To bottle or not to bottle?

[Rosshedley]

Hi Brewers,

I have brewed an 11 Litre all grain IPA.

Target OG was 1.061. Actual OG was 1.071 (taken with refractometer).

Target FG was 1.012. SG at 15 and 17 days (hydrometer) was 1.026. (Reading at 15 days with refractometer was 1.038, but I understand that this is inaccurate due to alcohol in liquid, yes?)

Will this be okay to bottle now?

I am guessing that it will a taste a little sweeter than the original recipe intended, due to more malt remaining. Should I still use 2 carbonation drops per 500 ml bottle (as instructed)?

Any help most appreciated.

Ross

 

[MaxStout]

That's only about 63% attenuation. Can you provide more info? Yeast strain, fermentation temps? Mash temp (if all-grain)?

The usual test is to take gravity readings a couple days apart. If it doesn't change, generally, it's ready to package. HOWEVER, if the fermentation was just stuck, you bottle at 1.026, and the yeast decides to wake up and keep going, you're likely to have over-carbed bottles, and maybe bottle-bombs.

 

[Rosshedley]

I think it was Magrove Jack's US West Coast Yeast M44.

I was aiming for Mash temp of 66 degrees c but it dipped below at times, and probably a little higher at times when I added heat to raise back up.

Fermentation temp was between 21-24 degrees c. Probably 22/23 mostly.

Thanks.

 

[davidabcd]

You did your due diligence with two gravity readings. Wouldn't hurt to do a full, three weeks though (after swirling the fermentation vessel to see if that helps you get more yardage out of your yeast). The amount of yeast should have been fine, maybe not optimal but enough to ferment what was there.
I would prime as directed.
My guess was your mashing temps were/are the reason for not getting closer to your FG.

 

[Rosshedley]

Thanks!

"My guess was your mashing temps were/are the reason for not getting closer to your FG."
-how come? As I got more malty goodness out of the malt than the recipe called for. Does something else happen to the mash at certain temps that make it harder to ferment for longer?

 

[IslandLizard]

how come? As I got more malty goodness out of the malt than the recipe called for. Does something else happen to the mash at certain temps that make it harder to ferment for longer?

Enzyme Activity In Mash

• IslandLizard
• Jun 10, 2018

 

[MaxStout]

66C works out to 150.8F, which isn't terribly high. The specs for M44 don't give a range of attenuation percentages, just states it as "high." With your mash temps and the yeast, and the fact you fermented on the high side of the yeast's range, I find it odd that attenuation is only 63% at this point. Is the thermometer you use for measuring mash temp calibrated well? Maybe you mashed higher than you think. Other possibilities could be old or stressed yeast, not enough aeration at pitch.

 

[Rosshedley]

Thanks everyone - super helpful as ever!

I have given the bucket a bit of a shake and I think I will wait a few more days (to a full 3 weeks) and if SG is still 1.026 I will bottle.

(So if I understand correctly, accurately maintaining mash temp results in just the right amount of dextrins and amylase being released for optimum fermentability, right?)

Cheers,

Ross

 

[RM-MN]

Thanks everyone - super helpful as ever!

I have given the bucket a bit of a shake and I think I will wait a few more days (to a full 3 weeks) and if SG is still 1.026 I will bottle.

(So if I understand correctly, accurately maintaining mash temp results in just the right amount of dextrins and amylase being released for optimum fermentability, right?)

Cheers,

Ross

In general this is true, especially if you are using a grain crushed at the local LHBS and a conventional mash tun. It does not seem to work this way with a very fine milled grain in BIAB as the conversion is over so quickly that non of the enzymes get denatured and work together to get an average mix of dextrines and fermentable sugars.

 

[IslandLizard]

(So if I understand correctly, accurately maintaining mash temp results in just the right amount of dextrins and amylase being released for optimum fermentability, right?)

Amylases (enzymes generally) get released when the grain is wet, it's mainly the rate of denaturation of beta amylase (at higher temps) that regulates worts' fermentability, leaving more (unfermentable) dextrins behind.

 

[IslandLizard]

In general this is true, especially if you are using a grain crushed at the local LHBS and a conventional mash tun. It does not seem to work this way with a very fine milled grain in BIAB as the conversion is over so quickly that non of the enzymes get denatured and work together to get an average mix of dextrines and fermentable sugars.

Although it makes sense the way you put it, has anyone actually done research on that?

IOW, mashing very finely milled grain anywhere between 150 and 160F has much less effect on a wort's composition (and fermentability) than a much coarser crush would? That's kind of an eye opener.

