Suppressive Effect of Decanoyl Ascorbate on the Oxidation of Fish Oil Encapsulated with a Polysaccharide

Abstract

6-O-Decanoyl l-ascorbate, which was synthesized by the immobilized lipase-catalyzed condensation of decanoic and l-ascorbic acids in acetone, was used for the microencapsulation of fish oil with maltodextrin (MD), gum arabic (GA), or soluble soybean polysaccharide (SSPS). The oxidation processes at 65°C and 12% relative humidity of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in the encapsulated fish oil were measured, and kinetically evaluated using the Weibull model. The oxidative stabilities of EPA and DHA in the microencapsulated fish oil were high, in the order of SSPS > GA > MD. Decanoyl ascorbate suppressed the oxidation of EPA and DHA in each system. It was indicated that the contribution of high concentrations of decanoyl ascorbate to the oxidative stability of the encapsulated fish oil is attributable to its antioxidative ability, which was due to the ascorbyl moiety in the decanoyl ascorbate molecule, but not to its emulsifying ability. In addition, it was found that the antioxidative effect of decanoyl ascorbate on the acids in the system sensitive to oxidation, such as in bulk and microencapsulated with MD, was high. Therefore, when using wall materials with a low suppressive ability for oxidation of the encapsulated oil, the application of decanoyl ascorbate would be effective.