Abstract

Secondary metabolites such as esters and higher alcohols produced by yeasts during fermentation were reported to have large effects on the final sensorial quality of fermented beverages. This work aimed to assess the fluctuations in beer esters and higher alcohols content due to process parameters variation during primary fermentation. Therefore, fermentation trails were conducted at industrial scale using a commercial lager brewing yeast. Esters and higher alcohols profiles were determined following fermentation efficiency by monitoring yeast growth, ethanol synthesis, specific gravity, pH and tank pression throughout the fermentative process. Results showed increase in yeast cells (58 ± 6,55x10⁶ cells/ml) due to the high yeast multiplication resulting in intense metabolic activity. Indeed, increased ethanol yield (3,83 ±1,07 %) recorded after 5 days demonstrated higher yeast activity during primary fermentation. Yeast grow was probably enhanced by wort fermentable sugars and free amino acid content. Interestingly, the production of 2-Methyl-1-butanol (44,82 ± 4,12 mg/l), and ethyl acetate (14,89±4,58mg/l) was significantly improved during the primary fermentation. However, acetaldehyde content increased simultaneously only within 3 fermentation days (10,51 ± 0,012mg/l ). These flavor-active compounds may contribute positively to the overall sensorial properties of the final beer.

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