University of Arkansas, Fayetteville


Conjugated linoleic acid (CLA) has anti-carcinogenic, anti-diabetic, and anti-atherogenic properties and is present in very small quantities in dairy and beef products. Obtaining optimum dietary CLA levels from these sources requires an undesirable increased intake of saturated fat A 20% CLA soy oil has been produced by UV photoisomerization of linoleic acid (LA) in soy oill, which is naturally low in saturated fat. However, no other high LA vegetable oils have been studied for their potential as CLA-rich oils. The objectives of this research were to: 1) commpare flax, sunflower, corn, soy and high LA safflower oils as sources of CLA-rich vegetable oils using laboratory-scale UV photoirradiation processing equipment, and 2) compare the oxidative stabilities of laboratory-scale processed oils. Seven hundred g of each oil was irradiated with 0.15% iodine catalyst on a laboratory-scale for 168 hours. Oil fatty acid analysis was done before and after processing as fatty acid analysis was done before and after processing as fatty acid methyl esters by gas chromatography-flame ionization detection (GC-FID) analysis. Oxidative stabilities of laboratory-scale processed oils were measured gravimetrically for up to 24 days at 64 degrees Celcius. High LA safflower oil produced the most CLA; soy oil produced slightly less followed by corn, with flax producing very little and sunflower none at all. Low CLA yieidls were due to carotenoids and lipid oxidation in flax oil and carotenoids and turbidity in sunflower oil. The results show that high LA oils should be highly refined before they are used for CLA production. There was no significant difference between the oxidative stabilities of high LA safflower oil and soy oil before or after irradiation, indicating that these oils are the most suitable for high-CLA production, although high LA safflower oil is more expensive.