Wheat Beer's Acidity: What's The Truth?

Wheat beer is a top-fermented beer with a large proportion of wheat relative to malted barley. It is typically light-coloured and has a pH of around 4 to 5, which is slightly more acidic than a typical beer. The acidity in wheat beer is due to the presence of organic acids such as malic acid, lactic acid, acetic acid, citric acid and succinic acid. The pH of the beer can be manipulated by the brewer to achieve the desired taste, with a lower pH resulting in a more acidic beer. The type of water and malt used in the brewing process also affects the acidity of the beer. Wheat beer is known for its refreshing taste and flowery fragrance, and its slight acidity is generally well-received by consumers.

Wheat beer's pH level

Wheat beer is slightly acidic, with a pH level ranging from 4.0 to 5.0. This acidity is derived from organic acids such as malic acid, lactic acid, acetic acid, citric acid, and succinic acid. The pH level of wheat beer can be affected by various factors such as the type of wheat, the saccharification process, and the yeast strain used.

The type of wheat used in brewing can impact the pH level of the beer. For example, a brewer might choose between the full, grainy taste of hard winter red wheat and the light, delicate flavour of a white summer variety. Wheat malt tends to have a slightly lower pH than base malt, contributing to the higher acidity in wheat beer compared to barley malt beer.

The saccharification process, or mash, also plays a role in determining the final acidity of wheat beer. Brewers typically aim for a mash pH between 5.2 and 5.6. A longer mash duration can result in higher acid production, so brewers should avoid keeping the wort above 72°C for an extended period. Additionally, the use of lactic acid to adjust the mash pH can impact the acidity of the beer.

The choice of yeast strain is crucial for wheat beer brewing due to its characteristic flavour metabolism. Different yeast strains can emphasise certain characteristics, such as clove and iso-amyl acetate, and fruity flavours. Finding the optimal fermentation temperature for the chosen yeast strain is essential to achieving the desired flavour profile.

Overall, while wheat beer is slightly more acidic than other beers, with a pH level ranging from 4.0 to 5.0, this acidity is essential for the refreshing and drinkable nature of wheat beer. Brewers can adjust the pH level through various means, including the selection of wheat, controlling the saccharification process, and choosing the right yeast strain.

The role of yeast in wheat beer

Yeast is a vital component in the creation of wheat beer. It is a unicellular fungus that metabolises the sugars in the wort (liquid made from boiling malted grain) and converts them into carbon dioxide, alcohol, and other compounds that give wheat beer its distinct flavour. The yeast species primarily responsible for this process is called Saccharomyces cerevisiae.

There are two main types of brewing yeast: ale yeast and lager yeast. Ale yeast, also known as top-fermenting yeast, is applied to the top of the wort and ferments at higher temperatures. This type of yeast is commonly used in wheat beer production and results in a more flavourful beer. Ale yeast ferments best at temperatures between 50°F and 70°F, and it is responsible for a wide range of beer styles, including witbiers, stouts, ambers, and IPAs.

Bavarian wheat beer yeast, a specific type of ale yeast, is excellent for creating wheat beers with complex notes of spice, clove, vanilla, bubblegum, and banana that complement the cereal notes of the wheat. Brewers must carefully separate this yeast from standard ale and lager yeasts to maintain the distinct flavour profile of wheat beers.

Lager yeast, on the other hand, is bottom-fermenting and works at the bottom of the wort at much lower temperatures. The yeast involved in bottom fermenting is a hybrid of Saccharomyces cerevisiae and Saccharomyces eubayanus, a wild yeast from Patagonia. Lager yeast prefers temperatures between 48°F and 58°F and is responsible for popular beer styles such as Pilsners, lagers, and bocks.

The choice of yeast strain significantly impacts the flavour profile, aroma, and overall character of wheat beer. By selecting the appropriate yeast, brewers can enhance the typical estery aromas and create a highly drinkable wheat beer with a bright and nice body.

How to control wheat beer's sourness

Wheat beer is slightly acidic, with a pH value between 4.0 and 5.0. The sourness of wheat beer is caused by the accumulation of five kinds of acids: malic acid, lactic acid, acetic acid, citric acid, and succinic acid. The sourness of wheat beer can be controlled by addressing the following factors:

Water Composition

The water used for wheat beer brewing should be chosen carefully. Water with high carbonate hardness of calcium and magnesium ions should be avoided, as the reaction of these ions with certain compounds can produce potassium dihydrogen phosphate, which has a stronger sour taste.

