Oil encapsulation by spray drying and fluidised bed agglomeration
Résumé
Many active components (anti-oxidants, aromas) are lipophilic substances, available in liquid form and have to be protected from the environment. Encapsulation of oil drops into a solid matrix is regarded as an efficient protection method and a means of formulating liquid compounds in a solid dosed form.
The aim of this study is to investigate the feasibility of encapsulation of a vegetable oil (ISIO4 (R), 5% w/w dry matter) used as a model into a mixture of maltodextrin and acacia guru. Encapsulation was completed in three stages, i.e. emulsification, spray drying and fluid bed agglomeration. Optimal operating conditions for spray drying and agglomeration were identified. Powders were characterized before and after agglomeration in terms of oil content and protection (dispersion into the matrix, surface oil content, oxidation) and powder handling properties (flowability, wettability, friability).
The proposed encapsulation method provided powders where oil droplets were well dispersed and protected (oil droplets diameter lower than 1 mu m in reconstituted emulsions, less than 2% of the total oil content at the particle surface, oil oxidation lowered compared to unprotected oil). Agglomeration did not change oil encapsulation properties of the spray-dried powder but considerably improved its wettability.