Canadian Grain Commission
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Prediction of germination energy of malting barley during long-time storage

Evaluation of various instrumental techniques for detection and measuring the degree of pre-germination in barley

In the absence of dormancy, Canadian malting barley varieties have a propensity to pre-germinate in the field under extended moist conditions during harvest. Although a visual inspection of barley, conducted during the selection processes, can identify severely sprouted grain, it cannot detect the incipient germination. The germination energy test does not indicate pre-germination in barley. Barley selectors and evaluators do not have a practical tool to predict how much of the initially selected barley will lose germination energy during storage. This makes it difficult to know how much grain to select initially. It is also disappointing and costly to farmers who are initially advised that their barley was selected for malting purposes and informed later that the grain is no longer acceptable for malting. There is, therefore, a clear need for a rapid and practical method for detection of pre-germination and prediction of safe storage time for malting barley.

This study investigated the following techniques to determine their suitability to detect and measure the degree of pre-germination in Canadian malting barley: rapid visco analysis (RVA), image analysis, near infrared reflectance (NIR) and Fourier transform infrared spectroscopy (FTIR).

Based on the results of this study, it appears that at the present time, neither NIR nor FTIR spectroscopy techniques are able to reliably detect and measure the degree of pre-germination in barley grain.

The results of this study suggest that grain appearance, as assessed by visual examination and/or image analysis, is not related to its composition and/or to the biochemical processes occurring in the grain. Therefore, the assessment of appearance via either method cannot, at the present time and/or the present state of technology, reliably detect and measure the degree of pre-germination in barley grain.

This study provided evidence that RVA is the suitable technique to detect pre-germination in barley. Since it is known that one of the signs of pre-germination is an elevated level of alpha-amylase in the kernel, and since the RVA parameters are very sensitive to the increasing level of alpha-amylase in the samples, it was concluded that:

  • The RVA test is able to detect the signs of pre-germination in barley samples.
  • The RVA test is able to measure the degree of pre-germination in barley as related to the amount of alpha-amylase in the samples.

The measurements of germination energy (GE) after accelerated aging of barley samples confirmed that:

  • Barley samples with the initially high RVA final viscosity (FV) values are capable of retaining their high germination energy (GE ≥ 95%) even when exposed to poor storage conditions.
  • Barley samples with the initially low RVA FV values show propensity to lose viability and exhibit low GE (<95%) after exposure and/or storage at poor conditions.