Produce CLA-rich soy oil by photo-isomerization.

Conjugated linoleic acid (CLA) is naturally found in dairy and beef products at 0.2% to 2% of total fat content. However, in order for us to obtain optimum CLA levels, more animal fat would have to be ingested, which would increase one's level of dietary saturated fat.

A more concentrated source of dietary CLA, which is low in saturated fat, would be highly desirable. Scientists at the University of Arkansas have come up with a much simpler way of producing CLA in the laboratory without using a lot of energy or expensive enzymes and microorganisms. Their approach involves the photo-isomerization of soy oil linoleic acid to CLA. This produces soy oil with about 20% CLA content. Specifically, their process uses simple photo-isomerization with an iodine sensitizer at 20 C, which yields few oxidation products.

The investigators wanted to develop a practical way, on the pilot scale level, to produce high-content CLA soy oil using photo-irradiation. Their approach involves heating degassed refined soy oil to 80 C in an oil reservoir. Iodine is added, and the mixture is continuously stirred under a blanket of nitrogen.

Then a flow controller pumps the oil through an illuminated laminar flow unit. The unit consists of two borosilicate glass plates--45 cm X 45 cm X 10 cm thick--in polypropylene-lined stainless steel frames. The volume of the unit can be changed by varying 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 can be recycled until the desired amount of quality CLA has been reached. The oil flow would then be directed towards an adsorption processing unit that removes the iodine from the oil. Deodorizing the filtered oil yields refined, bleached, deodorized high-content CLA soy oil.

This pilot-scale production technique could lead to a simpler, less expensive alternative to current microbial and chemical CLA technologies. The researchers have not done an economic study. But the only cost would be for a light source and low-pressure pumps with only ambient temperature adsorption processing. They are processing now in a pilot plant and are looking for interested companies.

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