Malt, as a one of the major raw materials in beer production, has a great influence on beer quality. Brewers expect to receive an ingredient that well matches their requirements. Malt specifications often play an essential role for the performance of the brewing process as well as on the final characteristics of beer. Malt itself also contributes to the extremely complex matrix of beer, which comprises of around 800 compounds. Beer ages with time – many (bio)chemical transformations take place resulting in an increase in the levels of beer off-flavours, in particular in the so-called “staling aldehydes”. Many investigations on beer aging phenomena, showed that storage, transportation and packaging have a major influence on the rate of beer staling. Nevertheless, the current state of the knowledge cannot identify the true secret of the origin of staling aldehydes in aged beer. To date the contribution of malted barley to beer flavour stability was insufficiently defined or even neglected.
The presentation will focus on different stages of malting process in the view of the formation of beer staling aldehydes (via Strecker degradation, fatty acid oxidation and Maillard reactions). The importance of precursor forms – the so-called “bound-state aldehydes” – will be highlighted. The presentation will also cover the experimental data from industrial-scale maltings in relation to the determined levels of aldehydes.