Attenuation Vs pitch rate or other thoughts?

[dave_77]

Hi all,
I have a sort of issue with attenuation levels, only really an issue from a numbers point of view as the beer taste fine(in my mind anyway) and therefore it's just bugging me and it's not helpful for some beer styles. Any thoughts or tips would be most appreciated.

I would say this year 90 % of my brews finish with 80% or higher attenuation and generally have a final gravity of between 1.006-1.009.
This doesn't bother me greatly as I like dry beers, but it does annoy me from a recipe and process stand point. When I want a beer with a little more body, just want a beer below 5.5% or the style suits a higher finishing gravity.

I use a robobrew and typically mash at a single temperature with a quick mash out at the end.
I have noticed the temperature in the grain bed is lower than the water from the recirculation pipe by a few degrees so tend to set the temp higher trying to keep the grain bed between 65-67c(the temp is usually set to 69c).
My batch sizes are 16l so I generally have 24l of total water and I will mash with around 16/17 litres so I would say my mash is thinner than some of the calculators and sparge the rest.

I'm sure it's not anything to do with yeast infections as I don't think there are any off flavours, Belgian strain characteristics or bottle bombs.

When using liquid yeast I overbuild a starter and harvest a third before pitching for future starters. Most of these yeasts are no further than 3rd generation. I use the brewfather pitch rate calculator and usually use the .75 setting under 1.060 starting gravity for estimating the cells needed. For dry yeasts a base it on 10b cells per gram for all yeasts and work it out from there.
Unless it's a Belgian yeast I tend to go for yeasts that have a range of 72-76% attenuation.
Any thoughts or ideas on why I could be getting 80% plus so regularly. Sorry for the drawn out explanation
Somebody has said that it could be the later generations of yeast becoming more attenuative?

My thoughts are that higher pitcher rates maybe could be the issue. I would say that I over pitch with dry yeast as sometimes I add 1 1/2 packets for 16l batch for a 1.060 wort(as I always base it on 10B cells we gram of yeast). The only times that I have had a final gravity above 1.010 is when I have pitched one packet of crossmyloof Celtic and fermentis s04. I have no way of measuring my yeast count on the starters I build?

 

[strange-steve]

There are some that say over-pitching can lead to higher attenuation and some that say it can actually reduce attenuation, however I can't find any decent sources to back either of these up. I did see one or two scientific studies on the effects of different pitch rates which showed no difference in attenuation, although there were some other differences.

Have you checked the temperature accuracy in your Robobrew?

 

[An Ankoù]

I would say this year 90 % of my brews finish with 80% or higher attenuation and generally have a final gravity of between 1.006-1.009.

Nearly all of mine do, too. I, too, prefer a drier beer. I tend to mash between 64-65C for at least five hours and often overnight as I organise my day around my brewing and vice versa. If I wanted a higher FG, I'd mash hotter: 66-68C for a shorter time, (until the starch test showed negative), mash out at a high temperature and even use a low attenuating yeast like Windsor or Young's Ale Yeast.
Don't know if any of that helps.

 

[dave_77]

There are some that say over-pitching can lead to higher attenuation and some that say it can actually reduce attenuation, however I can't find any decent sources to back either of these up. I did see one or two scientific studies on the effects of different pitch rates which showed no difference in attenuation, although there were some other differences.

Have you checked the temperature accuracy in your Robobrew?

There definitely is a variation between the grain bed and the bottom of the Robobrew where the probe is. I use a digital thermometer to check the grain and the recirculation pipe, and usually have to set the Robobrew 2-3 degrees higher to hit 66-67c. The only thing I haven't checked thinking about it is the digital thermometer. I have recently checked the hydrometer and my refractometer and they are accurate.

 

[dave_77]

Nearly all of mine do, too. I, too, prefer a drier beer. I tend to mash between 64-65C for at least five hours and often overnight as I organise my day around my brewing and vice versa. If I wanted a higher FG, I'd mash hotter: 66-68C for a shorter time, (until the starch test showed negative), mash out at a high temperature and even use a low attenuating yeast like Windsor or Young's Ale Yeast.
Don't know if any of that helps.

