BrewingScience July/August issue out now

In August 2024, the latest BrewingScience issue was published online. The scientific online-journal BrewingScience features peer-reviewed scientific papers with impact on the brewing industry. The brief article abstracts below provide a good initial overview of the content.

The latest BrewingScience issue contains the following articles:

Fermentation temperature impacts polyfunctional thiol biotransformation in beer

Hop-forward beers such as IPAs potentially draw their fruity and sometimes exotic tropical aroma profile in part from yeast biotransformation of hop compounds. This study examined how yeast strain and fermentation temperature influence the interplay of thiol release and fermentation ester production and ultimately the flavor of these types of beers.

How the amount and timing of dry-hopping affects beer turbidity

The aim of this study was to investigate the effects on beer turbidity after dry-hopping. Firstly, depending on the quantity of hop pellets added and secondly, when varying the dosing point while maintaining a constant hopping rate. Selected chemical and physical properties of the finished beer were also investigated for both scenarios (quantity and time of dry-hopping). Both the “trial quantity” (TQ) and “trial timing” (TT) resulted in significant effects with regards to the increase in turbidity in the dry-hopped beers. Gradually increasing dry-hop dosing rates in TQ correlated well with the greater turbidity according to both methods used, MEBAK and OD600. All dry-hopped beers in TT showed a significant increase in turbidity compared to the base beer.

This haze was further intensified with a very late dry-hop dosage at the end of maturation. The turbidity was, along with other selected variables, also analysed after the beer had been stored for 6 months at 20 °C, “trial storage” (TS). Both, the supernatant formed after storage and the homogenised beers were investigated. The results of the stored and homogenised samples showed highly comparable and, in some cases identical results compared to analyses of freshly bottled beers of TQ and TT. The effect of the dry-hopping variations of TQ and TT could still be demonstrated analytically in the supernatants and visually in the settled beers. Pictures were taken to visualise the behaviour of the various dry-hopped beers to link the results to the visual expectations that consumers have of commercially available beers.

The barley malting microbiome: influence on malt quality, control and characterization methods

The conversion of raw grains to malt is a pivotal step in the beer production process. By germination, the grains produce enzymes necessary for the conversion of starch into sugars during the mashing process, but also cell wall constituents are broken down which aids in wort filtration. Further, storage proteins are converted into soluble peptides and amino acids important for yeast nutrition during fermentation. However, the performance of the malting process and the quality of malt produced is also significantly influenced by the active microbial communities that naturally colonise the barley grains. These diverse microbial communities have the potential to produce extracellular enzymes, phytohormones, mycotoxins, and exopolysaccharides, and also compete with the grains for oxygen. While microbes can contribute positively to the break-down of cell wall β-glucans and arabinoxylans, they can also negatively impact the final malt quality by production of gushing precursors, compounds leading to premature yeast flocculation (PYF) and mycotoxins.

This review provides an overview of the current knowledge on the different microbial communities interacting with the barley grain on the field and during malt production, their influence on the quality of produced malt, and the brewing process. Further, current strategies to control the proliferation of detrimental microbial species during malting are presented, including a summary on recent techniques to identify, quantify and functionally characterise the barley malting microbiome.

Read the full articles at www.brewingscience.de.