Study of Beer Oxidation with O<sup>18</sup>

Owades, Joseph L.; Jakovac, Jack

doi:10.1080/00960845.1966.12006112

Cited by 13 publications

(7 citation statements)

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“…The decrease in total phenolic content was accompanied by a reduction in the antioxidant activity of the stored commercial lager beer samples. (Li et al., ) In their beer aging study with the stable oxygen isotope O 18 , Owades and Jakovac () described an incorporation of an atom of O 18 into approximately 65% of the molecules present in the tannin fraction (Owades & Jakovac, ). Gramshaw () also proposed an oxidative and acid‐catalyzed polymerization of beer polyphenols to haze‐active products (Gramshaw, ).…”

Section: Introductionmentioning

confidence: 99%

Phenolic Substances in Beer: Structural Diversity, Reactive Potential and Relevance for Brewing Process and Beer Quality

Wannenmacher

Gastl

Becker

2018

Comp Rev Food Sci Food Safe

115

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For the past 100 years, polyphenol research has played a central role in brewing science. The class of phenolic substances comprises simple compounds built of 1 phenolic group as well as monomeric and oligomeric flavonoid compounds. As potential anti-or prooxidants, flavor precursors, flavoring agents and as interaction partners with other beer constituents, they influence important beer quality characteristics: flavor, color, colloidal, and flavor stability. The reactive potential of polyphenols is defined by their basic chemical structure, hydroxylation and substitution patterns and degree of polymerization. The quantitative and qualitative profile of phenolic substances in beer is determined by raw material choice. During the malting and brewing process, phenolic compounds undergo changes as they are extracted or enzymatically released, are subjected to heat-induced chemical reactions or are precipitated with or adsorbed to hot and cold trub, yeast cells and stabilization agents. This review presents the current state of knowledge of the composition of phenolic compounds in beer and brewing raw materials with a special focus on their fate from raw materials throughout the malting and brewing process to the final beer. Due to high-performance analytical techniques, new insights have been gained on the structure and function of phenolic substance groups, which have hitherto received little attention. This paper presents important information and current studies on the potential of phenolics to interact with other beer constituents and thus influence quality parameters. The structural features which determine the reactive potential of phenolic substances are discussed.

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Section: Introductionmentioning

confidence: 99%

Phenolic Substances in Beer: Structural Diversity, Reactive Potential and Relevance for Brewing Process and Beer Quality

Wannenmacher

Gastl

Becker

2018

Comp Rev Food Sci Food Safe

115

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“…We have also employed two types of malt: a typical ("traditional") lager-style malt and one made from a low-proanthocyanidin barley. This has allowed us also to gain an appreciation of the relative significance of polyphenols in the "economy" of oxygendependent processes in mashing, it being recognised that the single most important "sink" into which oxygen flows in beer is the polyphenol fraction 33 .…”

Section: -2863(9'8-32mentioning

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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“…It is well known that oxidation during packaging causes deterioration of beer quality, haze and flavour stability. Generally accepted opinion is that the oxygen in the headspace is incorporated into compounds in the beer, especially polyphenols, carbonyl compounds and isohumulones during storage 37 . However, in case of stale flavour carbonyls, more recent work did not prove confirm this opinion as no O 18 oxygen isotope was incorporated into carbonyls in stored beer 9 .…”

Section: -2863(9'8-32mentioning

confidence: 99%

The Role of Malt and Hop Polyphenols in Beer Quality, Flavour and Haze Stability

Mikyška

Hrabák

Hašková

et al. 2002

Journal of the Institute of Brewing

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Pilot-scale brewing trials of a 12°P pale lager beer were conducted to look at the effect of a modified dose of hop and malt polyphenols on haze, flavour quality, and stability. Results confirmed that malt polyphenols, and particularly hop polyphenols, in the course of wort boiling, improved reducing activity values and the carbonyl content in fresh and stored beers. Hop polyphenols significantly increased reducing activity and decreased the formation of carbonyls (TBA value) in fresh and stored beer. Reduced content of malt polyphenols, combined with the use of hop CO 2 extract, caused an increase in the TBA value in beer. PVPP stabilized beers tended to be lower in reducing activity. Both malt and hop polyphenols affected the intensity of "harsh taste" in fresh beers and a significant influence from PVPP stabilization of beer was not observed. The staling degree of forcedaged beers depended on the polyphenol content in the brewhouse. Both hop and malt polyphenols had a positive impact on flavour stability. PVPP treatment of beer had a positive effect on the flavour stability of heat-aged beers. Polyphenols, especially hop polyphenols, slowed down flavour deterioration during the nine month storage period, but the primary effect was seen during the first four months of storage. Storage trials did not show any unambiguous effects for PVPP stabilization on beer flavour stability. Results confirmed the negative impact of malt and hop polyphenols on haze stability, and PVPP stabilization minimized differences in shelf life prediction values between beers prepared with the modified dose of polyphenols.

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Study of Beer Oxidation with O¹⁸

Cited by 13 publications

References 2 publications

Phenolic Substances in Beer: Structural Diversity, Reactive Potential and Relevance for Brewing Process and Beer Quality

Phenolic Substances in Beer: Structural Diversity, Reactive Potential and Relevance for Brewing Process and Beer Quality

Laboratory-Scale Studies of the Impact of Oxygen on Mashing

The Role of Malt and Hop Polyphenols in Beer Quality, Flavour and Haze Stability

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Study of Beer Oxidation with O18

Cited by 13 publications

References 2 publications

Phenolic Substances in Beer: Structural Diversity, Reactive Potential and Relevance for Brewing Process and Beer Quality

Phenolic Substances in Beer: Structural Diversity, Reactive Potential and Relevance for Brewing Process and Beer Quality

Laboratory-Scale Studies of the Impact of Oxygen on Mashing

The Role of Malt and Hop Polyphenols in Beer Quality, Flavour and Haze Stability

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Product

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Study of Beer Oxidation with O¹⁸