when did hops start being used in beer
Hops The first documented use of hops in beer is from the 9th century[citation needed], though Hildegard of Bingen, 300 years later, is often cited as the earliest documented source.[3] Before this period, brewers used gruit, composed of a wide variety of bitter herbs and flowers, including dandelion, burdock root, marigold, horehound (the old German name for horehound, Berghopfen, means "mountain hops"), ground ivy, and heather.[4] Early documents include mention of a hop garden in the will of Charlemagne's father, Pepin III.[5]
Beer head Beer head (also head or collar),[1] is the frothy foam on top of beer which is produced by bubbles of gas, typically carbon dioxide, rising to the surface. The elements that produce the head are wort protein, yeast and hop residue. The carbon dioxide that forms the bubbles in the head is produced during fermentation. The carbonation can occur before or after bottling the beer. If the beer continues fermenting in the bottle, then it naturally carbonates and the head is formed upon opening and/or pouring the beer. If the beer is pasteurized or filtered then the beer must be force carbonated using pressurized gas.