Brewer's spent grain: a new multipurpose feedstock?

An article recently published in the Journal of the Science of Food and Agriculture analysing Brewer’s spent grain (BSG), a by-product of the beer-brewing process, which is rich in sugars and proteins by summarizing and discussing how BSG can be advantageous in foods, in energy production and in chemical and biotechnological processes.

In his paper, ‘Brewer's spent grain: a valuable feedstock for industrial applications’, Solange Mussatto discusses the most recent efforts that have been made towards more advantageous uses of BSG which could help human health, generate energy, and produce paper.

Currently the main application of BSG is animal feed, however, recently investigations have been aimed at recovering compounds and how they could be added to human food products resulting in beneficial effects on health. Nutritionally BSG is high in fibre, protein, and minerals which can therefore provide health benefits such as accelerated transit time, increased fat excretion, and decreased gallstone incidence. According to Solange, further research is still required to improve the quality of the final product to make it suitable for humans as well as to evaluate consumer acceptance.

The world energy crisis has motivated researchers to consider the use of BSG in energy production. It is largely available and due to its chemical composition and low cost BSG is one alternative to generate energy. Solange also mentions how several studies have reported the possibility of producing biogas from BSG. This application can be considered especially suitable for obtaining thermal energy in breweries with few adverse environmental effects. BSG has also been considered as a promising raw material for the production of second-generation ethanol.

In regards to chemical processes BSG is able to obtain or produce compounds of industrial interest. Hydroxycinnamic acids can be recovered from the BSG structure by means of chemical treatment. Ferulic and p-coumaric acids have antioxidant properties and important industrial applications; the extraction of these acids offers new possibilities for the reuse of this industrial by-product in food, cosmetic and pharmaceutical areas. BSG is also considered a suitable raw material for use in the production of papers and it has already been used to prepare paper towels, business cards and coasters.

Finally BSG in biotechnological processes has been studied due to it being rich in polysaccharides, proteins and minerals. Recent studies have evaluated the possibility of using BSG as a carrier for cell immobilization. It can be successfully used for immobilization of S. cerevisiae in order to produce beer by a high-gravity continuous process. BSG is also a promising biocatalyst for use in winemaking at low fermentation temperatures.

Conclusion

Solange concludes by stating that in the last decade the research into BSG has been intensified which is possibly motivated by environmental and economic concerns.

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