Spray-Drying Microencapsulation of Polyphenol Bioactives: A Comparative Study Using Different Natural Fibre Polymers as Encapsulants

This research explores the spray-drying microencapsulation of polyphenols (PPs), quercetin and vanillin, using four different fibre polymers as encapsulants (sodium alginate, methyl beta-cyclodextrin (M beta CD), hydroxypropylmethyl cellulose (HPMC) and inulin). The microstructure, physico-chemical properties, PP content and reconstitution properties in water of the spray-dried powders were systematically evaluated and compared. Techniques used for powder characterisation were scanning electron microscopy, N-2 physisorption, Fourier transform infrared (FT-IR) spectroscopy and water activity measurements. High-performance liquid chromatography and viscosity measurements were used to characterise the solutions obtained by reconstitution of the spray-dried powders in methanol or water, respectively. Results show that the type of encapsulant strongly influenced powder morphology, powder surface area and encapsulation efficiency of PPs. Powders prepared using sodium alginate and M beta CD possessed more spherical particle shape, smaller average particle size and higher specific surface area than those using HPMC or inulin as encapsulants. For each encapsulant, higher encapsulation efficiencies were achieved for vanillin (37-53 %) than quercetin (9-19 %). Encapsulation efficiencies were inulin > M beta CD > HPMC > sodium alginate for vanillin-containing powders. Inulin, M beta CD and sodium alginate all gave similar encapsulation efficiencies for quercetin-containing powders. All powders possessed low water activity and excellent dissolution properties in water. Therefore, spray-drying microencapsulation using natural fibre encapsulants is a feasible approach for delivering the dual health benefits of PPs and dietary fibre to consumers. Spray-drying yields a product in a convenient powder form, which can be reconstituted in water or other beverages for direct consumption or used as a functional additive in solid food systems.