The starch in malt is converted to sugar by natural enzymes. Sugars are then fermented by yeasts. The aqueous extract (wort) is separated by filtration, hops added and boiled for several hours.Wort is then transferred to fermentation vessel (1-3 weeks).Yeast used is Saccharomyces carlsbergensis. Bottom-fermenting yeasts produce lagersTop-fermenting yeasts produce alesThe beer may be disinfected either by cold filtration through a 0.45 m filter or by pasteurization