1st AG (half batch) - the numbers don't add up..?

[BlackSands]

I've been meaning to do for some time a small batch AG using my usual partial mash process and gear so today is the day. I've designed up a 10 litre pale ale in Beersmith - 2.6kg base malts only (1.6kg GF ale malt and 1kg munich), mashed for 60mins @67ºC.

 

But, I've run into a bit of an 'issue'... the predicted pre-boil SG is supposed to be around 1.048. That's with with BH eff = 65%, which is where it usually sits for the final numbers (FG) to add up with my partial mashes. But this time it has exceed that by quite a bit: post-sparge it's more around 1.060 ? That's the value I get if I set that BH eff figure to 85%. Does this mean the mash conversion has been far more effective than I usually experience? Or is it that when doing a PM brews there's other factors related to the LME component that messes with the numbers such that it seems BH eff is only 65% ?

 

Another thing, the original pH was 5.4 but after a 10g gypsum addition I got it down to 5.24, could that be the thing that has made the difference? Or am I missing something else... ?

 

Anyway... it'll be interesting to see what the OG ends up being... and if it's much higher than expected... should I dilute??

 

 

 

 

 

 

[Otto Von Blotto]

The efficiency issue probably is related to it being a straight AG rather than a partial mash. The BH efficiency will be different when all the wort is created from a mash rather than only some of it. I would have done it the other way around for a first attempt - whatever the mash efficiency is in your partial mashes, alter the BH efficiency until the predicted mash efficiency lines up with that figure, then fiddle with the amount of base malts until you hit your target gravities in BS. It is a bit annoying that you can't actually set the mash efficiency in that program but you can work it out over a few batches of the same size and grain bill weight.

 

Your extraction efficiency won't have changed for that 10L portion, and if with your partials you are making 10L of wort from grains and then using a kit for the rest of it plus water, this 10L portion probably always sits around that 1.060 mark and the OG only goes lower due to dilution.

 

Having said that, 2.6kg base malts for a 10 litre batch is a fair bit, that's about equal to 6.5kg base malt in a 25 litre batch, which on a half decent system would likely result in a pre-boil SG above 1.048.

 

The mash pH has an effect but I doubt very much it would increase the SG by 12 points. You can dilute it with water in the FV if you like though, but you might have to increase the hopping to account for that. You'll probably have to increase the hopping to compensate for the overshoot on the gravity anyway really.

[BlackSands]

Thanks for the reply. Seems I've made a somewhat concentrated wort!

 

What I ended up doing was re-jigging the numbers so it will now be a 13 litre batch, and yeah... I extended the hop boil to compensate for the resultant bitterness 'dilution'. There's actually a fair bit of leeway there so +/- 5 IBU's aint going to worry me too much. The post-boil OG ended up at 1.069 so adding 3 litres of water brings it down to around 1.053 which is close to the intended figure. Not much I can do about colour dilution but it's still within APA spec, not that I'm overly worried about that!

 

Not sure I fully understand how it all the numbers work with regard to BS but either way, hopefully I'll end up with a drinkable beer!

 

 

[Otto Von Blotto]

Yeah, it does take a bit of getting used to. It also requires that equipment profile information is inputted correctly (pot size, boil size, boil off per hour, trub loss etc.). I've never used it for partial mashes so the only experience I have with Beersmith is for all grain, and I'm so used to using it for that that it's become second nature and I don't even think about it anymore.

 

Whatever the BH efficiency worked out at for this particular batch, use that figure if you do another one, then adjust grains accordingly to target OG and see if it gets you closer to it without having to do any dilution.

[BlackSands]

Whatever the BH efficiency worked out at for this particular batch' date=' use that figure if you do another one, then adjust grains accordingly to target OG and see if it gets you closer to it without having to do any dilution. [/quote']

 

It seems you have to treat the first batch as a bit of a trial, to determine that BH eff figure, which I now know is around 85%. I was working backwards with my PM brews... I'd measure the OG from the FV and then adjust the BH eff so that BS's estimated OG matched the measured figure. That gave me the 65% which I then used in subsequent PM batches.

 

Whether I do another of these half-batch AG's remains to be seen! It's a lot of work for a small batch size. I just wanted to do this at least once to kind of settle the debate in my own mind re: PM vs AG taste. I'd been reasonably satisfied that my PM brews, with 60% fermentables being grain, were so close to AG that I'd be hard pressed to tell the difference. Silly thing is, even if this proves me wrong it's still unlikely, for practical reasons, that I'll make the move to AG anyway!

