Influence of emulsifier type on the spray-drying properties of model infant formula emulsions

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Drapala, Kamil P.
Auty, Mark A. E.
Mulvihill, Daniel M.
O'Mahony, James A.
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The objective of this study was to compare the drying performance and physicochemical properties of model infant formula (IF) emulsions containing 43, 96 and 192 g L−1 protein, oil and maltodextrin (MD), respectively, prepared using different emulsifier systems. Emulsions were stabilised using either whey protein isolate (WPI), whey protein hydrolysate (WPH; DH 8%), WPH + CITREM (9 g L−1), WPH + lecithin (5 g L−1) or WPH conjugated with maltodextrin (DE 12) (WPH-MD). Homogenised emulsions had 32% solids content and oil globules with mean volume diameter <1 μm. Powders were produced by spray-drying with inlet and outlet temperatures of 170 and 90 °C, respectively, to an average final moisture content of 1.3%. The extent of powder build-up on the dryer wall increased in the order; WPH- MD << WPH ≤ WPI < WPH + LEC ≤ WPH + CIT. The same trend was observed for the extent of spontaneous primary powder agglomeration, as confirmed by particle size distribution profiles and scanning electron micrographs, where the WPH-MD and WPH + CIT powders displayed the least and greatest extent of agglomeration, respectively. Analysis of elemental surface composition of the powders showed that surface fat, protein and carbohydrate decreased in the order; WPH + CIT > WPH + LEC > WPH > WPH- MD > WPI, WPI > WPH > WPH- MD > WPH + LEC > WPH + CIT and WPH- MD > WPI > WPH > WPH + LEC > WPH + CIT, respectively. Additionally, differences in wettability, surface topography and oil globule distribution within the powder matrix and in reconstituted powders were linked to the emulsifier system used. Inclusion of the WPH-MD conjugate in the formulation of IF powder significantly improved drying behaviour and physicochemical properties of the resultant powder, as evidenced by lowest powder build-up during drying and greatest emulsion quality on reconstitution, compared to the other model formula systems.
Spray-dried emulsions , Infant formula powders , Protein conjugation , Powder stickiness , Emulsion stability , Particle microstructure
Drapala, K. P., Auty, M. A. E., Mulvihill, D. M. and O’Mahony, J. A. (2017) 'Influence of emulsifier type on the spray-drying properties of model infant formula emulsions', Food Hydrocolloids, 69, pp. 56-66. doi:10.1016/j.foodhyd.2016.12.024