How does the barley crop vary from year to year?
Back to Ask the Brewmaster.
For the answer to this, we turn to Chris White, President of White Labs. These comments, reprinted with permission, pertain to the 2002 crop.
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 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 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 at firstname.lastname@example.org.
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.