Adding sugar post pitching - ABV effect ?

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Bertie Doe
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Adding sugar post pitching - ABV effect ?

Post by Bertie Doe » Sun May 26, 2019 12:35 pm

A week ago I pitched yeast into 23 litres of wort. Initial gravity was 1037. So I'm 3 clicks short of Graham Wheelers 1040 recipe target for 4% ABV.

Activity is now slowing down, so how much white cane sugar to add, to get back on track please? Assume I'm boiling the sugar first in 0.5 litres of water. TIA.

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Re: Adding sugar post pitching - ABV effect ?

Post by guypettigrew » Sun May 26, 2019 1:39 pm

Your ABV will be a function of both the start and finish gravity. You'd be hard pressed to notice the difference between (say) a 3.7% and 4% beer.

If you do want to add sugar, though, 8g/L will give you an increase of 1.003. In truth, it's probably not worth bothering to add sugar.

Any idea why you ended up 3 points short?

Guy

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Kev888
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Re: Adding sugar post pitching - ABV effect ?

Post by Kev888 » Sun May 26, 2019 1:56 pm

Another way of calculating it is that (as this page tells us) 1kg of plain white sugar offers a potential gravity of 370 points in 1L. You require only 3 points extra but in a volume of about 23.5L, so that is roughly (3/370) x 23.5 =0.19kg of sugar (i.e. 190g).

Personally i prefer to make adjustments much earlier, but it should still work if you think it is worthwhile.
Kev

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Re: Adding sugar post pitching - ABV effect ?

Post by Bertie Doe » Sun May 26, 2019 5:09 pm

Thanks Kevin, that's a handy link - saved to favourites. Guy, the problem may lie with my interpretation of the instructions which came with the brewer. I may have messed up the maths. Instructions say ".... benefits from a wetter than normal mash consistancy. 20 litres per 5 kg"

So Graham's London Pride recipe requires for 23 litres uses 3750g pale 375g crystal = 4120. Total liquor 32.4 and mash liquor 10.3 litres, I'm assuming 32.4 minus 10.3 gives you 22.1 sparging litres.

When I applied the manufacturers' 20 lites per 5 kg, - 20 divided by 5 x 4.120 you get 16.5 to mash, therefore only 16 litres to sparge which is a lot less than Grahams 22.1 sparge litres. I guess this is where the 3 points have gone.

I have tried drier mashes in the past and followed the recipe 'to the T' but it has been very difficult to mix with the paddle. I'm conscious of a lot of dry spots in the porridge.
Bertie

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Re: Adding sugar post pitching - ABV effect ?

Post by guypettigrew » Sun May 26, 2019 5:41 pm

That may well be it. The usual ratio is 1Kg grain to 2.5L liquor. Hence Graham's 10.3L for the mash.

The amount of liquor you sparge with gets a bit complicated! You need to know how much you'll lose during the boil and how much you'll have left behind in the boiler, being held back by the hops. Then you know how much the pre-boil volume in the boiler should be to get you the final volume you're hoping for.

An example based on my kit; 37.5L in the boiler pre-boil gives me 25L in the fermenter. This is after a 75 minute boil using two 2.4kW elements and about 70-80g of hop cones. So I sparge until I have 37.5L, but I check regularly towards the end of the sparge to make sure the runnings haven't gone below about 1.008.

As to the dry spots, not a good idea! I add the grain to the hot water in two or, more usually, three lots. Usually about 5-5.5Kg per brew at the liquor ratio above. The brew paddle works best for me if I slice it through the grain/liquor mix before stirring it. The final kilo or so is always the most difficult to properly wet, but it can be done.

Hope this helps.

Guy

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Re: Adding sugar post pitching - ABV effect ?

Post by Bertie Doe » Sun May 26, 2019 6:55 pm

Thanks Guy for the info, I hadn't realised the importance checking the runnings. My measuring bowl only holds 0.5 kg, so there's plenty of lot additions between paddling.

My first brewer was an Electrim. Very simple, exposed element and loadsa fun jugging water onto the grain to sparge. Incidentally the Electrim had an internal diameter of 300 mm whereas my new brewer's grain sleeve is only 275 mm. I'm wondering if this narrower and taller grain mass may lead to inefficient water movement during the sparge? I know that's only about 10% smaller but ....

30+ years ago, the supplier of espresso machines to coffee shops, found that by increasing the width of the coffee basket from the old 52mm to 58mm (10% again) you got a much more efficient product. You got a tastier cup of Joe plus the new wider, shorter coffee puck was less prone to "channeling".

https://www.tecnora.in/blog/what-is-a-coffee-puck/

An efficient puck is a profitable cup, so good news for the end user. What's the diameter of your grain sleeve Guy?

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Re: Adding sugar post pitching - ABV effect ?

Post by guypettigrew » Sun May 26, 2019 8:52 pm

Hi Bertie

My mash tun is a stainless steel thermopot like this one.

The internal diameter is about 340mm. The depth of the grain above the false bottom is about 180-200mm. So, lots of surface area and less depth than you'll have.

Don't know how this would affect mash efficiency. Others can perhaps help out here.

Guy

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Re: Adding sugar post pitching - ABV effect ?

Post by Bertie Doe » Sun May 26, 2019 9:42 pm

Guy that's serious capacity at 38 L. The concern with my machine is sparge efficiency. The simple answer is to reduce the mash liquid and increase the sparge liquid on my next brew and report back. This may be some time as I did 2 X 23 L batches. Anyway thanks again Guy and Kev for the heads up on sugar calculations.

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Re: Adding sugar post pitching - ABV effect ?

Post by Kev888 » Sun May 26, 2019 10:12 pm

It somewhat depends on how you sparge, but the the reduced amount of sparging liquor (due to the thinner mash) will likely play a part. The minor difference in grain depth arising from a 275 vs 300mm diameter vessel probably won't have much effect, but if you have changed systems then there'll be all manner of differences that will add up.

It should be said that I don't think a 3-point difference is anything to be particularly concerned about. Though it would be nice if it were consistent, so that the next time that this (or a similar) beer is brewed the grain quantities can be tweaked very slightly in anticipation.
Kev

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