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Evaluation of Mashing Attributes and Protein Profile Using different grist composition of barley and wheat malt
A. Faltermaier, J. Negele, T. Becker, M. Gastl and E. Arendt

This study is focused on protein profile and processability of mashes as well as wort quality by varying grist composition by increasing wheat malt amount. In the first part of this study ? the screening, on mash relevant characteristics ? an increase of final attenuation, viscosity, soluble nitrogen and β-glucan, whereas a decrease of arabinoxylan (AX) and protease activity during the mashing process was detected. Between 55 ? and 62 ?C the amylolytic mash values extract and final attenuation rose most considerably. Proteolytic parameter declined strongly between these two temperatures. A wheat malt ratio higher than 50?% shows no benefit for brewing purpose in terms of processability and wort quality (extract and apparent attenuation limit. Due to the similar distribution of the extract graph it can be assumed that amylolytic enzyme activities and their changes during mashing of wheat malt are comparable to those of barley malt. Regarding mash temperature between 55 ? and 62 ?C the cytolytic mash attributes viscosity and β-glucan denoted the biggest increase, whereas AX showed the greatest decline. A relationship between viscosity and mash attribute AX and β-glucan couldn?t be detected at a sufficiently extent. Proteolytic parameter declined strongly during the first mashing stages (35 ? to 55 ?C) remained almost constant from 55 ? to 78 ?C. In consideration of processability and wort quality for wheat beer production insufficient soluble nitrogen (SN) values of barley malt can be compensated by good wheat malts as well as wheat malt ratio. In the second part of this study a protein profiling was performed to evaluate changes during the mashing process. Moreover, the differences in protein constitution of grist composition with increasing wheat malt amount were investigated. In mashes with increasing wheat malt no 17?kDa protein fraction was detected. Furthermore, no lipid transfer protein (LTP)?2 and 21?kDA fraction was discovered with raising barley malt amount. Wheat malt contained more turbidity active proteins with molecular weights of 21 and 25?kDa. These protein fractions comprise turbidity active and foam positive Protein?Z as well as α-Amylase/Trypsin inhibitors. With increasing barley malt content the portion of foam positive LTP?1 raised up to finally more than 50?%. Low-molecular foam promoting proteins increased during mashing, whereas middle-molecular, mainly turbidity active proteins, were mostly reduced. High-molecular enzyme active proteins between 55 and 63?kDa were completely degraded in all samples.

Descriptors: wheat, mashing, protein profile, grist composition

BrewingScience - Monatsschrift fr Brauwissenschaft, 68 (May/June 2015), pp. 67-77