I do know some homebrewers who mash in toward the high temp side and after a good stir to stabilize, drop the temps by adding some cold water or let their mash recirculation system take care of it, naturally. I'd say it take a good 10-15 minutes before their target mash temp has been reached, but coming from above, not from below.

 

[RPh_Guy]

I was aiming for Mash temp of 66 degrees c but it dipped below at times, and probably a little higher at times when I added heat to raise back up.

My guess is that this is what caused the low attenuation. When I was doing that my attenuation was low and unpredictable.

Instead of applying heat during the mash, simply insulate it better like with a blanket or in the oven. Dropping a few degrees doesn't matter.

 

[IslandLizard]

I was aiming for Mash temp of 66 degrees c but it dipped below at times, and probably a little higher at times when I added heat to raise back up.

66C is not crazy high. Even heating to 68C should not cause enzyme denaturation. But if during the heating process parts of the mash were above 70C for extended time, such as the bottom part of the mash during direct heating in a pot or kettle, those enzymes become toast at an increasing rate, beta-amylase, the one that makes your wort more fermentable, going first.

 

[RM-MN]

Although it makes sense the way you put it, has anyone actually done research on that?

IOW, mashing very finely milled grain anywhere between 150 and 160F has much less effect on a wort's composition (and fermentability) than a much coarser crush would? That's kind of an eye opener.

I do know some homebrewers who mash in toward the high temp side and after a good stir to stabilize, drop the temps by adding some cold water or let their mash recirculation system take care of it, naturally. I'd say it take a good 10-15 minutes before their target mash temp has been reached, but coming from above, not from below.

'Not research as such but i have been trying different temps with my BIAB to try to get higher FGs and the temperature at dough in doesn't seem to make much difference in the FG. Conversion with very finely milled grains is complete (based on iodine test) in less than 5 minutes.

 

[RPh_Guy]

'Not research as such but i have been trying different temps with my BIAB to try to get higher FGs and the temperature at dough in doesn't seem to make much difference in the FG. Conversion with very finely milled grains is complete (based on iodine test) in less than 5 minutes.

I would love for you to try an experiment to test your hypotheses:

Mash until iodine says starch negative. 5 minutes? Great.
Then immediately add an infusion of boiling water to reach 170°F or higher. This will denature the enzymes pretty quick. (You say they're done working anyway)
Leave it steep for whatever duration you think is needed for flavor.
Continue as normal and see what kind of attenuation you get.
If your attenuation is normal then you know you are right about the enzymes being finished when the starch test is negative.

 

[davidabcd]

Does something else happen to the mash at certain temps that make it harder to ferment for longer?

Looks like you got some good info above. I'd like to hear how it turns out.

 

[madscientist451]

I was aiming for Mash temp of 66 degrees c but it dipped below at times, and probably a little higher at times when I added heat to raise back up.

I started out with the BIAB, had problems maintaining the mash temperature and had high/low temperature swings as indicated above. I wasn't happy with the way the beer turned out, so I went with a BIAB in a round cooler for a while, but now I'm back doing a modified BIAB with insulation on the brew pot and a dunk sparge in a side pot.
I'm thinking the mash got a little hot, especially on the bottom of the pot and your fermentation is done.
You could bottle now, but 1.026 is pretty high for an acceptable IPA. I really dislike overly sweet IPAs, but maybe it will be OK for you.
Since its only 11L, perhaps experiment with it; I'd use about 4L of water and .5 kg of sugar (heat to just below boiling to sanitize) let it cool and dump it in. You could also use 2/3 sugar and 1/3 DME.
The sugar water will ferment out dry and the F/G of your whole batch will be lower, but your beer will have less body, which isn't a bad thing in an IPA, but your hop bitterness will be diluted somewhat as well.
There's a formula/blending calculator to determine exactly how much to add to reach a desired F/G somewhere on the internet, my suggested numbers are just a guess.
Since its an IPA, you could add some dry hops while the sugar water is fermenting. Or use the almost boiling sugar water to make a "hop tea" .
I would suggest checking out the free book "How to Brew", or buying the updated version:
http://www.howtobrew.com/

 

[Rosshedley]

So I bottled it today. It may have dropped to 1.025 after another few days (liquid was a bit cooler when reading was taken so hard to be sure). It's 6% vol and tastes delicious.

Ta for all the advice and will let you know how it turns out.

(Oh it was BIAB method I was using btw. Also my sparge water is cool - as helps me strain the liquid out the bag. Mentioning in case any of that makes any difference re advice above).