Immature barley seeds as a degrading factor for Canadian malting barley

Abstract

Canadian malt barley in the past was downgraded on visual detection of any immature barley kernels. The quality of malt made from immature barley has been investigated in the past, but conclusions were inconsistent. The factor, though, was removed from Canadian malting barley grades in August 2008. The present study used a different approach to investigate the effects of immature kernels on malt quality. A series of commercial malt barley samples were adulterated with varying levels of immature kernels. Samples were visually graded, malted and analysed for malt quality. Immature kernels were found to affect malt quality, but only significantly when samples contained 2% or more immature kernels. Soluble protein, which increased in samples with more immature kernels, was the quality factor of greatest concern. Canadian malt is often criticized for high soluble protein, which can lead to an unacceptably high wort colour. The research supported downgrading of samples on account of immature kernels, but only when the level was 2% or higher. However, grain inspectors consistently downgraded the experimental samples with as low as 0.2% immature kernels, as per the previous grade determinants. The new grade schedule has no tolerances for immature kernels, but this study supported reinstatement of a tolerance level of 2% immature kernels. Key words: Green seed, quality, malt, soluble protein, extract, wort colour