Whipped cream is a complex emulsion-based foam structure in which entrapped air bubbles are surrounded by partially coalesced fat droplets at the air/serum interface.  At least 40% of the fat must be crystalline to exhibit partial coalescence under the application of shear forces to cream, giving increased viscosity and stability against collapse.

Two possible mechanisms have been proposed for partial coalescence. In the shear-induced mechanism, partial coalescence is directly influenced by the shearing action of the whipping whisks and occurs when emulsion droplets collide and the film between them is pierced by the fat crystals. In the surface-mediated mechanism, the fat droplets attach to the protein-covered surface of the bubbles, releasing liquid fat which spreads onto the bubble surface causing interfacial aggregation.

Stabilizers such as whey proteins, added to cream, can influence whipping behaviour through effects on the interfacial tensions at the three-phase boundary layer. In whipped cream and aerated emulsions, milk proteins such as whey protein concentrate (WPC) may be used to influence the composition and physical properties of the interfacial layers around the fat droplets and air bubbles. Homogenized cream is preferred in manufacturing Iranian pastries due to its plasticity and higher viscosity. However, it needs to have foam stability and less drainage after whipping to meet market preferences.

A study by Emam-Djome et al.¹ investigated the influence of WPC at three different concentrations (0.7, 1.4 and 2.1 wt %) on the drainage, appearance and rheology of homogenized, sweetened, whipped creams. Homogenization was carried out at first and second stage pressures of 3.5 and 1.5 MPa, respectively. The addition of WPC significantly decreased maximum overrun and foam drainage, but increased whipping time. Foam whiteness decreased and yellowness increased with addition of WPC and with increasing concentrations of WPC. Apparent viscosity and dynamic oscillatory measurements suggested a WPC concentration of 2.1% as the threshold for gelation when shearing homogenized sweetened cream.

¹ Emam-Djome, Z; Mousavi, ME; Ghorbani, A-V; Madadlou, A (2008). Effect of whey protein concentrate addition on the physical properties of homogenized sweetened dairy creams. International Journal of Dairy Technology 61 (2) 183–191.

Click on the logo below to view an abstract of this paper from FSTA Direct.