Stout hasn't reached final gravity

[Hazelwood Brewery]

I can't see that grain bill getting within a bulls roar of 1,052 in 23 litres.

I think this is quite possible, I regularly get 23 litres at between 1.048 and 1.050 from

3.6Kg Maris Otter
300g Oats
200g Light crystal
100g Tortified wheat

The OP is mashing 800g more malt than me so you would expect a higher gravity than I achieve.

I think this efficiency is a factor of how fine the grist is and how long the mash is because I’ve also had the situation where my gravity is waaay lower than it should be and I’ve had to mash for hours to get the gravity near to where it should be - reflecting that I did think there was not a lot of “flour” in the grist as I mashed it in.

 

[Hazelwood Brewery]

I don’t think I saw any mention of water treatment or mash pH in this thread. Mash pH can affect enzymatic efficiency so could in theory affect fermentability of the wort?

 

[Larse]

I don’t think I saw any mention of water treatment or mash pH in this thread. Mash pH can affect enzymatic efficiency so could in theory affect fermentability of the wort?

I didn't take the pH, possibly something I should start doing, but I did treat the water. My water (well water) has a pH of 5.3 and very little solids and no chlorine.

So for this I added two tsps of Gypsum and 1/2 tsp of Potassium Chloride. Then boiled and cooled. Procedure from The Big Book of Brewing.

 

[Hazelwood Brewery]

I didn't take the pH, possibly something I should start doing, but I did treat the water. My water (well water) has a pH of 5.3 and very little solids and no chlorine.

So for this I added two tsps of Gypsum and 1/2 tsp of Potassium Chloride. Then boiled and cooled. Procedure from The Big Book of Brewing.

Your source water pH suggests low alkalinity surface water and you’ve added plenty of calcium which should result in a lower mash pH - which if I remember correctly would favour a more fermentable wort.

I might be barking up the wrong tree but was worth a thought.

I think taking pH readings is worth doing because it can help diagnose/explain issues.

 

[Larse]

I never took pH readings because I never had a problem with fermenting out until now. It was one of the possible causes in my own mind when I posted here, but you're the first to mention it. I have pH papers, so I'll start with those and see what they tell me.

On balance though, I think under-pitching was probably the root cause.

 

[foxy]

I never took pH readings because I never had a problem with fermenting out until now. It was one of the possible causes in my own mind when I posted here, but you're the first to mention it. I have pH papers, so I'll start with those and see what they tell me.

On balance though, I think under-pitching was probably the root cause.

You still aren't understanding the effects of the none fermentable sugars, if you use any of the apps for printing a recipe you will see a PPG value at the side of the entry of the grains being used. The none fermentable grains have already been converted to sugar by the kilning. Those sugars are still going to adding to your density even though they are not fermentable. This is one of the main reasons why so many stouts finish at 1,016 1,018. The others are crush of the grain, and mash temperature.
S.04 is a medium to high attenuating yeast and could easily ferment out the fermentable sugars in that grain bill which it did, the grain bill suggests it isn't a dry stout hence the more none fermentable grains.

 

[foxy]

I think this is quite possible, I regularly get 23 litres at between 1.048 and 1.050 from

3.6Kg Maris Otter
300g Oats
200g Light crystal
100g Tortified wheat

The OP is mashing 800g more malt than me so you would expect a higher gravity than I achieve.

I think this efficiency is a factor of how fine the grist is and how long the mash is because I’ve also had the situation where my gravity is waaay lower than it should be and I’ve had to mash for hours to get the gravity near to where it should be - reflecting that I did think there was not a lot of “flour” in the grist as I mashed it in.

Didn't see this. I agree, a higher gravity would be expected, but the OP had 900 grams of speciality grains which gave a gravity of 1,052 partially made up of unfermentable sugars and was perplexed that he couldn't get the gravity down. So if we remove the PPG value of the unfermentable grain and giving a BHE of 75% the OG and FG would be 1,046 - 1,011 respectively using S-04. Close enough to the target gravity figures given. Now while the OG of the actual shows a 6 point difference it won't necessarily translate to a 6 point difference to the FG as the two speciality malts, light and dark crystal will get some conversion to fermentable sugars by the enzymes in the Pale Ale malt so a 1,014-5 FG would be feasible.

 

[Sadfield]

So if we remove the PPG value of the unfermentable grains

How can they be unfermentable when PPG is a measure of fermentable sugar?

 

[Larse]

How can they be unfermentable when PPG is a measure of fermentable sugar?

I found this when searching for more information. Is this the case?

When the malts which are classed as none fermentable are kilned they kill the enzymes to convert the starch into sugar, What they don't do is eliminate the starch. So the diastatic power of the base malt can still convert the starch in the none fermentables.

 

[Sadfield]

I found this when searching for more information. Is this the case?

