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raw materials

Brewing barley

Different types of grains can be applied for the preparation of malt for brewing processes. Usually the type two-row barley is used. For the production of wheat beer the used grain is wheat.
The barley kernel is the plant’s fruit, which consists of the germ/embryo, the endosperm and the pericarp (fruit coat).
The embryo/germ represents the active part of the kernel. It consists of lipids and protein. In the endosperm, starch granules are embedded in a protein matrix. The endosperm is surrounded by the aleurone layer which contains lipids and protein. The endosperm is the centre for all biological and chemical reactions, during growth the endosperm is metabolised and delivers the energy for the development of the germ/embryo. The husk protectis the inner parts of the kernel. It consists of cellulose, lignin, pentosans, sugars and phenolic material. Beneath the husk, there is the pericarp and the testa. Both are semi-permeable membranes with the task to protect the grain by preventing a high water uptake and the entry of bacteria.


Hop

Hop is a perennial, climbing plant which belongs to the Cannabaceae family. In the brewing industry hops are very important raw materials. The female flowers (seed cones) are used in beer brewing by being added to the wort. Hop contains lupulin grains which carry oils and bitter resins and essential oils and tannins. These ingredients of the hop introduce a bitter, aromatic flavour into the wort and are also responsible for enhancing the beer foam and for inhibiting bacterial growth.
Fresh hop cones have a water content of 75 – 80 % and have to be dried at temperatures of 30 – 50 °C to reach a dry matter of 90 % percent.


Yeast

Yeasts can be divided into two groups: sporogenic and non-sporogenic yeasts. The non-sporogenic yeasts comprise top-fermented yeasts (Saccharomyces cerevisiae) and bottom-fermented yeasts (Saccharomyces carlsbergensis).
In an anaerobe milieu the yeasts produce alcohol from their nutrition medium which is the previously produced wort. Yeasts contain a lot of enzymes and one very important enzyme complex is called zymnase which consists of many different enzymes. Together these various enzymes accomplish the alcoholic fermentation.