Beer is an alcoholic drink, widely famous since ancient times, which is made from yeast and fermented malt by boiling hops in water to extract raw materials. Beer is mostly (~90%) made up of water but its main component is ethyl alcohol which has a chemical formula of C2H5OH.
Beer in markets is available in several flavors with a variety of alcoholic components which is what makes it a highly popular drink.
The key ingredient behind the flavor of the beer is hops. Although, a high-quality beer does not get its perfection just by adding hops, but also from the right pH value which plays a crucial role in the beer brewing process.
As said by professor Wendland himself, “The final pH of the beer gives you flavor and taste, and if you can keep track of that, this is how you make quality beer”.
So, what is the pH of beer? Is it acidic or alkaline in nature? Beers are found to have a pH of around 4.0 which means that they are acidic in nature. Multiple factors can account for the acidic nature of beers, one of which is the presence of alcohol that gets produced during fermentation. However, some additional salts like calcium sulfate and calcium chloride are added to balance out the acidity of beer to obtain the ideal pH value.
Before diving directly into the details, let us learn what the term ‘pH’ means in a chemical sense.
The pH scale ranges from 0 to 14, where the first half of the range i.e. 0 to 7 represents the acidic nature of a solution while the other half i.e. 7 to 14 represents basic nature.
Generally, beverages have a pH of 7, like water, which represents the neutral nature of the drinks. The brewers are no one but scientists who perfectly analyze and set the pH values, compositions, and temperatures to produce a beer that has the right flavor and taste.
The Concept of pH
A pH scale is a measurement method that is used in chemistry to giving information about the acidic or the basic nature of an aqueous solution.
Any solution having a pH lower than 7 is found to be acidic and with a pH above 7 is basic.
It is easier to understand the concept of pH by taking water as an example and to be specific, pure water.
Water has the chemical formula H2O, which by combining with H+ions forms hydronium ions (H3O+).
Pure water ultimately consists of water molecules along with the OH-and H3O+ions. Mathematically, pH is equal to the negative log of concentration, i.e.,
pH = – log[a]
Where a is the concentration of substance whose pH needs to be calculated.
Now, for pure water; pH = -log[H3O+].
In order to understand this, it is required to learn about Kw, which is the ionization constant of water and has a value of 10^-14.
This Kw is equivalent to the product of hydronium and hydroxide ion concentration, i.e.
Kw = [H3O+] [OH-] = 10^-14
Kw = [H3O+]^2 (This is because for pure water, the [H3O+] = [OH-])
Hence, [H3O+] = 10^-7
Therefore, the pH of pure water comes out to be 7.
The acidity or alkalinity of a solution depends on the amount of hydronium or hydroxide ions present in that solution.
If the solution has more hydronium ions than the hydroxide ions, then the solution will be acidic in nature.
Whereas if the situation is vice versa, then the solution will be basic in nature.
Role of pH in Beer Production
pH plays an important role in brewing high-quality beer. Its value must be kept in check during the several stages of the entire process.
The pH level keeps in check the color of beer, flavor, stability of the foam formed, extract potential, the bitterness of the hop, and the lautering process during the brewing of beer.
Low or high levels of pH affect the storage conditions of beer considerably.
A very high or a very low pH level of beer opens the door to bacterial growth which contaminates the drink. This is why an optimum pH value equivalent to that of a weak acid i.e. ~4.0 is required for a quality beer.
However, a regular check on the pH is needed to be done during every stage of the brewing process to avoid contamination.
pH during various stages of Brewing
As informed earlier, beer is mostly water. Henceforth the brewing process starts by taking water as the primary component.
Malt or any other type of grain is mixed or boiled with water to make what is known as wort. the pH of the wort and that of water is different. This is because the pH drops below 7 (pH of water) upon the infusion of grain and water.
Moving further, pH drops further when the fermentation of beer begins.
Vigorous fermentation is required to be done to reach the optimum pH value. pH continues to drop while the fermentation of beer takes place until the final pH value of the beer is achieved approximately after 24 hours.
This decrease takes place at a relatively slower rate and while this decrease takes place, the color of beer starts lightning itself, eventually reaching decolorization.
The final pH value indicates the stability of the produced beer. This value is quite different from the fermenting wort.
Sour or hazy beer indicates abnormal pH value and the presence of an unwanted alkaline substance in the beer.
Below is the flow chart of the process of brewing.
What Makes Beer Acidic?
As we have learned so far, beer production involves rigorous fermentation.
During this process, brewers add certain fermenting agents aside from yeast, like acid-producing bacteria especially while making sour beers.
Yeast produces carbon dioxide and alcohol (ethyl alcohol in most kinds of beer) as it absorbs the sugar present in the wort.
Upon fermentation, ethanol, after going through multiple chemical reactions, release several organic compounds like; acetic acid, lactic acid, succinic acid, and many more, which are responsible for the acidity of the beer.
Although, this alone is not the sole cause behind the acidic nature of the beer.
The carbonation of beer (presence of carbon dioxide in beer) is a major contributor in lowering the pH value down to the acidic range of the pH scale.
I also wrote the article on the acidity of alcohol. Check out the article on the pH of alcohol.
In terms of food products and food items, acidity is defined on the basis of a distinguishable sour taste.
Similarly, the tangy-sour taste of beer is an indication of its acidic nature.
Different kinds of beer and their pH
It has been found out that the total acid content in beer ranges from 220 to 500 parts per million.
Beer types vary depending on their acid contents which alter the pH value in each kind. For example, light beer has a very low acid content nearly equal to 0.07%.
Amongst the beer brewed with malted and unmalted grains, the former has a higher acid content, equivalent to ~0.2% whereas the latter has a lower acid content of ~0.1%.
Least Acidic Beer
The least acidic beers are the ones with a comparatively higher pH and a darker color tone. One such beer is the Barley Malt Lager Beer which is found to have a pH in the range of 4.0 – 5.0 respectively.
Whereas, ales are more likely to have pH ranging between 3.0 and 6.0.
Highly acidic beers, also known as sour beers can have a pH as low as 3.30.
Watch out for the below video regarding checking beer acidity.
Different kinds of beer have different pH values which are what make them distinct in taste from each other. Although all these pH values lie in the acidic range of pH scale, making beer an acidic drink. The optimal pH of a ‘refined’ beer finishes at 4.4 that has good beer clarity and better biological stability.
Therefore, the beer brewing process requires a brewer who has good skills in keeping an eye on the pH values during the whole process along with natural brewing skills.
It takes a deep understanding of a drop of physics, a spoonful of biology, and a pool of chemistry to brew the perfect beer.