Session Chair:
Aleksander Poreda (Head of Kraków School of Brewing, PL)
Binding of staling aldehydes to the beer matrix
By Carolina Maia et al., Nottingham University
Aldehyde adducts in beer include those with SO2, amino and sulfhydryl groups. Bound aldehydes are not reduced by yeast and are carried forward with the potential to be released and cause flavour change through shelf-life. Whilst this is known to be a major route to beer staling, surprisingly little is understood about the interactions between aldehydes and the beer matrix which give rise to the specific impacts of ageing on beer flavour. Here, we isolated and concentrated the beer matrix from 3 commercial lager beers by freeze drying and re-constitution. Free aldehyde concentrations were measured by HS-SPME-GC-MS in fresh beer and re-constituted matrix. Sulfite was completely lost during freeze drying, enabling independent adjustment for study of competitive binding between sulfite and other matrix components. A series of ‘challenge’ experiments were then conducted where the impacts of individual aldehyde additions on the displacement of other staling compounds were studied. Results provide new insights into the binding and displacement of aldehydes in beers as determined by the binding affinities of the individual compounds and the individual characteristics of a beer’s matrix.
Consistent detection of strict anaerobic beer spoilers including Megasphaera cerevisiae using an automate anaerobic jar system.
By Wade Begrow, Founders Brewing
Beer quality can be dramatically affected by strictly anaerobic bacteria including Megasphaera spp. In contrast to lactic acid bacteria (e.g. Lactobacillus brevis), Megasphaera can produce detrimental metabolites in beer such as hydrogen sulfide and organic acids including butyric acid and isovaleric acid. The risk of spoilage from strict anaerobes has intensified in recent decades because of advancements in low-oxygen packaging technology. Ultra-low total package oxygen values (<300 ppb) are desired to preserve beer freshness and shelf stability, but low TPO also opens the door for strict anaerobes to survive and potentially spoil beer after it has left the brewery.Traditional microbiological methods for bacterial beer spoilers may not be able to recover strict anaerobes including Megasphaera cerevisiae because of their inability to rapidly create and preserve anaerobic conditions during incubation. The inability to detect strict anaerobes can provide a false sense of security and could lead to serious product issues.The Anoxomat® III Anaerobic Culture System by Advanced Instruments is used extensively in clinical microbiology testing programs for detecting strict anaerobes.
Boosting intense natural fruity esters in beer with fermentation
By Luk Daenen et al., AB-Inbev
To explore the potential of non-Saccharomyces yeasts, a screening was performed based on flavour profile and fermentation performance by fermenting beer wort under anaerobic and aerobic conditions. Pichia kluyveri was found to produce exceptionally high quantities of esters such as isoamyl acetate, which is the main compound responsible for the pleasant banana aroma often found in beer. A further selection of P. kluyveri strains was made based on the ratio of isoamyl acetate over ethyl acetate which can impart a solvent character in high concentrations. By optimizing the conditions of brewing and fermentation, an intensely fruity beer can be produced which contains over 150 ppm isoamyl acetate which is about one hundred times the concentration typically found beer. This very fruity beer can be applied to enhance and diversify the natural fruitiness of lager beers, specialty beers, non-alcoholic beers, as well as other innovative beverages.
Entry and reduction of microplastics and microparticles in beer production lines
By Jörg Zacharias and Veronika Knöchel, Krones
Intensive debates are currently going on about the occurrence and effect of microplastics and microparticles in the environment. This also concerns producers of beverages. But research is still in its infancy and often reliable scientific data are lacking. Many studies focus on water as it allows for a simple analysis due to its homogeneous and transparent appearance compared to un-/filtered beer. But to this day no universal or standardized analytical method was established to define microplastics and microparticles quantities or limits. As a result, the focus is on the measurement of microparticles, and not in particular on microplastics. So, tests to find out where and to which extend microparticles are generated, entered and removed in beer filling plants were carried out using particle counters and fluorescence microscopy. These tests are done for various filling lines. Beverages, bottles, caps and the beer itself are measured at different stages. Bottle washer and filter systems are also considered. This leads to filling concepts with the lowest possible particle entry. First approaches of particle avoidance and removement have already been implemented and will be discussed.