Brewing a sustainable future: unlocking the potential of spent grains
In an era of increasing environmental awareness, the reliance on petroleum-based products extends far beyond fuel, permeating our daily lives in plastics, medicines, and food products. The brewing industry, surprisingly, offers a promising alternative source for these chemicals, potentially transforming waste into valuable bio-based resources that meet both regulatory standards and consumer expectations for performance and safety.
The brewing industry's hidden treasure
Beer and lager production primarily uses four ingredients: yeast, water, hops, and barley. After brewing, the remaining solids, known as brewing spent grains (BSG), are often discarded (at a cost) or given away to farmers for animal feed. Local brewery data indicates that approximately 200 kg of mixed grains are used per 1000 litres of beer. The UK alone produces around . BSG is in essence a source of organic carbon polymers that can be used across almost every manufacturing industry.
Current challenges in processing
Existing technologies can break down the polymers in BSG but they often come with high costs attached. These methods typically involve heating the substrate to over 600掳C at high pressures or using strong acids/alkali to break the structure. Such processes are energy-intensive with environmental challenges making it cheaply and effectively.
Innovative research at the University of Salford
At the University of Salford, researchers are exploring new ways to extract value from waste. PhD candidate Danny Wales, under the guidance of Dr Natalie Ferry, Dr Ale Diaz De Rienzo, and Dr Rosa Arrigo, is working on a greener, cleaner, more cost-effective method to extract valuable chemical compounds from BSG. This innovation has the potential to reduce the brewing industry's carbon footprint while providing breweries with an additional revenue stream. Through IBIC the University of Salford has partnered with The Lubrizol Corporation: Specialty Chemicals, a global innovator of science-based solutions, to explore BSG as a source of green alternatives to molecules found in products used by people every day.
Biological catalysts
The team is focusing on bacterial and fungal enzymes capable of breaking the molecular bonds within and between polymers found in BSG. By using different enzymes for specific breakdown processes, they aim to make . Danny's interest in brewing, which began during his master鈥檚 in biotechnology at Salford, has led him to apply his sequencing and genomics skills, to to find enzymes that degrade the most indigestible fractions of BSG.
Two target chemicals which Danny is intending to produce from the research are and , chemicals used in plastics and pharmaceuticals among other industries. These have a projected 2030 international value of 拢95.3billion and 拢589.1million respectively making them valuable commodities, producing a potential income for brewers from their waste.
The versatility of Furfural
Furfural, which can be obtained from BSG, is a versatile chemical ingredient. Through catalytic hydrogenation, furfural can be transformed into various valuable products:
- Furfuryl alcohol (FA): used in making resins, lubricants, plasticisers, and fibres.
- Tetrahydrofurfuryl alcohol (THFA): a green solvent used in printer inks and agriculture.
- Furan and tetrahydrofuran (THF): used as fuel additives or surfactants.
As part of the University of Salford consortium, Dr Rosa Arrigo is exploring the use of heterogeneous catalysts in these transformations.
Advancements in catalysis
Dr Rosa Arrigo and her team have made significant strides in converting furfural into useful compounds. Their recent publication in ChemCatChem highlights the use of . These NPs allow for lower hydrogen gas pressures during reactions, reducing costs and enhancing safety. The team are able to control the size and shape of the NPs, resulting in (fig 3).
This research highlights the importance of collaboration involving institutions from the UK, Italy and Spain with Diamond Light Source and the UK Catalysis Hub (at the Research Complex at Harwell). Advanced characterisation techniques, such as atomic-resolution imaging and spectroscopy, enabled the team to analyse the synthesised materials at the atomic level, providing deep insights into how their structure affects catalytic properties.
The impact of particle size
A key finding from Rosa鈥檚 research is the impact of nickel particle size on the hydrogenation process. Smaller particles primarily produce furfuryl alcohol, while larger particles lead to further hydrogenation into furan. This understanding allows for the selective production of specific chemicals, leading to .
Broader implications for the brewing industry
The innovative work at the University of Salford is just one part of a broader effort to advance biotechnology and support the brewing industry. The headed by Dr Ale Diaz De Rienzo and Prof Ian Goodhead, collaborates with brewers to sequence unique yeast varieties, test new equipment, and eliminate bacterial contamination in breweries. They are also launching brewing training as part of government-led apprenticeship programmes.
Recently Dr Silvia Tedesco from the has joined the team and is contributing her chemical engineering experience on lignocellulosic waste conversion to levulinic acid (which is usually co-produced along with furfural) in .
Through the power of industrial collaboration, researchers at the University of Salford are not only advancing scientific knowledge but also paving the way for a more sustainable and prosperous future for the brewing industry and beyond. Their work demonstrates how waste can be transformed from a source of environmental concern into a valuable resource, contributing to a greener and more sustainable future.
Written by Daniel Wales, Natalie Ferry, Rosa Arrigo (School of Science, Engineering and Environment at the University of Salford), and Silvia Tedesco (Centre for Sustainable Innovation at the University of Salford)