Processing of brewing by-products to give food ingredient streams
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Very large amounts of brewer’s spent grains (BSG) are produced in the world which is usually considered as a waste, or animal feed, rather than food for humans. Here, we report, for the first time, a new process at pilot scale for the separation of brewer’s spent grain and trub to solid and liquid streams that can be used in foods. A new type of continuous rotary drum press was used to process hot BSG to produce a liquid filtrate and a filter cake stream. Analysis showed that of the starting mass of BSG (ca. 120 kg), the liquid filtrate composed 50% of the mass, and the filter cake fraction composed 50% of the mass. The dry weight (DW) content of the BSG increased from 23 to over 35%. This led to concentration of insoluble dietary fibre (from 38 to 54%) and phenolics in the filter cake (from 102 to 150 mg/100 g DW as gallic acid equivalents). No fractionation of soluble species such as proteins occurred. Centrifugation of the filtrate from the rotary drum press led to a clarified supernatant stream and a paste. Concentration of insoluble dietary fibre and phenolics occurred in the paste (from 5 to 14% of DW and 61 to 114 mg/100 g DW as gallic acid equivalents), whereas soluble fibre and protein did not selectively partition. Given that the unit operations used here are scaleable and approved for food production, an industrially feasible route now exists to process brewers spent grains to ingredients.
KeywordsBrewer’s spent grains Filter press Pilot scale Trub Separation
We thank Hening-Holck Larsen and Novozymes foundation for a scholarship til Radhakrishna Shetty. We acknowledge the support of Groen Omstillingsfond project number 2014–98907. We thank Heidi Olander Petersen and Inge Holmberg for excellent technical assistance on Kjeldahl, Dumas, and antioxidant measurements. We thank Per Hägglund for advice on mass spectrometry measurements.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
Compliance with ethics requirements
This article does not contain any studies with human or animal subjects.
- 2.Kunze W (2004) Technology Brewing and Malting, 3rd edn. VLB, BerlinGoogle Scholar
- 4.Beer statistics (2017) https://www.brewersofeurope.org. Accessed 30 July 2018. ISBN 978-2-9601382-9-0
- 5.Weber G (2009) Untersuchungen zur Silierung von Biertrebern. Logos Verlag, BerlinGoogle Scholar
- 14.Osborne TB (1924) The vegetable proteins, 2nd edn. Longmans, Green and Co, LondonGoogle Scholar
- 15.Kupetz M, Geiinger C, Gastl M, Becker T (2018) Comparison of Dumas and Kjeldahl method for nitrogen determination in malt, wort and beer. Brewing Sci 71:18–23Google Scholar
- 16.Oehlenschläger J (1997) WEFTA interlaboratory comparison on nitrogen determination by Kjeldahl digestion in fishery products and standard substances. Inf Fischwirtsch Fischereiforsch 44:31–37Google Scholar
- 17.Jones DB (1941) Factors for converting percentages of nitrogen in foods and feeds into percentages of proteins. Circular 183, US Department of Agriculture Washington, DCGoogle Scholar
- 18.Elementar (2017) Dumas - a well-established method for n/protein analysis. Technical Note http://www.elementar.de/en/products/nprotein-analysis/rapid-max-n-exceed.html. Accessed 30 July-2018
- 19.Popov N, Schmitt M, Schulzeck S, Matthies H (1975) Eine störungsfreie mikromethode zur bestimmung des proteingehaltes in gewebehomogenaten. Acta Biol Med Ger 34:1441–1446Google Scholar
- 20.Glatter T, Ludwig C, Ahrne E, Aebersold R, Heck A, Schmidt A (2012) Large-scale quantitative assessment of different in-solution protein digestion protocols reveals superior cleavage efficiency of tandem lys-C/trypsin proteolysis over trypsin digestion. J Proteom Res 11:5145–5156CrossRefGoogle Scholar
- 28.Forssell P, Treimo J, Eijsink VGH, Faulds CB, Collins S, Schols HA, Hinz SWA, Myllymäki O, Tamminen T, Zoldners J, Viljanen K, Waldron KW, Buchert J (2011) Enzyme-aided fractionation of brewer’s spent grains in pilot scale. J Am Soc Brew Chem 69:91–99Google Scholar
- 33.Robertson JA, I’Anson KJA, Treimo J, Faulds CB, Brocklehurst TF, Eijsink VGH, Waldron KW (2010) Profiling brewers’ spent grain for composition and microbial ecology at the site of production. Food Sci Technol 43:890–896Google Scholar
- 34.Rørby K (2018) Effect on the properties of bread of using fractions from brewers spent grains as an ingredient. Masters thesis, Technical University Denmark, DenmarkGoogle Scholar
- 35.Jensen M (2018) Funktionelle effekter af separeret mask i pølser. Masters thesis, Technical University Denmark, DenmarkGoogle Scholar