Boosting ABV in a Porter Recipe

Hello Homebrew Forum,

I'm hoping to get some guidance on adjusting a recipe to increase the ABV without changing the overall flavor profile too much. I’m currently brewing a porter that’s around 5% ABV, but I’d like to bring it up to over 8% so it qualifies as an imperial stout for an upcoming homebrew contest. I’m using the following grain bill:

• Pale Ale
• Flaked Barley
• Smoked Malt
• Roasted Barley

To achieve the higher ABV, should I primarily increase the Pale Ale and Flaked Barley, or would it be better to adjust all the malts proportionally to maintain the same level of smokiness and overall balance etc?

Thanks in advance!

Did you try putting it through a brewing calculator like Brewfather? If it was me, I'd increase everything proportionally or if that means an unmanageable volume of wort, just leave as is and reduce the wort volume by boiling longer or sparging less.

LewisA said:

To achieve the higher ABV, should I primarily increase the Pale Ale and Flaked Barley, or would it be better to adjust all the malts proportionally to maintain the same level of smokiness and overall balance etc?

Thanks in advance!

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No, the more grain going in the less the efficiency. To make a BIG beer use a reiterated mash.
https://byo.com/article/reiterated-mashing-multiple-mashes-for-massive-brews/

Yes proportional.
Though I went with de-husked roast barley (7%), which is meant to give less harsh astringency (tea-bag tannin flavour).

But rather than struggling with a big mash, maybe do a partial mash recipe. Replacing part of pale malt grain, with LME or DME added during boil.

For my Award Imperial Stout, 21L 17% ABV. I mashed 5.7kg of grain, then added 3kg of TMM premium light LME at boil, and 1.2kg dextrose as ferment progressed (in 200g additions at days: 2; 6; 9; 11; 12; &15).
I tweaked the recipe (pale malt grain %) in Brewfather, so I'd use a full 3kg of LME.
The stout's been maturing on oak strips, since January, for sharing this Christmas.

You should make sure there's plenty of oxygen at start of ferment, with a whisk or bubbler; include yeast nutrient; and use a starter (so yeast isn't stressed by a high initial OG).

Prepare starter two days earlier- preferably from a boiled DME base with OG 1.040-1.050. Chill starter in fridge (the night before needed); once settled pour off liquid; then allow slurry to reach 19°C before pitching. ( I did a 1 gallon starter, with Nottingham yeast).
Alternative to starter, is to use the yeast cake from a previous batch of small beer (= low-med OG).

With strong beers, allow more headroom, for a larger Krausen. For the 17% stout, it needed double the volume! And on day two, I had to split the 21L batch between twio 26l bins.

I would go for proportional, be a bit on the cautious side and then adjust in the fermenter with little sugar if you need to. I am not a purist or numbers brewer I prefer to do things by taste.

MashBag said:

I would go for proportional, be a bit on the cautious side and then adjust in the fermenter with little sugar if you need to. I am not a purist or numbers brewer I prefer to do things by taste.

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Proportional won't work, what will work is splitting a grain bill mash one first then mash again using the wort from the first mash as the liquor for the second mash. Adding sugar or dextrose to a stout just thins it out, not wanted in a stout.

I agree it may thin it. But I am suggesting it to guarantee the numbers, and then only a smidge not a full sugar wash

MashBag said:

I agree it may thin it. But I am suggesting it to guarantee the numbers, and then only a smidge not a full sugar wash

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We don't know what the poster is brewing in, I would hazard a guess a small unit. If his grain bill is 5.5kg for a Porter/Stout then he will definitely have the capacity to double that without a massive loss in efficiency. In a small unit efficiency will drop dramatically.

LewisA said:

Hello Homebrew Forum,

I'm hoping to get some guidance on adjusting a recipe to increase the ABV without changing the overall flavor profile too much. I’m currently brewing a porter that’s around 5% ABV, but I’d like to bring it up to over 8% so it qualifies as an imperial stout for an upcoming homebrew contest. I’m using the following grain bill:

• Pale Ale
• Flaked Barley
• Smoked Malt
• Roasted Barley

To achieve the higher ABV, should I primarily increase the Pale Ale and Flaked Barley, or would it be better to adjust all the malts proportionally to maintain the same level of smokiness and overall balance etc?

Thanks in advance!

Click to expand...

I would just increase the base malt because I assume you are looking for the same volume but higher ABV. Increasing the smoked malt may make the beer too smoky and more roast barley might make the beer too roasty or even bitter.

Do remember you will increase absorption by the increased grain so you will need more water for the same batch size.

If you can’t fit all the grain in your mash vessel do two mashes and combine the wort for the boil. Use some of the wort from the first mash in the second to make up the volume if you don’t have enough water for the second mash.

