Outstanding Freeze-Thaw Stability of Mayonnaise Stabilized Solely by a Heated Soy Protein Isolate

There is an increasing interest in the development of cholesterol-free mayonnaise through the strategy to use food-grade polymeric emulsifiers to substitute or partially substitute egg yolk. In addition, mayonnaise-type emulsions or mayonnaise are usually susceptible to freezing. The work reported that a heated soy protein isolate (SPI) could perform as an effective sole stabilizer for mayonnaise-type high internal phase emulsions (HIPEs) with an outstanding freeze-thaw stability. Such HIPEs with a self-supporting morphology could be stabilized using the heated SPI at a protein concentration (c) as low as 0.3 wt.%. Increasing the c from 0.3 to 4.0 wt.% resulted in a progressive strengthening of gel network for the mayonnaise-type HIPEs, and the formation of finer droplets. All the as-formed HIPEs exhibited an elasticity-dominated rheological behavior, with the stiffness increasing the c. The elasticity of the gel-like HIPEs at low c values (e.g., 0.3 wt.%) was mainly associated with the formation of bridged emulsions, while that at high c values was more associated with the inter-droplet hydrophobic interactions between protein-coated droplets. All the mayonnaise-type HIPEs, formed even at a c value of 0.3 wt.%, were extremely stable against the freeze-thaw treatment. The high freeze-thaw stability seemed to be unrelated to the formation of ice crystals during the freezing. All the freeze-thawed HIPEs still exhibited a high long-term storage stability against coalescence, and their elasticity on the contrary became strengthened after the long-term storage. The findings have great implications for the development of cholesterol-free mayonnaise with a high freeze-thaw stability, suitable for food formulations.