Malting Process
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The Barley Grain
Barley Vigour
Hydrolase Action and Modification
Danish Malting Group

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In the malt house, barley grain germination is initiated by the uptake of water in a steeping vessel (A). The grain imbibes water during controlled cycles of water spraying or water immersion followed by aeration, until the water content of the grain reaches 42 to 48%. Water enters the grain via the embryo, and after approximately 24 hours, the first visible sign of germination is the appearance of the root, as a white 'chit'. The grains are then transferred to malting beds where germination is allowed to proceed over a period of around 5 days (B). The speed of germination is controlled by temperature and aeration of the malt bed, while moisture content is maintained by spraying. Further embryo growth, with the appearance of rootlets and acrospire, can lead to root entangling. The grain bed is regularly turned with a rotating screw to prevent grains matting together.

Green malt, produced after five days of germination, is kiln dried and partly cooked in a forced flow of hot air (C). Hydrolases produced during malting are partially inactivated during this process. Malt colour, enhanced by kilning at higher temperatures, may be desirable for production of darker beer, but it leads to further heat-inactivation of hydrolases. The brittle malt rootlets are separated from the malt and utilised in animal feeds.

The kilned malt is stable for storage and has a friable texture suitable for the milling process which proceeds brewing.

 

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This page was last updated 22/07/99. Send comments to