Think Foam Positive!
We all love beer’s flavor, and aroma. But what about its foam?
Foam is a defining feature of beer, and one of the characteristics that sets it apart from other carbonated beverages. An attractive cap of foam often says “It’s fresh!” and “It’s a good beer!” to the drinker. How is foam formed in a beer?
HOW IS IT FORMED? 🍺
Simply, foam is a mixture of gas and liquid. In beer, we are talking about a mixture of CO2 (or other beer gas) inside bubbles of beer.
Foam is produced when a beer is dispensed and results to the release of CO2 bubbles by the change in pressure. Usually, CO2 will pick up some foam-positive compounds throughout the brewing process, and dispensing (such as proteins, polysaccharides, etc) to help stabilize the foam.
ALL ABOUT STABILITY
So why is it that some beers have foam that lasts much longer than others? In general, when the foam has very small, uniform bubbles then the beer will have the greatest foam stability since there will be more layers to collapse and the liquid will drain very slowly back down into the beer. The more foam positive components a beer has, the stronger the stability is.
FOAM POSITIVE, OR NEGATIVE? ➕➖
Yes that's right, there are foam-positive, and foam-negative components. From raw ingredients, to brewing process, and to beer service, quality beer foam is a result of foam-positive balanced with foam-negative components.
Foam-positive components include iso-alpha acids from hops, proteins from malt, gas composition, and carbonation level. Foam-negative components include fats, ethanol, enzymatic yeast activity, and excessively modified malt. A dirty glass means a higher concentration of foam-negative components, so rinse your glass well!
It’s all a matter of balance, to get that final beer result, and the good quality foam. A good foam means a creamy, and lasting foam until the end of your beer.