Freeze–thaw stability of emulsions with soy protein isolate through interfacial engineering

• Multilayer emulsions stabilized by soy protein isolate were produced successfully.
• The effects of freeze–thaw cycles on multilayer emulsions were investigated.
• The multilayer emulsions exhibited a very good stability at freeze-thaw cycles.

In this paper, we examined to the influence of interfacial composition on freeze–thaw stability of oil in water emulsions. An electrostatic layer-by-layer deposition method was used to create the multilayered interfacial membranes with different compositions of primary emulsion (Soy protein Isolate); secondary emulsion (Soy protein Isolate – octenyl-succinate starch); tertiary emulsion (Soy protein Isolate – octenyl-succinate starch – Chitosan). The primary, secondary and tertiary emulsions were subjected to from one to two freeze–thaw cycles (−20 °C for 24 h, +25 °C for 18 h) and then their stability was assessed by ζ-potential, particle size, microstructure and creaming stability measurements. The crystallization behaviour of emulsions was studied by differential scanning calorimetry (DSC). Primary and secondary emulsions were unstable to droplet flocculation when the water phase crystallized, whereas tertiary emulsions were stable, which was attributed to the relatively thick biopolymer layer surrounding the oil droplets. These results showed the interfacial engineering technology used in the study could therefore lead to the creation of food emulsions with improved stability to freezing and thawing.