Ever come across a beer recipe that tells you to add malt about 20 or 15 minutes before the boil is over?

For the longest time I wondered what exactly was the purpose of that and I don’t know about you, but I hate doing stuff not knowing why I’m doing it… I like to always find a purpose for doing whatever is it that I’m doing… I guess it makes me more confident that I’m doing things right… don’t know?

But here’s what I’ve found about adding malt at knockout…

First off… knockout refers to the end of the boil (about 15 to 20 minutes before you turn off the heat)… and the very end is known as flameout…

I can see where the name flameout comes from, but haven’t quite figured out where the term knockout comes from… anyone?

So, the whole purpose of waiting till the end to add more malt is to boil a lower gravity wort… There is two reasons why you may want to do this although it is open for debate whether or not it makes a difference.

The first and most common one is better hop utilization.

Supposedly a lower gravity wort will allow you to extract more bitterness out of the hops and adding LME at knockout was an alternative to mimic the density of a full boil but only boiling 3-4 gallons as opposed to 5+ gallons.

Reason for this is that some electric stoves are not capable of bringing 5 gallons of wort to a boil or maintaining one with the lid off. Brewers had to resort to boiling only 3 or 4 gallons of wort and then diluting everything at the end.

By boiling only 3 to 4 gallons, hop utilization dropped and ideas like adding DME or LME at knockout started to spring up…

It then turned into a common practice and now many recipes will have that as the procedure to brewing a beer. Usually it’s higher gravity beers or those with high IBU’s.

The one I brewed that asked for a late addition of malt was a Russian Imperial Stout, but it’s hard to tell how much of a difference it makes since the recipe already included a lot of hops… I guess I may have to brew two batches side by side and compare that way…

I have turned to boiling 4 gallons for all my recipes and have noticed an increase in the amount of bitterness I get out of the hops in some smaller beers like pale ales,  amber ales, etc… I think the amount of time it takes to cool down 4 gallons as opposed to 3 also impacts the amount of bitterness you get out of the hops…

Now the other reason you may want to consider adding malt at knockout is to avoid wort darkening. Boiling a lower gravity wort will give you a lighter colored beer.

What are the reasons you add malt at knockout?

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