| Conjugated linoleic acid (CLA) has been recently produced by photoisomerization of soy oil linoleic acid with CLA yields being proportional to the degree of oil refining. However, the effect of specific minor oil components is not known. Therefore, the objectives were to (1) determine the effect of each soy oil minor constituent on CLA yields and (2) oxidative stability after processing; (3) discover interactions between soy oil minor constituents affecting CLA yields and oxidative stability; and (4) determine how Magnesol oil adsorption affects CLA yields. Soy oil with varying levels of peroxides, tocopherols, phospholipids, free fatty acids (FFA) and lutein, were each UV irradiated and CLA content and oxidative stability determined. Peroxide value (PV) of above 0.8 greatly decreased CLA yields, as did phospholipid concentrations above 1100 ppm. Tocopherols enhanced CLA production at low levels and reduced yields at high concentrations, while lutein and FFA had little effect. High CLA yields corresponded with lower oil oxidative stability. Minor components, particularly peroxides and phospholipids, need to be removed from the oil to optimize CLA yields. The interactions between the minor components showed similar trends as seen in the single component study. Magnesol adsorption removed large quantities of phospholipids and peroxides from soy oil and greatly increased CLA yields but reduced the oxidative stability. |
