Journal of the Institute of Brewing

Effective strategies to maximise dextrin formation in brewing

2024-06-10T12:12:33-07:00

Why was the work done: Dextrin is the non-fermentable product of starch hydrolysis and plays a role in enhancing the perceived palate fullness of beer. Therefore, increasing dextrin formation is a promising strategy to improve palate fullness, particularly in non-alcoholic and low-alcohol beers.

How was the work done: This study investigated the impact of adjusting the mashing profile of a 100% barley malt mash on the dextrin content and molecular weight distribution in the wort. Mash thickness, heating rate, and mashing-in temperature with and without the addition of a thermostable α-amylase were adjusted during mashing to evaluate the impact on dextrin content and molecular weight distribution. To benchmark this work, the dextrin content and molecular weight distribution was determined in five pilsener beers and their non-alcoholic counterparts.

What are the main findings: With the exception of one non-alcoholic beer which contained 72 g/L, the concentration of dextrin ranged from 15 to 30 g/L in the five commercial pilsner-type beers and their non-alcoholic equivalents. The molecular weight distribution of dextrin among the beers was similar, with 85-98% of the dextrin population characterised by a degree of polymerisation below 35. Various strategies were applied during mashing to evaluate the impact on the content and the molecular weight distribution of dextrin. A strategy that promoted dextrin formation was mashing with a lower water-to-grist ratio. This resulted in delayed starch gelatinisation influenced by increased solid extract content in wort. Furthermore, at a low water-to-grist ratio, faster mash heating (up to 2°C/min) or isothermal mashing at temperatures below 72°C had no impact on dextrin formation. Isothermal mashing at 78°C supplemented with thermostable α-amylase increased the dextrin level in wort up to 60 g/L, while the molecular weight distribution of dextrin was similar to that found in commercial beers.

Why is the work important: This study demonstrates that increased dextrin formation is achievable in beer but requires significant changes to the mashing process. These insights will enable brewers to enhance the palate fullness of beers, especially those which are non-alcoholic or low in alcohol.

The lowering of gushing potential from hydrophobin by the use of proteolytic enzymes

2024-05-22T09:12:42-07:00

Why was the work done: Gushing caused by hydrophobin originating from field fungal contamination of grain remains a significant problem in certain regions. We sought to explore whether the use of added proteinase enzymes could overcome the problem and allow the use of problematic grain.

How was the work done: Four commercial proteinases were studied for their ability to digest hydrophobin and remove its foaming potential. One of those enzymes was then explored for its utility as an addition to mashing with a view to lowering the gushing potential of the ensuing beer.

What are the main findings: The four enzyme preparations (Smizyme LP-G, Thermoase PC, Bromelain and Papain) were all capable of digesting hydrophobin. Of these, papain was chosen to assess whether the use of such an enzyme in mashing could ameliorate the gushing potential in finished beers. It was demonstrated that this can be achieved and without apparent detriment to the foaming potential of those beers.

Why is the work important: It is now possible for brewers to consider an alternative approach to rectifying gushing risks if they are confronted with problematic grain. It must be stressed that this technique will not address the other main risk from infections of this type, namely the production of mycotoxins. Even in a context where gushing is not a problem, this work has indicated that there should be little concern with addition of papain at the mashing stage from a perspective of decreasing the foaming performance of beer.

Heat resistance of Lactobacillus brevis, Pediococcus acidilactici and Enterococcus faecium in buffer (pH 4), alcoholic and alcohol-free beer

2024-07-10T14:31:07-07:00

Why was the work done: To measure the heat resistance of three vegetative bacteria in buffer (pH 4), alcoholic and alcohol-free beer. To verify that Pediococcus acidilactici ATCC 8042 and Lactobacillus brevis BSO 566 are as heat resistant as previously reported and to establish if Enterococcus faecium NRRL B-2354 could have application in validation studies for the pasteurisation of beer.

How was the work done: : The heat resistance of L. brevis, P. acidilactici and E. faecium in buffer, alcoholic and alcohol-free beer was determined using two approaches - capillary test tubes and flask method.

What are the main findings: E. faecium was the most heat resistant microorganism in all three liquids. D values were significantly greater, and z-values were similar or significantly greater than the corresponding values of L. brevis and P. acidilactici.

Why is the work important: E. faecium is used in the food industry as a pathogenic surrogate for the validation of thermal and non-thermal processes. The work reported here suggests that E. faecium can also be used for the validation of pasteurisation of beer. Its high z-value suggests that at higher pasteurisation temperatures (>65°C) it may be more resistant than yeast ascospores and could therefore be used as an indicator for flash pasteurisation.

Malting - ‘the middle parts of fortune’ - a history of innovation and the enduring quest for efficiency

2024-08-16T19:05:04-07:00

Why was the work done: The malting process has long been a target for innovation to improve malt quality. The efficiency of utilisation of labour, capital, water and energy, particularly the energy intensive kilning process is a key target for maltsters to reduce the environmental footprint and costs. Similarly, water use during steeping is a priority due to scarcity of water and regulations regarding the disposal of wastewater.

How was the work done: A comprehensive review of the literature was undertaken to identify prospects for improving the efficiency of the malting process.

What are the main findings: The malting process involves: (i) selection of barley variety of suitable quality (protein, microbiologically sound); (ii) cleaning and grading; (iii) steeping in water with dry rests over one to two days, moisture increases from 10-13 to >40% (ideally 42-45%); (iv) germination at 12-16°C in a flow of humid air to maintain malt moisture at 42-46%; (v) kilning at between 50-85°C with hot dry air and (vi) storage and blending of malt to specification. Analysis of these steps shows that there is potential to reduce water use and discharge by ~40% with the Optisteep® system. In terms of energy, kilning uses 80-90% of all malting energy (conventionally gas), which makes kilning attractive for energy savings. Marginal energy savings can be made by lowing malt moisture to <40% before germination/kiln transfer and reducing malt moisture to <9% rather than 4-6%. Novel solutions include using green malt and barley brewing which save energy (especially kilning). Although for brewing with unkilned green malt, significant challenges remain to be solved. However, over the past 25 years, maltsters have been successful in incrementally reducing kilning energy by 20-35% per decade.

Why is the work important: Increasing malting efficiency while maintaining or improving quality has important implications for reducing costs and reducing the environmental footprint of the malting process.

Reflections

2024-05-13T00:13:46-07:00

This issue of Reflections reports the latest update of ‘citation impact’ metrics for the Journal. The two year ‘Impact Factor’ has dropped marginally from 2.6 to 2.4 whereas the four year CiteScore has jumped from 4.8 to 6.2. These metrics capture the average citation per paper over time. With the Impact Factor this reflects a range of of citations over two years from 11 to none! Pleasingly, the publication KPIs that segment the process are showing encouraging signs of tightening, especially the previously problematic ‘time to create/edit pdf’. Changing tack, ‘appearances matter’. In this case, the cover for the ‘new’ Journal has been the fixed image used during the Wiley years. This has been replaced with a new cover image differentiated by colour to reflect the four issues by season. In terms of content, this issue contains three research papers and a major review from Evan Evans and colleagues on innovation and efficiency in malting.