A method to evaluate lipid oxidation in encapsulated systems

MARÍA L. HERRERA; ROBERTO J CANDAL

San Antonio, Texas

Congreso; 105th AOCS Annual Meeting & Expo; 2014

American Oil Chemists' Society

Encapsulation has been widely used to protect sensitive materials against evaporation, oxidation, and chemical reaction. However, when physical properties of encapsulating materials are evaluated, most authors use the extractable material for analysis. In other cases, the encapsulated lipids suffer more damage for oxidation than the extractable fraction. Most likely oxidation occurred during the different steps (heating and agitation) involved in the traditional methods. The aim of the present work was to develop a method to study oxidation of encapsulated lipid materials that not involves oxidative treatments. A concentrate of fish oil, coming mainly from salmon, enriched in DHA, EPA, and DPA was encapsulated in a sodium caseinate/trehalose matrix. The obtained powders were analyzed for physical chemical properties. Lipid material coming from washed powders dissolved in chloroform and not subjected to any other treatment, and fish oil extracted from powders with a traditional method were analyzed by MALDI-TOF. The extracted oil was oxidized as evidence from MALDI-TOF pattern and confirmed by peroxide value. On the contrary, encapsulated oil evaluated by direct dissolution of powder showed a MALDI-TOF pattern similar to the pattern of original oil. MALDI-TOF technique allowed to demonstrate something generally accepted but not well-proved: encapsulation protects lipids against oxidation.