Going to try partial mash

[Grinnan5150]

I used to be an all grain brewer but it's been about a year since I've brewed anything. Time and space available have put a damper on all grain brewing so I thought I would go partial mash.

I am a bit confused on volume of boil. I have read some instructions where people do a full boil and other instructions where people have boiled a concentrated wort and added the additional water after. The latter would be optimal for me because I have an electric stove which would make a full boil next to impossible.

Will doing a boil with a concentrated wort with the mashed wort and extract only still result in a good beer or do you have to do a full boil to pull off a good partial mash recipe? If you have to be a full boil I might as well continue with all grain. Any input or advice would be appreciated.

Thanks!

 

[kh54s10]

You can do either full or partial boil and a top up. Some feel the full boil give a better result. But you will need a pot big enough for the full boil and the power to boil it. I would not try to boil 7+ gallons on my glass cooktop.

If I were to brew on my propane burner, I would eliminate the extract and go with traditional all grain.

You can save space by mashing in a smaller tun or in the boil kettle then removing the grain. (bagged). But since you are doing a mash then a boil, the time saving, if any, is insignificant.

 

[Grinnan5150]

You can do either full or partial boil and a top up. Some feel the full boil give a better result. But you will need a pot big enough for the full boil and the power to boil it. I would not try to boil 7+ gallons on my glass cooktop.

If I were to brew on my propane burner, I would eliminate the extract and go with traditional all grain.

You can save space by mashing in a smaller tun or in the boil kettle then removing the grain. (bagged). But since you are doing a mash then a boil, the time saving, if any, is insignificant.

Good to hear a 2.5 to 3 gallon boil is doable. I have an electric glass top also and would not want to risk the weight of 7+ gallons.

 

[jan_b19]

I'll quote aomething from another user: Barleywater said this in another thread and i think it's something you would need to know when doing partial boiling.

The Bigger the Boil, the Better the Boil
The maximum threshold of IBUs in a given batch of beer is 100, anything over that is only adding to flavor (and head retention and mouthfeel). This maximum number is also only in worts of around 1.050. Now if you are boiling 3 gal down to about 2.5, and adding 2.5 gal of wort, then your maximum is already sliced down to 50 IBUs in a batch, and that is still with a wort gravity of 1.050 or below.

Now, with a full boil if you are trying to reach a final gravity 1.050, then you will have near 100% efficiency when it come to alpha acid isomerization and IBU absorption, and you can reach the 100 IBU mark, since you would be starting the boil around 1.044. When using LME, this will be about 7 lbs. If you put 7 lbs of LME into only 3 gallons of wort, then you are starting with a pre boil gravity of 1.084, boiling down to probably around 2.5gal at 1.100 before topping of with water to reach your OG of 1.050. Far above the ideal IBU efficiency gravity. This will leave you with a wort that has a max IBU rating of approx. 82.7, not too bad, but wait. After topping off, you will have only 41.4 IBUs.

So without doing a late extract addition you maximum IBU level would be 41.4, not quite the hop bomb you may have thought you were making.

Now, if you add say, half at the end, lets see what that does. You pre boil gravity will be around 1.042 (very close to that of a full wort boil), and you will boil off around to about 2.5 gal at 1.050, perfect. So now you have 100 IBUs, top off and you are at you maximum of 50 IBUs, still not the hop bomb you thought, but better. If you are only adding 2 gal of top off water, then you max IBU will be 60, 1.5 gal and the max IBU is 70, 1 gal is 80, .5 gal is 90 and not topping off can get you the maximum IBU level of 100.

So basically he's saying it's better to add 1/3 of your LME or DME at the beginning and 2/3 with 15 minutes left.
This is because the higher your pre-boil gravity the less effective hop additions will be. So it's better to start with a lighter gravity do your hop additions, add the rest of the extract with 15min left and maybe a aroma hop addition after that if necessary. In the end it will give you a better beer with a better aroma and taste.

 

[Grinnan5150]

I'll quote aomething from another user: Barleywater said this in another thread and i think it's something you would need to know when doing partial boiling.


So basically he's saying it's better to add 1/3 of your LME or DME at the beginning and 2/3 with 15 minutes left.
This is because the higher your pre-boil gravity the less effective hop additions will be. So it's better to start with a lighter gravity do your hop additions, add the rest of the extract with 15min left and maybe a aroma hop addition after that if necessary. In the end it will give you a better beer with a better aroma and taste.

Wow, thanks! I never thought of that before. I'm glad I know the science behind it now and will definitely give that a shot next batch. Adding DME that late in the boil doesn't affect the flavor of the beer?

 

[chickypad]

Adding DME at the end may improve the flavor especially in light beers by avoiding the concentrated boil. For full extract the 1/3, 2/3 rule is common but since you are doing partial mash you can just boil the wort from your mash and add all the extract at the end.

 

[Grinnan5150]

Adding DME at the end may improve the flavor especially in light beers by avoiding the concentrated boil. For full extract the 1/3, 2/3 rule is common but since you are doing partial mash you can just boil the wort from your mash and add all the extract at the end.

And by doing that, that doesn't affect the hop utilization?

 

[JohnSand]

You can use an online calculator like Brewer's Friend to help determine hop usage for full or partial boils, also for late extract additions. I don't think that halving your boil volume halves your hop extraction.
You can also do partial boils for BIAB batches on your stove. I have used a five gallon pot to make five gallon batches by topping off with second runnings in the pot, then topping off in the fermenter just as you would with extract.

 

[hagar]

Using the 1/3 - 2/3 trick with the extract will indeed affect your hop utilization. A calculator will help a lot with determining the effect on IBUs.

 

[MarcGuay]

I've done two partial-mash 2.5gal BIABs in a 3gal pot on a glass stovetop and it's gone well despite some off measurements that I need to iron out. Procedure was essentially:

- Mash grains in a bag in the 3gal pot
- Sparge with water from smaller 1.5gal pot
- Boil 2.25gal collected wort
- Add malt extract w/ 5 minutes left
- Cool
- Pour 1.75gal wort into fermenter, losing about .25gal to trub and chill
- Top up 1.5gal wort with 1gal water.

Haven't tasted the beers yet. I used this procedure as a base: https://www.homebrewtalk.com/showthread.php?t=75231.

 

[chickypad]

And by doing that, that doesn't affect the hop utilization?

Yes, as pointed out above a less concentrated wort should improve your hop utilization.