The main ingredients of beer in the Middle Ages were malted barley, water, and yeast. Sometimes rosemary and thyme were added to prevent the beer from spoiling (action against mold and yeast) and to give it flavor. This beer was cloudy and contained a lot of protein and carbohydrates, which made it a very nutritious drink, which was consumed by both peasants and the nobility.
European monks refined the process and institutionalized the use of hops for its flavor and preservative properties.
Before learning about hops, northern Europeans used aromatic herbs and wild plants, achieving a lighter, short-lived beer that was not suitable for transport. In the 12th century, the German king John Primus, known as Gambrinus, fought famine in his domain through the cultivation of barley, which greatly boosted the manufacture of beer.