Preparation and characterization of fat particles-in-water emulsions for the encapsulation of bioactive compounds using allanblackia seed fat and tween 20 and sodium alginate as emulsifying agents
Effective delivery of poorly water-soluble bioactive ingredients has been considered a great challenge in the pharmaceutical, food and cosmetic industries. The compartmentalized hydrophobic and hydrophilic regions of emulsion systems give them the advantage to encapsulate polar and non-polar compounds for effective delivery. However, the challenge associated with emulsions is their thermodynamic instability. This study investigated the stabilisation process of fully crystallised fat globules as a dispersed phase in an oil-in-water emulsion system prepared from a naturally occurring vegetable fat, a nonionic surfactant and a polysaccharide biopolymer. The crystallisation profiles of the fats from Allanblackia seed and shea nuts were determined. Based on the results Allanblackia seed fat was selected and used as the dispersed phase in the oil-in-water emulsion system. The emulsion was formulated in the presence of Tween 20 and sodium alginate. The mixed emulsifier system gave stability against aggregation of the fat particles hence preventing coalescing, creaming and flocculation and this was more significant at 2 % to 4 % sodium alginate content. The emulsion particle size and microstructure were dependent on the fat/water ratio and a viscoelastic system with G′ > G′′ at the lower frequencies and G′′ > G′ at higher frequencies (where G and G are….). The dispersed fat particles emulsion system was used to encapsulate sudan orange dye (a water insoluble dye) and the efficiency of the encapsulation was characterized by an increase in particle size (ranging from 246 to 250 nm) and varying size distribution. UV-Vis spectrophotometric analysis of the dye loading capacity, release rate and leaching capacity showed a successful entrapment of the dye in the fat matrix. This confirms Allanblackia seed fat as a potential solid fat for its application in the formulation of oil-in-water emulsions.
A thesis presented to The Department of Chemistry, College of Science, Kwame Nkrumah University of Science and Technology, in partial fulfilment for the award of the degree of Doctor of Philosophy in Chemistry, 2015