Foams on beer

Liquid gas foam lather, whipped cream, foam on beer... 

Foams are closely related to emulsions. In foams, the dispersed phase is not an oil or water, but it is a gas. One can use similar techniques for making foam and for making emulsions, and some of the properties are comparable. Foams are ubiquitous as well of course, the foam on beer is well known, but bread is a foam as well, as are ice cream, whipped cream, expanded polystyrene or styrofoam (which is a solid polymeric matrix with a large volume fraction of gas bubbles in it), and polyurethane foam, used, for example, for making mattresses. 

The carbon dioxide produced in this reaction is responsible for the foam on beer and the carbonation of naturally fermented wines and champagnes. In the second step, acetaldehyde is reduced by NADH to ethanol ... 

The science of HPLC analysis of a-, [ -, and iso-a-acids is mature, as indicated by the existence of collaboratively tested recommended methods. However, the recent increase in the popularity of the chemically modified compounds, with their wide-ranging effects on beer foam, bitterness, and antibacterial activities, means that it is difficult to rely on gross tests, such as spectrophotometry, for beer quality control. Although HPLC can be used effectively to achieve this, substantial coelution often occurs, particularly when more than one class of compounds is used (e.g., tetrahydro- and p-iso-a-acids). 

RJH Wilson, TR Roberts, RJ Smith, LL Bradley, M Moir. The inherent foam stabilizing and lacing properties of some minor, hop derived, components. EBC Symposium on Beer Foam Quality, 1998, pp 188-207. 

Roberts, R.T., Keeney, P.J., and Wainwright, T. (1978). Effects of lipids and related materials on beer foam. J. Inst. Brewing, 84, 9-12. 

Treatment to remove dissolved mineral matter is more complex. Dissolved bicarbonates of calcium, magnesium, sodium, and potassium cause alkalinity soluble calcium and magnesium salts cause hardness. Alkalinity and hardness may need to be adjusted for some food processing operations. For example, the formation of a head on beer is critically dependent on water hardness. Excessively hard water may cause discoloration and toughening of certain foods. On the other hand, hardness may be required to prevent excessive foaming in clean-up operations. 

Liquid Gas Foam Head on beer, bubble bath... 

Cell autolysis can occur with a loss in viability, vitality and cell contents being excreted into the fermenting wort. This has a number of consequences on beer flavour and stability, and especially foam stability. 

The balance between PrA occurring in the fermenting wort as a result of cell autolysis and/or enzyme excretion of whole cells is still an issue to be examined. Nevertheless, the occurrence of active PrA is important because of its negative effect on beer foam stability. 

Brewing yeasts contribute positively to beer mouth-feel by producing carbon dioxide and foam bubbles. The impact of yeasts on beer taste varies with the yeasts involved in beer fermentation. In the spontaneous fermentation of acidic beers such as lambics, the mn-Saccharomyces brettanomyces yeasts can ferment malto-oligosaccharides that... 

Gas Liquid Liquid foam Whipped cream, froth on beer. 

Surfactant molecules can be diverse in structure, and there are many examples of surfactants in everyday life, from the soaps we use to wash with, to the lipids that make up our cell membranes, and even to the proteins that help to stabilize the foam on your beer. ... 

Lipstick and/or remains of potato chips, released from a person during drinking, are known to have a strong destabilizing effect on beer foam. 

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