rrrom the best raw materials to the finest-tasting beer Nowadays, perpendicular tanks - known as 'apollos' - are used for both fermentation and storage. lb heat up the mash to 75°C, a part of the mas, pumped twice into thébrewing kettle, heated up to hpilijigpoint and then pumpedJmU mash tun. into the mash tun. In this way the tem perature is raised in stages until it reaches 75°C. That is the temperature at which the enzymes can best perform their task: dissolving proteins and con verting starch into sugars. Wort The warm mash goes to the sparg ing tun. The sparging tun has a double bottom; the upper, false bottom is perfo rated with thousands of tiny holes. The mash is filtered in the sparging tun. The 'husks' sink to the false bottom and form a layer which can sometimes be as much as half a metre thick. In the same way that a coffee filter works, the extract passes through the filtration layer to the real bottom. The dissolved extract is known as the 'wort'. The wort flows from the sparging tun into the wort copper where it is boiled. This boiling is very important as it terminates the enzymatic activity, sterilises the wort and ensures that the excess of dissolved proteins is floccu lated out. During boiling the hops are added to the wort. Hops give the beer its characteristically bitter flavour and improve its aroma and brightness. In addition, hops help to improve the firm ness of the head of foam and the beer's keepability. From the moment that the crushed malt was mixed with water until the boiling of the wort the brewing process has lasted eight hours. Cooling The wort has to be cooled down within a maximum of two hours to a temperature of 6-10°C, because that is the optimum temperature at which the yeast will shortly be doing its work. An ingenious system has been devised for cooling the wort. The warm wort and cold water flow past one another in separate systems in opposite directions. The wort cools down and the water be comes warm. This warm water can be used again in the brewhouse for sub sequent brews. During the cooling process the wort undergoes one further treatment. The proteins which have started to floccu late out during boiling are removed by means of a centrifuge system, whirlpool tanks or filters. Once the wort has reached the re quired temperature it is pumped via a pipeline to the fermenting vessels or tanks. Yeast and oxygen are added to it en route. U F. 1 N E K

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World of Heineken | 1989 | | pagina 8