MALTING QUALITY TRAITS - Canadian Malting Barley Technical ...

centre timing. A savings of 15 minutes in lautering time (90 minutes to 60 minutes for example)
could translate to 34 extra brews per week in a 24 hour, seven day operation, or one day less in a
24 hour a day, five day a week operation. This can have positive economic implications in terms of
energy/utility costs, manpower costs and/or increased capacity.
Wort Boiling
After lautering, or mash filtering, the wort is boiled for at least an hour in the
presence of hops. Evaporation rates of 7% per hour are common with vigorous boils.
The objectives of boiling are to:
• sterilize the wort
• inactivate all enzymes
• concentrate the wort to the desired specific gravity
• extract desirable hop bitterness and aroma
• coagulate some of the wort protein to improve beer stability
Boiling also increases the colour of the wort due to biochemical reactions similar to those which
occur in malt kilning. The specific gravity of the wort indicates how much sugar is present, from
which the amount of alcohol that will be formed by fermentation can be calculated. Most, if not all,
brewers, utilize high gravity brewing in their operations. Normal original gravities vary from 14 to
up to 18 o Plato. The residual hop material, coagulated proteins and tannins (collectively called “trub”)
are removed as “hot break” in a vessel known as a whirlpool. Worts produced from Canadian malts
are clearer than those made from barley of other origins. Clear wort has less fatty acid material,
and as such promotes a better final beer foam. Additionally, clear wort contains less nucleation sites
for gas breakout during fermentation (and subsequent overfoaming), allowing brewers to decrease
the head space volume in the fermenter. This allows for capacity increase in the fementation area
by increasing the volume in each fermenter. The reduction of overfoaming also decreases the loss
of bittering components that may cling to the wall of the fermenters after emptying. The loss of
bittering requires the brewer to increase his hop bill (adding cost) to meet product specifications.
This is especially true in large vertical fermenters.
Fermentation
Using a plate heat exchanger, the hopped wort is cooled to between 10 and 15 o C
before fermentation. Heat drawn from the wort is used to heat incoming brewing water
for subsequent mashes. Air or oxygen is usually injected into the cooled wort to ensure
sufficient oxygen is available for yeast metabolism in the early stages of fermentation. Yeast may be
added to the cooled wort en route to the fermentation vessel, or “pitched” directly into the fermenter
as it exits the cooler.
The strain of yeast chosen, wort composition and conditions of fermentation all have a profound
effect on the type and quality of beer produced. Lagers are generally produced by slow, cool
fermentations (10 to 15°C), at the end of which the yeast settles to the bottom of the fermentation
vessel, to be collected for repitching. Ale characteristics come from warmer (15 to 20°C) and more
vigorous fermentations. Ale yeast rises to the top of the vessel at the end of fermentation, where it
is “skimmed” for use in subsequent brews.
Fermentation, usually in closed vessels, proceeds for about seven days, during which time fermentable
sugars are converted to alcohol and carbon dioxide. The spectrum of fermentable sugars
and nitrogenous compounds in the wort not only influences the rate and degree of fermentation,
but also the levels of yeast metabolism by-products, which contribute to beer flavour and character.
Malt from Canadian barley varieties produces highly fermentable worts, allowing the modern brewer
to precisely adjust both mashing and fermentation conditions to achieve desired beer styles. When
compared to malts produced with barley from Australia and Europe, worts from Canadian barley
varieties are always more fermentable. Thus, the same malt source can be used to produce a range of
beers, such as Pilsener, dry and light beers, which differ in degree of fermentation, level of residual
Chapter Five
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