Brewer?s spent grain is the major by-product in beer production. It is
produced in large quantities (20 kg per 100 liters of produced beer)
throughout the year at a low cost or no cost, and due to its high protein and
carbohydrates content it can be used as a raw material in biotechnology.
Biotechnological processes based on renewable agro-industrial by-products
have ecological (zero CO2 emission, eco-friendly by-products) and economical
(cheap raw materials and reduction of storage costs) advantages. The use of
brewer?s spent grain is still limited, being basically used as animal feed.
Researchers are trying to improve the application of brewer?s spent grain by
finding alternative uses apart from the current general use as an animal
feed. Its possible applications are in human nutrition, as a raw material in
biotechnology, energy production, charcoal production, paper manufacture, as
a brick component, and adsorbent. In biotechnology brewer?s spent grain could
be used as a substrate for cultivation of microorganisms and enzyme
production, additive of yeast carrier in beer fermentation, raw material in
production of lactic acid, bioethanol, biogas, phenolic acids, xylitol, and
pullulan. Some possible applications for brewer?s spent grain are described
in this article including pre-treatment conditions (different procedures for
polysaccharides, hemicelluloses, and cellulose hydrolysis), working
microorganisms, fermentation parameters and obtained yields. The chemical
composition of brewer?s spent grain varies according to barley variety,
harvesting time, malting and mashing conditions, and a quality and type of
unmalted raw material used in beer production. Brewer?s spent grain is
lignocellulosic material rich in protein and fibre, which account for
approximately 20 and 70% of its composition, respectively.
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