Degradation of Tocopherols in Rice Bran Oil Submitted to Heating at Different Temperatures

Abstract

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.

Effect of Gum Arabic, β‐Cyclodextrin, and Sodium Caseinate as Encapsulating Agent on the Oxidative Stability and Bioactive Compounds of Spray‐Dried Kenaf Seed Oil

“…Besides that, Bruscatto et al. () reported that the extent of degradation of tocopherols in rice bran oil was complied with the order of α‐tocopherol > (γ + β) > δ‐tocopherol at 100 and 180 °C, which showed that the α‐tocopherol was the most susceptible to oxidize.…”

The Influence of Drying Process Conditions on the Physical Properties, Bioactive Compounds and Stability of Encapsulated Pumpkin Seed Oil

“…Opposite results were achieved by Calvo et al (2011Calvo et al ( , 2012, who encapsulated walnut and olive oils with the method of freeze-drying and found SFA saturated fatty acids, MUFA monounsaturated fatty acids, PUFA polyunsaturated fatty acids a Increase/decrease compared to the control sample that the content of tocopherols in the encapsulated samples differed insignificantly from that assayed in the samples of control oils. In general, high degradation of tocopherols in all analyzed powders could be explained by the presence of light and oxygen during the drying process (Anwar and Kunz 2011) since these compounds are not resistant to high temperatures (Bruscatto et al 2009). Furthermore, the homogenization process might decrease tocopherols too.…”

The influence of extraction methods on composition and antioxidant properties of rice bran oil

“…The tocols content (both tocotrienols and tocopherols) of RBD samples were evaluated by reversed-phase HPLC which is equipped with LC-10AV VP pumps, SPD-10AV VP (Shimadzu, Japan) and fluorescent detector (Bruscatto et al, 2009). The KINETEX PFP column (150 mm × 4.6 mm; 100 A), was used (Phenomenex, USA) and 90% methanol in deionized water acts as mobile phase.…”