Malt Proportion

The type and proportion of malt used can affect the acidity of wheat beer. Wheat malt has a slightly lower pH than base malt, resulting in higher acidity. To control the sourness, brewers can adjust the proportion of wheat malt, especially dark wheat malt, to less than 40% of the total inventory.

Saccharification Process

The saccharification process, which involves resting the protein in malt at 50°C for 10-15 minutes, should not be too long, as longer processes are associated with higher acid production. Brewers should also avoid keeping the finished wort above 72°C for an extended period, as this can lead to a decline in pH value.

Yeast Strain Selection

Choosing an appropriate yeast strain is crucial for wheat beer brewing. A typical yeast strain, such as WA18 from Angel Yeast, can enhance the estery aromas of wheat beer while displaying typical banana and slight spicy aromas. Brewers should also pay attention to controlling yeast activation conditions, aerobic conditions, extract nutrition components, and inoculated factors like temperature.

Sugar and Residual Sugar

Proper sugar control is essential for the full taste and acid control of wheat beer. Residual sugar can neutralize the acidity, contributing to a more harmonious taste.

Microbial Detection and Disinfection

Microbial detection through microscopy is necessary to reduce the introduction of unwanted bacteria, such as Escherichia coli and Lactobacillus, which can lead to abnormal sour tastes. Brewers should pay close attention to disinfection details, even in areas where bacteria may easily breed, such as pipe corners.

The mineral content of brewing water

Water is a key ingredient in beer, making up more than 90% of it. The mineral content of the water used in brewing can have a significant impact on the flavour and mouthfeel of the beer.

The principal ions present in brewing water are calcium, sodium, magnesium, potassium, sulphate, chloride, carbonate, and nitrate. Minor concentrations of iron, copper, and zinc are also found. The presence of these ions can affect the pH of the beer, which in turn influences the flavour. For example, a high concentration of carbonate ions can raise the pH of the beer, resulting in less fermentable wort and a harsher hop flavour. Brewers in different regions have traditionally used the water available to them to produce classic beer styles. For instance, Burton water, which is high in calcium and sulphate, is well-suited for brewing full-flavoured pale ales. On the other hand, Munich water, which is low in sulphates and chloride but contains carbonates, is ideal for producing darker, mellower lagers.

Understanding the water chemistry and adjusting the mineral content are crucial steps in refining brewing skills and creating a consistent, high-quality beer.

The fermentation process

Wheat beer is an alcoholic beverage produced by the brewing and fermentation of starches from cereal grains, most commonly malted barley, although wheat, maize (corn), rice, and oats are also used. The fermentation of the starch sugars in the wort produces ethanol and carbonation in the beer. Wheat beer is usually top-fermented and brewed with a large proportion of wheat, although it often also contains a significant proportion of malted barley.

Milling

Wheat kernels are smaller and denser than barley kernels, so a finer mill setting is required when milling wheat for brewing. However, it is important to ensure that the mill setting is not too fine, as this can cause the mash to become stuck.

Mashing

Mashing is the process of mixing the milled wheat and barley (known as the "grist") with hot water (known as "liquor" in brewing terms) in a mash tun. The mashing process takes around 1 to 2 hours, during which the starches are converted into sugars, resulting in a sweet wort. The temperature and duration of mashing can vary depending on the desired flavour profile of the beer.

Sparging

After mashing, the sweet wort is drained off the grains, and the grains are washed in a process known as "sparging" to collect as much of the fermentable liquid as possible. Sparging can be done at different temperatures, with colder temperatures resulting in a slower production of acids.

Boiling

The sweet wort is then put into a kettle or "copper" and boiled, usually for about an hour. During boiling, hops are added as a source of bitterness, flavour, and aroma. The longer the hops are boiled, the more bitterness they contribute to the beer.

Fermentation

The hopped wort is then cooled and yeast is added to begin the fermentation process. Fermentation can be carried out at different temperatures, with warmer temperatures resulting in more esters and a fruitier flavour profile. The type of yeast used also plays a crucial role in the flavour of the beer, with different strains producing different aromas and flavours.

Secondary Fermentation

After primary fermentation, the beer may undergo a period of secondary fermentation, especially if long storage is required before packaging or if greater clarity is desired.

Packaging

Once fermentation is complete, the beer is packaged into casks, kegs, cans, or bottles. Bottling can be done with or without filtering, and some beers are bottled with added sugar to produce carbonation.

Frequently asked questions