Yeasts in malting, with special emphasis on Wickerhamomyces anomalus (synonym Pichia anomala)

Arja Laitila (Corresponding Author), Tuija Sarlin, Mari Raulio, Annika Wilhelmson, Erja Kotaviita, Timo Huttunen, Riikka Juvonen

Research output: Contribution to journalArticleScientificpeer-review

22 Citations (Scopus)

Abstract

Malted barley is a major raw material of beer, as well as distilled spirits and several food products. The production of malt (malting) exploits the biochemical reactions of a natural process, grain germination. In addition to germinating grain, the malting process includes another metabolically active component: a diverse microbial community that includes various types of bacteria and fungi. Therefore, malting can be considered as a complex ecosystem involving two metabolically active groups. Yeasts and yeast-like fungi are an important part of this ecosystem, but previously the significance of yeasts in malting has been largely underestimated. Characterization and identification of yeasts in industrial processes revealed 25 ascomycetous yeasts belonging to 10 genera, and 18 basidiomycetous yeasts belonging to 7 genera. In addition, two ascomycetous yeast-like fungi belonging to the genera Aureobasidium and Exophiala were commonly detected. Yeasts and yeast-like fungi produced extracellular hydrolytic enzymes with a potentially positive contribution to the malt enzyme spectrum. Several ascomycetous yeast strains showed strong antagonistic activity against field and storage moulds, Wickerhamomyces anomalus (synonym Pichia anomala) being the most effective species. Malting studies revealed that W. anomalus VTT C-04565 effectively restricted Fusarium growth and hydrophobin production during malting and prevented beer gushing. In order to broaden the antimicrobial spectrum and to improve malt brewhouse performance, W. anomalus could be combined with other starter cultures such as Lactobacillus plantarum. Well-characterized microbial mixtures consisting of barley and malt-derived microbes open up several possibilities to improve malt properties and to ensure the safety of the malting process.
Original languageEnglish
Pages (from-to)75-84
Number of pages10
JournalAntonie van Leeuwenhoek
Volume99
Issue number1
DOIs
Publication statusPublished - 2011
MoE publication typeA1 Journal article-refereed
Event1st International Pichia anomala mini-Symposium - Uppsala, Sweden
Duration: 10 Feb 201012 Feb 2010

Keywords

  • Malting
  • yeast
  • Wickerhamomyces
  • Pichia
  • Fusarium
  • lactic acid bacteria
  • biocontrol

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