If air is whipped into a glucose syrup or a food product containing a glucose syrup the rate at which the air bubbles pass out of that syrup will depend largely on the viscosity of the system. Thus lower DE syrups will retain air for longer periods than higher DE syrups as a result of their high viscosity and additionally they impart strength and some flexibility to the walls of the gas bubbles. They also thus slow the diffusion of air from the bubbles to the surrounding atmosphere and by maintaining bubble integrity slow diffusion from bubble to bubble.
In some foods, air retention is a desirable attribute, e.g. ice cream and instant whips whilst in others, it is not desirable, e.g. hard-boiled sweets. Low DE products are thus used to trap air and stabilize aerated systems. For the same reason, low DE products offer better possibilities for emulsion stabilization than high DE products as they slow the coalescence of oil droplets. Conversely low molecular weight components (high DE syrups) improve the development of foam by greatly increasing the flexibility of the walls of the air bubbles. A compromise must therefore be made between foam development and foam stabilization when selecting a glucose syrup for this application.