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I'm putting together an "all glass" kit with two carboys and want to brew a DIPA but I'm a little concerned about temperature ranges where I'll be fermenting. I'm looking at somewhere between 15-18 Celsius. A friend told me that using an Ale yeast in that range will give the beer a bad flavor. I'm a little skeptical but realise anything is possible. With this being my first go I'd really like to nail it. Any insight is appreciated.

Cheers,

Ethan N.

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Also I've seen that different Ale yeasts obviously have different temperature ranges (which makes me skeptical about my friend's claim) but don't know if fermenting at the low ranges will do anything even subtly foul to the taste. –  Ethan Noore Nov 8 '11 at 21:23
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4 Answers

up vote 10 down vote accepted

Fermentation temperature does play a pretty big role in how the beer is going to taste. If the temperature is too high you can get excessive amounts of ester production and also can produce higher alcohols and phenolics that are undesired. If the temperature is too low, ale yeast can be sluggish or go dormant too soon causing under attenuation. It can also fail to reabsorb byproducts from fermentation such as diacetyl. You would seem to be on the very low end of the fermentation range for ale yeast at 15-18C. This temperature range may work well with hybrid yeast such as Alt(wyeast 1007) or steam beer yeast(wyeast 2112).
An optimal range for most ales would be around 19-20C(66-68F).

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Thank you! That's very helpful. –  Ethan Noore Nov 8 '11 at 21:48
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Remember that it is the temperature of the beer that is important, not the air. Fermentation is exothermic; which can cause the temperatures in the fermenter to be a few degrees(F) higher than ambient. –  Dustin Rasener Nov 9 '11 at 17:08
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Yes, yeast have an optimal temperature range.

Too cold

They become dormant and won't ferment all of the sugars impacting the flavor, mouth feel and alcohol content

Too hot

They flip out and produce fusel alcohols that can taste like cleaners or solvents. You can shake some of these flavors off during secondary but if there's too many they'll stick around. A Banana flavor in beer could be attributed to high esters during fermentation, diacetyls is another.

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Thank you both for the insight. It's very helpful. –  Ethan Noore Nov 8 '11 at 21:51
    
I think I'll find a fermenting place that's a little warmer. Thanks again. –  Ethan Noore Nov 8 '11 at 22:33
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One more important point about temperature that isn't immediately obvious to newer brewers is that the ambient temperature of the room is NOT the temperature of the fermenting beer. Fermentation is an intense activity that produces a lot of heat, and the stronger the beer, the more heat is generated as the yeast go nuts eating all the sugars.

For a DIPA, I would expect that on day 2-3 of active fermentation, you'll see the temp of the fermenting beer be as much as 10 degrees Fahrenheit higher than the air temperature of the room the beer is in. And for an IPA-style brew, this higher temp can really make the beer taste wrong.

To combat this, get a big tub/drum/whatever to put the carboy/bucket in, along with a few gallons of water. Put frozen water bottles or ice packs in the water daily and keep an eye on the temps every 10-12 hours, especially during the first 5 days of fermentation or so. As fermentation slows down, the temperature will slowly drop back down to near ambient temps.

Of course, if you are starting the yeast off on the cool side of their preferred range, then maybe the rise in temps will just bring it up to the high end of their acceptable range, in which case everything is fine by itself. But just be prepared to act quickly if you see the temps go above the recommended high range.

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That's very helpful. I suspected the yeast produced SOME heat during fermentation but didn't realize it would be that much. I had planned on setting up a thermostat/switch and radiant heater setup to try and stay in range, but it looks like I need to be more concerned with the temperature of the beer. Thank you! I'll post updates and stats once I go live. –  Ethan Noore Nov 9 '11 at 14:34
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This very strongly depends on which yeast you use; some yeasts throw pretty strong off-flavours if fermented warmer than their recommended range, others are extremely tolerant.

I have never heard of bad flavours coming from fermenting at a temperature lower than recommended. The only thing that a lower-than-recommended temperature can do, that I am aware of, is to ferment much slower and possibly even not at all.

Since you mention that this is your first go, I'll point out that the stronger styles of beer (and a Double IPA most definitely counts!) are much more challenging beers to make well. It will almost certainly be drinkable, will most likely be impressive, but it will be very difficult to make a strong beer that is great. Sooner or later I suggest you try making some straightforward 1.045-1.050 beers, while they don't sound nearly as interesting it is actually possible to make something incredibly good.

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Thank you. I talked with a local brew supply store owner and he suggested pitching with "pacman" or "1056" yeasts. He's actually going to help with the recipe too. Very helpful with this being my first batch, as I don't know what I don't know. –  Ethan Noore Nov 9 '11 at 15:56
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Very good points (although some British yeasts like S-04 do throw diff flavors when cold, but its an edge case). Ethan, I'd suggest using US-05, which is a dry yeast version of 1056. Its not just close to 1056, its the same strain, just in dry form. Its cheaper and easier to work with. –  Graham Nov 9 '11 at 16:52
    
I've cooked my wort and pitched my yeast (wyeast 1187). I hate that I didn't see you're comment @Graham I would have liked to try out the US-05. I think I'm in good shape though. I pitched a little high at 25C (78F) but the wort cooled to 18C (65F) by the time my airlock really got bubbling. I'm now into primary fermentation day 2. I'm going to be looking for a surge in temp like you said. Cheers! –  Ethan Noore Nov 29 '11 at 18:16
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