Increased protein-thiol solubilization in sweet wort by addition of proteases during mashing

Lund, Marianne N.; Lametsch, René; Sørensen, Mikael Blom

doi:10.1002/jib.155

Cited by 2 publications

(2 citation statements)

References 26 publications

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“…In another approach to increase protein-derived thiol concentrations in beer, proteases were added during mashing for increased solubilization of protein-derived thiols into the wort and final beer. , This methodology was shown to increase the amount of free thiols in beer from 37 μM to 57 μM. Sulfur-derived off-flavors were detected by sensory analysis in fresh protease-treated beer, but only to a minor extent and these off-flavors disappeared during storage .…”

Section: Resultsmentioning

confidence: 99%

Kinetic Models for the Role of Protein Thiols during Oxidation in Beer

Andersen

Gundermann

Danielsen

et al. 2017

J. Agric. Food Chem.

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Thiol-containing proteins have been suggested to have antioxidative properties in beer. A kinetic model has been setup for the reactivity of thiols during early stages of oxidative degradation of beer. Kinetic analysis based on the proposed reaction mechanism allowed evaluation of the relative reactivity of beer components, such as bitter acids from hops and polyphenols. The rate constants for the reaction of 1-hydroxyethyl radicals, which are generated during radical mediated oxidation of ethanol in beer, with hop bitter acids and thiols were very similar, and the concentration of these compounds in beer is therefore essential for the relative reactivity. For a standard pilsner beer with 35 international bitter units with typical concentrations of thiols and hop bitter acids, thiols were found to react with ca. 9% of 1-hydroxyethyl radicals, while bitter acids from hops accounted for ca. 88% of the reaction with 1-hydroxyethyl radicals. Polyphenols were not found to account for any major part of the reaction with 1-hydroxyethyl radicals due to low reaction rates and low concentrations in pilsner beer compared to the other components. The kinetic model suggests that the concentration of thiols has to be increased in order to contribute with any significant antioxidative protection and that the fate of thiols during oxidation must be considered since some thiol oxidation products may induce further damage.

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Section: Resultsmentioning

confidence: 99%

Kinetic Models for the Role of Protein Thiols during Oxidation in Beer

Andersen

Gundermann

Danielsen

et al. 2017

J. Agric. Food Chem.

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“…Comparing the initial level of amino acids (45M1: 2372 mg/L; 45M2: 3278 mg/L; 63M1: 2102 mg/L; 63M2: 1839 mg/L), it was confirmed that the mashing procedure which included a 45°C step increased the free amino acids. The enhanced proteolytic enzyme activity at 45°C results in higher amounts of the reactants (35). Regarding the effect of malt modification (assessed by soluble nitrogen), there was no consistent trend in the sum of amino acids in the initial wort.…”

Section: Sugars and Amino Acids In The Wort Boiling Processmentioning

confidence: 88%

Formation and degradation of 3‐deoxyglucosone as a key intermediate for ageing indicators during wort boiling

Nobis¹,

Wendl²,

Becker³

et al. 2021

J. Inst. Brew.

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The metabolite 3-deoxyglucosone (3-DG) is formed by carbohydrate caramelisation or the Maillard reaction. 3-DG is a precursor in the Strecker reaction forming beer ageing compounds, such as 2-methylbutanal or 3-methylbutanal. Although 3-DG is known as intermediate, recent studies have focused on 3-DG in beer. Foremost, the thermal load during wort boiling provides the best conditions for 3-DG formation and degradation, however, the reactivity of the dicarbonyl during the boiling process has not yet been explained. As a key intermediate, 3-deoxyglucosone could be a critical indicator for beer ageing stability. The 3-DG formation and reactivity during wort production depends on its precursor reactants (amino acids and glucose). The concentration in wort of these substances was varied using two malts with different malt modification along with two different mashing programmes. 3-Deoxyglucosone reactivity was observed by analysing dehydratisation to HMF (HPLC-UV), interconversion to 3-deoxygalactosone (3-DGal, HPLC-UV) and selected Strecker aldehydes (GC-SPME-MS). This study shows that wort boiling is the most important process in 3-DG formation as it contributes 47% of the final content compared with malting (28%) and mashing (25%). With degradation reactions, 3-DG is mainly interconverted to 3-DGal and, contrary to the literature, it could not be confirmed that enhanced 3-deoxyglucosone content affects Strecker reactions. The interconversion reaction during wort boiling determines the dicarbonyl potential of beer and influences the ageing stability.

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Increased protein-thiol solubilization in sweet wort by addition of proteases during mashing

Cited by 2 publications

References 26 publications

Kinetic Models for the Role of Protein Thiols during Oxidation in Beer

Kinetic Models for the Role of Protein Thiols during Oxidation in Beer

Formation and degradation of 3‐deoxyglucosone as a key intermediate for ageing indicators during wort boiling

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