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Up- and down-scaling for more, but true-to-type, beer

  1. Top of page
  2. Up- and down-scaling for more, but true-to-type, beer
  3. When industry faces reactor scale-down
  4. Effects of CO2 gradients on microbial fermentations

Nienow et al., Biotechnol. J. 2011, 8, 911–925.

Craft brewers and brewer industry experts have long struggled to accelerate the process of brewing while maintaining beer quality and flavor. Major scientific breakthroughs resulting from scale-down and scale-up studies have contributed to technological advances in brewery. The industrial brewing process has become faster, more efficient, and safer. However, considerable progress is still to be done. In this issue, Alvin Nienow and colleagues provide an in-depth review of the currently used fermentation equipment used in small- and large-scale beer production. The authors highlight the importance of mechanical agitation as opposed to fermentations mixed by CO2 evolution as well as the removal of undesirable fermentation products and the location of bubble formation in industrial fermentation tanks.

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When industry faces reactor scale-down

  1. Top of page
  2. Up- and down-scaling for more, but true-to-type, beer
  3. When industry faces reactor scale-down
  4. Effects of CO2 gradients on microbial fermentations

Noorman, Biotechnol. J. 2011, 8, 934–943.

Scale-down studies provide data that should be efficiently extrapolated to the industrial scale. However, the lack of detailed information on the characteristics of large bioreactors typically hinders the effective prediction of large-scale operation conditions. In this issue, Henk Noorman, from the DSM Biotechnology Center (Delft, The Netherlands), employs the industrial workhorse Saccharomyces cerevisiae to simulate the fluid and metabolic dynamics of a 30-m3 bioreactor in small scale. The author pinpoints that the combinatorial use of microbial physiology and fluid dynamics provides more reliable down-scale simulations for large-scale applications.

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Effects of CO2 gradients on microbial fermentations

  1. Top of page
  2. Up- and down-scaling for more, but true-to-type, beer
  3. When industry faces reactor scale-down
  4. Effects of CO2 gradients on microbial fermentations

Baez et al., Biotechnol. J. 2011, 8, 959–967.

Mixing in industrial-scale bioreactors dampens the formation of heterogeneous environments that might affect the microbial cell physiology. Indeed, accumulation of CO2 in large-sized bioreactors affects growth, metabolic activity, and product formation of microbial cultures. In this issue, Octavio Ram�rez and co-workers from the Institute of Biotechnology at the National Autonomous University of Mexico firstly describe a two-compartment scale-down system to simulate variations of dissolved CO2 in large-scale bioreactors. The effects were evaluated at the transcriptional level in Escherichia coli expressing green fluorescent protein (GFP). The authors show that E. coli is able to recover rapidly from the metabolic stress resulting from high CO2 levels when sufficient mixing is provided. These findings provide evidence for the usefulness of mixing, even if poor, in industrial applications.

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