Brewing science

The ICBS is located within the Bioenergy & Brewing Science Building at the University of Nottingham Sutton Bonnington Campus. Professor David Cook introduced the history of the Sutton Bonnington campus site since its purchase by the university in the 1950s when the site was an agricultural college. The first chair in brewing science was awarded to Professor Katherine Smart and an MSc course in brewing science was launched in 2006 followed by a range of shorter training courses delivering training to students already working within the brewing industry. A bioenergy centre added to the established brewing science facility in 2009 and, in 2013, the centre was rebranded as the ICBS in recognition of the international reach of the research publications, students and consultancy work associated with the centre. In recent years, the ICBS has become more active with the brewing industry with an initiative to launch student-brewed beers with local partner breweries starting in 2015 and the current ICBS involvement in delivering the new UK government apprenticeship scheme. Currently the ICBS offers various short courses and two MSc programmes: a one-year full time MSc in Brewing Science and Practice and a three-year part time MSc in Brewing Science for students already employed within the brewing industry. The centre also has a number of PhD students with students and staff involved in various collaborative projects with other science departments and industry.

Professor Cook outlined and explained the key research priorities for the ICBS: freshness and flavour; diversification through functional grain based beverages; new approaches to creation of non-alcohol and low alcohol beers (NAB/LAB); and, production capacity release to improve the economics of beer production.

‘Beer – it’s all about the yeast’

Dr Chris Powell of the ICBS presented an entertaining and fascinating glimpse into the importance of yeast in beer production. We learnt that all commercial brewing yeasts are Saccharomyces strains with different strains used in ale and lager production. Typically, lager production uses S. pastorianus in a long and cold fermentation process to produce the relatively bland flavour of lager and ale production uses S.cerevisiae in a short and warm fermentation process to produce the complex ester-like notes common to ale beers. Aside from Trappist beer production processes, modern commercial breweries all use yeast strains that do not occur in the wild. Dr Powell also explained the biochemistry of fermentation and outlined at a chemical level the role of yeast in development of the complexity of flavours. We learnt how the physiology of commercial yeast strains are challenged by the intensity of modern brewing practices: where the yeast is ‘pitched’ into concentrated solutions of ‘wort’ causing osmotic shock to cells with associated cellular damage and physiological responses that negatively impact productivity and flavour quality. Dr Powell described various approaches taken by brewers to minimise such negative impacts during brewing of concentrated beers and highlighted how the ICBS research seeks to harness metabolic and genetics knowledge to better understand yeast physiology and help identify strains of yeast that are tolerant to the high sugar concentrations in modern worts.

Bringing clarity to a murky world – the chemistry of beer filtration

Rod White, Assistant Professor in Brewing Science, joined the ICBS following a career in the brewing industry. Rod applies his manufacturing process experience in research with the aim to improve the efficiency and sustainability of beer production. His presentation focussed on an ongoing project investigating techniques to improve the reliability of membrane filtration technology for clarifying beer. He explained that beers are traditionally conditioned then filtered, using diatomaceous earth, to remove particles greater than 5 microns and eliminate yeast haze. The brewing industry is increasingly using polyethersulphone membranes in crossflow filtration in place of the traditional diatomaceous earth due to lower cost and general ease of operation. Membrane filtration can however be unpredictable with some breweries experiencing issues with membrane blockages for particular products. Professor White’s project has involved collaboration with a local hospital that has afforded the group access to a state of the art particle size analyser. His team use the analyser to investigate the impact of enzymes and other additives on membrane filter performance.

Predicting beer shelf life using Electron Spin Resonance spectroscopy

Professor Cook provided an insight into another ongoing project using electron spin resonance (ESR), also known as electron paramagnetic resonance (EPR) as a tool to predict the shelf life of packaged beers. In this application, ESR is applied to measure the levels of free radical species produced in beers during industry standard ‘forcing tests’ and correlate this with shelf life for specific products. The forcing test involves holding samples at test specific elevated temperatures for set periods to initiate and encourage oxidation processes. Key factors affecting oxidative stability include storage temperature and the presence of endogenous anti-oxidant chemicals, in particular sulphur dioxide produced during the yeast fermentation process. Professor Cook explained how the ESR technique is applied in studies using the addition of naturally derived free radical reaction inhibitors, including resins and polyphenols derived from the hops and natural metal chelants. Metal chelants reduce iron and other metal species which are critical to the free radical reaction pathway. Oxidative stability varies with the type of beer product, with stout ales having a shorter initiation or lag period and faster rate of oxidation than some lager products. The complexity of the flavour in stout beers however, is such that oxidation may impair flavour less for this type of product than for lager beers. Research has included correlation of headspace GS-MS analysis with ESR and sensory assessment of flavour and odour.

Draught beer quality – cause for celebration or concern?

David Quain presented an entertaining look into his research interest area: draught beer quality at the tap. David Quain outlined the key factors identified as being responsible for the long-term decline in the world and UK market for draught beers: political, economic, social, technological and quality. His research has recently focussed on UK draught beer quality and involved a study of the quality of draught beer sold in the East Midlands. The findings of this study highlight issues with microbial contamination of cask/keg beers and ciders when served in British pubs, manifested by the haziness of beers/lagers/ciders in the glass and higher turbidity levels for served products compared to ‘as delivered’ product. Professor Quain explained that the microbes that most often proliferate in draught beers are non-pathogenic but lead to unpleasing qualities in the served beer due to haze and/or taints. The research identifies that the cause of the decline in quality of draught beers after delivery to the pub is likely to be related to several root factors: modern pub design frequently featuring elongated lines between keg/cask and bar tap; non-optimal keg and cask storage temperature; and, poor hygiene and maintenance of delivery lines and nozzles. The research highlights that the assumption that the alcohol content of beers and lagers prevents significant microbial contamination is false. Microbial biofilms readily form in poorly cleaned lines and nozzles leading to contamination of beers within the cask/keg during change over, with further microbial proliferation occurring within the cask/keg during storage at warmer than optimum temperatures in the typical non-refrigerated beer cellars common in British pubs. We also learnt that differences in approach to the employment and retention of staff in British pubs compared to some other European countries might also be affecting the quality of draught beer served due to poorer hygiene and maintenance of the delivery lines and taps in pubs with non-professional bar staff and high staff turnover. This research has confirmed that certain draught beer products are more susceptible to microbial contamination than others and there is an opportunity to investigate this further to better understand the inherent properties that reduce the susceptibility of beers to microbial contamination.

Following the presentations, the attendees enjoyed a tour of the ICBS pilot plant and laboratories. The site tour afforded us a chance to view the InBev brewing facility and the ICBS Nano Brewery, laboratory scale brewing equipment and analytical capabilities. The tour concluded with the opportunity to taste the impressive first batches of novel beers brewed by this year’s new cohort of MSc students.

The Royal Society of Chemistry local section members attendees provided much positive feedback throughout the site visit and afterwards. Many thanks to Professor David Cook and his colleagues at the ICBS for arranging such a fascinating site visit and allowing us to glimpse the range of sciences involved in modern brewing.