Evaluation of stability photo-oxidative of canola oil and corn oilin the presence of synthetic antioxidants/Avaliacao da estabilidade foto-oxidativa dos oleos de canola e de milho em presenca de antioxidantes sinteticos

• Published in: Ciência rural 2014-04, Vol.44 (4), p.728
• Main Authors: Tolentino, Marina Caldeira, Kanumfre, Francieli, Bersot, Luciano dos Santos, Nagata, Noemi, Carneiro, Paulo Irajara Borba, Rosso, Neiva Deliberali
• Format: Article
• Language: Spanish
• Subjects: Antioxidants (Nutrients); Corn
• ISSN: 0103-8478

The stability of vegetable oils in relation to oxidation depends on the balance between the composition and the presence of antioxidants and pro-oxidants. The objective of this study was to evaluate the effect of the presence of antioxidants in vegetable oils in the protection of photo-oxidation. Samples of canola oil and corn oil in the presence and absence of the antioxidants, butylated hydroxytoluene (BHA), propyl gallate (PG) and tertbutylhydroquinone (TBHQ), were subjected to photo-oxidative stress at room temperature for 60 days. The photo-oxidation reaction followed a first order kinetics. The rate constant for the period of 20 days of photo-oxidation showed that the PG antioxidant showed greater protective effect for canola oil and TBHQ showed a greater protective effect for corn oil. The UV and H NMR data at 60 days showed that the three antioxidants had a protective effect on photo-oxidation. The UV data showed increased absorption at the 232nm band due to photo-oxidation and the formation of conjugated dienes. The reduction in intensity of this absorption band in photo-oxidation with time of exposure revealed that the protection, both for the canola oil and for the corn oil, was more effective with the PG antioxidant. The rates of [R.sub.oa] oxidation and residual fraction of diallyl, allyl and vinyl hydrogens also showed that the PG antioxidant showed the best performance in protecting both oils.