Construction of a novel beer proteome map and its use in beer quality control
Introduction
Beer foam quality is one of the important characteristics that a consumer uses to determine beer quality. Foam quality is defined by its stability, lacing, whiteness, intensity, strength, and creaminess (Bamforth, 1985). In clear beer, colloidal haze formation is also a serious quality problem. Consumers judge a beer as stale or not fit to drink if it displays colloidal haze. Foam stability (Bamforth, 1985, Evans and Sheehan, 2002) and haze formation (Asano et al., 1982, Iimure et al., 2009, Siebert, 1999) have been assumed to be major quality traits controlled by proteins. In beer foam stability, several beer proteins have been identified as either foam-positive or negative. Previous reports suggested that protein Z (Evans et al., 1999, Evans et al., 2003, Kaersgaard and Hejgaard, 1979, Maeda et al., 1991) and lipid transfer protein 1 (LTP1) (Jégou et al., 2000, Sorensen et al., 1993) play important roles in beer foam stability. In addition, recent studies have suggested that barley dimeric α-amylase inhibitor-1 (BDAI-1) and yeast thioredoxin are foam-positive and foam-negative proteins, respectively (Iimure et al., 2008, Okada et al., 2008). In beer colloidal haze, CMe component tetrameric α-amylase inhibitor (CMe), BDAI-1 and hordein were suggested as haze active (Asano et al., 1982, Evans et al., 2003, Iimure et al., 2009, Robinson et al., 2007, Siebert, 1999). However, conclusive identification of protein factors causing beer foam stability and haze formation still requires validation. One of the reasons for the poor understanding of protein factors may come from the lack of knowledge of the spectrum of proteins in beer. Thus, comprehensive analysis of beer protein identity is necessary to reveal the relationship between beer proteins with respect to quality characters including foam stability and haze formation.
Barley cultivar and the level of protein modification during malting are also known as important malting related factors that can modify beer quality (Evans et al., 1998, Iimure et al., 2008). Protein modification is judged by malt modification which is conventionally measured in the brewing industry as the Kolbach index (soluble nitrogen/total nitrogen × 100). Therefore, the understanding of beer protein also requires an understanding of the effect of different barley cultivar and malt modification combinations in important quality proteins (i.e., hordeins, protein Z).
Proteome analysis, which separates a sample of proteins by two-dimensional gel electrophoresis (2DE) which is followed by mass spectrometry analysis and database searches, is a powerful tool to comprehensively detect the spectrum of proteins present in a beer sample. In several reports, proteins from barley grain and malt were analysed by 2DE and major protein spots were identified (Bak-Jensen et al., 2004, Østergaard et al., 2004). Also major beer proteins were identified by mass spectrometry (Hao et al., 2006, Perrocheau et al., 2005). Similarly, Iimure et al., 2008, Iimure et al., 2009 identified foam proteins and haze active proteins using a proteome analysis.
To expand these pioneering analyses, this study develops a comprehensive proteome map of beer for Japanese style lager beer. Recent advancements in protein analysis enable the development of a proteome map with greater resolution by identifying relatively minor spots. The use of the proteome map is applied practically, to assess eleven beer samples that were prepared with different barley cultivars and levels of malt modification. The efficient application of protein spot intensities on 2DE images is discussed to control foam stability and haze formation.
Section snippets
Barley sample, malting and malt quality analysis
The barley-malt materials used in this study are described in Table 1. Each 75 kg barley grain sample from a single cultivar (>2.5 mm screen) was processed according to Okada et al. (2008). For cultivars F, G and H, two different ex-steep moisture levels, i.e., low (36–37%) and high (43–44%), were used to influence malt modification, thus assess its influence on beer protein composition. Malt quality characters were analysed according to the standard methods of the European Brewery Convention (
Identification of major beer proteins on the 2DE gels
Proteins in standard beer samples (i.e., Beer F(L)), were separated by 2DE (pI 4–7 and 6–9) (Fig. 1) and individual protein spots were analysed by MALDI-TOF-MS or LC-MS/MS followed by database searches to determine spot identity. The search engines identified 85 out of 199 protein spots which were categorised into 12 protein species (Table 2). According to the source of sequences on the databases, 8 out of the 12 protein species were derived from Hordeum vulgare subsp. vulgare and the remaining
Discussion
A total of 85 protein spots on 2DE gels (Fig. 1 and Table 2) together with data set for the 2DE images were identified in the current proteome analysis. Perrocheau et al. (2005) also analysed beer proteins by 2DE and mass spectrometry but resulted in identification of only 31 protein spots. Hao et al. (2006) identified major proteins in beer foam by mass spectrometry following sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS–PAGE), which made protein composition comparison
Acknowledgements
We are grateful to T. Yazawa, K. Ito and N. Yatabe, the Bioresources Research and Development Department, Sapporo Breweries Ltd. for their technical assistance. We are also grateful to K. Takoi for the beer sample preparation. This study was supported by the Program for Promotion of Basic Research Activities for Innovative Biosciences, Japan (PROBRAIN).
References (39)
Yeast thioredoxin genes
The Journal of Biological Chemistry
(1991)- et al.
The impact of the physiological condition of the pitching yeast on beer flavor stability: An industrial approach
Food Chemistry
(2004) - et al.
Identification of novel haze-active beer proteins by proteome analysis
Journal of Cereal Science
(2009) - et al.
Identification and functional characterization of a novel mitochondrial thioredoxin system in Saccharomyces cerevisiae
The Journal of Biological Chemistry
(1999) - et al.
The identification of a barley haze active protein that influences beer haze stability: Cloning and characterization of the barley SE protein as a barley trypsin inhibitor of the chloroform/methanol type
Journal of Cereal Science
(2007) - et al.
Characterization of haze-forming proteins of beer and their roles in chill haze formation
Journal of the American Society of Brewing Chemists
(1982) - et al.
Two-dimensional gel electrophoresis pattern (pH 6–11) and identification of water-soluble barley seed and malt proteins by mass spectrometry
Proteomics
(2004) The foaming properties of beer
Journal of the Institute of Brewing
(1985)- et al.
Throughout the brewing process barley lipid transfer protein1 (LTP1) is transformed into a more foam-promoting form
- et al.
Yeast proteinase in beer
Carlsberg Research Communications
(1983)
European brewery convention
The influence of malt foam positive proteins and non-starch polysaccharides on beer foam quality
European Brewery Convention Monograph
The impact of malt derived proteins on beer foam quality. Part II. The influence of malt foam-positive proteins and non-starch polysaccharides on beer foam quality
Journal of the Institute of Brewing
Don’t be fobbed off: The substance of beer foam, a review
Journal of the American Society of Brewing Chemists
Application of immunological methods to differentiate between foam-positive and haze-active proteins originating from malt
Journal of the American Society of Brewing Chemists
Comparison of foam quality and the influence of hop α-acids and proteins using five foam analysis methods
Journal of the American Society of Brewing Chemists
Beer foam: Achieving a suitable head
The acidification power test and the behavior of yeast in brewery fermentations
Technical Quarterly-Master Brewers Association of the Americas
Identification of the major proteins in beer foam by mass spectrometry following sodium dodecyl sulfate–polyacrylamide gel electrophoresis
Journal of the American Society of Brewing Chemists
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