Improvement of Oxidative Stability of Conjugated Linoleic Acid (CLA) by Microencapsulation in Cyclodextrins

Oxidative stability of conjugated linoleic acid (CLA) encapsulated in α-, β-, and γ-cyclodextrins (designated CLA/CDs microencapsules) was studied by measuring the headspace-oxygen depletion in airtight serum bottles and by measuring the peroxide values (POV). The rate of oxygen depletion was reduced from 41.0 (control) to 21.5, 2.1, 1.2, and 1.1 μmol/L·h-1 by CLA/α-CD microencapsules at 1:1, 1:2, 1:4, and 1:6 mole ratios, respectively, indicating that CLA oxidation was completely protected by a 1:4 mole ratio of CLA/α-CD. Such a protective effect by CLA/β-CD or CLA/γ-CD microencapsules was achieved at a 1:6 mole ratio, but the effect by CLA/β-CD was slightly greater than that by CLA/γ-CD. The protective effect of α-, β-, and γ-CDs for CLA oxidation was confirmed by their POV-reducing abilities in CLA/CDs. These results suggest that α-CD was the most effective for the protection of CLA oxidation by microencapsulation, followed by β-CD and γ-CD. Keywords: Conjugated linoleic acid (CLA); cyclodextrins (CDs)...