Partial hydrophobic modification of alginate using dodecenyl succinic anhydride for fish oil encapsulation

Abstract

Background. As a hydrophilic compound, alginate needs to be modified to perform both as an emulsifier and matrix for fish oil encapsulation. Dodecenyl succinic anhydride (DSA) was selected for the modification due to its mild reaction conditions and the fact that no side product is generated. The purposes of this research were to prepare partial hydrophobic groups of modified alginate, which were subsequently used for a fish oil encapsulant. Material and methods. The viscosity average molecular weight (Mv) of commercial alginate was adjusted using sonication. The degraded alginate was modified using DSA by mixing alginates in the desired ratio for 4 h at pH = 10. The fish oil emulsion was stabilized using the modified alginate and subsequently freeze-dried to obtain fish oil particles. The effect of the Mv of alginate and the alginate-DSA ratio was analyzed for emulsion stability. The performance of native and modified alginate in fish oil encapsulation were also compared. Results. Alginate modification using DSA was influenced by the Mv of alginate as described by degree of substitution. This modification reduced the fish oil oxidation degree up to 8%. The modified alginate using 400 kg/mol and a mol ratio of 1:4 emulsion prevented separation for up to 18 h. The dynamic second-order model was well fitted to represent the separation emulsion (R2 > 0.89). The fish oil encapsulation using the modified alginate showed higher loading capacity, and better anti-rehydration properties than the native one. The use of modified alginate also reduced the degree of oxidation <4% after 24 h. Conclusion. Modification using DSA improved the alginate capability to stabilize the emulsion and encapsulating fish oil.