THE BEST TEST
BY TRUDY KELLY FORSYTHE • PHOTOS COURTESY OF MARTA IZYDORCZYK
When barley germinates prior to harvest or in the bin it can cause significant problems for the maltster to achieve a high-quality malt product. Maltsters generally reject barley that exhibits significant pre-harvest sprouting. The livestock industry also typically discounts pre-sprouted feed barley.
Farmers and end-users can test for pre-germination. While barley can be visually inspected simply by removing the hulls to look for visible sprouts, pre-germination is not so easily detectible. In the laboratory, the germination energy test assesses the germination potential of barley kernels placed in a moist petri dish. The level of alpha amylase, an enzyme that increases during germination and an indicator of pre-harvest sprouting, can also be tested. As well, a rapid viscosity analysis (RVA), like a falling number test, can be conducted.
While each method provides valuable information, RVA has become a favoured choice for detection and assessment of pre-germination because it is a quick, objective and practical test. To do the analysis, barley is ground, mixed with water and heated within a machine known as a rapid visco analyzer. The machine stirs the mixture with a paddle. The level of resistance to its movement generates an RVA value between zero and 160 units. A number above 120 indicates the barley is sound. Between 50 and 120 units it is considered moderately pre-germinated. Less than 50 is more severely pre-germinated and rated poor quality.
Marta Izydorczyk, a research scientist and program manager with the Canadian Grain Commission, said RVA values indicate risk of germination loss in storage. For barley above 120 RVA units, the risk of germination loss during storage is very low. For moderately pre-germinated barley with RVA values between 50 and 120, the risk is intermediate. And, for severely pre-germinated barley with RVA values below 50, the risk of germination loss during storage is very high.
“This is basically a tool that allows whoever is handling barley to know how to deal with their stock,” said Izydorczyk. “If you have pre-germinated barley, it should be used for malting as soon as possible, whereas if you have sound barley, then you are pretty sure you can store it for a long period, and it will retain the germination energy and produce good quality malt even one year after harvest.”
TIPS FOR BEST RESULTS
Pre-germination can result when a crop near maturity is exposed to rain or humidity. Certain malting barley varieties such as CDC Copper and CDC Churchill have been bred for lower enzyme levels and tend to resist sprouting.
As well as growing such varieties, farmers can take additional steps to achieve the best RVA results, said Peter Watts, managing director of the Canadian Malting Barley Technical Centre. These include seeding and harvesting barley as early as possible to avoid wet conditions and targeting a maximum of 13.5 per cent moisture content for harvest.
“Barley harvested with low moisture, below 13.5 per cent, has less likelihood to experience a drop in RVA after it’s harvested,” said Watts. “Barley harvested with higher than 13.5 per cent moisture may need to be dried to avoid germination loss, or a fall in RVA.”
Proper storage with good aeration will keep barley in top condition and avoid loss of germination energy over time, or a drop in RVA value.
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