LILLE 2024

Aldehydes are key players in the complex interplay of compounds responsible for beer flavour instability. Yet, the flavour stability of non-alcoholic and low-alcohol beers (NABLAB) made with maltose- and maltotriose-negative yeasts remains largely unknown, with limited understanding of the underlying mechanisms. This study investigated the impact of selected alternative yeasts on aldehyde concentrations in fresh NABLAB and the evolution of these compounds during forced ageing (90 days at 30°C). The findings indicate that the low wort gravity in NABLAB production with these yeasts results in lower aldehyde levels in the wort. The alternative yeasts showed a remarkable ability to minimise aldehyde concentrations in the final NABLAB. Intriguingly, aldehyde levels generally remained low and stable during prolonged storage, except for furfural. We further investigated the influence of incorporating oat flakes, rye malt, buckwheat, einkorn and khorasan at 40% in fresh and forced-aged NABLAB made with these alternative yeasts. This study sheds new light on the flavour stability of biologically produced NABLAB and offers valuable insights into the potential of barley malt substitutes.

Flavour instability of pale lager beer remains one of the greatest challenges for breweries – independent of their size. While factors such as heat stress, oxygen exposure, and yeast vitality have been extensively explored, the influence of brewhouse materials on the concentration of aging indicators in a real-life scale remains an understudied aspect. This research delved into the intricate relationship between brewhouse parameters (e.g. boiling system and brewhouse material) and aroma-relevant aldehydes, aiming to uncover their potential impact on the flavor stability of beer.
In this study, a investigation across 21 diverse breweries with vastly different facilities, ranging in size from 2,000 hl/a to approximately 3.0 million hl/a was performed. Amongst other parameters, aroma-relevant aldehydes were monitored from raw materials through the entire wort production process and in the final beer (fresh and forced aged).
The findings revealed a continous decrease of aldehydes throughout the wort production process, with the initial levels derived from malt proving to be a pivotal factor. Interestingly, despite the variation in brewhouse materials, no clear correlation between thes

Beer bottle refermentation is a complex process involving the introduction of additional yeast strains, typically Saccharomyces and Brettanomyces, to enhance flavor diversity, carbonation levels, and beer stability. This study investigates the intricate flavor dynamics and sensory attributes associated with different beer bases, comparing the use of various Saccharomyces and a Brettanomyces strain for bottle conditioning over time and storage conditions. Conducted at a pilot scale, the study employs both analytical methods and sensory evaluations by trained assessors to determine flavor profiles comparatively with same beers with traditional CO2 saturation. The research yields valuable insights into the distinct contributions of each yeast strain to the overall flavor profile of the beers, uncovering the dynamic interplay between yeasts and their profound influence on flavor development over time. It offers a scientific exploration of the science behind refermentation process, serving as a valuable resource for brewers aiming to craft and diversify beers through yeast-driven processes.

The characteristic hoppy flavor of pale ales is known to deteriorate over time. Recent findings suggest that hop constituents complex metal ions in beer thereby suppressing their negative effect on beer flavor stability. This study investigates the impact of hop pellets and hop extract in the whirlpool on the concentration of metal ions in wort and beer and the resulting flavor properties during aging. In lab scale, whirlpool additions of extract and pellets reduced metal ion concentrations in wort, especially Fe. Based on identified dose- and product-related effects, 2.5-hL brewing trials were performed with selected dosages of extract or pellets revealing significant differences in resinous and sweaty flavor between dosage levels and, to a lesser extent, between products. Beer flavor stability was predicted using ESR spectroscopy and verified by forced aging and monitoring beer flavor changes by sensory evaluation. Results indicate that extract and pellet whirlpool hopping both improve beer flavor stability by reducing the formation of age-related off-flavors and by supporting retention of flavors related to freshness with only minor variations between the two hop products.