Following on from my previous blog on splitting batches, I recently split a batch of my English Brown Ale recipe. The reason for trying this experiment is to compare two Mangrove Jack yeasts. Whenever I have brewed this beer, I have always used the Mangrove Jack M15 Empire Ale yeast. That will be the base beer for this experiment. The test batch will be using Mangrove Jack M42 New World Strong yeast.

The Empire Ale yeast states on the packet ‘A top-fermenting ale yeast suitable for a variety of full bodied ales, with exceptional depth. Ferments with full, rich dark fruit flavors.’

The New World Strong is described as ‘A top-fermenting ale strain suitable for many types of ales of all strengths. Ferments with a neutral yeast aroma to ensure the full character of the malts and hops are prominent in each beer.’

So, both yeasts appear to be appropriate for this style based on the information available to us. As I mentioned, I have previously used Empire Ale on this Brown Ale, but also on my English Milds and I have found it to be an excellent yeast for darker British beers.  

The only beer I used New World Strong on before this experiment was my XXX Bitter recipe. Originally, I used the Mangrove Jack M07 British Ale yeast, but since that was discontinued, I needed to find a replacement. I was disappointed with the results of the New World Strong on that beer and have not used it since….until this brewday.

Knowing I would split the batch, I brewed a batch to yield 9 gallons in the fermenters and consequently 7.5 gallons in the kegs. I will have a 6 gallon batch using the Empire Ale yeast and a 3 gallon batch using the New World Strong.

I simply scaled up my recipe by 50% to cover the increase from 6 to 9 gallons using the BeerSmith brewing software to guide me on water quantities and water profile changes. When brewing a darker English beer, I typically adjust my water profile to match that of the London profile in BeerSmith. The water additions show the water profile to be ‘Balanced’ on the scale of hoppy to malty. This is just my preference and not necessary to get great results out of either yeast.

After what amounted to a pretty uneventful brewday I was left with the appropriate amount of cooled wort and both fermenters were placed together in the same fermentation chamber.

Original Gravity on the wort was exactly as BeerSmith had predicted at 1.056

I set the temperature to 64F and left them for a couple of hours to acclimatize to the temperature. I also set the packets of yeast in there too for them to reach the appropriate temperature. Later, I oxygenated each wort and pitched the yeast. Both yeasts fermented quickly and climbed up into the airlocks.


Throughout primary fermentation, both of these fermenters stayed together in this chamber and any changes to the chamber temperature for Diacetyl Rest and Cold Crashing were completed with both beers in the chamber. I did not use a secondary vessel other then the kegs in which the beers were racked for carbonation.

At kegging it was obvious that the beers were very different, with the Empire Ale version being my favored at tasting. With a somewhat surprising gap, the Final Gravities were very different too.

Empire Ale  
OG 1.056
FG 1.014
ABV 5.5%

New World Strong
OG 1.056
FG 1.008
ABV 6.3%

So, the New World Strong yeast dried out the beer much more than the Empire Ale yeast. In fact, it was noticeably drier in the taste and was fairly two dimensional in its overall flavor profile. While the Empire Ale beer was more complex that the New World Strong. It had more layers and the nutty, chocolate flavors appropriate to the style were evident. The New World Strong version was quite two-dimensional.

Now, that isn’t to say that the New World Strong yeast isn’t a good yeast. It just wasn’t to my liking for this style of beer and the descriptions on the packets were otherwise very accurate. The Empire has exceptional depth, while the New World Strong appears to be quite neutral

I will continue using the Empire Ale yeast for this style and others. As I mentioned above, I really enjoy it in dark English beers and I have since used it on an English Mild, an English Bitter & an Oatmeal Stout. I hope to be able to report those results as well and hopefully my experience with this split batch helped your brewing.

Brown Ale Recipe 
(6 gallons)

9lb 12oz -- Muntons Planet Base Malt

12oz -- Gambrinus Honey Malt

12oz -- Briess Special Roast

8oz -- Muntons Crystal 60

8oz -- Dingemans Biscuit Malt

6oz -- Muntons Pale Chocolate

1.5oz -- East Kent Goldings @ 60 mins (24.2 IBU)

0.5oz -- East Kent Goldings @ 5 mins (1.6 IBU)

1 Pack Mangrove Jack Empire Ale Yeast.

Mash for 60 minutes @ 150F

Ferment @ 64F

--Nigel Curtis

Homebrew Consultant, Come and Brew It Radio Host, Cask Beer Lover, Regularly Taunted British Ex-Pat, Thrower of Shoes