Exactly, if they were truely non-fermentable the ppg would be zero.

 

[Sadfield]

The IOB standard mash method used to give ppg values is 65°c for 60 minutes. Not to dissimilar to used here. So should extract fermentable sugar from grains with a ppg value.

 

[foxy]

How can they be unfermentable when PPG is a measure of fermentable sugar?

It’s a measure of sugar, not necessarily fermentable.

 

[Larse]

Not in this definition.

 

[foxy]

Not in this definition.
View attachment 105120

Exactly, all malt has PPG and they all add to gravity but they don’t all add to fermentablity.
Look at the speciality malts not base malts.

 

[Larse]

Exactly, all malt has PPG and they all add to gravity but they don’t all add to fermentablity.
Look at the speciality malts not base malts.

It can't produce alcohol if it doesn't add to fermentability. From the same website it says: "PPG stands for Points per Pound per Gallon. This is a unit of measure to approximate the number of gravity points of fermentable sugar a malt or grain can produce."

It then gives a table of typical PPG from different malts including Chocolate and Crystal malts. The quote I gave earlier states that the diastatic power of the base malt can convert the starches in non-fermentables.

So it's very confusing. You're saying they can't be converted yet other sources say that base malts can convert them and that they have a usable PPG.

Then there's this account from an archived article about Guinness: "McGovern notes that unlike those in corn and rice, the starches in raw barley do not have to be gelatinized before mashing. So no cooking is required. The enzymatic action of pale malt is strong enough to convert the starch into the sugars required for fermentation. So you won’t find any cereal cookers at the Guinness plant."

 

[foxy]

It can't produce alcohol if it doesn't add to fermentability. From the same website it says: "PPG stands for Points per Pound per Gallon. This is a unit of measure to approximate the number of gravity points of fermentable sugar a malt or grain can produce."

It then gives a table of typical PPG from different malts including Chocolate and Crystal malts. The quote I gave earlier states that the diastatic power of the base malt can convert the starches in non-fermentables.

So it's very confusing. You're saying they can't be converted yet other sources say that base malts can convert them and that they have a usable PPG.

Then there's this account from an archived article about Guinness: "McGovern notes that unlike those in corn and rice, the starches in raw barley do not have to be gelatinized before mashing. So no cooking is required. The enzymatic action of pale malt is strong enough to convert the starch into the sugars required for fermentation. So you won’t find any cereal cookers at the Guinness plant."

PPG is gravity points that doesn’t equate to fermentability. You are now talking about adjuncts whose starches will be converted by the base malt enzymes that is not in dispute. You will get some conversion of light crystal, less conversion on the dark crystal and less again on the chocolate and roast grains.
Some, including myself steep those non fermentable grains and add to the boil. They are mostly there for colour, flavour and adding body to the stout.

 

[Sadfield]

Exactly, all malt has PPG and they all add to gravity but they don’t all add to fermentablity.
Look at the speciality malts not base malts.

They add some.

Why would they go to the considerable cost and effort of malting everything, except roasted barley, before roasting to get zero fermentable sugar?

 

[foxy]

They add some.

Why would they go to the considerable cost and effort of malting everything, except roasted barley, before roasting to get zero fermentable sugar?

As I said in the previous post, it is for flavour and colour. Why do Guinness not mash their roast barley?

 

[peebee]

It’s a measure of sugar, not necessarily fermentable.

Absolutely!

A flippin "arcane" measurement though. Any attempt to split it into "fermentable" or "nonfermentable" has to account for the yeast strain doing the fermenting, and that's even if going to the trouble of splitting out reducing and non-reducing sugar variants ... naa, PPG is useless! Only good for kicking off arguments ... Ah, I see it's meeting that expectation!

You got a laughing face reaction from "Sadfield" for your post. That's Sadfield's lame attempt at "sarcasm" I reckon ... but you probably already knew that?

 

[Larse]

PPG is gravity points that doesn’t equate to fermentability. You are now talking about adjuncts whose starches will be converted by the base malt enzymes that is not in dispute. You will get some conversion of light crystal, less conversion on the dark crystal and less again on the chocolate and roast grains.
Some, including myself steep those non fermentable grains and add to the boil. They are mostly there for colour, flavour and adding body to the stout.

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

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

When the malts which are classed as none fermentable are kilned they kill the enzymes to convert the starch into sugar, What they don't do is eliminate the starch. So the diastatic power of the base malt can still convert the starch in the none fermentables. Chucking the none fermentables in at 77 C mash out one is getting the desired colour and flavour without increasing the fermentable wort, the enzymes in the base malt has denatured with the increase in temperature, so can't convert the starches left in the unfermentable grains. This is the way I interpret it, I could add more roast, even chocolate. It isn't going to make any difference to the outcome.
Maybe this table will help.
http://www.brewunited.com/grain_database.php#key