[Waylon]

Well done with your efficiency Blacksands,

 

Time to step up and make the time more worth while and do triple batches mate!

Although I guess if you setup suits partial mashes then stay happy with that...

[joolbag]

Keen to hear your thoughts Blacksands. How did the pre-boil and FV samples taste? Any different to your PM brews?

 

My first PM is cold crashing now. It's the 'Brew A' IPA can with 3kg pale malt, 250g Carapils and 150g crystal malt to bump up the fermentables. I don't know how to work out the % that the AG contributes to the bill.

 

Definitely tastes better than the kit with 1.7kg of DME! Really smooth bitterness and malt backbone. I late hopped it with Centennial and Chinook, trying to get more of a dank and resinous character to this brew rather than citrus

[ChristinaS1]

My first PM is cold crashing now. It's the 'Brew A' IPA can with 3kg pale malt' date=' 250g Carapils and 150g crystal malt to bump up the fermentables.[/quote']

 

That is a big partial! Think you should call it a partial extract rather than a partial mash.

 

Cheers,

 

Christina.

 

 

[Beerlust]

My first PM is cold crashing now. It's the 'Brew A' IPA can with 3kg pale malt' date=' 250g Carapils and 150g crystal malt to bump up the fermentables.[/quote']

 

That is a big partial! Think you should call it a partial extract rather than a partial mash.

Yep, that's like saying I added a kit to a full brew!

 

That one is gonna be a biggun'!

 

Cheers,

 

Lusty.

[BlackSands]

Well done with your efficiency Blacksands' date='

 

Time to step up and make the time more worth while and do triple batches mate!

Although I guess if you setup suits partial mashes then stay happy with that...[/quote']

If my living circumstances were different I'd certainly consider full-batch AG, but I just don't have the room at the moment unfortunately.

 

How did the pre-boil and FV samples taste? Any different to your PM brews?

To be honest' date=' I didn't really notice much of a difference. I think the reason is as I'd mentioned in the other thread is that when I do a PM brew I pair my grain up with the OS lager can, which is essentially just light LME. I suspect in your case - possibly because you've used the IPA can, the extract component is perhaps more apparent? [img']unsure[/img]

 

I don't know how to work out the % that the AG contributes to the bill.

Do you use Beersmith? As mentioned I just worked backwards. Measured the actual OG and then adjusted the BH efficiency% figure so that it's predicted OG matched what I actually measured. That then became the number I used when designing other PM recipes. My mashing is now pretty consistent so the figure works out to be pretty close each time.

 

I've typically been finding 2.6kg grain + 1.7kg can + a small sugar top-up gets me up to around a 1.050 / 5% ABV.

 

 

 

 

 

 

 

[joolbag]

I haven''t yet downloaded Beersmith. I will soon though to take the guesswork out of it and to build some of my own AG recipes. I'm using the IanH spreadsheet at the moment.

 

Blacksands, I have some partial mashes (not high OG ones) designed and will be brewed in the next couple of months. One is using a TC Bootmaker's Pale Ale kit. One is an IPA using 1.5kg Briess unhopped LME. The other is an XPA using 1.5kg Briess unhopped LME. And the last is a Dortmunder Export using 1.5kg Briess Munich LME. I will certainly report back on each brew!

 

I designed this "Brew J" recipe with 55 IBU and OG of 1.056. I hit that number (or maybe one point below) using the kit plus the grain bill as listed above.

 

I suppose you could call it a partial kit rather than partial mash! It is an IPA, so needs to be big!

[BlackSands]

I designed this "Brew J" recipe with 55 IBU and OG of 1.056. I hit that number (or maybe one point below) using the kit plus the grain bill as listed above.

 

Out of curiosity I punched your bill into Beersmith - looks like you could have gone even bigger on this one and still been well within style!

[joolbag]

Oh for sure! 1.056 just falls into IPA territory. The Stone IPA recipe I am planning to partial mash/extract will have 1.5kg Briess LME and 4.1kg grain in the mash for a target OG of 1.065. Lots of IBUs early in the boil too (Magnum and Perle). Def not a session beer

[ChristinaS1]

I haven''t yet downloaded Beersmith. I will soon though to take the guesswork out of it and to build some of my own AG recipes. I'm using the IanH spreadsheet at the moment.

 

Jools' date=' Ian's Spreadsheet is not designed for partial mashes; it is strictly for kits. Have you ever used the Brewer's Friend Recipe calculator? It is free if you don't want to save your recipes. It has a partial mash option in their drop down list.

