Biology Reference
In-Depth Information
Chapter 51
Beer and Wort Proteomics
Takashi Iimure , Makoto Kihara , and Kazuhiro Sato
Abstract
Proteome analysis provides a way to identify proteins related to the quality traits of beer. A number of
protein species in beer and wort have been identifi ed by two-dimensional gel electrophoresis combined with
enzyme digestion such as trypsin, followed by mass spectrometry analyses and/or liquid chromatography
mass/mass spectrometry. In addition, low molecular weight polypeptides in beer have been identifi ed by
the combination of non-enzyme digestion and mass analyses. These data sets of various molecular weight
polypeptides (i.e., proteomes) provide a platform for analyzing protein functions in beer. Several novel
proteins related to beer quality traits such as foam stability and haze formation have been identifi ed by ana-
lyzing these proteomes. Some of the proteins have been applied to the development of effi cient protein or
DNA markers for trait selection in malting barley breeding. In this chapter, recent proteome studies of beer
and wort are reviewed, and the methods and protocols of beer and wort proteome analysis are described.
Key words
Beer, Wor t, Proteomics, Two-dimensional gel electrophoresis, Mass spectrometry
1
Introduction
Beer is one of the oldest fermented beverages, and is the most
widely consumed alcoholic drink. The raw materials of beer are
barley malt, hops, and sometimes adjuncts such as starch from corn
and/or rice. Beer is produced by a number of processes including
malting, mashing, wort boiling, fermentation, maturation, and
fi ltration. The malting process consists of three steps: steeping,
germination, and kilning. Various enzymes such as protease, amy-
lase, and
-glucan in the
malting and mashing steps. Proteins and starch are degraded into
amino acids and fermentable sugars as sources of nitrogen and car-
bon, respectively, to grow brewing yeast. In the wort boiling pro-
cess, proteins and protein-polyphenol complexes coagulate and
precipitate. Therefore, the resultant barley-derived proteins are
both protease- and heat-stable. Several modifi cations such as glyca-
tion, acylation, and partial digestion also occur in these processes.
In addition to these modifi ed proteins, beer contains low molecular
β
-glucanase degrade proteins, starch, and
β
