Influence of particle size and ionic strength on the freeze-thaw stability of emulsions stabilized by whey protein isolate

The influence of particle size and ionic strength on the freeze-thaw (FT) stability of emulsions stabilized by whey protein isolate (WPI) was investigated in this study. The destabilization of emulsions during the FT process could be suppressed in a way by decreasing the particle size of the initial emulsions, which was the result of retarding the coalescence between oil droplets. To further improve the FT stability of emulsions, different amounts of NaCl were added before emulsification. The emulsions with the ionic strength at 30???50 mmol/L exhibited good FT stability. Notably, the ionic strength in this range would not lower the freezing point of emulsions below the freezing temperature used in this study. Salt addition could improve the structural properties of proteins, which was available to strengthen the rigidity and thickness of interfacial layers, sequentially building up the resistance that the destruction of ice crystals to emulsions. Moreover, stronger flocculation between emulsion droplets could promote the formation of a gel-like network structure dominated by elasticity in the emulsion system, which might effectively inhibit the movement of droplets, and improve the FT stability of emulsions eventually. The result was of great significance for the preparation of emulsion-based foods with improved FT stability. ?? 2022 Beijing Academy of Food Sciences. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co., Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

This study investigated the influence of particle size and ionic strength on the freeze-thaw stability of emulsions stabilized by whey protein isolate (WPI). Decreasing the particle size of the initial emulsions suppressed the destabilization during freeze-thaw process. Adding NaCl at different amounts improved the freeze-thaw stability of emulsions, with an optimum ionic strength range. Salt addition enhanced the structural properties of proteins and promoted the formation of a gel-like network structure, inhibiting the movement of droplets and improving the freeze-thaw stability of emulsions.