Food Structure


The structure of spray-dried whippable emulsions (toppings) containing different types of lipid surfactants, was investigated by electron microscopy using the freeze-fracture technique. The size distribution of the lipid particles within the powders varied with the type of the surfactant used. After reconstitution of the topping powders in water. a strong destabilization phenomenon took place to an extent depending on the type of the surfactant. Simultaneously a crystallization of coalesced lipid particles occurred along with an increase in viscosity of the emulsions. The degree of crystallization was measured by p-NMR. It has been concluded that these phenomena are closely related to whippability and foam firmness.

The structure of whipped topping emulsions (foam) is characterized by the presence of large lipid crystals at the surface of air bubbles. This structure is different from the structure of whipped liquid (imitation) cream or dairy cream, where the air bubbles are predominantly stabilized by agglomerated fat globules from which the surface membrane has been partly removed during the whipping process.

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