Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 1, 2003
Publication Date: November 1, 2003
Citation: Abidi, S.L., Rennick, K.A. 2003. Nonvolatile components and frying performance of high-oryzanol rice bran oil. Journal of the American Oil Chemists' Society. 80:1057-1062. Interpretive Summary: During deep fat frying, oil undergoes complicated chemical reactions that will cause the oil to turn bad and dark in color. The oil will also develop off-flavor in the fried foods caused by decomposition materials formed during frying. To learn more about these compounds and how to control their formation, rice bran oils fortified with stabilizing agents were used for frying french fries. Oils with high-sterol content were found to improve frying oil quality/stability. These results can be used by manufacturers of snack foods and by fast-service restaurants where the majority of deep-fat frying takes places in the U.S.
Technical Abstract: Polar isolates of high-oryzanol rice bran oil (HORBO), refined- bleached-deodorized rice bran oil (RBO), and partially hydrogenated soybean oil (PHSBO) used for French fried potatoes were analyzed for nonvolatile components by high-performance size exclusion chromatography (HPSEC) with evaporative light scattering detection (ELSD). The HPSEC system employed three mixed-bed polystyrene/divinylbenzene columns and a mobile phase of tetrahydrofuran as eluent. In all frying experiments, both HORBO and RBO yielded predominantly dimeric and monomeric materials and their concentrations of polymeric species were greater than PHSBO. At the end of frying (168 h), the major degradation products from HORBO, RBO, and PHSBO were dimer (8.93 mg/100 mg oil), monomer (10.5 mg/100 mg oil), and diglyceride (22.4 mg/100 mg oil), respectively. Examination of concentration distribution data for the test oils indicated that polymer formation during frying had the following order: RBO > HORBO > PHSBO. This trend is explicable in terms of lipid unsaturation and sterol antipolymerization rationales. Comparisons of HPSEC- ELSD results from the two rice ran oils revealed that amounts of polymeric materials in HORBO were invariably less than those found in RBO. Additional frying tests (percent polar materials, percent polymerized tryglycerides, and food oil sensor tests) showed an enhancement in oil quality and stability with increasing oryzanol contents as follows: PHSBO > RBO > HORBO.