Stability and rheology of water-in-oil-in-water multiple emulsions made with protein-polysaccharide soluble complexes

•Layer-by-layer technique produced higher viscoelasticity in multiple emulsions.•Pre-formed technique multiple emulsions droplet size decreased with aging.•Both techniques yielded more stable multiple emulsions at pH of 4.3. The morphology, stability, and rheological properties of water-in-oil-in-water (W1/O/W2) multiple emulsions (ME) stabilized by whey protein concentrate (W)-carboxymethylcellulose (C) soluble complexes (SCW/C) were evaluated. The interaction pH values (pHi) to generate SCW/C were established through zeta potential and turbidity determinations. Six ME variations were prepared using a constant weight ratio (WR) between W and C of 3:1 (where maximum interaction occurred) and by varying the way in which the biopolymers were adsorbed at the interface (layer-by-layer, LL, or pre-formed complex, PF) and pHi (3.7, 4.0 and 4.3). The ME initial volume-surface diameter (D3.2) of the oil droplets ranged from 2.4 to 3.2μm, which on turn contained numerous flocculated water droplets. Higher viscoelastic moduli values (G′ and G″), more pronounced shear thinning behaviour and smaller changes in droplet size with storage time were displayed by ME made with a pHi value of 4.3, WR3:1, and LL biopolymers adsorption technique.