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



Abstract

The effectiveness of the grading system of the Canadian Grain Commission in predicting end use quality of malting barley was compared to machine-based methods. A series of malting barley samples from the 2003 harvest were analysed for grade, colour and size. The barley was malted and the malt analysed for quality. Results supported the grading system with barley grading Special Select showing the best overall malting quality. Statistically, the grades, based on one inspector's observations, showed the same ability as colour measurement by imaging to predict several barley and malt quality parameters. However, the machine-based method was better at several parameters. The imaging system also offered the potential of more objectivity over time compared to grades determined by different inspectors on different days. These findings were based on the quality of a limited number of samples from one harvest and need to be repeated using additional samples with varying degrading factors.

Plump barley was found to produce, under standard processing conditions, adequately modified malt with good levels of malt extract. In contrast, intermediate sized kernels had significantly lower malt extract and the malts were over modified using standard processing conditions. Thousand kernel weight, a specification frequently used to indicate malt barley quality, gave a good indication of potential malt extract of plump barley but with intermediate-sized barley, it only gave an indication of processing requirements.

Thousand kernel results were compared to those from the Single Kernel Characterization System (SKCS), which measures and calculates the mean weight, diameter, hardness and moisture of 300 kernels per barley sample. Both methods correlated similarly with malt quality. Variability of size among 300 kernels of sample, as indicated by SKCS's standard deviation of kernel diameter and weight, explained additional variability in final malt quality, in particular malt modification.