Relationship between Kolbach index and other quality parameters of wheat malt

Abstract

In order to determine suitable Kolbach indices in wheat malting, the relationships between the Kolbach index and other quality parameters in wheat malt were studied. Eight white wheat malts with different Kolbach indices (31.4, 33.1, 37.0, 37.6, 39.5, 40.7, 42.8 and 45.5%) from the same wheat variety were prepared. The increase ratio of the ALSP (albumins and other soluble proteins) and the decrease ratio of the glutenins were found to have a significant positive correlation with the Kolbach index, and the corresponding r-values were 0.883 and 0.975 (p<0.01). The ALSP of the wheat malts had a positive correlation with chromaticity, extract, free amino nitrogen (FAN), viscosity, acidity, xylan glycosidase activity, endo-b-1,4-xylanase activity and malting loss (p<0.05). When the Kolbach indices were 31.4, 33.1, 37.0, 37.6 and 39.5%, there was a positive correlation between the soluble xylan and the viscosity, and the r-value was 0.888 (p<0.05). Comparing the malts, it could be concluded that, for this particular wheat variety, when the Kolbach index was 39.5%, the wheat malts exhibited the best characteristics; the extract was 81.98%, the FAN content was 166.03mg per 100mg, the saccharifying power was 496.72 WK, the viscosity was 1.61 cP, and the saccharification time was 6 min. © 2012 The Institute of Brewing & Distilling.