Proanthocyanidin-Free Barley-Malting and Brewing

Erdal, Kenneth

doi:10.1002/j.2050-0416.1986.tb04404.x

Cited by 24 publications

(11 citation statements)

References 12 publications

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“…Therefore screening procedures designed for the more elongated grain of barley are unlikely to work satisfactorily for sorghum :Recommended Methods of the Institute of Brewing 1977). The pericarp-testa of sorghum grains has higher levels of polyphenol pigmentation than the corresponding layers of barley grains (Erdal 1986;Palmer 1989). Barley and sorghum grains, like all cereal grains, are described as caryopses (dry fruits).…”

Section: Pericarp-testamentioning

confidence: 98%

Sorghum as brewing material

Palmer

EtokAkpan

Igyor

1989

World J Microbiol Biotechnol

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Section: Pericarp-testamentioning

confidence: 98%

Sorghum as brewing material

Palmer

EtokAkpan

Igyor

1989

World J Microbiol Biotechnol

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“…8). The finite level of polyphenolic material in the latter malt represents those polyphenols other than the haze-forming proanthocyanidins 22 . Soluble polyphenol levels in wort were lower when mashing of the conventional malt was under aerobic conditions, consistent with the oxidative polymerisation, insolubilisation and removal of proanthocyanidins.…”

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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“…Colloidal haze in beer is caused by precipitation of malt proteins by barley and hop proanthocyanidins. If no stabilizing treatment of the beer is performed, visible haze in a brillant filtered beer kept at room temperature will often develop within weeks (ERDAL 1986).…”

mentioning

confidence: 99%

Genetic Control of Flavonoid Biosynthesis in Barley

Jende-Strid

2004

Hereditas

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Mutations in genes associated with the pathway of flavonoid biosynthesis can readily be induced in barley and since 1977 more than 700 mutants have been isolated in which the biosynthesis of anthocyanin and/or proanthocyanidin is affected. Diallelic crosses have localized a majority of the mutants to 28 different complementation groups (Ant genes). Mutations in ten of the Ant genes result in a blocked synthesis of proanthocyanidins in the testa layer of the grains, whereas mutations in 18 Ant gene loci only affect anthocyanin synthesis in various organs of the plants. Seven Ant genes have been localized to a chromosome. A number of investigations have been carried out to characterize the ten known Ant genes acting on the biosynthesis of proanthocyanidins. Grains of mutants in different Ant genes and wildtypes were analyzed for contents of flavonoids and other phenolic compounds and the activity levels of several of the enzymes in the flavonoid pathway were studied. The gene locus Ant 18 has been isolated both in the form of cDNA and genomic clones. Ant 17, Ant 18, Ant 19, Ant 22, and Ant 26 are structural genes. Ant 13 is a regulatory gene coding for a transcription factor necessary for transcription of at least three structural genes in the flavonoid pathway. The action of the genes Ant 21, Ant 25, Ant 27, and Ant 28 is not fully understood. They might be regulatory genes.

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Proanthocyanidin-Free Barley-Malting and Brewing

Cited by 24 publications

References 12 publications

Sorghum as brewing material

Sorghum as brewing material

Laboratory-Scale Studies of the Impact of Oxygen on Mashing

Genetic Control of Flavonoid Biosynthesis in Barley

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