I think I'm going to start looking for a yeast for a lower attenuation range for the beers that I want to finish a little higher..I had considered Windsor or MJ empire ale for english and also wyeast 1322 Northwest ale for something more subtle( not used any of these yeasts).

 

[peebee]

Hi all,
I have a sort of issue with attenuation levels, only really an issue from a numbers point of view as the beer taste fine(in my mind anyway) and therefore it's just bugging me and it's not helpful for some beer styles. Any thoughts or tips would be most appreciated. …

Your experiences follow what we had to put up with in the 1970-80s, before we got the Lallemand yeasts (e.g. "Windsor") or Fermentis yeasts (e.g. S-04). The older unbranded (or branded, like "Boots"!) dried yeasts were very aggressive attenuation-wise, and the few, very expensive (heck, they still are!), liquid yeasts (Wyeast mostly?) were the preserve of only very keen home-brewers.

But low attenuating yeasts are only part of the story. "Low attenuating" generally means the yeast isn't too enthusiastic about fermenting dextrins, even the simple tri-saccharides like malto-triose. If the dextrins aren't there (all converted to simpler sugars) these "low attenuating" yeasts can still appear to be "high attenuating" (I succeeded in coaxing 82% attenuation out of Wyeast 1187, which only gets a 68-72% average attenuation rating).

Remember the calculators all quote what Americans consider is a good attenuation (i.e. on the high side; low attenuation is labelled "not clean"!) because that's the sort of beer they are used to. And increasingly so this side of pond too. So a Target Pitch Rate of "0.75" (millions of cells/(mL × °P)) will be quite high. I use 0.65 by default, but even that might be un-necessarily high? Also remember what @strange-steve said earlier: "some say over-pitching can lead to higher attenuation and some that say it can actually reduce attenuation"; well add to that "and visa-versa"! Some say under-pitching can lead to higher attenuation! Its suck-it-and-see time. All the calculators are based on interpretation of fairly limited empirical data (experimental results), so should be seen as a guide and only ever be subjected to the simplest of one's own interpretations (which also explains why different calculators vary so much).

So, that narrows down your issue to mashing, as you suspect. It also explains the outbreak of headaches amongst folk that have read this far! Sorry, I do get carried away (sometimes literally by men with white coats on?). I'll come back later and subject (torture) remaining followers to my suggestions about mashing in "one-pot" systems …

 

[dave_77]

Your experiences follow what we had to put up with in the 1970-80s, before we got the Lallemand yeasts (e.g. "Windsor") or Fermentis yeasts (e.g. S-04). The older unbranded (or branded, like "Boots"!) dried yeasts were very aggressive attenuation-wise, and the few, very expensive (heck, they still are!), liquid yeasts (Wyeast mostly?) were the preserve of only very keen home-brewers.

But low attenuating yeasts are only part of the story. "Low attenuating" generally means the yeast isn't too enthusiastic about fermenting dextrins, even the simple tri-saccharides like malto-triose. If the dextrins aren't there (all converted to simpler sugars) these "low attenuating" yeasts can still appear to be "high attenuating" (I succeeded in coaxing 82% attenuation out of Wyeast 1187, which only gets a 68-72% average attenuation rating).

Remember the calculators all quote what Americans consider is a good attenuation (i.e. on the high side; low attenuation is labelled "not clean"!) because that's the sort of beer they are used to. And increasingly so this side of pond too. So a Target Pitch Rate of "0.75" (millions of cells/(mL × °P)) will be quite high. I use 0.65 by default, but even that might be un-necessarily high? Also remember what @strange-steve said earlier: "some say over-pitching can lead to higher attenuation and some that say it can actually reduce attenuation"; well add to that "and visa-versa"! Some say under-pitching can lead to higher attenuation! Its suck-it-and-see time. All the calculators are based on interpretation of fairly limited empirical data (experimental results), so should be seen as a guide and only ever be subjected to the simplest of one's own interpretations (which also explains why different calculators vary so much).

