The aim of this work was to determine the impact of temperature on fermentation and maturation, and the volatile composition of beer and yeast viability on an industrial scale. Fermentations were conducted at 8.5, 10 and 11.5°C with maturation at −1°C. During fermentation and maturation, the changes in extract, yeast growth and esters, alcohols and carbonyl compounds were investigated. Experiments confirmed that the temperature of fermentation had a significant impact on the course of fermentation and maturation. As the wort fermentation temperature increased, the content of acetaldehyde and vicinal diketones decreased whilst the content of esters and higher alcohols increased. Copyright © 2018 The Institute of Brewing & Distilling

The aim of the study was to determine the effect of the initial beer wort aeration on the process of fermentation, maturation, content of the volatile components of beer and abundance and vitality of yeast biomass. The experiments were performed on an industrial scale, with fermentation and maturation performed in fermentation tanks with a capacity of 3800 hL. The wort was aerated with sterile air in quantities as follows: 7, 10 and 12 mg/L. During fermentation and maturation, the changes in the content of the extract, yeast growth and vitality and more importantly volatile components were investigated. The experiments showed that differentiated aeration has a significant impact on the course of fermentation and metabolic changes. With the increase in wort aeration, the content of acetaldehyde decreased and the concentration of higher alcohols increased. On the other hand, the contents of esters and vicinal diketones did not change. The level of aeration did not affect the final quality of beer. Copyright © 2017 The Institute of Brewing & Distilling

Contents of selected volatile esters and fusel alcohols and their relation to the sensory quality of a bottom-fermented lager beer fermented under high-gravity conditions (15.5 °P) were analyzed using response surface methodology (RSM, Box–Behnken design). The influence of various pitching rates (6–10 mln cells/mL), aeration levels (8–12 mgO₂/mL), times (4.5–13.5 h) of filling CCTs (cylindroconical fermentation tanks; 3850 hL), and fermentation temperatures (8.5–11.5 °C) on the contents of selected esters, as well as on concentrations of amyl alcohols and on the sum of higher alcohols in beer, was determined in a commercial brewery fermentation plant. Beers produced throughout the experiments met or exceeded all criteria established for a commercial, marketed beer. Statistical analyses of the results revealed that within the studied ranges of process parameters, models with diversified significance described the concentrations of volatiles in beer. The multiple response optimization procedure analyses showed that the values of process parameters that minimized higher alcohols in beer (97.9 mg/L) and maximized its ethyl acetate (22.0 mg/L) and isoamyl acetate (2.09 mg/L) contents, as well as maximized the sensory quality of beer, (66.4 pts) were the following: Pitching rate 10 mln cells per mL; fermentation temperature 11.5 °C; aeration level 8.8 mg/L; and CCT filling time 4.5 h.

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.

The growth and viability of yeast cells used for fermentation of lager beer (anaerobic process) were optimized under high-gravity brewing conditions (15.5 °P) in an industrial plant. The influence of different levels of pitching rates (6–10 million cells/mL), aeration (8–12 mgO₂/L), times (4.5–13.5 h) of filling cylindroconical tanks (CCTs) (3850 hL), and different fermentation temperatures (8.5–11.5 °C) on the multiplication of yeast biomass and the percentage of dead yeast cells was investigated using a response surface methodology (RSM, Box–Behnken design). The obtained results of the influence of the tested parameters on the increase in yeast biomass and their viability were characterized by statistical significance (p < 0.05). Except for the fermentation temperature, which had no effect on the viability of fermenting yeast cells, all independent variables affected both the yeast growth and yeast cell viability.

Control of selected fermentation indices by statistically designed experiments in industrial scale beer fermentation | Krzysztof Kucharczyk, Krzysztof Żyła, Tadeusz Tuszyński | Agricultural Journals