Stout hasn't reached final gravity

[foxy]

Yet the website I linked says it does equate to fermentability.

And it was you who said this a couple of years ago:

Yes and I just said it again a few moments ago. The fermentable sugar to be got from highly kilned malts is going to add some fermentability but very little. They will be adding more none fermentable sugar than fermentable as you found out.

 

[Stu's Brews]

There seems to be a lot of confusion in this thread about what gravity points, PPG and fermentability mean, to try and provide some clarity...

Specific gravity points are simply a measure of the total amount of sugar dissolved in a liquid. It does not provide any indication on how fermentable those sugars may be. Original gravity is controlled by how much sugar is extracted from your grain (i.e. quantity of grain, grain type, mash efficiency) and how much liquid evaporates during the boil. PPG describes how many gravity points you can expect to extract from one pound of grain in one gallon of wort.

Fermentability is a term used to describe how easy it is for yeast to ferment the dissolved sugars and subsequently produce alcohol. A high level of fermentability will result in a lower final gravity (less sugar is left in solution, more alcohol is produced). A low level of fermentability will have the opposite effect. Fermentability is controlled by mash temperatures, mash pH and the type of grains used. Higher temperatures will give lower fermentability as more long-chain sugars will be present in the wort. A slightly higher mash pH (e.g. 5.4 v 5.2) can decrease fermentability. The use of crystal, roasted or dextrin malts can all result in lower fermentability.

You can have any combination of high or low original gravity and high or low fermentability. These are two of the key tools a brewer can use to adjust the overall balance of a beer.

Disclaimer: other factors may also affect the original gravity and fermentability but I've tried to keep it brief by focusing on the main ones.

 

[Sadfield]

If OG has been overshot to the point where 3L dilution is required, then the degree of fermentability of 500g of roasted malt isn't going to have much bearing on the outcome. There clearly wasn't an issue with the mash.

At least we've clarified that unfermentable grain is partly fermentable.

 

[peebee]

You can have any combination of high or low original gravity and high or low fermentability. These are two of the key tools a brewer can use to adjust the overall balance of a beer.

Nice summary. Sound conclusion. Just one slip I could see: "... two of the key tools ...". There's only one!

The other, for "high and low fermentability" doesn't exist for homebrewers (that's a challenge! I want someone to prove me wrong with where I can get one from). It would be really handy to have more idea of the resultant sugars in the wort: How much Maltose, how much Malt-triose, how much even longer chained stuff (plus miscellaneous stuff like glucose, sucrose, etc.). But we have no such tool and have to make "educated guesses", although with experience you can make quite good "educated guesses". And then you have to pair that with what you know about the yeast you are using: What it can or can't do with "malt-triose", or is it (gawd forbid) a var. diastaticus strain? Again, with experience of the yeast you can make quite good "guesses".

But that other tool would be dead handy!

 

[Stu's Brews]

Nice summary. Sound conclusion. Just one slip I could see: "... two of the key tools ...". There's only one!

The other, for "high and low fermentability" doesn't exist for homebrewers (that's a challenge! I want someone to prove me wrong with where I can get one from). It would be really handy to have more idea of the resultant sugars in the wort: How much Maltose, how much Malt-triose, how much even longer chained stuff (plus miscellaneous stuff like glucose, sucrose, etc.). But we have no such tool and have to make "educated guesses", although with experience you can make quite good "educated guesses". And then you have to pair that with what you know about the yeast you are using: What it can or can't do with "malt-triose", or is it (gawd forbid) a var. diastaticus strain? Again, with experience of the yeast you can make quite good "guesses".

But that other tool would be dead handy!

Maybe just a poorly written sentence on my behalf... I meant that those are two things that a brewer can control:

1. You can influence whether you have a high or low gravity through increasing/decreasing the amount of malt used.
2. You can influence whether you have high or low fermentability through increasing/decreasing the mash temperature.

I'd be similarly interested in a 'tool' that can give you insight into the wort composition - would be fascinating to see how it varies for each brew.

 

[Hazelwood Brewery]

There seems to be a lot of confusion in this thread about what gravity points, PPG and fermentability mean, to try and provide some clarity...

