Hot Mash (72 C), Low Target Gravity, Not so vigorous fermentation

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scottfro

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So I did my first 46 L batch with 22 lb of 2-row malt and 2 lb barely flakes. I ended up with a final gravity of 1.048 (was shooting for 1.058) and the yeast are definitely at work but not nearly as active as I'm used to. I put blow off tubes on both carboys but neither were needed as the kraeusen only got to a thickness of 1" or so. The beer is definitely churning a lot and the airlock was ripping for the first few days.

Am I worrying about nothing or is there something in my brewing process I need to improve (beyond improving my efficiency)?

This is also the first time I've used a yeast starter grown up from a yeast slant I cultured myself. Could the yeast health contribute to this?
 

david_42

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You may have had a fast ferment and it's nearly done. With a good starter, a couple days is all it takes. Since you grew it from a slant, all of the yeast are active and healthy.
 
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scottfro

scottfro

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i kept a pretty close eye on it so i don't think i missed it. plus i have no junk from the kraeusen left on the side of the carboy or in the blow off tube.
 

BigEd

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A 72C mash temp is really hot, 70C is generally considered the maximum and the range of 65-68C is where you usually want to be. You will have certainly produced a much lower percentage of fermentable sugars so that may be one of the reasons the fermentation was on the sluggish side.
 
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scottfro

scottfro

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thats what i had a feeling off. had trouble getting my thermometer to give me a consistent reading. sometimes was 65 C sometimes 72 C. Not quite sure what the deal is.

will my FG be higher than I am used to or is having less ferementable sugars represented by the OG reading?
 

TexLaw

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If your temperature readings varied that much, then your mash was not well mixed, so you had some drier pockets and probably some doughballs. That will reduce your efficiency. If your mash is well mixed, you should have a consistent (or nearly so) temperature throughout your mash. If you had parts of your mash that stayed at 72C, that also can reduce your efficiency.

With a lower OG, you can expect a lower FG. However, I don't know what your target mash temperature and FG were,

Yeast health doesn't seem to be an issue. Blowoffs aren't always necessary, especially with a beer that may have a lower OG. I also don't know how much headspace you had in your carboys. An inch of krausen and three days of vigorous fermentation sound fine.


TL
 
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scottfro

scottfro

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Thank you for the thoughts.

I stirred the mash quite a few times to try and get the temp to even out. I'm wondering if my thermometer is going bad? It seems to read accurately but also seems to fluctuate so easily.
 
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