So, that narrows down your issue to mashing, as you suspect. It also explains the outbreak of headaches amongst folk that have read this far! Sorry, I do get carried away (sometimes literally by men with white coats on?). I'll come back later and subject (torture) remaining followers to my suggestions about mashing in "one-pot" systems …

Thanks for your points, I would be interested in your thoughts on all in one systems.

I had always been happy with my consistency when doing 12l batches BIAB on the stove, I used to put the oven on the lowest setting and the mash temp would be held perfectly.

I like using the Robobrew but having the thermometer on top of the heating elements is good to prevent scorching but doesn't give you an accurate reading for the grain bed. So I generally manually check the top temp and adjust the system target temp a few degrees higher. Mind you I did read or listen to a brulosophy experiment with high and low mash temp and I didn't make much of a difference to attenuation/fermentability (from memory).
From everyone's comments I think it's likely to be a combination of different generations of harvested yeast and maybe pitch rate. I think this because whenever I use 1 packet of s04, us05, crossmyloof Celtic or Pia the final gravity is within a couple of points of target. The brews I have used 2nd/3rd generation liquid yeast are always higher and always add some margin for error in my starter size.
The second thought which you touched on, that alot of my beers probably are 80-85% pale or lager malt so maybe as there isn't ever a high level of specialty malts with a potentially lower mash temp is making a highly fermentable wort.

 

[Sadfield]

Isn't the case that over pitching means there's more yeast able to consume sugar and over attenuate a beer, but as it doesn't go through a healthy growth phase, yeast viability is lower at the end of fermentation? So probably a case of how much work they get through initially.

Wyeast state over pitching can lead to fast fermentation, low ester production and thin bodied beers.

 

[strange-steve]

Isn't the case that over pitching means there's more yeast able to consume sugar and over attenuate a beer

Yeah apparently so but I can't find much research to back this up. I'm no yeast expert but at a "normal" pitch rate wouldn't you expect complete fermentation of all fermentable sugars, assuming ideal conditions? What happens when there's a higher yeast population? How much of an over-pitch would it take to make a noticeable difference?

There's an interesting paper below which studies the impact of pitch rate on various aspects of fermentation but there seems to be very little difference in apparent attenuation with pitch rates ranging from 12.8M cells per ml up to 74.9M/ml.
https://drive.google.com/file/d/0B68_EfTWcRxpWDFvVVhSR2RUendITmtBREpEMGZzT3N0TVUw/view?usp=drivesdk

 

[Sadfield]

@strange-steve I think it goes back to what @peebee said about maltriose. Yeast consume sugars in order of complexity, simplest first. All but a few yeasts will metabolise it to some degree, but not completely. Therefore, more cells will chip away further at that portion of the wort, before flocculation. Which would match what wyeast say about thinning the body.

I'm only looking at that doc on a small phone screen, but doesn't figure1 show lower apparent extract for 2 and 3 fold pitch rates?

 

[strange-steve]

I'm only looking at that doc on a small phone screen, but doesn't figure1 show lower apparent extract for 2 and 3 fold pitch rates?

It's definitely a little lower although the resolution of the graph isn't great so it's difficult to tell by how much, but even for a fairly big over-pitch it looks to be a small difference. Post-fermentation apparent extract isn't actually mentioned in the conclusion which makes me think they were pretty close.

Edit: That being said, and regarding the OP, he mentions around 80% AA when expecting 72 - 76%, and for a 1.050 wort that's only really a difference of 2 to 4 points in the FG, so maybe...

 

[matt76]

Hey @dave_77 , my experiences are pretty similar. I do 10-12L(ish) full-volume no-sparge brews using a Klarstein Maischfest - not a million miles from the Robobrew but it doesn't have a recirculation pump. Depending what I'm brewing I'll mash anywhere (nominally at least!) between 65-70degC.

