14E-35 |
Stability of alpha and gamma-tocopherol and tocotrienol, and oryzanol during heating |
W. WANG, Z. Xu, and J. S. Godber. Dept. of Food Science, Louisiana State Univ. Agricultural Center, 111 Food Science Bldg., Baton Rouge, LA 70803-4200 Justification: The capabilities of alpha-tocopherol(alpha-T), gamma-tocopherol(gamma-T), alpha-tocotrienol(alpha-T3),gamma-tocotrienol(gamma-T3), and oryzanol in rice bran oil of preventing development of heart disease and cancers have been reported. Recently it has been proposed to use rice bran oil as frying or cooking oil for health purposes. However, information relative to the thermal stabilities of these compounds is limited. Determining their stabilities in rice bran oil could help establish appropriate uses for rice bran oil that maximize their health functions. Objectives: To investigate the changes of alpha-T, gamma-T, alpha-T3, gamma-T3, and oryzanol in rice bran oil at different heating temperatures. Methods: Rice bran oil was heated at 100,130,160 and 190°C. The heated oil was sampled at 10,25,40 and 55 min. Determination of the concentration of alpha-T, gamma-T, alpha-T3, gamma-T3, and oryzanol was performed using a normal phase HPLC method with UV detector. Results: No significant decrease was found for any of the compounds at 100 °C for 55 min. alpha-T, alpha-T3 and oryzanol had 38% and 45% remaining at 130°C for 55 min, respectively. These compounds were reduced to less than 10% at 160 °C for 40 min whereas 38% of gamma-T and 41% of gamma-T3 were retained. At 190 °C, alpha-homologues decreased to less than 5%, whereas 20% of the gamma-homologues remained when heated at 190 °C for 40 min. No significant decrease was found for oryzanol. Significance: The antioxidant compounds of rice bran oil are relatively stable at 100 °C. They could be significantly degraded at the temperatures above 130 °C for longer cooking time. Gamma-homologues are more stable than either alpha-homologue, whereas oryzanol is relatively stable at high temperature. These results could be helpful to food producers using rice bran oil to maximize its health function during processing.
Session 14E, Nutraceuticals & Functional Foods: General I
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