Canadian Grain Commission
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Measuring barley kernel colour and size to predict end use malt quality

Results and discussions - Grades and malt quality

Special Select samples showed the best malt quality despite the concerns outlined above regarding sample source and longer storage times (Table 2). The Special Select samples took up significantly less water during processing, as indicated by lower steep-out moistures. Processors aim for steep-out moistures of 44-45 % in order to ensure adequate modification of the endosperm, however, in this case there was no apparent effect on modification as indicated by similar ß-glucan levels among all grades. In fact top grade samples showed significantly better friabilities, an overall indicator of endosperm modification, than samples from the other two grades. Friabilities are often reduced by inadequate protein modification. However, soluble protein, which is often too high in Canadian malting barley, was significantly lower in Special Select than either other grade and Select had significantly lower soluble protein than Standard Select. Special Select, therefore, showed adequate modification, as indicated by better friabilities, without the production of excess soluble protein. Wort colours, which can be unacceptably dark as a result of excess soluble protein, were not significantly different among grades.

Standard Select did show significantly higher diastatic power than both other grades and significantly higher α-amylase levels than the Special Select samples. Enzyme levels for all grades, though, were still well within the commercially acceptable range for Canadian malt. Differences in enzyme levels were most likely due to the significantly lower steep-out moistures for samples in the top two grades as protein levels, a key determinant of enzyme levels, were not significantly different among grades. Malt extract, a key component of malt quality, was very similar among the three grades.

Table 2. Effect of Canadian Grain Commission malting barley grade on malt quality
CGC Malt Barley Grades Special Select Select Standard Select
a, b, c row means with different superscripts, differ significantly (p<0.01) based on Duncan's Multiple Range Test
Plump kernel, % 92.3 89.8 89.4
Barley protein, % 12.0 12.2 12.2
Germination energy (4 mL), % 96 98 98
Germinative index (4 mL), % 7.8 8.2 8.5
Steep-out moisture, % 43.6 c 44.3 b 44.9 a
Malt extract, % 80.5 80.4 80.5
Soluble protein, % 4.56 c 4.74 b 4.95 a
ß-glucan, ppm 64 72 70
Diastatic power, °L 116 b 126 a b 134 a
α-Amylase, D.U. 58.3 b 65.1 a 67.4 a
Wort colour, ASBC units 2.05 2.01 2.12
Friability, % 88.5 a 83.6 b 82.2 b

In summary, the value of Canadian Grain Commission's grading system was supported in the present study. Special Select, the top malting grade, showed better overall malt quality, due to lower soluble protein and greater friability, than the other two grades despite the longer storage conditions of all the Special Select samples. The Select samples also showed slightly better overall quality than Standard Select samples.