MALTING QUALITY TRAITS - Canadian Malting Barley Technical ...

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Chapter Five
sugar and alcohol content. This is a direct economic benefit to the brewer; more of the extract is
fermentable. As well, the higher protein in Canadian barley results in the high levels of free amino
nitrogen (FAN) present in well modified Canadian malt, which provide the yeast with enough nutrients
to ferment worts with high adjunct levels and higher original gravity, up to 20 degrees Plato.
The higher levels of protein and FAN can prevent the sluggish fermentations that often occur when
the adjunct ratio is raised. Additionally, the high FAN negates the need for the brewer to add artificial
yeast foods (that can be costly and may not be perceived by the consumer as acceptable in their beer
i.e. addition of Zinc Sulphate solution or diammonium phosphate.)
Maturation, Filtration and Stabilization
From the fermenter, beer is transferred to large tanks where it matures for a period of 10 to 21
days at -1°C. During maturation, residual yeast settles out, and further complexing of proteins and
polyphenols may occur, forming hazes, which are subsequently removed by filtration. In addition
to filtration through diatomaceous earth, beer may be further stabilized by either pasteurization or
sterile filtration prior to final packaging. High levels of ß-Glucan in the fermented beer can cause
filtration problems, but this is not a problem with Canadian malt, due to its inherent low levels of
ß-Glucan. The effect of ß-Glucan on beer filtration is to extend the time required to complete a filter
run, and/or to decrease the amount of beer that can be filtered in a single run. These two factors have
an economic impact in increased cost of filtration material (either diatomaceous earth or membranes)
as well as the added manpower costs for the increased time required for filtration. Finally, there
can be a negative impact in quality of the beer due to increased frequency of filter start-ups (due to
shorter runs). The beer used in start-up of a filter has a high oxygen content, and this beer is either
disposed of or is blended back into the beer that is to be filtered. As oxidation leads to staling and
other undesirable flavour changes affecting the shelf life of beer, care must be taken to avoid uptake
of oxygen throughout the brewing process, and particularly during packaging.
Beer Quality
Since the “discovery” in the late 1970s of dimethylsulphide (DMS) and its precursor DMSP, and
their effect on beer flavour, Canadian maltsters and brewers have led the way in understanding and
controlling DMS and DMSP in malt and beer. Today, most brewers have specifications for these
compounds in their malt, as well as in the finished product. As a result, Canadian malt has very low
levels of these compounds. There was a time when a 90 to 120 minute boil was necessary to ensure
low levels (