Frothing

The generation of swarms of small, light bubbles within a liquid through agitation or fermentation. Frothing is essential to cappuccino milk, whipped cream, beer heads and fermented batters, where proteins or other surface-active agents stabilise the bubble films. In processing, uncontrolled frothing — e.g. during fermentation, evaporation or pumping — causes overflow, product loss and cleaning problems, and is suppressed with antifoaming agents or mechanical foam breakers. Foam stability, bubble size and drainage rate are the key physical parameters measured in quality control.