WHEAT quality researchers have made a breakthrough, finding that late maturity alpha amylase (LMA), previously thought to be a grain quality defect, had no impact in their trials on the baking quality of flour made with wheat with high levels of LMA.
Jean-Philippe Ral, research team leader of the CSIRO cereal quality group, has been researching LMA for six years and said the finding could save growers big dollars by minimising unnecessary downgrades of wheat deliveries.
He pointed to the 2016 LMA event in the United States which cost wheat growers in the Pacific North West region alone $US150 million due primarily to lost exports to Japan.
Both LMA and pre-harvest sprouting are currently identified by low falling numbers tests, however Dr Ral said if a test was developed that distinguished between the two phenomena, it could mean less wheat was downgraded.
“Previous studies are clear, pre-harvesting sprouting is definitely detrimental to baking quality, the grain germinates and enzymes are produced that impact its end use qualities,” Dr Ral said.
“On the other hand, LMA does not have the same influence on flour characteristics, yet because of the way the falling numbers test works, it can’t be differentiated from the more harmful sprouting.
“No consistent or significant phenotypic correlation was found between LMA-related low falling numbers results and any of the quality traits, providing evidence that LMA has limited impact on bread baking end product functionality.”
Dr Ral said if a test differentiating between LMA and sprouting could be developed it would mean better returns for growers as they would have less wheat downgraded each year.
“It is something to look at, because the industry has been using the falling number test ever since the 1960s,” he said.
LMA is triggered through environmental stress, in particular cold shock, during the grain fill period in late spring, with the compound remaining present in the wheat grain kernel in the aleurone layer through harvest, although it is impossible to diagnose visually.
Dr Ral said it could be particularly problematic in years where mild spring weather was followed by a sudden cold snap.
He said it had become an increasing issue in recent years.
“We don’t know everything about LMA but it has certainly been more visible since the green revolution and with improved wheat varieties, perhaps there was an alteration to wheat’s dormancy requirements that have impacted the way LMA is formed but we don’t really know for sure,”he said.
“We know a variety like Seri is very susceptible to LMA but others, such as Hartog, are virtually LMA proof, so at some stage the Holy Grail would be to find a gene that just stops LMA occurring, although that may be some way off.”
In spite of the finding that LMA is not having an impact on baking quality, Australian farmers should not expect a change in receival standards any time soon.
Wheat Quality Australia executive officer Hugh Robertson said at present the industry traded on falling numbers tests and did not differentiate between LMA and sprouting.
“If we could effectively segregate between the two problems it would be different, but for now I expect the status quo to remain, the falling numbers test has been in place since the 60s so a new, more sophisticated test could be a generation away yet,” Mr Robertson said.
“It is good research, confirming what a lot of people thought, but the timeframe for the findings to have an impact might be quite drawn out.”
The research work was part of a project involving CSIRO and the Grains Research and Development Corporation.