Editing Haze
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Low molecular polyphenols increase the reduction power of beer, while when simple phenols or polyphenols monomers react with proteins, no haze is formed (Siebert 1999). Haze is composed of complexes between condensed polyphenols and water-soluble proteins.<ref name=sibpla>Šibalić D, Planinić M, Jurić A, Bucić-Kojić A, Tišma M. [https://link.springer.com/article/10.1007/s11696-020-01276-1 Analysis of phenolic compounds in beer: from raw materials to the final product.] ''Chem Zvesti.'' 2021;75(1):67–76.</ref> | Low molecular polyphenols increase the reduction power of beer, while when simple phenols or polyphenols monomers react with proteins, no haze is formed (Siebert 1999). Haze is composed of complexes between condensed polyphenols and water-soluble proteins.<ref name=sibpla>Šibalić D, Planinić M, Jurić A, Bucić-Kojić A, Tišma M. [https://link.springer.com/article/10.1007/s11696-020-01276-1 Analysis of phenolic compounds in beer: from raw materials to the final product.] ''Chem Zvesti.'' 2021;75(1):67–76.</ref> | ||
Colloidal instability due to interactions between polyphenols and proteins limits the shelf life of beer. A lag phase is usually observed in lager beers before chill-haze development [23–25]. The time needed to form critical amounts of tanning polyphenols leading to visible chill-haze particles corresponds to the lag phase. As described by Leemans et al. [25] for different batches, the longer the lag phase, the better the colloidal stability.<ref name=coljer>Collin S, Jerković V, Bröhan M, Callemien D. [https://link.springer.com/referenceworkentry/10.1007/978-3-642-22144-6_78 Polyphenols and beer quality.] In: Ramawat KG, Mérillon J-M, eds. ''Natural Products.'' 1<sup>st</sup> ed. Springer; 2013:2334–2353.</ref> | Colloidal instability due to interactions between polyphenols and proteins limits the shelf life of beer. A lag phase is usually observed in lager beers before chill-haze development [23–25]. The time needed to form critical amounts of tanning polyphenols leading to visible chill-haze particles corresponds to the lag phase. As described by Leemans et al. [25] for different batches, the longer the lag phase, the better the colloidal stability.<ref name=coljer>Collin S, Jerković V, Bröhan M, Callemien D. [https://link.springer.com/referenceworkentry/10.1007/978-3-642-22144-6_78 Polyphenols and beer quality.] In: Ramawat KG, Mérillon J-M, eds. ''Natural Products.'' 1<sup>st</sup> ed. Springer; 2013:2334–2353.</ref> | ||
Catechin does not rapidly induce strong haze. Upon storage, however, it does. Likewise, colloidal instability caused by dimers and trimers is enhanced after oxidation (not true for tetramers and pentamers) [26–28]. Free radicals are known to enhance haze [29]. Tannoids have been defined by Chapon [30] as intermediates in the oxidation of simple flavanoids to tannins, forming complexes with proteins. On the other hand, according to O’Rourke et al. [28], oxidized flavanols cause chill haze, but only subsequent polymerization leads to tannoids and permanent haze [28, 31]. Leemans et al. [25] have proposed a model in which aldehydes and oxygen play key roles in tanning polyphenol formation [25, 31]. Not only dissolved oxygen but also shaking, higher temperature, polyphenol-rich raw materials, light, and heavy metals will significantly increase colloidal instability [25, 31].<ref name=coljer/> | Catechin does not rapidly induce strong haze. Upon storage, however, it does. Likewise, colloidal instability caused by dimers and trimers is enhanced after oxidation (not true for tetramers and pentamers) [26–28]. Free radicals are known to enhance haze [29]. Tannoids have been defined by Chapon [30] as intermediates in the oxidation of simple flavanoids to tannins, forming complexes with proteins. On the other hand, according to O’Rourke et al. [28], oxidized flavanols cause chill haze, but only subsequent polymerization leads to tannoids and permanent haze [28, 31]. Leemans et al. [25] have proposed a model in which aldehydes and oxygen play key roles in tanning polyphenol formation [25, 31]. Not only dissolved oxygen but also shaking, higher temperature, polyphenol-rich raw materials, light, and heavy metals will significantly increase colloidal instability [25, 31].<ref name=coljer/> |