Effects of moisture content and presence of γ‐tocopherol on the stability of α‐tocopherol in stripped corn oils
2016
Jung, Jinyeong | Gim, Seo Yeong | Lee, Chankyu | Kim, Mi‐Ja | Lee, JaeHwan
The stability of α‐tocopherol in stripped corn oils with or without added γ‐tocopherol was determined under different levels of relative humidity (RH) ranging from 0 to 93% at 60°C. The degree of oxidation was determined by the headspace oxygen content and conjugated dienoic acid (CDA) assays and the remaining α‐ and γ‐tocopherols were also analyzed. The stability of α‐tocopherol was significantly influenced by the presence of moisture, the concentration of α‐tocopherol, and the presence of γ‐tocopherol. Samples containing up to 100 ppm α‐tocopherol showed the lowest stability under 75% RH whereas those containing 200 ppm α‐tocopherol had the highest stability under 93% RH. Samples under 0% RH had the lowest α‐tocopherol stability in the presence of γ‐tocopherol. Generally, higher concentrations of γ‐tocopherol resulted in the retention of more α‐tocopherol in stripped bulk oils. Practical application: Tocopherol isomers are typical lipophilic antioxidants in oils. Many lipid‐rich foods contain tocopherol isomers to extend the shelf‐life of the products. The stability of α‐tocopherol was significantly influenced by the presence of moisture, the concentration of α‐tocopherol, and the presence of γ‐tocopherol. Generally, higher concentrations of γ‐tocopherol resulted in the retention of more α‐tocopherol in stripped bulk oils. Using the knowledge obtained in this study, shelf‐life of foods containing oils can be enhanced by modifying the moisture content and concentration and types of tocol isomers. Generally, α‐tocopherol and γ‐tocopherol were more stable at RH 32% and RH 75%, respectively in stripped bulk oils.
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