Dear Mr. Wizard,

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.

Jonathan Kinzinger
via e-mail

Mr. Wizard replies:

This question brings up three key points:

1. water pH and its affect on brewing
2. methods used to adjust pH and
3. 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!

Dear Mr. Wizard,

I have recently made a steam ale that I fermented in the primary at 55° F with a dry ale yeast. When fermentation was complete, I racked to a secondary and dropped the temperature to 38° F in my refrigerator. I would like to bottle this batch, and I have a few questions.

1. Obviously I have to take the carboy out of the fridge and allow it to warm to room temperature. Will this affect my yeast and cause fermentation to begin with any yeast cells that are still alive?
2. Do I need to add any yeast to this batch as I bottle it?
3. Once bottled, do I mature it in the bottle at room temperature, or do I need to keep it as cold as I fermented it to ensure quality?

David Weber
via e-mail

Mr. Wizard replies:

If this beer was properly fermented, it should have been completely fermented before you chilled it. The most reliable method to know whether a fermentation is done is to compare the specific gravity of your batch to that of a forced fermentation on the same wort. A forced fermentation is basically performed by taking a sample of your wort, overpitching it with yeast, and fermenting it warm. This method gives a good indication of how low the fermentation will go. But this is kind of a pain!

Instead, I usually watch the fermentation bubble, taste it for dryness, and measure the specific gravity over a couple of days. If all seems normal, I cool the batch two days after I’ve decided fermentation is complete. This all relates to your first question. If a fermentation is complete before chilling, it will not re-ignite when warmed. If a fermentation is incomplete and it is chilled, it will stop fermenting. Ales typically quit fermenting around 55° F, and lagers usually poop out around 38° F. If that same batch is now warmed up and it contains living yeast, which it probably does, it will begin to re-ferment. This is not the idea!

When homebrew is primed with priming sugar or wort, the assumption is that all of the carbonation will arise from the primings added, not a combination of primings and a mystery amount of residual fermentables from the "fermented" beer. Although almost all of us are willing to make this assumption, it is prone to failure.

Commercial breweries that consistently bottle condition their beers rely very heavily on forced fermentations, because priming beer with a mystery load of residual fermentables can give rise to explosive results! It is hard to say whether you will need to add yeast to your beer on bottling day. If the beer had a nice strong fermentation and it hasn’t been held at 38° F for more than a few weeks, you probably will be okay without an additional yeast charge. However, if the wort was initially underpitched and fermented weakly, or if you used a very flocculent strain, an additional boost may be needed.

Usually if a sample of the beer looks a little cloudy and you intentionally carry a little yeast from the bottom of the fermenter into the bottling bucket during racking, the beer will carbonate. As for warming the beer, rack it cold, adding the priming sugar, bottling it, and then letting it come to room temperature in the bottle. This method will make your racking from the secondary into the bottling bucket cleaner. Once it’s bottled, hold the beer at about 70° F for one to two weeks to ensure complete fermentation of the priming sugars. Then cool it to refrigeration temperatures for storage.

Some would argue for a cooler conditioning temperature, but there is very little flavor formation during the bottle fermentation. Also, if the yeast is sluggish, you may not get complete carbonation with a 55° F bottle fermentation.

Mr. Wizard, BYO's resident expert, is a leading authority in homebrewing whose identity, like the identity of all superheroes, must be kept confidential.