Late Extract Additions and Impact on Hopping
Many authors (including me) recommend that you do a full wort boil (5 gallons/19 L if that is to be the final volume of wort at pitching) when brewing with malt extract, having added all the extract at the beginning. That’s a good rule of thumb, for it ensures a proper hot break, and means that it is relatively easy to calculate hop bitterness and to reproduce it from beer to beer. But, as always there are cases where you may not want to follow the rule, the first being that maybe you just don’t have the equipment or space to do a full wort boil. But there is another case where you deliberately add a portion of the extract late on in the boil.
In fact malt extract does not need an extended boil, since it has already been boiled in its manufacture. If you use a 90-minute boil (as you might with an all-grain beer) an extract-based beer can be thin and lacking in mouthfeel because of excessive breakdown in proteinaceous material. That is why most brewers recommend a 45- to 60-minute boil for extract beers. And it is clear that adding a significant amount of extract towards the end of boiling will limit the breakdown of protein residues which will help both the beer’s head retention ability and its body.
But the main reason for late extract addition is to make your beer paler than if all the extract was added at the beginning. This is because during boiling certain reactions occur in the wort, which result in browning and darkening. The extent of browning is partly a function of boiling time and of the concentration of the wort, so that the longer the boil and the higher the wort concentration the darker the wort will be. Therefore, if you add, say, two thirds of the total amount of extract 15 minutes before the end of a 60-minute boil you can expect your beer to be paler than if all the extract was added at the start. Exactly how much paler is impossible to say without carrying out an involved series of tests coupled with color measurements, to which homebrewers are unlikely to have access. But if you are brewing a light-colored beer this approach is obviously a good insurance against getting too dark a color, and it is one that is used successfully by a number of homebrewers. Of course it would be of most value if brewing an American light lager, or a genuine Pilsner, but many brewers consider it useful to use late extract addition in all their pale beers. You can also do it with dark beers, but I don’t recommend it, not just because the lessening of color is unimportant in such beers, but because most of them benefit from the flavor compounds that are produced by the browning reactions. And do be careful with late addition — turn off the heat source and make sure all the extract is fully dissolved before turning it on again. If it is not dissolved it will scorch and caramelize on the bottom of the pot and your efforts will have been in vain.
This browning effect is caused by what are called Maillard reactions, whereby reducing sugars react with amino acids to form a variety of compounds. One group of these compounds is known as melanoidins because they are highly colored; other, usually simpler, molecules are produced that are intensely flavored and can have beneficial effects on the palate of the beer, especially dark beers. As a flavor reference one source states that the ultimate product of Maillard reactions is caramel. Indeed caramel flavoring is usually manufactured by heating sugar in the presence of ammonium ions, although it can be produced without the presence of the latter.
That’s a little bit of the chemistry behind late extract addition and its effect on beer color, but we need not get too much into that for it should be obvious to even the most simple-minded astrophysicist that the technique is a very useful one for an extract brewer, whether using only extract or using the partial mash plus extract technique. It is not much good for brews produced using steeped grains plus extract, because the grains in that case are usually highly-colored and full of melanoidins anyway!
But are there any downsides to using late extract addition? Well, there is one drawback, and a quick trawl around homebrewing websites reveals a common complaint about this technique — that the beer is too bitter. The reasoning behind this is that for most of the boil time the wort specific gravity is significantly lower than that of the final wort going to fermentation. As a result, hop utilization is much higher and the beer is likely to end up with a higher concentration of iso-alpha acids than would have been the case if all the extract had been present at the commencement of the boil and the wort SG during boiling would have been closer to that of the final wort SG. Since bittering hop additions are usually calculated for the full wort gravity in the boil, a beer produced by late hop addition is going to have a higher bittering level than you originally targeted. This will obviously be most noticeable in a lightly-flavored, delicate beer which may well be just the type of beer which benefits from this technique in terms of color.
Well, I am nothing if not a critical scientist, and my first inclination was to ask, “How many of these people did a control test, as all good experimentation requires?” In other words, were the beers produced by late extract addition significantly higher in bitterness than those where the extract was added at the start?
