Microencapsulation of Conjugated Linoleic Acid (CLA)‐Rich Oil with Skimmed Milk Components Protects against Polymerization

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Abstract
Oils rich in conjugated linoleic acid (CLA) are currently used in functional foods because of the positive health effects of some CLA isomers. In this work, microencapsulation of a CLA‐rich oil (containing approx. 80% of a mixture of 9c, 11 t, and 10 t, 12c‐ linoleic acid) with skimmed milk components is proposed as a means to protect it from oxidation and polymerization. The main physicochemical characteristics, i.e. glass transition temperature, mean oil globule size, and distribution, were evaluated. Microencapsulated samples, both intact and devoid of free oil fraction, along with the bulk oil, were oxidized at 30 °C in the dark for 3 months. Throughout storage, free and encapsulated oil fractions were separately extracted from samples and analyses including substrate loss by Gas liquid chromatography‐Flame ionization detection, polymer determination by High performance size exclusion chromatography‐Refractive index detection, and tocopherol content determination by High performance liquid chromatography‐Fluorescence detection were performed. Results showed that free oil oxidized much more rapidly than encapsulated oil. High amounts of polymers accumulated in samples with considerable high levels of tocopherols remain in encapsulated oil fractions. In samples devoid of free oil, a drastic change in the physical properties occurred but the oil polymerized to a similar extent to that found in the encapsulated fractions of intact samples.
Funding Information
  • Ministerio de Economía y Competitividad (AGL 2013-45110-R)

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