SCIENCE
B R U T
I PA
Mechanism of amylase activity α-Amylases Amyloglucosidases
Amyloglucosidases
β-Amylases
Reducing end
Glucose
Maltose
Fig 3: Beta amylase acts as an exoenzyme
2-4 litres per tonne, although this ought to be optimized
of the yeast strain concerned. The two most popular
for individual processes. The enzyme requires thorough
options are a neutral ale strain such as Lallemand BRY97
distribution throughout the mash to ensure uniform
or a Champagne strain such as the Lallemand CBC-1.
breakdown of starch and so it is recommended that the
A Champagne strain will only ferment simple sugars
enzyme is added incrementally throughout the mashing
such as glucose, fructose and maltose, meaning that
process.
starch breakdown needs to be comprehensive to ensure
An enzyme addition to the fermentation vessel has
a completely dry final product. A clean US style ale
the advantage of a much lower dose rate and complete
strain will ferment both maltotriose and maltose so,
breakdown of any remaining dextrin material but has the
if starch breakdown is not complete due to less than
disadvantage of the presence of an active enzyme in the
ideal mashing conditions, or a lack of fermenter enzyme
final beer. The consequence of this is that great care
addition, it may be more forgiving to the brewer. Clearly
must be taken to ensure that fermentation has proceeded
the desired final sensory characteristics of the beer also
to dryness prior to packaging the final product. Failing
need to be considered at this stage.
to ensure starch breakdown and fermentation have
References: Michael J. Lewis, Tom W. Young, Brewing, 2002
completed to satisfactory levels will lead to increasing levels of sweetness in filtered or yeast free beer and
Brut IPA recipe
pressure buildup and potential bottle bombs in bottle conditioned beers. The recommended dose rate is an addition of AMG to the fermentation vessel at the start of fermentation at a level of 10ml/hl. The Lallemand recommendation is an addition of enzyme to both the mash and the fermenter. This ensures
T
he grist for a Brut IPA should be predominantly pale with some wheat added for head retention if desired. Hop bitterness should be low, in the
fermentation in a good timeframe, especially when
region of 15-25IBU. Alcohol content tends to be between
using a Champagne strain, as well as complete starch
4.5% and 6.5%. Lallemand have created an example
breakdown.
recipe, as well as best practice procedures which can be
The yeast strain chosen for fermentation of Brut IPA is choice for the brewer; however, the choice should be made in full awareness of the physiological properties
60
November 2018
seen on the following pages. (right) We have also put together a ‘best practices’ procedure (overleaf). u
Brewers Journal