Rennet-assisted modification for enhanced freeze-thaw stability in sodium caseinate-stabilized high internal phase...

Poor freeze-thaw stability seriously limits the application of Pickering emulsions in the frozen food industry. This study developed sodium caseinate-stabilized high internal phase emulsions (NaCas-HIPEs) with enhanced freeze-thaw stability through rennet modification. The freeze-thaw stability and 3D printing properties of NaCas-HIPEs significantly improved as rennet addition increased from 0 % to 0.5 (w/v). NaCas-HIPEs with 0.5 % rennet even maintained a stable oil-in-water emulsion structure after five freeze-thaw cycles. Changes in enthalpy and freezing/thawing point demonstrated that rennet modification improved freeze-thaw stability by reducing the ice crystal formation. Additionally, increasing rennet concentration significantly enhanced the apparent viscosity and viscoelasticity of NaCas-HIPEs, restricting ice crystal growth and preventing droplet aggregation during freezing and thawing. This improvement is attributed to the strong gel networks formed by rennet-induced casein between droplets, as shown by the cryo-SEM microscopy and SDS-PAGE analysis. This study presents an effective method for producing freeze-thaw stable emulsions, offering promising applications in the rapidly growing ready-to-eat food industry.