Simply put, the head is the foam at the top of. This frothy foam is actually caused by bubbles of carbon dioxide that float up to the top of the
glass. The acceptable time for the head is to stay on top of the beer for at least three minutes, before it begins to disappear. The occurrence of the head is mainly determined by small irregularities in the glass that cause the carbon dioxide bubbles to form.
The composition of the beer also plays a vital role in helping the head take its own course – the more proteins there are in a beer, the smaller and firmer bubbles, and vice-versa. The shelf life of the head has nothing to do with the quality and flavor of the beer, and causes no effect on the consumer’s health.
