Enhanced oxidative stability of a hydrophilic arginine-conjugated linoleic acid complex

The application of conjugated linoleic acid (CLA) as a functional food ingredient has been limited due to its high cost of purification and insolubility in water. Recently, we reported a method to produce high-purity CLA using two-step urea-inclusion crystallization and a hydrophilic arginine-CLA (Arg-CLA) complex. The present study compared the oxidative stability and antioxidant activity of CLA and Arg-CLA. Hydroperoxide production from CLA increased about 12-fold at 10 hr after heat treatment at 100(R)C, whereas Arg-CLA did not exhibit significant hydroperoxide production. Furthermore, the Arg-CLA complex showed synergistic antioxidant activity in a 2,2'-azinobis(3-ethylbenzothiazoline)-6-sulfonic acid (ABTS) radical scavenging assay. Arg-CLA at 20 mM scavenged 89% of ABTS radicals in 3 h, whereas CLA alone quenched only 48% under the same conditions. Our results indicate that a hydrophilic Arg-CLA exhibits enhanced oxidative stability and antioxidant activity, which could expand the scope of CLA application in various food industries.