Birra

Beer drinkers prefer some foam on the top of a newly-poured glass, and a poor foam leads to a subjective judgment that the beer is poor quality.
Ingredients such as propylene glycol alginate (PGA) may be added to beer to stabilize the foam head and to aid resistance to a breakdown of foam in the presence of detergent residues or grease on the glass. Addition of a very low concentration of propylene glycol alginate will provide a stable, longer-lasting beer foam. Propylene glycol alginate has the properties of an emulsifier and hydrocolloid which can form stable foams for beer and other beverages.

A variety of agents are used in the clarification of wine and removal of unwanted coloring - wine fining - but in more difficult cases it has been found that the addition of sodium alginate can be effective.

Meanwhile, Carrageenan (as the beer wort fining agents) can keep your beer a beautiful golden color by removing the haze in beer caused by proteins in the grain.