While experienced brewers can tell when something wrong without the need for pH meters and thermometers, we mere-mortals need a little help.
That help comes in the form of pH meters. They are important tools for making sure that the balance between acidity and alkaline in the fermentation process is correct.
A pH meter is necessary regardless of what you brew, whether it is beer, wine, or distilling. To make things a little easier, digital pH meters are a popular tool that allow you to measure the pH with greater accuracy.
However, pH meters need to be calibrated properly before they are used, to obtain an accurate result.
To keep your digital meter from degrading, it must be properly stored.
How Do You Calibrate and Use a pH Meter for Brewing?
Any pH meters you buy will have already been calibrated.
However, they lose accuracy when transported as well as over time. Generally, a calibration buffer solution will be supplied with the pH meter.
The buffer solution has a specific pH which you can use to test the meter and then calibrate the pH scale. There is usually a little screw on the pH meter which you must turn to correctly set the pH level. You may need to move the scale to make it more acidic, or more alkali.
Digital pH meters have a calibration button that you press when the probe is submerged in the buffer solution. Once it has had a moment to stabilize, you press the calibration button again and the meter will self-adjust to bring its reading in line with the buffer solution pH.
There are usually two buffer solutions, a 7 pH and 4 pH to which the pH meter will set itself. In more sophisticated laboratory models, a 10 pH buffer solution may also be used.
What is pH and How Does it Affect Fermentation?
PH levels affect the shape of proteins. During fermentation, a collection of enzymes produced by the yeast is responsible for the many metabolic processes that occur.
An enzyme is a protein that performs the metabolic process. As an example, sucrase is an enzyme that breaks sucrose down into fructose and glucose. This means that they act as organic catalysts.
Proteins are made of amino acids strung together in a long line, based on DNA. The amino acids bond into a long polymer. From there, cross-linking occurs between the R groups in amino acids. This is what makes the shape of the protein unique.
Due to cross-linking, the proteins turn into a 3D shape.
Some amino and basic amino acids are acidic. This is because of the R group in amino acids. If the pH increases, the shape of proteins will be affected, by disrupting bonds on the protein.
As fermentation progresses, we observe that the rate increases when it is more acidic, i.e., the pH is lower. This is due to the yeast-producing enzymes that ferment glucose having adapted to the acidic conditions.
The end result is that the correct pH range will allow the fermentation to proceed at the correct rate and will inhibit microbial action that damages the end product. It will also help good microbial action that improves the final alcoholic beverage.
How Do You Measure the pH?
When measuring any alcoholic process, it is important to draw samples daily, especially if you are new to brewing.
These samples should be drawn from a tap in the middle of the fermentation vessel. This is done to ensure that fermentation is not disturbed. More importantly, this is done to prevent oxygen from entering the fermentation vessel, as it will reactivate a respiratory phase.
There are many ways to measure your pH level.
The simplest way is as follows:
Measure the pH level by using either a digital pH meter or pH strips. The first indicator to look for is a drop in the pH level over the first couple of days.
This indicates that the fermentation is starting correctly.
You will notice warning signs with these measurements as well.
If you find that the pH level continues to drop, you can adjust the pH upwards to avoid a failed or stalled fermentation.
The pH for fruit fermentation should be kept between a maximum of 3.0 and a minimum of 5 (ideally between 3.5 and 4.5).
When using grain mashes, keep the pH between 5 and 7 (ideally between 5.5 and 6.5).
The pH requirements can be confirmed based on the technical specifications of the yeast strain chosen.
The temperature tolerances are also indicated per yeast type. These are normally between 22 and 28 degrees for distillation yeasts.
What is the Ideal pH for Fermentation?
As we have established, the pH scale is a measurement of the total acidity or alkalinity of a substance.
The scale measures from 0 to 14.0, with 7.0 being neutral.
Any substance that has a pH of less than 7.0 is considered acidic. Any substance that has a pH of more than 7.0 is considered alkaline, or basic.
Yeast cells in fermentation can tolerate a pH of 4.0 to 8.5 but will work best when the pH is between 4.0 and 6.0. This means that the yeast cells require a slightly acidic environment to do their best fermenting.
Additionally, the pH factor of the fermentation solution will determine the process of sugar reaction to bioethanol. When there is a fermentation solution that is very acidic or very alkaline, it can inhibit the fermentation process.
This reduces the amount of bioethanol produced.
For most brewers, the ideal pH level for alcohol is between 5.0 and 5.5.
|Sour Beer||Between 3.0 and 3.5|
|Cider||Between 2.9 and 3.3|
|Wine||Between 2.9 and 4.2|
|Whiskey Wash||Between 3.68 and 4.78|
|Vodka Wash||Between 6.0 and 7.0|
These pH levels are ideal because the yeast is happiest in this range.
The yeast converts as much of the sugar to ethanol as it can. Generally, it is ideal for most fermentation, purely based on the requirements the yeast needs to thrive.
What Happens if the pH is Too High or Too Low?
With either one, you are going to have fermentation that does not have a good conversion of sugar to alcohol.
If it is too high, you may expose your fermentation to a bacterial infection, most prevalent with wine.
If it is too low, however, there is a high chance of your fermentation stalling or lagging completely to zero activity.
How Do You Adjust the pH?
Before you can adjust your pH level, you need to first determine the pH level you have and then, the target level you wish to achieve. Once you have done this, you can add either an acidic or alkaline substance to the liquid.
The ideal chemical to use for adjusting your pH level is Potassium Carbonate. The main reason for this, aside from the fact that the Potassium itself is very beneficial to the yeast, is that Potassium Carbonate will dissolve and react almost immediately with little to no fallback.
There are, however, other carbonates that are equally as effective and beneficial. These will normally have some time lag between addition and effect. This means that it is easy to “overdose” the fermentation and end up with a pH that is either too high or too low.
If this happens, you can bring down the pH by using Citric Acid, which is preferred due to it being relatively safe as well as being a natural acid. Just like Potassium Carbonate, it reacts immediately with little or no fallback.
What is the Best Way to Make the pH Lower and Higher?
You may be wondering how to adjust the pH, whether lower or higher.
The best option to increase your pH level is to use Calcium Carbonate. To decrease your pH level, use Calcium Chloride or Calcium Sulfate.
These products will do the job correctly without affecting the flavor.
If these are not available, or if you happen to be brewing with very soft water, the addition of phosphoric acid can accomplish acidification of the mash.