Phenolic Constituents of Beer and Brewing Materials. Ii. The Role of Polyphenols in the Formation of Non-Biological Haze

Gramshaw, J. W.

doi:10.1002/j.2050-0416.1967.tb03070.x

Cited by 27 publications

(16 citation statements)

References 29 publications

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“…This suggests that the haze stage of complexity is reached in a jump, by a two or three-fold increase in molecular size; this would fit with the observation that polyphenolic dimcrs or trimcrs arc very effective in causing ha2pii.i8.as K nas been pointed out that this poly merization could arise by a quinone-type oxidative coupling or possibly by acid-catalysed polymeriza tion of polyphenols. 18 The general picture, supported by the observations of Woof,48 is that in mashing both oxidative and hydrogen-bonded links arc formed between pro tcoses and polyphenols. Possibly, if these combina tions were isolated without further oxidation, the hydrogen-bonded proteoses could be separated, but, if this precaution is not taken, oxidation to dark, insoluble products readily occurs.…”

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confidence: 85%

Haze- And Foam-Forming Substances in Beer

Bishop¹

1975

Journal of the Institute of Brewing

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A study of recent literature on haze-and foam-forming substances in beer suggests the following picture:Traces of true protein, apparently above 150,000 in molecular weight (MW), exist in beer. Apart from these, the main complex nitrogenous substances are present in compounds in the 5,000-70,000 MW region. Nevertheless, these are not proteins, but amino-acid complexes (proteoses) coupled with non-nitrogenous substances.As is well known, haze and haze precursors are proteoses coupled with polyphenols. These two species can be joined by hydrogen bonds to give compounds which are readily dissociated. However, a much firmer, covalent, linkage can be formed. This type of linkage arises from oxidation of polyphenols to quinones, which in turn can oxidize and couple with several groupings on proteoses. One of the most probable points of attack is the sulphydryl group of cystine, and the relatively high percentage of cystine in haze indicates that this occurs. It seems likely that this reaction, to form acidic complexes, occurs mainly in the initial stages of mashing and boiling. In beer, further coupling between pairs or triplets of polyphenolic or quinolic groupings can take the products into the very high molecular weight region of hazes.Correspondingly, the foam-enhancing proteoses tend to be lower in cystine content and to show less combination with polyphenols. However, they too are largely in the form of complexes and the evidence suggests that here the proteoses are mainly combined with glucose polymers, a reaction which takes place during kilning and possibly during boiling. These complexes are less acidic than the poly phenolic ones and tend to be rather lower in molecular weight.

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confidence: 85%

Haze- And Foam-Forming Substances in Beer

Bishop¹

1975

Journal of the Institute of Brewing

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“…As these interactions and their involvement in beverage haze formation have already been reviewed by (Siebert, ), the structural features required for a polyphenol to be haze‐active will only be discussed briefly. Even though polyphenols with a higher degree of polymerization are known to be more haze‐active than lower molecular weight polyphenols (Gramshaw, ), one aromatic ring bearing two hydroxyl groups is sufficient to interact with proteins (Siebert & Lynn, ). In order to cross‐link proteins and thus form haze, a polyphenol needs to have at least two binding sites (Siebert & Lynn, ).…”

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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

113

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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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“…Beer contains a complex mixture of polyphenols and they are thought to be involved in the formation of beer haze. These polyphenols can be classified as (I) monomeric polyphenols and (2) oligomeric and polymeric polyphenols. One of the dominant and well-characterized monomeric polyphenols in beer is catechin.…”

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confidence: 99%