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[EN] In this project the flavor and ethanol composition of a craft Pilsen beer provided by a micro-brewery called Boga will be analyzed. The first aim of this study is to identify the flavor active compounds found in such beer and study their respective abundance evolution throughout fermentation using the GC-MS technique. The second aim is to determine its ethanol concentration through MIR spectrometry.

High quality market supplying is decisive for the beer industry due to the increasing competition and diversity in the sector. The beer-fermentation step represents 70% of all time spent on industrial beer production and it requires highly rigorous control instrumentation so it is not to become a process’ bottleneck. Numerous by-products are formed during the fermentation step and when they are not under strict control, their excess may turn into unpleasant scent and flavour on the final product. Among the sub products formed during the fermentation stage, total vicinal diketones (diacetyl and 2,3pentanedione) are the main components, since they are limiting for subsequent processing steps, besides having a low perception threshold by the consumer and giving undesirable taste and odor. On this particular work, the effects of three process variables were analysed aiming to reduce vicinal diketones concentration on the final product, and to reduce fermentation time. After yeast acidification, with Phosphoric acid, a 50% increase on cell concentration on the fermentation stage, and 0.5 °C changes on fermentation temperature, the results showed a 38% reduction on fermentation hours and 66.3% reduction on vicinal diketones production over fermentation