Microencapsulation of flaxseed oil by complex coacervation of with apricot tree (Prunus armeniaca L.) gum and low molecular chitosan: Formation and structural characterization

Chitosan and Prunus armeniaca gum exudate complex coacervation was developed to encapsulate the flaxseed oil (FSO), which is high in polyunsaturated fatty acids (PUFAs). Flaxseed oil microcapsules were produced by complex coacervation method using chitosan (CH; low molecular weight); 1 % w/v), apricot tree's ( Prunus armeniaca L.) gum (PAGE; 0.05, 0.1 and 0.2 % w/v), tween 40 and potassium hydroxide, as a cross-linking agent, the various ratios of CH/PAGE (1:1, 2:1 and 3:1) and different ratios of wall: core ratios (20:1, 30:1 and 40:1) was considered. Also, the characteristics of microcapsules were investigated using SEM, DLS, DSC, FTIR, SGF, as well as encapsulation efficiency (EE %), antioxidant and chemical properties, release behavior, morphological of microcapsules and unencapsulated oil. The optimum microsphere termed M4 was selected which was composed of CH: PAGE ratio of 3:1 with PAGE concentration of 0.05 % and the FSO to biopolymer ratio of 1:20, based on its higher EE %, antioxidant activity, oxidative stability, and lower release rate. Morphological properties by SEM indicated that using excessive concentrations of PAGE (0.1 and 0.5 %) led to non-uniform coacervates which led to reduction of EE % and increase in surface oil. DSC and FTIR analysis indicated that FSO was physically entrapped within the complex polyelectrolytes structure. Complex coacervation is a promising method to preserve the highly sensitive FSO to oxidation and the produced microspheres can be used to promote functional food products.