On the contribution of malt quality and the malting process to the formation of beer staling aldehydes: a review

Abstract

Despite decades of extensive research, beer flavour instability remains a challenge for both brewing and malting industries. Malt impacts the brewing process as well as the quality of the final beer. It also affects the stability of beer flavour, as it delivers to the brewing process various compounds with the potential to compromise the desired flavour characteristics of beer. These include staling aldehydes and their precursors, such as amino acids, reducing sugars, α‐dicarbonyls and bound‐state aldehydes. In general, the content of these compounds depends on barley variety and quality, the malting regime and final malt quality. Malt that represents a low potential for beer staling, i.e. that has low values of Kolbach Index, heat load, colour, LOX activity, Strecker aldehydes, transition metal ions and high antioxidative activity, leads to beer with enhanced flavour stability. However, the consistent production of malt with the desired quality remains challenging. Approaches to achieve this include adjustment of steeping and germination conditions, allowing control of grain modification and thus, the reservoir of aldehydes precursors. Also, the application of alternative kilning technologies may reduce the applied heat load, responsible for the formation of staling aldehydes and triggering development of the oxidising free radical species. This review provides an evaluation of current knowledge on the contribution of the malting process and malt quality to the formation of beer staling aldehydes. © 2021 The Authors. Journal of the Institute of Brewing published by John Wiley & Sons Ltd on behalf of The Institute of Brewing & Distilling.

A Comprehensive Evaluation of Flavor Instability of Beer (Part 1): Influence of Release of Bound State Aldehydes

“…The formation of Hex and T2N is influenced by the concentration of lipids (varying by environment and cultivar) and the enzymes involved in their degradation during malting and brewing. Thus, their concentration is independent of the N species [20].…”

“…They originate mainly from the malt used in the brewing process. The number of reactants (amino compounds) in barley depends on the barley variety and crop year [20]. During germination, barley crude proteins are enzymatically degraded (proteolytic malt modification).…”

Production of non‐alcoholic beer via cold contact fermentation with Torulaspora delbrueckii

“…Control of aldehyde content in NABs is critical to producing acceptable beers. As noted by Filipowska et al (14), the initial concentrations of aldehydes in pale malts may vary significantly, highlighting the importance of careful malt selection. In the same study, it was shown that aldehyde levels can vary depending on malting conditions.…”

Assessment of Staling Aldehydes in Lager Beer under Maritime Transport and Storage Conditions

“…This staling process leads to a continuous loss of beer bitterness, associated with the degradation of iso-α-acids, as reported by Caballero, et al [5]. Moreover, the appearance of haze, evolution of color, and changes in volatile composition, such as loss of esters and a simultaneous increase in staling aldehydes, are the main modifications to beer flavor stability critically reviewed and reported [4,[6][7][8][9]. Additionally, Lehnhardt, et al [10] discussed changes in beer sensorial profile during storage, namely in terms of an aged flavor.…”