For plenty of good reasons, the term "trans fat" leaves a bad taste in the mouths of health-conscious consumers. Typically, trans fatty acids are bad for health, but scientists at the University of Arkansas Division of Agriculture have coaxed out significant health benefits by juggling the molecular structure of soy oil.
|Vishal Jain, a Ph.D. student from Mumbai, India, irradiates soybean oil with UV light in a process that increases the content of conjugated linoleic acid. Also known as CLA, the compound provides health benefits, including enhancing the immune system and lowering risks of cancer and diabetes. The method uses a UV light source that is submerged in a glass vessel full of oil. Jain said the process operates at room temperature for six days. (Image courtesy of University Of Arkansas, Fayetteville)|
Studies have also shown that humans eating diets rich in CLA reduced body fat and waist size, Proctor said.
Proctor and Jain have used the converted oil to produce potato chips that contain high concentrations of CLA. Proctor calls them "healthier potato chips."
"It is still important to have a low fat diet and we do not propose increasing the fat intake, but a few chips will provide needed CLA," Proctor said.
"Our goal is to develop a popular food item that offers high concentrations of CLA without increasing saturated fat intake," Proctor said. "Potato chips suit this purpose well. Subsequent studies may include development of high-CLA salad oils and dressings."
Marjorie Fitch-Hilgenberg, associate professor of human environmental sciences and director of the dietetics program in Dale Bumpers College of Agricultural, Food and Life Sciences at the U of A, said trans fatty acids occur naturally in meat and dairy products, but in small amounts. Of greater health concern, she said, are the higher concentrations of trans fats artificially produced when hydrogen is added to vegetable oils — producing hydrogenated oils — to extend shelf life and make solid shortenings.
Such trans fats increase levels of low-density lipoproteins, or LDL cholesterol, Fitch-Hilgenberg said, and reduce high-density lipoproteins, or HDL, which counteract the artery-clogging effects of LDL.
Proctor said their process uses only refined soy oil, which does not introduce the health risks associated with hydrogenated oils. When CLA is synthesized, the result is a trans fat oil with health benefits.
CLA occurs naturally in beef and dairy products, but at such low levels that no benefit is obtained in a normal, healthy diet, Proctor said. In an earlier experiment, Proctor found that CLA could be synthesized in soy oil by irradiating it with ultraviolet and visible light, although that first process still produced only low amounts, similar to that present in beef and dairy.
Proctor and Jain experimented with an instrument that exposes oil to UV light more evenly and produces significantly higher CLA content of soybean oil. The photo-irradiated oil contains 25 percent CLA, Proctor said. Beef and dairy products contain less than 1 percent.
The term "trans fatty acids" refers to the manner in which carbon atoms are bound together in the oil molecules. Jain adds iodine as a catalyst to destabilize double bonds that connect the carbon atoms. Proctor said energy from the photo irradiation causes those double bonds to shift position, a chemical change that results in the formation of CLA. Later, the iodine is filtered out of the product.
"Changing the position of the double bonds makes all the difference in the world," Proctor said.
Proctor has received a $275,000 USDA grant to build a pilot plant that will process a greater volume of oil in less time. Jain is working on the project for his doctoral thesis and expects to have the experimental plant up and running by the end of January.
Proctor said other graduate students are working on related projects, looking for other ways to take advantage of the photo irradiation process.
Proctor is also working with an attorney to explore labeling requirements for food products containing trans fatty acids. Existing labels required for all foods containing trans fats would not indicate the healthier nature of CLA-rich oils.
Source: University Of Arkansas, Fayetteville. January 2007.