Beer Polypeptides and Silica Gel Part II. Polypeptides Involved in Foam Formation

Leiper, Kenneth A.; Stewart, Graham G.; McKeown, Ian P.

doi:10.1002/j.2050-0416.2003.tb00595.x

Cited by 42 publications

(45 citation statements)

References 15 publications

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“…The largest is the polypeptides known as the "40 kD Protein" or Protein Z, with an average size of 46.9 kD found in all the beers. Next is Lastly there are two negative bands at 13.5 kD and 11.9 kD which, as will be explained in a subsequent paper 12 , are foam related. In addition, there are bands at 21.3 kD in the all malt beer and 31.0 kD, 17.1 kD and 14.9 kD in the syrup adjunct beer.…”

Section: Sxep Weqtpiwmentioning

confidence: 84%

“…found was greater than the reported size due to glycosylation. These polypetides are further discussed in a later paper 12 . The amino acid profile of the total protein samples was similar to the findings of Dale et al 5 .…”

Section: (-7'977-32 'Sqtswmxmsr Sj XLI Xsxep Tvsximrmentioning

confidence: 92%

“…This enabled identification of the polypeptides responsible for haze formation. Foam polypeptides were also extracted and analysed, the results will be discussed in a subsequent paper 12 .…”

Section: -2863(9'8-32mentioning

confidence: 99%

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Beer Polypeptides and Silica Gel Part I. Polypeptides Involved in Haze Formation

Leiper

Stewart

McKeown

2003

Journal of the Institute of Brewing

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Beer contains approximately 500 mg/L protein depending on the brewing procedures employed. This protein is in the form of polypeptides, the majority of which lie within the 10-40 kD size range. Some of these polypeptides are responsible for causing colloidal haze, others enhance foam stability and the remainder appear to have no function in beer except to contribute to mouthfeel. The polypeptides responsible for haze formation are those that can combine with polyphenols to produce a visible cloudy haze. This is undesirable as it can have a negative effect on the beer's shelf life. One way to reduce this effect is to remove these polypeptides using silica gels. It is important that this removal is selective, and the desirable foam enhancing polypeptides are not removed.Data will be presented to show that beer polypeptides are glycosylated and that silica preferentially adsorbs glycoproteins, particularly those with protein components rich in the amino acid proline. The molecular size and composition of glycoproteins recovered from untreated beer, cooked adjunct, silica exposed to beer and beer aged for one year are presented. Glycoproteins involved in foam, and the apparently functionless polypeptides, will be discussed in a subsequent paper.Key words: Amino acids, beer stability, carbohydrates, mashing, polypeptides, silica gel. -2863(9'8-32It has been known for many years that silica gel is an effective beer stabilizer as it selectively removes those polypeptides that are responsible for causing haze formation. However, it is not clear what size of polypeptides are involved and what proportion of total beer protein they constitute. Also, it is not clear to what extent silica structure effects the ability to adsorb haze-causing polypeptides.Beer contains approximately 500 mg/L protein. Most of this is in the form of polypeptides that are in the 5-100 kD size range. Due to the combined hydrolytic and destructive effects of malting, mashing, boiling and fermentation, there is a very small range of polypeptides present in beer. Three major components have been identified, a polypeptide of 40 kD known as Protein Z 9 , a polypeptide of 9.7 kD known as LTP1 19 which is involved in foam stability, and a group of polypeptides that range between approximately 10 kD to 30 kD. These originate from barley hordein, are rich in the amino acids proline and glutamic acid and are involved in haze formation 3 .The formation of permanent haze occurs when the proline-rich polypeptides combine with specific polyphenols, particularly the flavanol dimers procyanidin B3 and prodelphinidin B3 17 . This haze forming reaction can be prevented by removing either the protein component with silica gel, or the polyphenol component with PVPP (polyvinylpolypyrrolidone).Silica gel (SiO 2 ) is a highly porous structure with a large surface area. Its surface is covered with silanol (SiOH) groups that bind to proline residues in polypeptides. Silica is highly selective for haze protein due to the high levels of proline present in these polypeptides...