Specific gravity points are simply a measure of the total amount of sugar dissolved in a liquid. It does not provide any indication on how fermentable those sugars may be. Original gravity is controlled by how much sugar is extracted from your grain (i.e. quantity of grain, grain type, mash efficiency) and how much liquid evaporates during the boil. PPG describes how many gravity points you can expect to extract from one pound of grain in one gallon of wort.

Fermentability is a term used to describe how easy it is for yeast to ferment the dissolved sugars and subsequently produce alcohol. A high level of fermentability will result in a lower final gravity (less sugar is left in solution, more alcohol is produced). A low level of fermentability will have the opposite effect. Fermentability is controlled by mash temperatures, mash pH and the type of grains used. Higher temperatures will give lower fermentability as more long-chain sugars will be present in the wort. A slightly higher mash pH (e.g. 5.4 v 5.2) can increase fermentability. The use of crystal, roasted or dextrin malts can all result in lower fermentability.

You can have any combination of high or low original gravity and high or low fermentability. These are two of the key tools a brewer can use to adjust the overall balance of a beer.

Disclaimer: other factors may also affect the original gravity and fermentability but I've tried to keep it brief by focusing on the main ones.

All good Stu apart from one detail I think. Both a lower mash temperature and a lower pH favour beta-amylase which produces more shorter chain sugars and consequently a more fermentable wort.

 

[Stu's Brews]

All good Stu apart from one detail I think. Both a lower mash temperature and a lower pH favour beta-amylase which produces more shorter chain sugars and consequently a more fermentable wort.

Ah yes, good catch. Will amend the original post to avoid any confusion.

I suspect that compared to mash temperature, mash pH is a relatively small contributor to fermentability, provided you are in the optimal 5.2-5.4 range.

 

[peebee]

All good Stu apart from one detail I think ...

Another! Poor guy will be getting a "persecution complex".

Sorry, didn't pick that up, but I don't take much notice of these "too minor to be bothered proving one way or other" issues (sssh ... don't tell Larse I said that). Bit like mash stiffness; another unlikely issue to babble on about.

[EDIT: Oops, mixing up issues ... I'll just shuffle that about ... okay?]

[EDIT2: Crikey, @Larse is giving me a "laugh-out-loud" reaction for my original post. He must be splitting his sides now? Well, some days I just don't know which way up I am.]

 

[Stu's Brews]

Another! Poor guy will be getting a "persecution complex".

I'm glad I put a disclaimer on the post now!

 

[foxy]

I'm glad I put a disclaimer on the post now!

Sorry Stu, there is another fly in the ointment, grain crush. This will also have a bearing on conversion of base malt, I did read somewhere that approximately 6% of base malt may not be crushed denying access to the starch.
In all of my beers the none fermentable grain is added at mash out when the enzymes are de-natured saving any confusion with expectations of gravity.

If OG has been overshot to the point where 3L dilution is required, then the degree of fermentability of 500g of roasted malt isn't going to have much bearing on the outcome. There clearly wasn't an issue with the mash.

At least we've clarified that unfermentable grain is partly fermentable.

Well I consider that an error by someone brewing their first stout, easily made, maybe he was fortunate there wasn't a lactose addition. There was no need to dilute back. But why would Malt Miller forecast an OG, FG based on the base malts?

 

[Sadfield]

Well I consider that an error by someone brewing their first stout, easily made,

But it wasn't @foxy.

I had ~23l of wort which came out at 1.052. I've been getting these kinds of overshoots ever since I started adding 5% rice hulls to the grist, so just topped up with ~3.8l water to get ~27l.

The was an overshoot of 7 gravity points, liqouring back was necessary to keep the beer as intended.

Mash temp was 66° which I pretty much nailed for the hour.

What the above suggests, is there wasn't any issues with the mash or water treatment. That there was good chemisty and lautering.

 

[foxy]

But it wasn't @foxy.




What the above suggests, is there wasn't any issues with the mash or water treatment. That there was good chemisty and lautering.

