Influence of emulsifier type on the spray-drying properties of model infant formula emulsions
Year: 2017
Journal: Food Hydrocolloids
Authors: Drapala, KP; Auty, MAE; Mulvihill, DM; O'Mahony, JA
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 mu m. Powders were produced by spray-drying with inlet and outlet temperatures of 170 and 90 degrees 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. (C) 2017 Elsevier Ltd. All rights reserved.
