Thermogravimetric Analysis of Cyclodextrin-Fatty Acid Complex Formation and Its Use for Predicting Suppressed Autoxidation of Fatty Acids

Abstract

Linoleic acid, ethyl eicosapentaenoate and ethyl docosahexaenoate were emulsified with cyclodextrins (CDs), dehydrated and then autoxidized. Autoxidation of the encapsulated sample proceeded over time and reached the level of the unoxidized fatty acid fraction, Y_∞, after which no further autoxidation occurred. The Y_∞ value increased with the increasing molar ratio of CD to fatty acid. Thermogravimetric (TG)analyses of these encapsulated samples suggest that some of the fatty acids were included in the CD-cavity. Furthermore, the fraction of fatty acids included into CD, which was determined by a TG analysis, correlated well with the Y_∞ value. It also seems that the fatty acids included into CD were highly resistant to autoxidation, whereas the remainder were rapidly oxidized at the same rate as that of the free fatty acids.