Author
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Warner, Kathleen |
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Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 9/5/2005 Publication Date: 12/28/2005 Citation: Warner, K.A. 2005. Effects on the flavor and oxidative stability of stripped soybean and sunflower oils with added pure tocopherols. Journal of Agricultural and Food Chemistry. 53(26):9906-9910. Interpretive Summary: Vegetable oils and oil-containing foods for the consumer market need to be able to stay on the supermarket shelves for long periods of time. Some foods with certain types of oil or fat do not have long shelf lives and can become rancid and unacceptable. In order to improve the shelf life of oils and oil-containing foods, oils with different amounts of natural compounds to prevent shortened shelf life were tested. We found that some of the natural antioxidants in soybean oil increased shelf-life storage in the dark better than the natural antioxidants in sunflower oil. We also discovered that one of the natural antioxidants in sunflower kept the oils from deteriorating if they were held in lighted storage conditions. Results of this research will help both plant breeders and users of vegetable oils in the development of oils with optimum natural antioxidant compositions to achieve good quality, healthful oils and oil-containing foods and will benefit consumers, oil processors and food manufacturers. Technical Abstract: Effects of tocopherols on oxidative stability of vegetable oils were studied by adding pure tocopherols--alpha, beta, gamma, and delta--in their naturally occurring ratios to purified soybean and sunflower oils. Soybean and sunflower oils were stripped of minor constituents and the tocopherol profile typical of sunflower oil-high alpha, high beta, low gamma and low delta was added. The tocopherol profile typical of soybean oil-low alpha, low beta, high gamma and high delta was added to stripped sunflower and soybean oils. Stabilities of oils by autoxidation and photoxidation were evaluated at 60oC in the dark and at 7500 lux light intensity at 30oC. Completely stripped oils had the lowest stability, as expected but results varied between light and dark oxidation. In dark oxidation, soybean oil with the sunflower tocopherol profile had the lowest levels of peroxides and total volatile compounds, whereas sunflower oil with sunflower tocopherol profile had the highest levels. In flavor analysis, oils with the soybean tocopherol profile were more stable than oils with the sunflower tocopherol profile. In contrast, addition of sunflower tocopherols significantly improved light stability of either oil type compared to oils with soybean tocopherols. The soybean tocopherol profile which is high in gamma and delta tocopherols and low in alpha tocopherol was significantly more effective in inhibiting autoxidation in the dark; however, the sunflower oil tocopherol profile which is high is alpha and low in gamma and delta prevented light oxidation significantly more than the soybean tocopherols. |