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Section: Sxep Weqtpiwmentioning

confidence: 84%

Section: (-7'977-32 'Sqtswmxmsr Sj XLI Xsxep Tvsximrmentioning

confidence: 92%

See 1 more Smart Citation

Beer Polypeptides and Silica Gel Part I. Polypeptides Involved in Haze Formation

Leiper

Stewart

McKeown

2003

Journal of the Institute of Brewing

Self Cite

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“…There are three major groups of protein in barleybrewed beer. The first consists of a group of proline-rich fragments originating from hordein (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32) that are involved in haze formation (14)(15)(16). The second is lipid transfer protein 1 (LTP1; 9.7 kDa in pure form), involved in foam stability (17)(18)(19).…”

Section: Introductionmentioning

confidence: 99%

Changes in protein molecular weight during cloudy wheat beer brewing

Zhang

et al. 2015

J. Inst. Brew.

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To investigate the changes in protein in cloudy wheat beer (CWB) brewing, the molecular weight (M w ) of protein components in wort, fermenting wort, beer and beer foam were analysed by high-performance size-exclusion chromatography. It was found that the M w of protein during brewing was mainly distributed between 100 and 0 kDa. From mash to the final beer, the most abundant protein component was the 7.6-2.1 kDa fraction, which occupied more than 40% of the total protein.The extraction of soluble protein from malts into wort mainly focused on the protein rest process, where the 100.0-32.1 and 7.6-2.1 kDa fractions increased significantly. In addition, the 100.0-13.2 kDa fraction was the predominant thermolabile protein that decreased during lautering and boiling. The dominant protein constituting the fine coagulum, the 100.0-13.2 kDa fraction, also decreased during fermentation and maturation. The CWB, defoamed CWB and CWB foam had similar protein M w distributions, while the CWB foam concentrated much more protein and the 7.6-2.1 kDa fraction was the major protein in the CWB foam.

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“…The structural and chemical modifications that barley grain ns-LTP1s undergo during the brewing process result in increased foaming potential of the corresponding beer protein. The foam promoting forms of ns-LTP1s have an improved amphilicity and adsorption at air-water interfaces of beer 7,87 . Such an improvement is related to glycation via Maillard reactions on malting, acylation on mashing, and structural unfolding on wort boiling 119 .…”

Section: Ns-ltp1 Role In Beer Foam Formation and Stabilizationmentioning

confidence: 99%

Barley Grain Non-specific Lipid-Transfer Proteins (ns-LTPs) in Beer Production and Quality

Gorjanović

2007

Journal of the Institute of Brewing

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Plant non-specific lipid-transfer proteins (ns-LTPs) are known for their ability to transfer various lipids between membranes in vitro. These ubiquitous basic proteins, that all share alpha structure stabilized by four disulphide bridges, are characterized by the presence of a hydrophobic cavity able to accommodate lipid molecules. According to molecular mass, this multigene family is subdivided into two subfamilies, ns-LTP1 (9 kDa) and ns-LTP2 (7 kDa); both located in the aleurone layer of the cereal grain endosperm. Ns-LTP1 is a prominent protein in barley grain, malt and beer. Numerous studies performed on its structure and function confirm its important role in grain protection, as well as brewing technology. As the major beer protein crucial for many aspects of brewing, ns-LTP1 can affect beer production and quality. Comparatively, there is less data available on the less abundant ns-LTP2. In this review, the focus is on recent progress on the structure, biological and technological function of barley grain ns-LTP1 and ns-LTP2, with an emphasis on their importance in brewing.

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Beer Polypeptides and Silica Gel Part II. Polypeptides Involved in Foam Formation

Cited by 42 publications

References 15 publications

Beer Polypeptides and Silica Gel Part I. Polypeptides Involved in Haze Formation

Beer Polypeptides and Silica Gel Part I. Polypeptides Involved in Haze Formation

Changes in protein molecular weight during cloudy wheat beer brewing

Barley Grain Non-specific Lipid-Transfer Proteins (ns-LTPs) in Beer Production and Quality

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