Effect of aqueous composition on the freeze-thaw stability of emulsions

The freeze-thaw induced coalescence of sodium caseinate stabilized n-hexadecane emulsions was investigated as a function of added protein (0–2 wt.%), fat (0–40 wt.%) and aqueous sugar (0–2 wt.% sucrose, maltose, glucose, corn syrup solids) contents. For all variables there was a critical dependence on aqueous phase composition. Emulsions were stable to small decreases in aqueous protein or sugar content to a critical point below which the extent of destabilization increased linearly. We hypothesize the stability of frozen emulsions depends on the mechanical capacity of the lamellae separating them to resist the pressure of the growing ice phase. Sugar serves to reduce the amount of ice (as measured by differential scanning calorimetry) and hence the pressure, while aqueous protein reinforces the lamellae.