Although a bit more work doing two boils, an easy way to make an imperial version of a beer is to take your standard 5% brew and split it. Making a Imperial porter out of the first runnings and a mild out of the sparge. The advantage is you'll already know your efficiency, which is where most people have issues.

LewisA said:

To achieve the higher ABV, should I primarily increase the Pale Ale and Flaked Barley, or would it be better to adjust all the malts proportionally to maintain the same level of smokiness and overall balance etc?

Click to expand...

It's...complicated, it's the sort of thing that really comes with experience and knowing how your kit and your yeast respond. So there's no "simple" answer. But one big difference is that you need to look after your yeast a lot more. First off just check that it can cope with the alcohol, you're nudging the limits of what say Windsor can take - but you also have to worry about the stress of being in a concentrated sugar solution as well. It's much less stressful to say have a 1.065 wort and then add the last 1.015's worth of fermentables in the form of sugar part way through fermentation, that way the yeast aren't exposed to a full ~1.080's worth of concentration-stress.

Adding sugar is great for strong dark beers, as you can use dark sugar, maybe even a little (it goes a long way) treacle, for extra flavour. So TLDR - I'd scale everything up by 40% or so, then take it up to 8% by adding the remaining fermentables as dark sugar.

The "Rochefort" yeasts are great for these kinds of beers, as they have great alcohol tolerance, and are British in origin with attractive fruitiness. You can't beat Rochefort dregs for complexity, but BE-256 is useful as being dried it doesn't need so much aeration, which is always helpful in high-ABV beers. There''s lots of good advice in this presentation :
https://quaff.org/wp-content/uploads/2012/11/HighGravityFermentation-1.ppt

You might also want to look at Fuller's recipe for the 10% version of their porter :
https://www.homebrewtalk.com/thread...m-the-horses-mouth.642756/page-3#post-8674860

CML Windsor and Notty are a nice partnership.

MashBag said:

CML Windsor and Notty are a nice partnership.

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The Firm and Midland

Avoiding diastatic yeasts. BE256 and S-33 (Windsor) together will leave behind the least amount of maltose, maltotriose and dextrins. This will enhance the drinkability and also IMHO make for stable packaging, without creep and over carbonation with age, that some experience with imperial stouts. Plus the ester combination from both works well.


Residual Sugars.

Thanks, everyone, for your responses—there's a lot to think about here, and it's way more complex than I initially expected....

I tried adjusting the OG adjuster on Brewfather, but as some of you pointed out, increasing it raises all malts equally, which would push the EBC off the scale. That said, since the roasted malt is only 13.5% of the total grain bill, I think it falls within an acceptable range? Not sure what affect the smoked malt would have but perhaps it might become unpalitable (3kg)?

Thanks also to those who mentioned checking the water volume. I hadn’t thought to check, but including the grain, the total volume comes to around 40 litres, which works with my setup. My only concern is that it suggests just 2 litres for sparging, which seems very low?

Thanks for all the suggestions on liqud and sugar. I think I'd prefer to stick with all-grain if possible and avoid adding sugar or liquid malt, even if it complicates things 10-fold.

Before considering reiterated mashing, this particular recipe I have calls for an extended mash (about 2 hours at different temps, excessive perhaps but if it works, don't fix it), and I've added a bit of ABV margin (targeting 9.5%, with a minimum of 8%). Do you think a long mash alone could suffice, or would reiterated mashing still be the only option beneficial? Don't get me wrong—I enjoy brewing, but 2 x 2 hours + boil is a long time

Lastly, could someone clarify reiterated mashing for me? My understanding is: mash normally, do a small sparge, discard the grains, add fresh malts and mash again (with the same liquour), sparge again, and then boil down to the target volume. Is that correct?

Regarding yeast, I was thinking of using the trusty Notty, but I see some of you recommending using two or three types. What’s the advantage—does it enhance the flavour profile?

Thanks again for all the advice and apologies for the many questions— I really appreicate your help!

Just on the yeast, the suggestion is to use different ones that complement each other in fermenting the more unfermentable sugars. Thus reducing the final gravity and increasing ABV.

First question is what is the capacity of your kettle? Second question is can the kettle hold 6-7kg of grain with 5 litres/kg of mash liquor which will give you a better conversion. *
If not then the reiterated mash is really the only alternative, don't order all the grains together get them bagged separately, use half of the pale ale malt, smoked malt and flaked barley (you didn't give the weight of your grain bill) mash that in the full volume of mash liquor allowing for two losses to grain, and one boil. Mash for one hour as a single saccharification mash, there is no need for stepped mash. Squeeze as much wort from the spent grain, use that wort as the mash liquor for the second batch of pale ale malt, smoked malt and flaked barley. After 1 hour add the roast barley while ramping up for mash out, as Hazlewood suggests don't double up on the smoked barley or roast barley, both can be very unforgiving. Boil for one hour and check your hop additions, they will have to be increased to suit the higher SG.