Hop Utilization
TroubleShooting
Jonathan Kinzinger asks,
I am under the impression that for the most efficient hop utilization, the water used should be about 5.3 pH. Is this true? If so, how do I adjust my pH? I generally use malt extract and add it to regular tap water. I just don’t feel my beer is bitter enough.
This question brings up three key points:
- water pH and its affect on brewing
- methods used to adjust pH and
- adjusting bitterness.
The first point regarding water pH pops up every so often, and I usually let it pass. It is important to distinguish among water pH, mash pH, and wort pH.
Water pH is absolutely meaningless to brewing, period. Mash pH and wort pH are what count. Water with a very high pH can give a mash with a normal pH (5.2 to 5.4) if the water has the right stuff, namely calcium, to react with the phosphates and proteins of malt to bring the mash pH into range.
The key point to remember about water pH is that natural waters are buffered to varying degrees. The buffering power of water resists pH change. High-pH water with a high buffering capacity might cause brewing problems, whereas water with the same pH that has a very low buffering capacity may work just fine.
Since you’re brewing with extracts, mash pH is not an issue. If you were mashing, then you would want your mash pH to be about 5.2 to 5.4. Mash pH can be adjusted down by adding calcium sulfate (gypsum), calcium chloride, or organic acids such as lactic acid or phosphoric acid to the brewing water. Calcium reacts with phosphates and proteins in malt to reduce mash pH, and the acids reduce the pH because they are acids.
Incidentally, calcium does not reduce the pH of water, and it is really frustrating to try to adjust water pH with gypsum — the water gets milky white but the pH doesn’t change!
Mash pH can be raised by adding calcium carbonate or sodium bicarbonate. These salts are typically only used for brewing dark beers. Mash pH is important because malt enzymes and wort/beer flavor are affected. This strays from the questions a bit, but mash pH is really important because it tolerates very little variation, even in hypothetical terms.
Wort pH can be adjusted to give some different effects to beer. Wort pH influences hop utilization, hop flavor, wort color development, beer flavor, and the susceptibility of wort spoilage by microorganisms. Hop utilization is actually favored by high pH conditions (around pH 8) that simply are not found in a normal brew kettle.
Pre-isomerized hop extracts are made by extracting the alpha acids from the other components in hops and heating them in an alkaline (high pH) environment to isomerize them. Pre-isomerized hop pellets (also known as stabilized pellets) are made by adding magnesium hydroxide, a strong base, to the hops during the pelletizing process and then heating the pellets.
To directly answer one of your questions, pH 5.3 is not the optimal pH for hop utilization. However, don’t adjust your wort pH to 8 hoping to optimize hop utilization.
Hops contain more than alpha acids. Some of the other components, such as tannins, are astringent. If you have a high-pH wort and add hops to the boil as you normally would, the resulting beer is likely to taste very harsh. This is because these undesirable flavor compounds are more soluble in high pH conditions. The higher-pH wort boil would also lead to significant wort darkening due to the Maillard reaction (browning).
Many brewers actually reduce wort pH during boiling to give a “smoother” bitterness at the sacrifice of hop utilization. In the scheme of a pint of beer, hops are cheap. The typical pint of homebrew may contain 15 cents worth of hops. If you don’t like the bitterness level in your beer, add more hops at the beginning of the boil. Tweaking wort pH to optimize hop utilization will most likely lead to one huge disappointment. Happy hopping!