Degradation of tocopherols in rice bran oil submitted to heating at different temperatures.
The objective of this study has been to evaluate the stability of alpha-, (gamma+beta)-, and delta-tocopherols in rice bran oil chemically refined submitted to heating in a heater without air circulation and shielded from light, at temperatures of 100 degrees C and 180 degrees C. The collection of samples took place after 48, 96, 144, 192, 240, 336, and 432 h of heating and were stored in amber-colored flasks and frozen (-18 degrees C). The analyses of tocopherols took place in accordance with the method by Chen and Bergman (2005), with slight modifications, utilizing a system of high efficiency system of liquid chromatography. It was observed that the alpha-tocopherol is present at higher concentration in rice bran oil (328.4 mg/kg), followed by (gamma+beta)-tocopherol (99.1 mg/kg), and delta-tocopherol (7.7 mg/kg). The alpha-tocopherol in rice bran oil submitted to 100 degrees C showed a reduction of 28.65% at the end of 432 h of heating whereas when submitted to 180 degrees C temperature; its reduction was of 100% at the end of 240 h of heating. The contents of (gamma+beta)- and delta-tocopherol in rice bran oil at the end of 432 h of heating at 100 degrees C was of 79.9 and 6.4 mg/100 g, respectively.
Bruscatto
M H
MH
Departamento de Ciência e Tecnologia Agroindustrial, Universidade Federal de Pelotas, Campus Universitário s/n. Caixa Postal 354. Pelotas- RS/Brasil. CEP 96010-900.
Zambiazi
R C
RC
Sganzerla
M
M
Pestana
V R
VR
Otero
D
D
Lima
R
R
Paiva
F
F
D002851:Chromatography, High Pressure Liquid; D006361:Heating / Q000295:instrumentation; D006358:Hot Temperature; D010938:Plant Oils / Q000737:chemistry*; D000073879:Rice Bran Oil; D024505:Tocopherols / Q000737:chemistry*
D010938:Plant Oils; D000073879:Rice Bran Oil; D024505:Tocopherols