Bittering effects in late extract addition
1. Let’s assume, for simplicity’s sake that we are going to make 5 gallons (19 L) of a pale beer using 6 lbs. (2.7 kg) malt extract syrup, and adding 1.5 oz. (43 g) of hops at 5% alpha-acid. We’ll add all the hops and 1⁄3 of the extract at the start of the 60 minutes boil, and the remaining 2⁄3 for the last 15 minutes, using a full 5-gallon (19-L) boil.
The gravity at start is (2 x 36)/5 = 1.014, gives 33 IBU in 45 minutes boiling. Now gravity in last stage is (6 x 36)/5 = 1.043, which gives as yielding 14 IBU in 15 minutes boiling. Therefore total IBU this way would be 47. If all the extract had been added at the start, then at 1.043 throughout the boil would give a wort with only 28 IBU.
2. Let’s do it all over again, but this time using only a 3-gallon (11-L) boil. The gravity at the start will be (2 x 36)/3 = 1.024, which will give 30 IBU for a 45 minute boil. But gravity for the last 15 minutes will be (6 x 36)/3 = 1.072, and the calculator says that will provide 11 IBU. So that means total IBU would be 41 by this method. If all the extract were to be added at the start, then we would have had 21 IBU in the finished wort.
What all this means
In the first case, the difference between late extract addition and total addition at the start is 19 IBU, while in the second it is 20 IBU. If those numbers are correct then this is certainly a big difference in bitterness for a beer of OG 1.043, and would certainly be noticeable in the taste of the beer. So all those brewers who tried late extract addition and said that the bitterness of their beers was way over the top were correct! That verifies the old brewing adage of “always taste it and rely on what your palate tells you.”
You can also see that doing a 3-gallon (11-L) boil gives about 6 to 7 IBU less than you would get for a 5-gallon (19-L) boil, whether you use late extract addition or add it all at the beginning of the boil. Such a difference is marginal and might not be enough to be perceived by all drinkers. So all you “3-galloners” might not be so far off the money as you may have been led to believe!
Finally, this strongly suggests that if you want to do a late extract addition you must adjust the amount of hops you use if you don’t want to overshoot on bitterness. But by how much should you reduce the hop addition? Well, you could just work it out for yourself as I have done using Tinseth’s calculator. Or you could use the numbers I have given above to make an approximation as to how much to add. These show that for a 5-gallon (19-L) boil you would need to reduce the amount to 28/47, or 60% of the original quantity to bring it down to 28 IBU as from early extract addiction, while the corresponding number for a 3-gallon (11-L) boil would be 21/41, or 50% of the original to bring it to the 21 IBU you would get from early addition. However, if you wanted to get 28 IBU in a 3-gallon (11-L) boil with late addition you should only reduce the hops to about 70% of the original amount. Of course, these numbers are just guidelines and should be used with care; they may be very different for different recipes and different original gravities.
Reservations
All the bitterness calculations above assume that Tinseth’s equation is correct, which may not be the case. He himself admits that the constants in his equation are empirically derived; that is they are chosen to make the data fit the equation, and are not absolute. In fact, they may apply only to his brewing procedures, and could be different for somebody else. And, he derived this equation using whole, fresh hop cones, so that quite different results could be obtained if you were using pellets. Finally, Tinseth’s equation only gives IBU for the wort, and we know that IBU levels in the beer will be lower. Losses of iso-alpha acids occur throughout processing, particularly when foam is formed, so that the major loss occurs in fermentation. Always remember it’s the taste not the math that counts.
Conclusions
Late extract addition is a very useful technique for any extract brewer who wants to keep his or her beer as pale as possible. I recommend that you try it, providing that you make the appropriate adjustment to the amount of hops used, or it can cause your beer to be excessively bitter. That may take a bit more thought than you want to put in, but this is life and you get nothing for nothing. And if any of my number handling has confused you, remember to let your palate be your judge!
