Pregermination in grain

UK maltsters exhibit a poster at EBC Prague May 2005
An unexpected benefit from the HGCA Grain Sampling project (GSAP)

In January 2004 representatives of the MAGB and Banks Cargill Agriculture met at Banks Cargills laboratory in Sandy to see if a truly definitive method could be agreed for the detection of pregermination in malting barley.

This is a potential problem, that only occurs infrequently in crop years, and one which is linked to growing conditions for the grain. Because it does not occur often it has tended to be tested for using a variety of methods, the recognised 'official' test method using Fluroescien Dibutyrate, which has never been considered suitable for testing grain at intake to a store or maltings. Furthermore, it has recently become very difficult to obtain the chemical needed for the 'official' method.

There are other methods which involve staining the grain, to help view the embryo and see if a physical change has taken place. The most common staining agent used is 2,3,5-triphenyl tetrazolium chloride, more commonly referred to simply as the 'Tetrazolium staining test'. Because the pregermination only happens occasionally, and the Tetrazolium Staining Test needs a certain amount of knowledge for accurate interpretation, this has always been seen by the industry as a potential source of discord between the barley seller and the buyer.

The workshop of industry experts that met at Sandy in January 2004 was therefore most timely. All involved were experts at evaluating the different testing systems used, and they were able test a range of barleys using both the 'official method' and the Tetrazolium staining method. Moreover, some funding from the HGCA GSAP project enabled a photographer to be on site to take directly comparative images. The Tetrazolium staining photographs were accessible from the 'Laboratory' section of this website from April 2004, and the images were most useful in selecting malting barley from the 2004 crop, which did have some signs of pregermination.

At the request of UK maltsters, two of the malting industry experts at the Sandy workshop, Stan Sole and David Griggs, took information on this useful work to the EBC Conference in Prague in May of this year, and have submitted a paper to the EBC proposing that the Tetrazolium staining test, using the workshop interpretive photographs, now be accepted as the new 'official method'.

Stan Sole, on the left, and David Griggs take well earned refreshment in front of their Pregermination display poster at EBC Prague in May 2005

Dave Griggs told the MAGB secretariat that "The poster was well received and elicited a good deal of discussion with representatives of non-UK malting companies. Most maltsters were aware of tetrazolium staining for the determination of germinative capacity, but few were currently also using the technique for the assessment of pregermination. This provides another example of where UK maltsters are actively managing their raw material quality and ensuring only barley of the correct standard is accepted at intake. The Analytica-EBC method for germinative capacity by tetrazolium staining is being revised to include the assessment for pregermination."

The handout for the EBC Prague, giving details of the pregermination testing procedure is available as a PDF file by clicking on the stained grain below:


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