title: Revealing the beneficial effect of protease supplementation to high gravity beer fermentations using "-omics" techniques.
abstract: BACKGROUND
  Addition of sugar syrups to the basic wort is a popular technique to achieve higher gravity in beer fermentations, but it results in dilution of the free amino nitrogen (FAN) content in the medium. The multicomponent protease enzyme Flavourzyme has beneficial effect on the brewer's yeast fermentation performance during high gravity fermentations as it increases the initial FAN value and results in higher FAN uptake, higher specific growth rate, higher ethanol yield and improved flavour profile.
  
  
  RESULTS
  In the present study, transcriptome and metabolome analysis were used to elucidate the effect on the addition of the multicomponent protease enzyme Flavourzyme and its influence on the metabolism of the brewer's yeast strain Weihenstephan 34/70. The study underlines the importance of sufficient nitrogen availability during the course of beer fermentation. The applied metabolome and transcriptome analysis allowed mapping the effect of the wort sugar composition on the nitrogen uptake.
  
  
  CONCLUSIONS
  Both the transcriptome and the metabolome analysis revealed that there is a significantly higher impact of protease addition for maltose syrup supplemented fermentations, while addition of glucose syrup to increase the gravity in the wort resulted in increased glucose repression that lead to inhibition of amino acid uptake and hereby inhibited the effect of the protease addition.
authors.affiliation: Center for Microbial Biotechnology, Department of Systems Biology, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark.
authors.forename: Maya P
authors.initials: MP
authors.lastname: Piddocke
authors.forename: Alessandro
authors.initials: A
authors.lastname: Fazio
authors.forename: Wanwipa
authors.initials: W
authors.lastname: Vongsangnak
authors.forename: Man L
authors.initials: ML
authors.lastname: Wong
authors.forename: Hans P
authors.initials: HP
authors.lastname: Heldt-Hansen
authors.forename: Chris
authors.initials: C
authors.lastname: Workman
authors.forename: Jens
authors.initials: J
authors.lastname: Nielsen
authors.forename: Lisbeth
authors.initials: L
authors.lastname: Olsson
mesh_terms: D001515:Beer; D010450:Endopeptidases / Q000378:metabolism*; D005285:Fermentation; D020869:Gene Expression Profiling; D005947:Glucose / Q000494:pharmacology; D018471:Hypergravity; D055442:Metabolome; D009584:Nitrogen / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000254:growth & development / Q000378:metabolism
chemical_list: D010450:Endopeptidases; C412470:flavourzyme; D005947:Glucose; D009584:Nitrogen