Foam
Appearance
Foam is a dispersion of a gas in a liquid or solid. The low density of foams make them excellent insulators as well as flotation devices. Their lightness and compressibility make them ideal packaging materials. Many bakery products such as bread are examples of foam.
Foam in chemical industry
Foam is a serious problem for chemical industry, expecially for biochemical processes. Many biological substances, for example proteins, easily create foam on agitation and/or aeration. Foam is a problem because alters the liquid flow and blocks oxygen transfer from air (therefore preventing microbial respiration in fermentation processes). For this reason, antifoam compounds, like silicone oils, are added to prevent these problems.
See also: quantum foam, Styrofoam