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Keywords:

  • Canola oil;
  • Emulsions;
  • Hexanal;
  • Hydroperoxide;
  • Oxidation;
  • Soybean oil;
  • Tocopherols

The effect of differing concentrations and ratios of α- and γ-TOH on oxidative stability over time was determined by measuring the development of hydroperoxides and volatile secondary oxidation products (hexanal) within a series of oil-in-water (o/w) emulsion systems produced from both canola oil (CO) and soybean oil (SBO). Overall rates for hydroperoxide and hexanal formation were lower in CO than in SBO. In CO emulsions, γ-TOH was a stronger antioxidant than α-TOH, and their interaction in mixtures was additive. In SBO emulsions, α-TOH was a better antioxidant at lower concentrations, while γ-TOH was better at higher concentrations. The interaction between α- and γ-TOH was synergistic at low concentrations, but either additive or antagonistic at higher concentrations, depending on the concentration and ratio of the two TOHs. In both CO and SBO emulsions, α-TOH became less effective at higher concentrations, while γ-TOH activity increased with increasing concentrations.

Practical applications: Tocopherols are widely used natural antioxidants in human and pet foods, cosmetics, and supplements. This work provides information about the different antioxidant activities of α- and γ-TOH and their interactions in o/w emulsions made with two of the most widely produced and utilized vegetable oils. This information can be applied to determine the best levels and ratios of tocopherols to protect emulsions depending on the type of oil that is used.