04 July 2024

BrewingScience May/June issue out now

Nuremberg | The online-journal BrewingScience features peer-reviewed scientific papers with impact on the brewing industry. The May/June 2024 issue is out now. It was sponsored by Hopsteiner. The brief article abstracts below provide a good initial overview of the content, the full articles can be read online at https://www.brewingscience.de.

The latest BrewingScience issue contains the following articles:

Review: “Are the days of Congress mashing over?”

The operating parameters chosen for the small-scale mash to determine malt quality are critical in defining malt quality. These key malt quality parameters include extract, attenuation, Kolbach Index (KI), wort FAN, viscosity, β-glucan, colour etc. The Congress mash (45 °C – 30 min, 0.2 mm grist grind, 1:4 grist : water, ramp to 70 °C (1 °C/min), rest 25 – 60 min, lautering at 1:9 G:W ratio, RT) is currently the industry agreed small-scale mashing protocol for malt quality analysis. The Congress protocol appears to have its origins from a German Brewers Convention in Vienna in 1815, later formalized in 1907. As such, the Congress mash was developed to assess the malts of the time that were less modified and homogenous than before the innovations of malting engineers Nicholas Galland and Charles Saladin (c. 1870 – 1890) that ushered in modern pneumatic malting production.

Prof Martina Gastl (TUM, Germany) concluded that the Congress mash favours cytolytic (and proteolytic) modification compared to modern mashing practice that mash in at 60 – 65 °C which favours amylolytic modification. Prof Barry Axcell (South African Breweries Ltd., RSA), among others, critiqued malt quality analysis for providing brewers with inferior practical information with respect to high gravity brewing, lautering, attenuation, foam, flavor and colloidal stability. Central to improving malt quality analysis was a complete revaluation of the small-scale mashing protocol. This review sequentially considers what the likely optimum parameters are.

The review concludes that potential starch hydrolysis into fermentable sugars is best determined by mashing in at 65 °C for 60 min (compromise between starch gelatinization and DP enzyme thermostability), a grist grind of 0.7 mm (possibly 0.4 mm), addition of 1.4 mM Ca2+ (56 ppm Ca2+), a 1:3 grist:water ratio (higher gravity) and mash out temperature of 78 °C which is broadly in line with modern commercial brewing practice. For small-scale practical convenience and efficiency, ‘lautering’ at 1:9 G:W ratio and at RT, as with the Congress mash was preserved. Comparison of this style of mash shows broad agreement (correlation) with the Congress mash for extract, attenuation, wort FAN, KI, β-glucan and protein, however the ranking of samples is substantially different. This perspective is important for brewers, but critical for malting barley breeders whose selection indices between candidate breeding lines are largely based on agronomic and quality rank to provide improved resolution between high malting quality progeny.

Influence of winemaking by-products on the phenolic activity of beer

This research explores a novel approach in beer production by incorporating waste materials such as grape seeds and skins, derived from wine processing, into the brewing process. This initiative holds promise for effective waste utilization, advancing craft beer, and utilizing cost-effective raw materials. Experiments explore the integration of grape by-products into beer production, evaluating their impact on polyphenol levels and sensory characteristics. The laboratory and pilot brewhouse trial results revealed a significant increase in the total polyphenol content when 0.6 % grape seeds were added during the boiling process. Specifically, the total polyphenol value doubled, reaching up to 500 mg/l compared to the 250 mg/l found in classical pilsner-type beer. The study indicates that grape seed addition is significantly more effective than grape skin addition under the same conditions, yielding around 1.5 times or more polyphenols. Sensory evaluations revealed a preference for beers supplemented with white grape seeds compared to red grape seeds, providing a unique taste experience with a pleasant grape aroma. Moreover, beers with grape seed additions exhibited elevated levels of specific polyphenolic compounds, particularly catechin and epicatechin.

Additionally, the antioxidant capacity of the beer slightly increased with grape seed incorporation and colloidal stability was not negatively affected.

Insights into a systematic analysis of novel brewhouse worts in comparison to conventional lauter tun worts and its effects on the brewing process

The present paper, as continuation of the review “Relevant process steps influencing wort and beer composition and quality: A review” [1], deals with the results of a systematic analysis of novel brewhouse worts, based on an integrated, dynamic lautering technology, in comparison to conventional lauter tun worts and its effects on the whole brewing process. In order to balance and compare the influence on the wort composition and the impact of certain ingredients, top- and bottom-fermented beers are produced on a 30-liter scale using the conventional and a novel brewing technology. It is shown that the alternative brewhouse technology and the resulting process influence the entire brewing and fermentation process as well as the finished beer.

Compared to the conventional brewhouse, the novel brewhouse system exhibits advantageous differences. Nutrient-rich wort is produced for the yeast and high final fermentation degrees are achieved during the fermentation process. The results show, the new brewhouse technology is a suitable alternative to the existing brewhouse technology.

The present paper, as continuation of the review “Relevant process steps influencing wort and beer composition and quality: A review” [1], deals with the results of a systematic analysis of novel brewhouse worts, based on an integrated, dynamic lautering technology, in comparison to conventional lauter tun worts and its effects on the whole brewing process. In order to balance and compare the influence on the wort composition and the impact of certain ingredients, top- and bottom-fermented beers are produced on a 30-liter scale using the conventional and a novel brewing technology. It is shown that the alternative brewhouse technology and the resulting process influence the entire brewing and fermentation process as well as the finished beer. Compared to the conventional brewhouse, the novel brewhouse system exhibits advantageous differences. Nutrient-rich wort is produced for the yeast and high final fermentation degrees are achieved during the fermentation process. The results show, the new brewhouse technology is a suitable alternative to the existing brewhouse technology.

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