value (âH) due to adsorption of antioxidants. Goto et al. (1993) model was applied to extraction yield data and successfully characterized extraction behavior. Values of partition coefficient K and mass transfer coefficient Kp were calculated and reported.
| Identifer | oai:union.ndltd.org:LSU/oai:etd.lsu.edu:etd-08032005-093651 |
| Date | 04 August 2005 |
| Creators | Patel, Paresh Manilal |
| Contributors | Terry Walker, Richard Bengtson, J Samuel Godber, Valsaraj Kalliat, Charles Monlezun, Ioan Negulescu |
| Publisher | LSU |
| Source Sets | Louisiana State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lsu.edu/docs/available/etd-08032005-093651/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached herein a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to LSU or its agents the non-exclusive license to archive and make accessible, under the conditions specified below and in appropriate University policies, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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