This mixture, which is now called Mash, is heated to different temperatures where enzymes break down the starches in the mash into fermentable sugars. The hops give the beer a pleasant, bitter taste. The boiled wort is left to cool and then transferred to fermentation tanks with aeration where the yeast is added. The yeast turns the sugars within the wort into alcohol and carbon dioxide. It is now that the wort actually becomes beer.
Fermentation takes about a week after which the beer is called green beer.
The green beer is transferred to cold storage tanks, where it matures over a period of three weeks at a temperature of 0 degrees C. During this period the beer clarifies and its flavour matures. The carbon dioxide formed at this time will eventually help to produce the head on the beer. After maturation the beer is filtered under pressure through a natural filter known as Kiesselghur. This filters out everything that makes the beer cloudy without in any way altering the taste. At this point we finally have Nile beer.