Lipid encapsulation in glassy matrices of sugar-gelatin systems in freeze-drying

Entrapment of lipid in glass forming matrices in freeze-drying was investigated. Dispersion of lipid in aqueous solutions of three different sugars was formed by addition of protein and using homogenisation process. Two different levels of proteins in the ratios of 9:1 and 8:2 (sugar:protein) were used. Three different homogenisation processes were used to vary the emulsion droplet size of dispersed lipid. A novel ultra high-pressure homogenisation treatment with pressure levels up to 255 MPa (5MPa in second stage) was used to form emulsion before freeze-drying. The non-fat solids formed a glass in freezing which led to entrapment of dispersed oil. Ultra high-pressure homogenisation at pressure levels higher than 155 MPa caused alterations in emulsifying properties of sugar/gelatin systems. Changes in emulsifying properties of encapsulation matrices affected entrapment of dispersed lipid components. Droplet size of the dispersed phase was a significant factor for encapsulation efficiency. Emulsions with smaller droplet diameter gave higher entrapped amounts of lipid than emulsions with larger droplets. The glass forming properties and physical state of freeze-dried matrices were also determined. Knowledge of glass forming properties of an encapsulation matrix is needed for entrapment and predicting the stability and release properties of entrapped components.