Chapter 10

Wort Boiling

Wort Composition

Sweet wort is viscous, sweet, dense, sticky and more or less colored. Standard brewery wort contains approximately 90 percent carbohydrate, which consists of sucrose, fructose, glucose, maltose and maltotriose, together with dextrin material. The wort sugar profile depends on the raw ingredients (mainly barley malt) and wort preparation procedures, and also relies on the type and the quantity of adjuncts employed. Wort pH is typically in the range pH 5.0 to 5.3. The color is highly dependent on the materials used for production and varies between a very pale brown through to almost black.

Raw Materials

Wort composition is influenced by the nature of the raw materials and management of the processes used in its preparation. With regard to the raw materials, the nature of the brewing water, the blend and addition rate of hops, the blend and types of malt and the nature of any adjunct are all influential.

Processing Conditions

During wort preparation, the conditions of mashing and boiling are of particular significance. Low mashing temperatures favor continued activity of heat-labile malt proteases and therefore elevated concentrations of amino nitrogen are formed. Conversely, higher mashing temperatures favor amylolytic activity at the expense of proteolysis and in consequence the ratio of fermentable sugar to amino nitrogen increases.


Approximately 75 to 80 percent of the total grist weight is extracted during mashing, and the remainder (the insoluble material) is removed from the process along with the spent grains. The carbohydrate fraction of this extract mainly comprises starch degradation products and soluble components of the malt modified during malting. The predominant simple sugars of the wort are: monosaccharides (glucose and fructose), disaccharides (sucrose and maltose), and trisaccharides (maltotriose).

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