A hypothetical - Dry malt extract

[Scobieb]

Hi Guys,

I've been using the great spreadsheet on this forum to create my latest brews. Just a question that I'm curious about:

I note on the brewday page it tells you how much dry malt extract to put into the boil to get the desired gravity. What would happen if you put more DME in at the initial boil stage and less with 5 minutes to go? Presumably the gravity would higher?

 

[bum]

The final gravity will be approximately the same (may be some small difference in boil-off at different gravities but really not worth worrying about here, I don't think). What happen though is that the different gravity during the boil will change how much IBU you get out of the boil.

If you do want to add more for the full length of the boil for some reason then make sure you enter it that way into the spreadsheet so your hoping is calculated more correctly.

[EDIT: are you still brewing 5L batches? You should really be able to go full volume without much trouble (assuming you have a large enough pot).]

 

[QldKev]

The resulting gravity would be the same, as only water evaporate off.

But since you are now boiling with a higher gravity, then your hop utilization would be lower.

 

[Scobieb]

Hi Guys,

Yes I'm still brewing 5 litre batches.

So if you threw in all the malt, then you wouldn't necessarily get the required IBU value from the Hops? Is that right?

Is there a way on the spreadsheet to reflect that?

 

[QldKev]

Hi Guys,

Yes I'm still brewing 5 litre batches.

So if you threw in all the malt, then you wouldn't necessarily get the required IBU value from the Hops? Is that right?

Is there a way on the spreadsheet to reflect that?

Yep, your IBU would be lower in the high gravity.

Not sure on the spreadsheet, never use it sorry.

 

[bum]

It's not that you won't get the IBU for a full volume/total extract amount boil - this is actually the best set of circumstances for your beer.

The issue is that extract brewers often do small boils for their hopping so they need to do some shifty calculations to get it right in the end when they dilute to full volume. It sounds like the spreadsheet might have you thinking you have to do the same.

I don't use the spreadsheet myself but I am certain it'll let you work out a full volume boil. Someone will steer you right soon enough.

 

[Scobieb]

Thats okay. Thanks Kev.

I notice the amount of DME to put in the original boil is dependant on the amount of Grains being used. Are you able to explain why that is so?

 

[QldKev]

Thats okay. Thanks Kev.

I notice the amount of DME to put in the original boil is dependant on the amount of Grains being used. Are you able to explain why that is so?

Having never used the spreadsheet, I'm taking a guess that all the hop utilization calculations are based on a set gravity. So the more gravity points from the grain, the less DME needed to reach the target gravity of the boil.

 

[Yob]

If it's ianH's spreadsheet, doesnt it have the HCF (Hop calculation factor) box to check? Its been a long time since Ive used it or even looked at it but from memory thats what it's function was.

 

[Scobieb]

If it's ianH's spreadsheet, doesnt it have the HCF (Hop calculation factor) box to check? Its been a long time since Ive used it or even looked at it but from memory thats what it's function was.

It does I hadn't spotted that yob. So presumably if I make it yes it calculates the IBU based on me adding all the malt at once?

 

[carniebrew]

The reason the spreadsheet tells you how much LME/DME to add to your boil water is so that you'll get around a 1040 boil gravity. This is considered optimal for extracting the goodness out of the hops. However, it's not just about gravity, as I mentioned in the other thread...it's also about the total volume of your boil. The HCF is for boil volumes less than about 8 litres, and uses a formula to calculate how much less IBU you get from your hops in those small volume boils.

If you can boil more than 8 litres, then ignore the HCF (leave it off), and follow the spreadsheet's suggestion for how much extract to add...then add all your remaining extract with a few minutes or so to go in the boil, just to make sure it's all blended in. Then chill, add that to your fermenter, top up as needed and stir it heaps before taking your OG reading.

 

[bum]

His full batch size is 5L and I strongly suspect he won't need the HCF.