The role of mixing sequence in structuring O/W emulsions and emulsion gels produced by electrostatic protein-polysaccharide interactions between soy protein isolate-coated droplets and alginate molecules

Multilayer emulsions produced by electrostatic protein-polysaccharide interactions have received increased interest recently, but the addition sequence of oppositely charged dispersions for emulsion preparation has rarely been investigated. The purpose of this study was to investigate the effect of addition sequence of oppositely charged soy protein isolate (SPI)-stabilized emulsions and alginate solutions on the stability and structure of emulsions involving electrostatic protein-polysaccharide attraction and the structural and rheological properties of emulsion gels produced by internal gelation. Stable multilayer emulsions containing unflocculated alginate/SPI-coated droplets were produced by adding low levels of SPI-stabilized emulsions into alginate solutions at pH 3.0, and emulsion gels prepared from the above emulsions had higher L* values and storage modulus than emulsion gels prepared by adding alginate solutions into SPI-stabilized emulsions. Unstable emulsions containing flocculated droplets were obtained on adding high levels of SPI-stabilized emulsions into alginate solutions or adding alginate solutions into SPI-stabilized emulsions (independent of concentration) at pH 3.0 with mild stirring. The findings of this study are important for preparing stable multilayer emulsions and structuring emulsion gels by changing the addition sequence of oppositely charged dispersions for emulsion preparation.