A two-substrate kinetic study of peroxidase cationic isoenzymes in barley malt

Clarkson, Simon P.; Large, Peter J.; Bamforth, Charles W.

doi:10.1016/0031-9422(92)80005-y

Cited by 13 publications

(5 citation statements)

References 20 publications

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“…Peroxidases have been reported to play a role in the metabolism of oxygen during mashing and also to affect colour and clarity of the wort and probably influence beer flavour [37]. Interestingly, peroxidase isozymes in germinated barley have shown different efficiency in producing these effects [38]. Accordingly, cultivar variations observed in the present study may be directly linked to beer quality parameters.…”

Section: Discussionmentioning

confidence: 67%

Barley peroxidase isozymes

Laugesen

Bak-Jensen

Hägglund

et al. 2007

International Journal of Mass Spectrometry

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Section: Discussionmentioning

confidence: 67%

Barley peroxidase isozymes

Laugesen

Bak-Jensen

Hägglund

et al. 2007

International Journal of Mass Spectrometry

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“…Solutions of inhibitors were vacuum deaerated prior to addition to anaerobic mashes. POD was assayed as described by Clarkson et al 20 and LOX according to Biawa and Bamforth 13 .…”

Section: %8)6-%07 %2( 1)83(7mentioning

confidence: 99%

“…H 2 O 2 (20 mM) gave maximal lowering of polyphenols, indicating that this level of peroxide is ample to saturate the POD. (The K m value of peroxidase for H 2 O 2 in crude extracts of barley is 57 µM 20 : an enzyme typically operates at maximal rate at 10 × K m , and 20 mM represents a concentration 35 times higher than this). In all instances polyphenol levels were lower in worts mashed under aerobic conditions, which would suggest that a proportion of polyphenol removal is not via POD/H 2 O 2 action.…”

Section: Sp]tlirsp Pizipwmentioning

confidence: 99%

Laboratory-Scale Studies of the Impact of Oxygen on Mashing

Stephenson

Biawa

Miracle

et al. 2003

Journal of the Institute of Brewing

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An assessment of the impact of oxygen and hydrogen peroxide on mashing and wort parameters has been made on a laboratory scale. Oxygen has been stridently eliminated by using an anaerobic chamber during mash analysis. Additionally the relative importance of proanthocyanidin species has been assessed by comparing the behaviour of "conventional" malt and a malt produced from a low proanthocyanidin variety. It seems that oxygen and peroxide act independently in causing the oxidation of thiolcontaining materials and polyphenols in mashes and that oxygen is not primarily exerting its impacts through the intermediacy of peroxide. The removal of thiols (presumably at least in part through the production of disulphide bridges between proteins) and of polyphenols (presumably via polymerisation) both contribute to increased wort turbidity and decreased rates of wort separation after mashing. Three inhibitors (nordihydroguaiaretic acid, ethylenediamenetetraacetate and potassium cyanide) have been employed in an attempt to differentiate between enzymic and non-enzymic events and also to identify whether lipoxygenase and peroxidase are catalysing key events. Whilst it seems that peroxidase has a key role in catalysing the oxidation of polyphenols by H 2 O 2 , it does not appear that either peroxidase or lipoxygenase is involved in the removal of measurable thiol. Nonetheless a significant proportion of the thiol elimination is likely enzyme-catalysed. We have been unable to demonstrate the production of hydroperoxides in mashes, but added hydroperoxide is undetectable, which suggests that these materials are either lost by onward conversion or by adsorption onto spent grains.

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“…Roy Parsons and I were the first to draw meaningful attention to a role for reactive oxygen species as a key underpinning cause of oxidative damage to wort and beer (68). In the pursuit of understanding how the development of such radicals could be prevented, we investigated a number of enzymes, notably superoxide dismutase ( (69), including soybeans as a source of a particularly heat-tolerant version of this enzyme, (70)), catalase and peroxidases (71)(72)(73)(74)(75). Our work also highlighted to significance of minimising the levels of certain metal ions in wort and beer, notably iron and copper (76-81) and, as we later confirmed, manganese (82).…”

Section: Flavour Instabilitymentioning

confidence: 99%

The Horace Brown Medal. Forever in focus: researches in malting and brewing sciences

Bamforth

2020

J. Inst. Brew.

Self Cite

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The paper reviews a career of more than forty years researching topics in malting and brewing science. Some themes attracted particularly close attention, namely the endosperm cell walls of barley, dimethyl sulphide, flavour stability, foam and the impact of beer on health. However, the scope has been far broader than that. The underlying imperative was to pursue research that was close to application and always focussed on a specific need in the processes involved in the production of beer. © 2020 The Institute of Brewing & Distilling

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A two-substrate kinetic study of peroxidase cationic isoenzymes in barley malt

Cited by 13 publications

References 20 publications

Barley peroxidase isozymes

Barley peroxidase isozymes

Laboratory-Scale Studies of the Impact of Oxygen on Mashing

The Horace Brown Medal. Forever in focus: researches in malting and brewing sciences

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