| Abstract
| - The effect of protein and peptide addition on the oxidation of eicosapentaenoic acid ethyl ester (EPE)encapsulated by maltodextrin (MD) was investigated. The encapsulated lipid (powder lipid) wasprepared in two steps, i.e., mixing of EPE with MD solutions (± protein and peptides) to produceemulsions and freeze-drying of the resultant emulsions. EPE oxidation in MD powder progressedmore rapidly in the humid state [relative humindity (RH) = 70%] than in the dry state (RH = 10%).The addition of soy protein, soy peptide, and gelatin peptides improved the oxidation stability of EPEencapsulated by MD, and the inhibition of lipid oxidation by the protein and the peptides was moredramatic in the humid state. Especially, the oxidation of EPE was almost perfectly suppressed whenthe lipid was encapsulated with MD + soy peptide during storage in the humid state for 7 days.Several physical properties such as the lipid particle size of the emulsions, the fraction ofnonencapsulated lipids, scanning electron microscopy images of powder lipids, and the mobility ofthe MD matrix were investigated to find the modification of encapsulation behavior by the addition ofthe protein and peptides, but no significant change was observed. On the other hand, the proteinand peptides exhibited a strong radical scavenging activity in the powder systems as well as in thesolution systems. These results suggest that a chemical mechanism such as radical scavengingability plays an important role in the suppression of EPE oxidation in MD powder by soy proteins,soy peptides, and gelatin peptides. Keywords: Autoxidation; eicosapentaenoic acid; maltodextrin; soy peptide; soy protein; gelatin peptide;antioxidant activity
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