Production of instant soymilk powders by ultrafiltration, spray drying and fluidized bed agglomeration

Abstract

Production of instant soymilk powders was completed in three stages – ultrafiltration, spray drying, and fluidized bed agglomeration. Ultrafiltration increased total solids, protein, and fat contents, but decreased carbohydrate and ash contents of soymilk, leading to an increase in particle size, wettability, and dispersibility of the resultant spray-dried powders. However, all the spray-dried soymilk powders were very small (<25 μm) and very cohesive leading to their poor flowability. Agglomeration of the spray-dried powders with maltodextrin as an aqueous binder solution using a fluidized bed agglomerator improved the handling and reconstitution properties of the powders. The optimum binder concentration was found to be 10% w/v maltodextrin which resulted in the largest particle size of the agglomerated powder (260 μm) having a good flowability and low cohesiveness. The wettability of this agglomerated powder (wetting time = 42 s) was good but its dispersibility (61%) could be improved.