Identification of novel haze-active beer proteins by proteome analysis

Takashi Iimure, Nami Nankaku, Megumi Watanabe-Sugimoto, Naohiko Hirota, Zhou Tiansu, Makoto Kihara, Katsuhiro Hayashi, Kazutoshi Ito, Kazuhiro Sato

Research output: Contribution to journalArticlepeer-review

58 Citations (Scopus)


Colloidal haze reduces beer quality considerably. Four haze samples were analyzed by two-dimensional gel electrophoresis (2DE) in order to identify haze-active proteins. Several protein spots were observed in all of the four haze samples. Using mass spectrometry analysis followed by a database search identified these spots as barley dimeric alpha-amylase inhibitor (BDAI-1), CMb component of tetrameric alpha-amylase inhibitor (CMb) and trypsin inhibitor CMe precursor (CMe). These proteins were considered to be haze-active. Since haze-active proteins are adsorbed by silica gel in the beer filtration process, we eluted proteins adsorbed onto silica gel (PAS) and identified their species. These major PAS were identified as protein Z4, protein Z7 and trypsin/amylase inhibitor pUP13 (TAI), rather than BDAI-1, CMb and CMe. Furthermore, we analyzed proline compositions in the beer proteins, PAS and the haze proteins. Consequently, we found that the proline compositions of PAS were higher (ca. 20 mol%) than those in the beer proteins (ca. 10 mol%), although those of the haze-active proteins such as BDAI-1, CMb and CMe were 6.6-8.7 mol%. Our results suggest that BDAI-1, CMb and CMe are not predominant haze-active proteins, but growth factors of beer colloidal haze.

Original languageEnglish
Pages (from-to)141-147
Number of pages7
JournalJournal of Cereal Science
Issue number1
Publication statusPublished - Jan 2009


  • Barley
  • Beer colloidal haze
  • Proteome analysis

ASJC Scopus subject areas

  • Food Science
  • Biochemistry


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