terminal gravity

Wyeast’s description of Trappist High Gravity 3787 saying that it “benefits from incremental feeding of sugars during fermentation.” This has got me looking into this process. My plan is to feed an AG brew using John Bull LME. For more information I emailed Wyeast and got this reply:

I would let it drop to about 1.050 before dosing. If you are dosing
with LME, be aware that this will have a pretty high terminal gravity
due to the percentage of unfermentables in the LME. I.e. this beer may
be pretty sweet. Also, is the LME microbiologically stable? If not you
may want to boil with some water before dosing. As for O2, your normal
oxygenation will be fine.

Jess

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This raises two questions.

First has to do with the “high termanal gravity” of LME. I was under the impression the LME was just concentrated wort and would have the same potential SG as using the same type of grain.

The other thing is the “microbiologically stable” reference. I haven’t been able to find any information on John Bull products on the Internet. I was under the impression that all quality LME was safe for “no boil” brewing. Does anyone have information on this?

LME is going to have unfermentable sugars. Every manufacturer differs so you have some control. In a really big beer I would use something that was fully fermentable for the additions and set the final gravity with the initial mash conditions. Also easily fermented sugars such as sucrose or dextrose will be much easier for the stressed out yeast to ferment.

GT

This is a bit confusing. I was trying to stay away from sucrose or dextrose believing that they would change the flavor profile. The LME was going to be John Bull Maris Otter which is suppose to be 100% Maris Otter malted barley and has a potential SG of 1.038. This doesn’t compare to dextrose’s potential of 1.046, but is inline with the grain that will be used in the original mash. I guess it is somewhat of a balancing act, but I hate to experiment too much with a batch that will be somewhat expensive. What percentage of fermentables can come from dextrose before it has a detrimental effect on the beer? Or should I be asking what percentage of dextrose will actually add to the character?

Are you dead set on LME? DME is probably much easier to work with in this situation.


TL

No Tex, I’m not set on anything, just want to get it right. The DME is a good suggestion. The potential of 1.044 is right up there with dextrose.

These potentials are coming from the BeerSmith grain chart, but I don’t fully understand it. I was under the impression that things like honey and candi sugar were 100% fermentable, yet the chart has them having less potential then the Maris Otter.

The other thing that is confusing is the column for “Max in batch.” Candi sugar is listed as 20%, but dextrose is at 5%. It they both ferment out cleanly why would there be a difference?

After 8 weeks in the primary, I moved this beer to the secondary yesterday. The theoretical OG was 1.133 and the IBU 104. I know that this beer will take a lot of aging, but the taste was still disappointing. The gravity came down to 1.033 which may be all that I can expect, but it was very sweet without enough bitterness to balance it out.

The feeding schedule consisted of three additions. The first was a Maris Otter concentrate. The next two were both 3 pounds of Turbinado sugar boiled in a 3 pints of water. I did not do any aeration at feeding. Just gently stirred.

I plan to leave this in the secondary until at least fall. Is there much hope for the flavor to improve greatly over time?