But it was. He did say it was his first stout. Water treatment, a well water with a pH of 5.3 I wouldn't even consider drinking it never mind brewing with it.

 

[Stu's Brews]

Sorry Stu, there is another fly in the ointment, grain crush. This will also have a bearing on conversion of base malt

You are right - I was lumping that into mash efficiency as a whole can of worms in itself, along with other things like mash thickness.

 

[Sadfield]

But it was. He did say it was his first stout. Water treatment, a well water with a pH of 5.3 I wouldn't even consider drinking it never mind brewing with it.

Low mash pH affects proteins.

"While we don’t want wort pH to be greater than about 5.6 for any wort, we don’t want that pH to get too low either. One reason is that low pH enhances the performance of Proteolytic Enzymes in the mash that literally chop up the wort’s long and medium length protein chains into tiny “bodyless” remnants. Too much of that activity is the main cause of thin beer." - Brungard

Post in thread 'Effects of an uncorrected low mash pH' https://www.homebrewtalk.com/threads/effects-of-an-uncorrected-low-mash-ph.528601/post-8207866

Lower pH and lower temperature is still going to favour β-amylase activity and produce a less dextrinous wort. And the OP still, got better than expected mash efficiency.

 

[foxy]

Low mash pH affects proteins.

"While we don’t want wort pH to be greater than about 5.6 for any wort, we don’t want that pH to get too low either. One reason is that low pH enhances the performance of Proteolytic Enzymes in the mash that literally chop up the wort’s long and medium length protein chains into tiny “bodyless” remnants. Too much of that activity is the main cause of thin beer." - Brungard

Post in thread 'Effects of an uncorrected low mash pH' https://www.homebrewtalk.com/threads/effects-of-an-uncorrected-low-mash-ph.528601/post-8207866

Lower pH and lower temperature is still going to favour β-amylase activity and produce a less dextrinous wort. And the OP still, got better than expected mash efficiency.

View attachment 105145

View attachment 105147

With a pH of 5.3, then the buffering of the grains, adding gypsum the mash pH is going to drop considerably. I haven't calculated the mash pH but it is going to be extremely low. That is if the well water has a pH of 5.3 it if it is an error.

 

[Larse]

With a pH of 5.3, then the buffering of the grains, adding gypsum the mash pH is going to drop considerably. I haven't calculated the mash pH but it is going to be extremely low. That is if the well water has a pH of 5.3 it if it is an error.

Sorry, I mixed up my notes on this one. I added precipitate of chalk, not gypsum.

 

[Hazelwood Brewery]

I believe precipitate of chalk is primarily calcium carbonate and is barely soluble in water. The acidic water may help a little but I don’t know if that would be enough.

The reason you boil water and then cool it is to precipitate out (remove) calcium carbonate.

If I’m right, I doubt you added much carbonate because of its insolubility and I doubt you removed much because your source water had very little to start with. My guess is you ended up pretty much where you started with your well water though the boiling would have helped kill off any beasties.

 

[Larse]

I believe precipitate of chalk is primarily calcium carbonate and is barely soluble in water.

The reason you boil water and then cool it is to precipitate out (remove) calcium carbonate.

If I’m right, I doubt you added much carbonate because of its insolubility and I doubt you removed much because your source water had very little to start with. My guess is you ended up pretty much where you started with your well water though the boiling would have helped kill off any beasties.

Yeah, this wasn't boiled though. Just heated to ~75°. (Again, sorry for the confusion caused by my reading from the wrong notes). Only treatment was the precipitate of chalk. As I understand it, it will at best add 0.1 - 0.2 pH points.

 

[Hazelwood Brewery]

Yeah, this wasn't boiled though. Just heated to ~75°. (Again, sorry for the confusion caused by my reading from the wrong notes). Only treatment was the precipitate of chalk. As I understand it, it will at best add 0.1 - 0.2 pH points.

For darker beers you could do with some alkalinity. For most people an easy source of alkalinity is tap water. Is there any reason you can’t use your tap water?

If you can use tap water you could do with knowing the alkalinity of your tap water and then blend tap water and well water to get the profile you need.