Abstract
The levels of selected volatile components that affected the sensory properties of a lager beer were optimized under high-gravity brewing conditions (15.5 °P) in an industrial plant. The influence of different pitching rates (6–10 million cells/mL), aeration levels (8–12 mg/L), times (4.5–13.5 h) of filling CCTs (cylindroconical tanks, 3850 hl), and fermentation temperatures (8.5–11.5 °C) on the contents of acetaldehyde, diacetyl, acetone, 2,3-pentanedion, dimethyl sulfide (DMS), and on the sensory properties of beer were investigated. Response surface methodology (RSM, Box–Behnken design) was used to research the possibilities for optimizing the concentration of selected volatile components and sensory properties of bottom-fermented lager beers. Statistical analyses of the results showed that the experimental factors had a significant influence (R-squared for the original model with no significant lack-of-fit) on some of the volatile components. Based on the Multiple Response Optimization analysis, the values of independent factors that ensured the highest beer sensory quality were the following: a pitching rate of 10 million cells per mL; a fermentation temperature of 11.5 °C; an aeration level of 12 mg/L; and a CCT filling time of 4.5 h. These results proved that RSM modelling can be successfully applied to optimize fermentation and lagering processes in an industrial plant to manufacture lagers of enhanced sensory quality.
Highlights
The main processes that generate a broad range of flavor components in beer include malting, mashing, and boiling of wort with hops
Information provided by Alves and coworkers [3] using headspace solidphase microextraction followed by gas chromatography mass spectrometry (HS-SPME/GC-MS) identified an additional 60 volatile organic metabolites at different steps of the beer production processes that contributed to the sensory quality of a lager beer
Within the studied ranges of pitching rate, aeration level, times of filling CCTs, and fermentation temperature, the experimental factors had a significant influence on the acetaldehyde and dimethyl sulfide (DMS)
Summary
The main processes that generate a broad range of flavor components in beer include malting, mashing, and boiling of wort with hops. Yeast cells synthesize secondary volatile metabolites along with ethanol and carbon dioxide. These secondary substances are mostly produced at very low concentrations, they comprise many classes of compounds that are thought to be responsible for the complex aromas of fermented beverages, including beer, wine, and sake [1]. Meilgaard reviewed a list of around 100 flavor constituents responsible for individual flavor notes and discussed their interactions determining the overall character of a given beer brand [2]. The regulation and control of the synthesis of yeast-derived flavor-active beer compounds such as ethanol, CO2 , carbonyls (aldehydes/ketones), higher/fusel alcohols, esters, vicinal diketones (VDK) Information provided by Alves and coworkers [3] using headspace solidphase microextraction followed by gas chromatography mass spectrometry (HS-SPME/GC-MS) identified an additional 60 volatile organic metabolites at different steps of the beer production processes that contributed to the sensory quality of a lager beer.
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