Beer is one of the most popular alcoholic beverages. During 1985, team of the National Scottish Museum in Edinburgh, has uncovered in Rome, in one of Hebrid Islands, terracotta pot with unknown ingredients, from the Neolithic Age. The analysis of the findings obtained the beverage is beer, made of oats, barley, honey, and ferns. The drink, which many claim that actually is food, is already used in the prehistoric period.
Produced by the Celts, Germans, Slavs and Scythians ... It was produced from barley, wheat, oats and buckwheat, and many older people have been adding various spices and honey. Today's main ingredient is hops began to be used only in the 13th century. Beer consumption center in the old century were in Armenia, Mesopotamia and Egypt. The Greeks and Romans later took a beer from these areas.
Ingredients of precious liquid: water, ethanol, carbon dioxide and the residual portion extract (dry matter) of malt. The proportion of ethanol depends on the concentration of dry matter in the malt from which the beer is produced and the degree of fermentation. Depending on the type of beer, a volumetric proportion of alcohol may be different, i.e. less than 0.5% for "soft" beers and more than 8% for barley wine. Lager beer containing up to 0.5% carbon dioxide, which gives it a freshness, and significantly affect the foam. The stability of foam depends on the concentration and chemical composition of fermented extract, so the beer with more extract mostly has stronger foam. Ability to hold foam depends on the amount and composition extract.
Beer should make foam upon pouring in to glass so it's dense and firm foam remain on the surface for at least 3 minutes. Carbon dioxide bubbles that rise from the bottom to the surface help to maintain the foam. Extract beers are mostly carbohydrates and a small amount of protein, amino acids, glycerol and the parts of the hops. From composition of extract depends fullness of taste of beer. The chemical composition extract does not only depend on the type of malt, but also on a way of production of malt and fermentation, and the final stage of fermentation at the end of fermentation.