 

Another nice thing about the Brewer's Friend calculator is it will tell you the percentage of the grist that any of the ingredients makes, which is important when you are designing recipes.

 

https://www.brewersfriend.com/homebrew/recipe/calculator/

 

Did I already tell you this in the partial mash thread? I can't be bothered to check. If so, please forgive me. [img']wink[/img]

 

Cheers,

 

Christina.

[joolbag]

Hey Christina, I bastardised Ian's spreadsheet so that I can enter in partial mash. I hit the right numbers so my formulas, etc seem OK.

 

I will get Beersmith soon, long overdue.

 

I did have a look at brewers friend, thank you. But it seemed like a lot of work for a recipe I couldn't save! So i abandoned ship about halfway.

 

PS on my two all-grain brews and this one partial mash my efficiency has been consistent on this system. 65% brewhouse efficiency. Would prefer higher, but consistency is good, so will punch this I to Beersmith when I get it. Then can work on increasing efficiency later

[Bolchy]

Hey Christina' date=' I bastardised Ian's spreadsheet so that I can enter in partial mash. I hit the right numbers so my formulas, etc seem OK.

 

I will get Beersmith soon, long overdue.

 

I did have a look at brewers friend, thank you. But it seemed like a lot of work for a recipe I couldn't save! So i abandoned ship about halfway.

 

PS on my two all-grain brews and this one partial mash my efficiency has been consistent on this system. 65% brewhouse efficiency. Would prefer higher, but consistency is good, so will punch this I to Beersmith when I get it. Then can work on increasing efficiency later[/quote']

Just screenshot the recipe. Its saved then.

[Otto Von Blotto]

It seems you have to treat the first batch as a bit of a trial' date=' to determine that BH eff figure, which I now know is around 85%. I was working backwards with my PM brews... I'd measure the OG from the FV and then adjust the BH eff so that BS's estimated OG matched the measured figure. That gave me the 65% which I then used in subsequent PM batches.[/quote']Yeah, you pretty much do have to do that. I started with 70% BH efficiency when I began AG all that time ago, then one brew suddenly decided it was going to overshoot the OG and increase the ABV by 1%, so I ended up with a 6.4% German lager . I ended up increasing the nominal BH efficiency to 75%, and began hitting my numbers properly. I had some issues with it a couple of years ago but those were rectified and I'm now back hitting that number regularly and often exceeding it by 2-3%.

 

Whether I do another of these half-batch AG's remains to be seen! It's a lot of work for a small batch size. I just wanted to do this at least once to kind of settle the debate in my own mind re: PM vs AG taste. I'd been reasonably satisfied that my PM brews' date=' with 60% fermentables being grain, were so close to AG that I'd be hard pressed to tell the difference. Silly thing is, even if this proves me wrong it's still unlikely, for practical reasons, that I'll make the move to AG anyway! [/quote']I reckon it's probably worth doing another one, or even another two or three, just to see if you keep hitting that efficiency figure. It's hard to set an efficiency to work off if it's up and down like a yo-yo but if the number is pretty consistently around the same figure, then it's a lot easier to pick a number and have recipes turn out as intended.

 

I can however understand not bothering with the whole process of AG for such a small batch size, I would be the same I reckon. I have no desire to replicate Waylon's 34000 litre batches either, but 10L is a bit small for the time it takes. I'm happy with the 21/25 litre batches I make now; I get a keg from each one so I can have variety on my taps and I don't have to move huge amounts of wort around either.

[BlackSands]

How did the pre-boil and FV samples taste? Any different to your PM brews?

To be honest' date=' I didn't really notice much of a difference.

[/quote']

 

Ok, I take that back.... just took a sample (SG=1.016) and yeah, it's different. It's not a huge difference by any means but I do get more of that fresh, clean grain taste coming through.

 

The difference I noted between extract and my PM's (60% grain) and now my PM's vs this test AG is roughly about the same I'd say - i.e. the degree of 'improvement', i.e. move toward a cleaner & fresher taste, is similar. Given that, I'd say PM's, with a decent amount of grain do seem to sit somewhere in the middle. Which of course makes sense, I'd just assumed there'd be a point where a PM with enough fresh grain would reach some taste-threshold where the full AG benefit was not really detectable, but it's looking like that assumption may be wrong.

 

The degree to which it matters is of course a personal thing and something brewers will have to balance against the extra commitment and investment required to brew AG.

 

I will of course reserve final judgement once this one is ready to drink, but I think from today's sample I already know my answer: AG is better.