Use photoisomerization to produce CLA-rich soy oil.

Conjugated linoleic acid (CLA) is naturally found in dairy and beef products at concentrations of 0.2 to 2% of total fat. However, in order for us to obtain optimum CLA levels, we'd have to ingest more animal fat, which would increase our dietary saturated fat intake. A more concentrated source of dietary CLA, low in saturated fat, would be highly desirable.

Scientists at the University of Arkansas have reported a much simpler way of producing CLA without high-energy input or using expensive enzymes and microorganisms in the laboratory. Their approach involves the photoisomerization of soy oil linoleic acid to CLA to produce soy oil that has 20% CLA. The technique uses an iodine sensitizer at 20 C that yields few oxidation products. This novel pilot-scale route, for which the researchers are seeking a patent, has the potential to be a simpler, less expensive alternative to current microbial and chemical CLA technologies, which would be key to its commercialization.

The researchers wanted to develop a practical pilot-scale way of producing high-CLA soy oil by photoirradiation. They heated degassed refined soy oil to 80 C in an oil reservoir. To this they added iodine, and the mix was continuously stirred under a nitrogen blanket. Oil was pumped through an illuminated laminar flow unit by a flow controller. The unit consisted of two borosilicate glass plates, 45 cm X 45 cm X 10 cm thick, in polypropylene-lined stainless steel frames.

The volume of the flow unit could be varied by changing the distance between the glass plates from 1 L to 4 L. Light sources can be placed on either side of the reaction tank to ensure maximum light exposure. The oil would be recycled until the desired CLA quantity and quality are reached. The oil flow would then be directed towards an adsorption processing unit that removes the iodine. Deodorizing the filtered oil would yield refined, bleached soy oil with high CLA content

Further information. Andrew Proctor, N-204, Department of Food Science, 2650 N. Young Ave., University of Arkansas, Fayetteville, AR 72704; phone: 479-575-2980; fax: 479- 575-6936; email: aproctor@uark.edu.