Dark Mild - Multi-Yeast Experiment

A little while ago, Greg, a fellow CAMRA club member, and I started talking about doing a cooperative brew. We share a number of common interests: brewing, breadmaking, cooking, kids; so it seemed a great idea to share a brewing session. We both enjoy English session ales, so we figured we would brew a dark mild, as they are not commonly available here in the U.S. and are best drunk fresh. Additionally, to make things interesting, we decided to do a yeast experiment.

I have often heard people state that the liquid yeast products that brewers pay a premium for are far superior to the dry yeast equivalents. Some things about the two yeast forms can definitely be attributed to fact. Liquid yeast strains can be designated as pure and without contamination, which means with proper sanitation, a brewer has very little chance of getting wild yeast contamination. Dry yeasts always have some wild yeast contamination as part of their manufacturing process. This is minimized, but how great is the risk of infection? Several podcasts and homebrewing magazines have done experiments on the dry versus liquid yeast packages, but Greg and I wanted to do our own.

The plan was to use one common wort source, split in half, and then to use two different yeasts to determine the yeast form's impact. Further, we wanted to use dry and liquid yeast strains that came from the same historical source. So, we picked Wyeast 1968 London ESB and Safale S-04 Dry English Ale. Both of these strains are based on the Whitbread yeast strain (http://en.wikipedia.org/wiki/Whitbread). This should provide us with a situation where the dry versus liquid yeast difference would be maximized, if any existed at all.

The following stats applied to both beers:
SG: 1.039 (both yeasts)
FG: 1.011 liquid, 1.012 dry
Starter Size: 1 L liquid, no starter dry (10 gram pack)
Pitching Temp: 72 F (both yeasts)
Fermentation Temp: 68 F (both yeasts)
Fermentation Length: 4 days liquid, 3 days dry

The results were extremely close. The liquid yeast beer (Duval glasses in picture) was slightly lighter in color than the dry yeast batch. The liquid yeast beer also had a slightly more definable aroma, but it came from a keg, so the aroma could well be from a slightly higher carbonation rate. The most definable difference was in the intensity and length of flavor. The liquid yeast batch's flavor lasted longer and was more intense than the dry yeast, but not by a large factor. I did not get any off flavors from the dry yeast, and I think it was quite comparable to the liquid offering.

Bottom line was that they were VERY close. Given that the dry yeast is much cheaper and it is easier to use, I think I would recommend using dry yeast when a version that has been well received by the brewing community is available.

Thanks for a great brew day and tasting, Greg. It was a lot of fun.