Synergetic Co-Production of Beer Colouring Agent and Solid Fuel from Brewers’ Spent Grain in the Circular Economy Perspective

Abstract

Brewers’ Spent Grain is a by-product of the brewing process, with potential applications for energy purposes. This paper presents the results of an investigation aiming at valorization of this residue by torrefaction, making product for two purposes: a solid fuel that could be used for generation of heat for the brewery and a colouring agent that could replace colouring malt for the production of dark beers. Decreased consumption of malt for such purposes would have a positive influence on the sustainability of brewing. Torrefaction was performed at temperatures ranging between 180 °C and 300 °C, with a residence time between 20 and 60 min. For the most severe torrefaction conditions (300 °C, 60 min), the higher heating value of torrefied BSG reached 25 MJ/kg. However, the best beer colouring properties were achieved for mild torrefaction conditions, i.e., 180 °C for 60 min and 210 °C for 40 min, reaching European Brewery Convention colours of 145 and 159, respectively. From the solid fuel properties perspective, the improvements offered by torrefaction in such mild conditions were modest. Overall, the obtained results suggest some trade-off between the optimum colouring properties and optimum solid fuel properties that need to be considered when such dual-purpose torrefaction of BSG for brewery purposes is implemented.

Evaluating the potential applications of brewers' spent grain in biogas generation, food and biotechnology industry: A review

“… Jackowski et al. (2021) [ 69 ] Improvement of the fuel properties using torrefied BSG and using torrefied BSG as a beer colouring agent. Torrefaction of BSG was conducted at temperatures ranging between 180 °C and 300 °C, with a residence time between 20 and 60 min, resulting in formation of a torrefied BSG with higher heating value of 25 MJ/kg.…”

Optimization of Phenolic Compound Extraction from Brewers’ Spent Grain Using Ultrasound Technologies Coupled with Response Surface Methodology

“…Owing to its significant chemical composition, BSG can be used for different purposes. In general, BSG is sold as animal feed, for energy production and agricultural applications, but it can be very attractive for application in the food, pharmaceutical and cosmetic industries [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26].…”