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The Formation and Hydrolysis of Barley Malt Gel‐Protein Under Different Mashing Conditions
Author(s) -
Pöyri S.,
Mikola M.,
SontagStrohm T.,
KaukovirtaNorja A.,
Home S.
Publication year - 2002
Publication title -
journal of the institute of brewing
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.523
H-Index - 51
eISSN - 2050-0416
pISSN - 0046-9750
DOI - 10.1002/j.2050-0416.2002.tb00550.x
Subject(s) - mashing , proteolysis , chemistry , hydrolysis , chromatography , biochemistry , monomer , hydrolyzed protein , enzyme , organic chemistry , polymer
The effect of oxidation and proteolysis on the amount of gel‐protein aggregate was investigated both in vivo during mashing and in vitro . The oxidation of the free thiol groups of proteins to disulphide bridges during mashing appeared to be a good indicator of the formation of gel‐protein aggregate. The pH optimum of the oxidation varied according to the isothermal mashing temperature. The results suggested that the oxidation of the thiol groups maybe a result of some kind of enzymatic activity. In vitro experiments showed that the proteolysis of the gel‐protein aggregate was strongest at pH 5.0 and temperature denaturation occurred only at temperatures over 80°C. Mashing experiments on the other hand suggested that the proteolysis of the monomer subunits of gel‐protein (i.e. B‐ and D‐hordein) had a stronger effect on the final amount of the gel‐protein aggregate than the hydrolysis of the aggregate.