Whether you're an all-grain or extract brewer, keep reading because
the same base malt this article discusses is used to make liquid malt
extract. This information is also covered in Carl Townsend's Ask the
Brewmaster column in the Pacific Gravity Gazette, however, we think
it's important enough to repeat it here. While we've been lucky so far
with the domestic 2-row malt we've had in stock, it's never too early
to take precautions.
The trade press has been full of stories this year about the poor
barley crop. The Milwaukee Business Journal, for instance, reported
earlier this year that the crop was the smallest in more than 65 years,
driving up costs for brewers.
The barley crop creates more urgent problems for brewers besides
rising costs, however. The barley crop itself was poor, which has
led to malt with higher protein, more beta glucan and other complex
carbohydrates, which creates fermentation difficulties. Malting companies
expect this to continue for another three to six months, until the
new crop works its way to brewers.
Many brewers have already experienced and worked though problems,
but some may have not had trouble yet. You're not out of the woods
yet, however, because you may have more trouble when making high gravity
beers for the holidays, which have a higher amount of malt. Even when
the malt quality is good, trouble with certain batches can be apparent
when brewing high gravity beers.
First off, you may have noticed that the fermentation takes longer
to reach full attenuation. The telltale signs are normal fermentation
for the first few days, but the fermentation hits a wall and stops
2-4 Plato (8-16 gravity points -ed.) higher than expected. The yeast
is normal and vitality is high, but the complex sugars facing the
yeast can be more than they can metabolize.
If given a few extra days, sometimes the yeast can work its way through
the complex sugars and reach full attenuation with no further effort
on the brewer’s part. The best corrective action for the brewer
is to work the sugar profile in the mash. Try lowering the temperature
of the mash. Record the best temperature, as this may be the one you
will want to use for the next six months. Enzymes can be added to
the mash, particularly if doing a high gravity beer. Alpha-amylase
enzymes would be most beneficial. If you experience run-off problems,
beta-glucanase enzymes can be used.
On the fermentation side, there are several things you can do. Over-pitching
your yeast can help by having more cells to attack the abundance of
complex sugars. Raising the fermentation temperature once 5 Plato
(1.020 ed.) is reached can also help. If the fermentation is stuck,
you can employ a strategy used by wine makers, who commonly experience
stuck fermentations, due to the high alcohol involved and the low
nutrient value of wine. Wine makers will commonly pull yeast from
the bottom and restart it in a small quantity of aerated, fresh must.
They let this go for 12 to 24 hours before adding back to the fermentation.
It is important to have the yeast active, because it is always difficult
to get yeast to ferment in a beer or wine that is already fermenting,
because of the alcohol present and the lack of oxygen. So if you add
more yeast, regardless if it is from the fermentation or new yeast
from our lab, do so only after getting the yeast active.
Also, consider using yeast nutrients if you do not already do so.
Servomyces can help because zinc deficiency will add to the problem
of slow/stuck fermentations. If the yeast is healthy, it is better
able to cope with fermentation stress. If you have any other questions,
I would be happy to provide you with further advise. Just write me
Chris White is President of White Labs Inc. and is a chemistry
and biochemistry lecturer at the University of California, San Diego.
He has a Ph.D in biochemistry.