Oleic-acid-rich sunflowers give trans-fat alternative - study
against oxidation, giving them a longer shelf life, as well as
having an improved health profile, suggests new research.
However, while the news of another potential trans-fat replacement oil will be readily accepted in the US, public concerns over genetically modified food sources seem certain to present a barrier to the introduction of such an oil in Europe, and particularly the UK.
"Vegetable oils undergo extensive oxidative deterioration during storage, marketing, or deep fat-frying. These secondary products adversely affect flavour, aroma, taste, nutritional value and overall quality of foods," explained lead author Stephanie Smith from Ohio State University.
"Genetic modification of sunflower oil, to decrease linoleic acid and increase oleic acid, could increase the oxidative stability during storage and deep fat-frying, as well as improve the health benefits," she said.
The researchers compared the GM sunflower oil, rich in oleic acid (87 per cent) and low in linoleic acid (5.45 per cent), with regular sunflower oil (17 per cent oleic acid, 71.6 per cent linoleic acid), soybean oil, corn oil and peanut oil.
Writing in the Elsevier journal Food Chemistry, Smith and her co-workers report that under tests of the oxidative stability of the oils, the high oleic acid containing sunflower oil performed better than the regular oil for measures of oxidation rate, lipid oxidation, formation of volatile off-flavours, and thermal stability.
In general, the corn oil was most stable for these measures, they note.
"Genetically modified high oleic sunflower oil had a higher oxidative stability during storage than had regular sunflower oil," said the researchers. "Similarly, the thermal stability evaluation results indicate a greater stability for modified high oleic sunflower oil than for regular sunflower oil."
"The oxidative and thermal stabilities of edible oils appear to be related to linoleic and linolenic contents, decreased linoleic and linolenic contents result in increased oil stability," they said.
By reducing the linolenic acid content the shelf life can be extended, said the researchers, and therefore eliminate the need for hydrogenated oils, so-called trans-fats.
Numerous studies in the literature show that trans fatty acids raise serum levels of LDL-cholesterol, reduce levels of HDL-cholesterol, can promote inflammation, can cause endothelial dysfunction, and influence other risk factors for cardiovascular diseases (CVD).
Sunflower seed production around the world was set at 7.48 million metric tons in 2001-02, increasing to 10.46 in 2005-06. Consumption increased from 7.52 to 9.84 million metric tons.
Source: Food Chemistry Volume 102, Issue 4, Pages 1208-1213 "Oxidative and thermal stabilities of genetically modified high oleic sunflower oil" Authors: S.A. Smith, R.E. King and D.B. Min