I tend to give the mash a good stir now and then and raise/lower the grain basket a couple of times to even out the temperatures, and for sure I notice temperature differences before and after (maybe 4-5degC).

I can get my mash temp pretty much spot on to start with and it's OK for the first hour, after this the heater will kick in and it tends to overshoot before it cuts out again. Add to this the fact I've started doing overnight mashes, I reckon the temperature is probably yo-yo-ing for up to 9 hours +/- 4 or 5degC either side of the desired mash temp!

As a result I'm frequently finding my brews attenuating a lot more than expected, even when I mash at 70degC supposedly for more body. It's a little bothersome when your intended 5.0-5.5% ESB ends up at 6.7%! Typically I'm using CML Pia, Hell pus dabbling with Midland and Beoir. Since I do smaller batches I tend to pitch only half a pack for ales, but a full pack of Hell for lagers.

(Weirdly, the Porter I made recently with Beoir stopped well short of the expected FG - though it was mashed at 70degC)

I know the temperature probe on the bottom of the Klarstein is out by a few degrees so I've learned to correct for this when setting temperatures, but for the most part I don't use it.

What I would say for sure is calibrate your thermometers in boiling water and melting ice. I did this recently and was surprised to discover that:
- my "trusty" mechanical meat probe thermometer is actually reading high by 2degC (meaning my actual mash temps have for ages been 2degC lower than I thought)
- a glass alcohol thermometer I have as a spare measured 108degC in boiling water so that one is way out!
- And an IKEA "Fantast" digital one I picked recently up is actually spot on.

So yeah, I'm afraid I don't have any answers for you but I don't think you're alone! My feeling is that CML yeasts might in general be quite keen attenuators (certainly Pia and Hell) but also I need to see what difference it makes over my next few brews now I've discovered I have been mashing a couple of degrees lower than intended.

 

[Pennine]

a couple of ideas

you can leave the top off the mash and give it a good stir a few times. 69 is pretty high and you should be getting around 1.015 depending on your SG.

you might want to bleach your fermenter, could have a possible diastaticus infection even though you dont taste it.

are you using sugar?

 

[dave_77]

Hey @dave_77 , my experiences are pretty similar. I do 10-12L(ish) full-volume no-sparge brews using a Klarstein Maischfest - not a million miles from the Robobrew but it doesn't have a recirculation pump. Depending what I'm brewing I'll mash anywhere (nominally at least!) between 65-70degC.

I tend to give the mash a good stir now and then and raise/lower the grain basket a couple of times to even out the temperatures, and for sure I notice temperature differences before and after (maybe 4-5degC).

I can get my mash temp pretty much spot on to start with and it's OK for the first hour, after this the heater will kick in and it tends to overshoot before it cuts out again. Add to this the fact I've started doing overnight mashes, I reckon the temperature is probably yo-yo-ing for up to 9 hours +/- 4 or 5degC either side of the desired mash temp!

As a result I'm frequently finding my brews attenuating a lot more than expected, even when I mash at 70degC supposedly for more body. It's a little bothersome when your intended 5.0-5.5% ESB ends up at 6.7%! Typically I'm using CML Pia, Hell pus dabbling with Midland and Beoir. Since I do smaller batches I tend to pitch only half a pack for ales, but a full pack of Hell for lagers.

(Weirdly, the Porter I made recently with Beoir stopped well short of the expected FG - though it was mashed at 70degC)

I know the temperature probe on the bottom of the Klarstein is out by a few degrees so I've learned to correct for this when setting temperatures, but for the most part I don't use it.

What I would say for sure is calibrate your thermometers in boiling water and melting ice. I did this recently and was surprised to discover that:
- my "trusty" mechanical meat probe thermometer is actually reading high by 2degC (meaning my actual mash temps have for ages been 2degC lower than I thought)
- a glass alcohol thermometer I have as a spare measured 108degC in boiling water so that one is way out!
- And an IKEA "Fantast" digital one I picked recently up is actually spot on.

