
News from the Lab: Fermentation trials
By Neva Parker
White Labs
It’s officially summer and
it is getting HOT in San Diego! We’ve been very busy over the past few
months with several different projects, in addition to growing that
wonderful yeast.
One of our main objectives
has been on performing a variety of fermentation trials. Many of these
focus on different yeast strains and how their fermentation
characteristics differ from one another, but we are also working more on
changing brewing conditions to discover how this really affects the
yeast cells. A major factor in yeast performance is fermentation
temperature, so we felt this was something we really needed to maintain
in order to recreate normal brewing conditions. With the help of some
colleagues, we designed a water bath for our lab-scale (1L)
fermentations.
This water bath uses a small
glycol chilling unit to circulate water at a set temperature through our
holding chamber to regulate the temperature of our fermentation flasks.
Since temperature is such a
major component in fermentation, I ran several trials using our
20-gallon brewing system and temperature-controlled conical fermentors
to see how changes in temperature can effect the flavor profile of the
finished beer. In addition, I performed a second set of experiments
where I altered the original gravity of the wort. For both of these
trials, we were able to use our Gas Chromatograph-Head Space to measure
the levels of flavor-active compounds in each beer and compare the
results.
I focused on diacetyl,
esters (iso-amyl acetate & ethyl acetate), and fusel alcohols (n-propanol
& iso-amyl alcohol). What I found was that both esters and fusels
increased with increasing temperature, as well as with increasing OG.
Diacetyl decreased with higher fermentation temperatures, while
increasing the OG did not seem to have an effect on diacetyl levels. For
more detailed information about these trials, please see my article in
the May/June issue of Zymurgy Magazine (published by the American
Homebrewers Association).
Also on the horizon for
White Labs is the infamous Yeastman. More work is being done and
progress is being made. You’ll soon be seeing this bar-code tracking
system producing your Certificate of Quality, giving your more detailed
information about your particular yeast culture. In addition, the
inventory tracking component will help us help you!
Once it is implemented on
our website, you will be able to receive an instant response as to when
your yeast culture can be available to ship to you! After all, it’s
all about the customer – look for this feature in the near future!
Postscript: Brett kits
Considering barrel-aging?
Did you know that most barrels (new or old) contain some level of
Brettanomyces? If you’re not going for that farmhouse style ale, you
can test your barrels!
We have available a simple
to use Brettanomyces detection kit. It’s as easy as 1- swab an area
inside your barrel, 2 – spread the swab onto specially formulated
Brett plates, and 3 – incubate for 3-5 days. Call 1-888-5-Yeast-5 for
more information!
Neva Parker
is lab manager for White Labs. |