In the early days of modern homebrewing, many 5-gallon (19-L) homebrew recipes called for boiling several pounds (a few kilograms) of malt extract in as little as 1.5 gallons (5.7 L) of water for 60 minutes. This thick wort would then be diluted to 5.0 gallons (19 L) in a bucket or carboy fermenter. If you followed these instructions, you ended up with beer (and you were psyched) — but you noticed that the color was frequently much darker than a comparable commercial beer.
As the sophistication of homebrewing knowledge increased, brewers were told to address the problem by boiling larger volumes of wort. (Buying fresh extract also helped.) This helped to a degree, but homebrewers wishing to make very pale beers were often left disappointed.
In the early 2000s, homebrewers started withholding a portion of their malt extract until the end of the boil. The idea behind this was that brewery-grade malt extract was made from wort had already been boiled. It did not require the long boil that all-grain wort does to coagulate the break material. All that is required is some time exposed to heat to sanitize it. In addition, by boiling your hops in low-gravity wort — made from steeping grains and small amount of malt extract — your hop utilization would improve when compared to boiling them in a very high gravity wort. This way of brewing — sometimes called the late extract addition method — quickly became standard practice.
Although everyone does this now, new brewers may wonder why and intermediate brewers may wonder about some of the variables in the process. With that in mind, here is a rundown of adding malt extract late in the boil and how it influences the character of your beer.
How Much Gets Added Early vs. Late?
Homebrewing recipes differ in the amount of malt extract that is withheld until the end of the boil. Many times, roughly half of the malt extract is boiled in roughly half the volume of the batch. As such, the specific gravity of the wort being boiled is around working strength. (In other words, if you’re brewing a 12 °Plato/OG 1.048 beer, you are boiling wort at around 12 °Plato/SG 1.048.) In other recipes, nearly all of the malt extract is withheld until the end of the boil.
You need to boil the hops in wort, not water. If you boil the hops in just water, you will yield a lot of bitterness, but the quality of the bitterness will be very coarse. As such, you either need to steep a fair amount of specialty grains (that contain sugar), perform a small partial mash, or add a small amount of malt extract to make wort to boil the hops in. The specific gravity of this wort does not need to be very high. I don’t know the absolute minimum density you can get away with, but 5 °Plato (~SG 1.020) is plenty.
Anywhere on the scale between withholding roughly half of your malt extract and withholding all but the small amount needed to make weak wort will work well. The more you add near the beginning, the less you need to dissolve late in the boil. For the lightest colored beers, or ones for which you want the most hop bitterness, try withholding as much of the extract as you can.
When to Add the Malt Extract
The only thing that needs to be done to the malt extract is to sanitize it. And, if it came from a can, it likely was sanitary (unless the can was bulging). Once dissolved into the wort, all it takes is a few seconds at temperatures over 170 °F (77 °C) and the wort is sanitized. As such, the extract can be added in the last couple minutes of the boil, or even at or after knockout.
One question that frequently crops up is whether brewers should keep the boil clock running while they are stirring in extract and boiling has stopped. The answer is that the consequences to picking either action is minimal.
Adding the malt extract will cool the wort below boiling temperature, but probably not below the temperature that alpha acids isomerize at. The rate of isomerization is lowered at temperatures below boiling, but an appreciable amount of isomerization is likely occurring if you’re above 170 °F (77 °C). If I’ve added hops in the 15 minutes or so before stirring in the extract, and am expecting IBUs from them, I stop the clock. If I’ve added one early dose of bittering hops, I don’t stop the clock because I’ve probably got almost all I’m going to get out of them by the end of the boil. However, the consequences of picking one action over the other aren’t that great — a little more or less bitterness is all.
LME vs. DME
You can use liquid malt extract (LME) or dried malt extract (DME) for the early or late additions. Dried malt extract tends to foam when added to boiling wort; on the other hand, liquid malt extract sinks to the bottom of the brewpot and can easily scorch if you’ve left the heat on. If you are trying to brew the lightest colored beer possible, use fresh liquid malt extract. Otherwise, either form of malt extract is fine.
Whenever you are adding sugars to the kettle, remember that diluting them in wort first will let you stir them in quickly. This minimizes the odds that they will get scorched.
With Partial Mashing
The late extract addition method works great with partial mash formulations of stovetop brews. The brewer makes an all-grain wort from the partial mash and boils the hops in it, then adds malt extract near the end of the boil to reach his or her target gravity (in the fermenter).
Homebrewers who use the late extract addition method have a reasonably wide range of options that will work well. If you are looking to brew a beer that is very light in color, getting fresh liquid malt extract and withholding most of it until the very end of the boil (or even the whirlpool) would be your best bet. Making sure that none of the extract scorches is also key to brewing a very light beer from malt extract. If you’re looking to brew a very hoppy beer, withholding most of the extract until the last few minutes of the boil (or until the whirlpool) is also the way to go. If you’re brewing an amber or darker beer that isn’t incredibly hoppy, you could add about half of your extract early in the boil, allowing you to save time dissolving the late addition.