So yeah, I'm afraid I don't have any answers for you but I don't think you're alone! My feeling is that CML yeasts might in general be quite keen attenuators (certainly Pia and Hell) but also I need to see what difference it makes over my next few brews now I've discovered I have been mashing a couple of degrees lower than intended.

Yes, I definitely seems to be common.
The only thing I haven't checked yet is my electric thermometer yet with the ice water..so need to do that before the next brew.
It doesn't bother me too much for most of my favourite styles as I prefer them dry. One of my beers I have been trying to nail is American Amber and I have been feeling a final gravity of 1.010-1012 would balance out the bitterness a bit(always end up at 1.007-1.008 and 6% ish), same thoughts with a best bitter.

 

[dave_77]

a couple of ideas

you can leave the top off the mash and give it a good stir a few times. 69 is pretty high and you should be getting around 1.015 depending on your SG.

you might want to bleach your fermenter, could have a possible diastaticus infection even though you dont taste it.

are you using sugar?

The grain bed(if my manual thermometer is correct) is usually around 64-66c but the Robobrew has to be set to 69c to maintain that temp at the top of the system. Usually give it a stir a couple of times and pump extra hot wort back over the top after stirring.

Don't think it will be diastaticus as since getting kegs and a fermzilla I only use diastaticus yeasts in my buckets and bottle condition..just feel as though there is less places to hide compared to kegs and the fermzilla you can't clean over a certain temp.

 

[peebee]

Okay! Where'd I leave off? We've got more from @strange-steve and @Sadfield emphasising what a can-of-worms yeast attenuation is. I'm glad I've got all that out the way in my last post as it should be obvious how that subject can descend into blazing rows (I've done enough of them in the past!). So here I'm working on mash temperature and fermentability:

Starting with that Brulosophy experiment with high and low mash temp. I read that a while back and immediately fell out with any Brulosophy article as a result. Try mashing brews at 62C and 72C (it is quite feasible to mash at these temperatures; I know because I do it), compare the results and try saying there is no difference!

But it can illustrate what I think is the problem. How does anyone know the mash is at these temperatures?

With "one-pot" solutions the temperature probe is in the space with the element. The system even has a by-pass so you can't be sure the recycled flow is actually running through the mash bed. And if the recycled flow isn't over-flowing into the by-pass, you can get "channelling" (wort taking the line of least resistance) so temperature in the mash bed is inconsistent. So dealing with the first of these issues:

Always throttle back the recirculating flow (I generally halve it) so the by-pass is never in play. The pumps are impeller types and not troubled by throttling the output (with a tap will do, don't stop the flow though!). The pumps are troubled by throttling the input, but one-pot systems do not have such an option (to my knowledge).

The second issue is harder to deal with. Channelling also means dipping a thermometer into the mash bed isn't very reliable. Step one is ensure you start with the right temperature throughout the mash bed. And that means the right strike temperature.

Whoa! I've got controversial! I have a Grainfather one-pot system and it's instructions for use has no concept of "strike temperature" and I assume other systems to be the same (?): It is expected that recirculation will restore the mash temperature in short order. Will it? The thermometer will certainly show a quick return to mash temperature. Reassuring, but is it reflecting the temperature throughout the mash bed? I think not!

It's not difficult to use "strike temperature" with one-pot systems, but it probably requires a bit of imagination to apply it. Once the grain is all mixed and if the strike temperature was well calculated the system should hold that temperature pretty well (Step two). Critical temperature steps are probably best avoided for the same reason, but a "mash out" is not a critical step (more controversy), just ensure the step has some dwell time to at least try to allow the mash bed to catch up.



Footnote: Where I'm coming from. My "other" system is a 70L 3V HERMS brewery with lots of temperature monitors, so I feel well immersed in the temperature goings on of mash tuns! That said, it has an annoying "feature" of having very slow convergence between set temperature and mash temperature. Working on that just gives me more idea of how to manage mash tun temperatures.

 

[PhilBrew]

But it can illustrate what I think is the problem. How does anyone know the mash is at these temperatures?

