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!

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.