Proteome analysis of the wort boiling process

A comprehensive proteome map was constructed of brewers wort. The map consisted of protein identification on two-dimensional gel electrophoresis (2DE) images and identified 63 out of 202 protein spots, which were categorized into 20 protein species. To analyze the modification of protein Z during wort boiling, protein Z spots on 2DE gel of the sweet wort, the boiled wort and the trub were analyzed by matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI TOF-MS) and then the spectra were compared. The analysis identified several specific signals detected only in the trub, suggesting that specific modification occurred in the precipitated protein Z during wort boiling. The protein Z spot on the 2DE gel of the precipitate was further analyzed by liquid chromatography mass spectrometry/mass spectrometry. The analysis identified low molecular weight fragment (1.3. kDa) derived from wound induced protein (barwin) in the protein Z spot of the trub. These results suggested that protein Z was precipitated by binding with comparatively small size specific fragment(s) derived from sweet wort protein, i.e., barwin during wort boiling. Our results and understandings have application for quality assurance and control in commercial brewing practice, and development of DNA markers for malting barley breeding.