... and maybe that statement illustrates what I think is the problem ... too much emphasis on brewery engineering, and not enough on brewing ...

It doesn't bother me too much for most of my favourite styles as I prefer them dry. One of my beers I have been trying to nail is American Amber and I have been feeling a final gravity of 1.010-1012 would balance out the bitterness a bit(always end up at 1.007-1.008 and 6% ish), same thoughts with a best bitter.

... so here's a thought, if setting your Robobrew to mash at 69C consistently results in FGs of 1.007-8 when you were hoping for 1.010-12 ... why not try setting your Robobrew to mash at 71-72C ... and if that still gets you too low an FG try a bit higher again ... and leave all this calibrating thermometers and trying to understand where temperature differentials emanate from, till when you've got a pint of American Amber/Best Bitter with an FG=1.0010-12, like you want it, in your hand

Cheers, PhilB

 

[Keruso]

Hi all,
I have a sort of issue with attenuation levels, only really an issue from a numbers point of view as the beer taste fine(in my mind anyway) and therefore it's just bugging me and it's not helpful for some beer styles. Any thoughts or tips would be most appreciated.

I would say this year 90 % of my brews finish with 80% or higher attenuation and generally have a final gravity of between 1.006-1.009.
This doesn't bother me greatly as I like dry beers, but it does annoy me from a recipe and process stand point. When I want a beer with a little more body, just want a beer below 5.5% or the style suits a higher finishing gravity.

I use a robobrew and typically mash at a single temperature with a quick mash out at the end.
I have noticed the temperature in the grain bed is lower than the water from the recirculation pipe by a few degrees so tend to set the temp higher trying to keep the grain bed between 65-67c(the temp is usually set to 69c).
My batch sizes are 16l so I generally have 24l of total water and I will mash with around 16/17 litres so I would say my mash is thinner than some of the calculators and sparge the rest.

I'm sure it's not anything to do with yeast infections as I don't think there are any off flavours, Belgian strain characteristics or bottle bombs.

When using liquid yeast I overbuild a starter and harvest a third before pitching for future starters. Most of these yeasts are no further than 3rd generation. I use the brewfather pitch rate calculator and usually use the .75 setting under 1.060 starting gravity for estimating the cells needed. For dry yeasts a base it on 10b cells per gram for all yeasts and work it out from there.
Unless it's a Belgian yeast I tend to go for yeasts that have a range of 72-76% attenuation.
Any thoughts or ideas on why I could be getting 80% plus so regularly. Sorry for the drawn out explanation
Somebody has said that it could be the later generations of yeast becoming more attenuative?

My thoughts are that higher pitcher rates maybe could be the issue. I would say that I over pitch with dry yeast as sometimes I add 1 1/2 packets for 16l batch for a 1.060 wort(as I always base it on 10B cells we gram of yeast). The only times that I have had a final gravity above 1.010 is when I have pitched one packet of crossmyloof Celtic and fermentis s04. I have no way of measuring my yeast count on the starters I build?

I suspect its the mash temperature. I just did a little test with the grainfather recipe builder with one of my recipes I made recently. Using Wyeast 1335 attenuation 73-76%, mash temp 66℃. Expected FG 1.015. Changing just the mash temp to 63℃ drops the expected FG to 1.010. Increasing the mash temperature to 68℃. changes the expected FG to 1.018 The actual beer OG was 1.068 and the FG was 1.018 which I thought was a bit high but acually thats 73.5% attenuation which is in the manufacturers range. Interestingly because ABV calculations are not linear, an OG of 1.060 and a FG of 1.016 is near enough the same 73.5% attenuation. I still find that hard to grasp. Even at 1.018 FG the beer is not sweet, it has a superb body and mouthfeel, just like a proper cask real ale. Superb. It seems brewing with a higher OG means a higher FG but the beer will be stronger. Raising mash temp means less fermentable sugar and it will finish higher. You could try adding maltodextrin, raises FG but doesnt add sweetness.

 

[dave_77]

Okay! Where'd I leave off? We've got more from @strange-steve and @Sadfield emphasising what a can-of-worms yeast attenuation is. I'm glad I've got all that out the way in my last post as it should be obvious how that subject can descend into blazing rows (I've done enough of them in the past!). So here I'm working on mash temperature and fermentability:

Starting with that Brulosophy experiment with high and low mash temp. I read that a while back and immediately fell out with any Brulosophy article as a result. Try mashing brews at 62C and 72C (it is quite feasible to mash at these temperatures; I know because I do it), compare the results and try saying there is no difference!

But it can illustrate what I think is the problem. How does anyone know the mash is at these temperatures?

With "one-pot" solutions the temperature probe is in the space with the element. The system even has a by-pass so you can't be sure the recycled flow is actually running through the mash bed. And if the recycled flow isn't over-flowing into the by-pass, you can get "channelling" (wort taking the line of least resistance) so temperature in the mash bed is inconsistent. So dealing with the first of these issues:

Always throttle back the recirculating flow (I generally halve it) so the by-pass is never in play. The pumps are impeller types and not troubled by throttling the output (with a tap will do, don't stop the flow though!). The pumps are troubled by throttling the input, but one-pot systems do not have such an option (to my knowledge).

The second issue is harder to deal with. Channelling also means dipping a thermometer into the mash bed isn't very reliable. Step one is ensure you start with the right temperature throughout the mash bed. And that means the right strike temperature.

Whoa! I've got controversial! I have a Grainfather one-pot system and it's instructions for use has no concept of "strike temperature" and I assume other systems to be the same (?): It is expected that recirculation will restore the mash temperature in short order. Will it? The thermometer will certainly show a quick return to mash temperature. Reassuring, but is it reflecting the temperature throughout the mash bed? I think not!

It's not difficult to use "strike temperature" with one-pot systems, but it probably requires a bit of imagination to apply it. Once the grain is all mixed and if the strike temperature was well calculated the system should hold that temperature pretty well (Step two). Critical temperature steps are probably best avoided for the same reason, but a "mash out" is not a critical step (more controversy), just ensure the step has some dwell time to at least try to allow the mash bed to catch up.



Footnote: Where I'm coming from. My "other" system is a 70L 3V HERMS brewery with lots of temperature monitors, so I feel well immersed in the temperature goings on of mash tuns! That said, it has an annoying "feature" of having very slow convergence between set temperature and mash temperature. Working on that just gives me more idea of how to manage mash tun temperatures.

Good points on the temperature issues on the grainfather/Robobrew type systems. As I generally do 16l batches( I like to brew every 2 weeks). I have never used the overflow pipe and try to get the temp up and then as you say throttle back to keep around an inch of wort above the grain to maintain the temp. The point about the strike temp is true and I find a need to set the temp at around 73-75c and keep recirculating and stiring to get the temp up.

 

[dave_77]

I suspect its the mash temperature. I just did a little test with the grainfather recipe builder with one of my recipes I made recently. Using Wyeast 1335 attenuation 73-76%, mash temp 66℃. Expected FG 1.015. Changing just the mash temp to 63℃ drops the expected FG to 1.010. Increasing the mash temperature to 68℃. changes the expected FG to 1.018 The actual beer OG was 1.068 and the FG was 1.018 which I thought was a bit high but acually thats 73.5% attenuation which is in the manufacturers range. Interestingly because ABV calculations are not linear, an OG of 1.060 and a FG of 1.016 is near enough the same 73.5% attenuation. I still find that hard to grasp. Even at 1.018 FG the beer is not sweet, it has a superb body and mouthfeel, just like a proper cask real ale. Superb. It seems brewing with a higher OG means a higher FG but the beer will be stronger. Raising mash temp means less fermentable sugar and it will finish higher. You could try adding maltodextrin, raises FG but doesnt add sweetness.

I did try 5% carapils in the last IPA, didn't have much difference still finished at 84% attenuation with MJ New world yeast( that yeast does seem high anyway).