Why is your wheat beer prone to sourness?

I think the reasons for the abnormally sour taste of beer can be divided into two categories:

• One is abiotic acidity: that is, the acidity produced by non-biological fermentation, such as the acidity produced by water quality, water quality regulator, and malt;

• One is biological sourness: that is, it is infected with acid-producing bacteria such as lactic acid bacteria or acetic acid bacteria.

Let’s analyze the reasons in detail and what precautions should be taken during the brewing process:

Abiotic acidity

• Water quality

When brewing beer, water with different hardness and ion content should be selected according to the characteristics of beer. If making wheat wine, the calcium and magnesium ions of non-carbonate hardness in the water should not be too high, because calcium sulfate, magnesium sulfate and dipotassium hydrogen phosphate react to generate acidic potassium dihydrogen phosphate, which makes the mash and wort. Acidity increases.

A simple way to distinguish carbonate hardness and non-carbonate hardness: carbonate hardness is the hardness formed by dissolving calcium and magnesium bicarbonate in water; boil the water, if there is a lot of scale, it means bicarbonate hardness higher. On the contrary, the non-carbonated hardness may be higher.

In addition, pure water is not recommended for brewing wheat beer because the pH of pure water is low.

Water quality has a great influence on the flavor of beer, so it is recommended that you find a professional organization to test and analyze the water quality before brewing, so as to formulate the corresponding saccharification process.

• Water quality adjustment

When adjusting water for saccharification, the amount of calcium sulfate or magnesium chloride added should be determined according to the water quality indicators. If it is used wrongly or in excess, it will increase the acidity of the wort.

• Malt

The acidity of malt is generally expressed by PH value. The pH value of basic malt (such as light Australian wheat) is generally around 5.9; wheat malt is relatively low in pH and high in acidity compared with light Australian wheat. Therefore, wheat beer has a slightly sour taste compared to pilsner pale beer.

If the selected malt has a higher acidity, it is self-evident that it will affect the taste of the beer. Therefore, when buying malt, it is important to clarify the requirements of the indicators, what kind of wine to make, and what kind of malt to choose.

Biological acidity

If the beer brewing system is contaminated with miscellaneous bacteria such as lactic acid bacteria or acetic acid bacteria, it is difficult to completely remove it, just like the new coronary pneumonia virus, you do not know where it hides. Therefore, every time the beer brewing is cleaned and disinfected, don’t have the fluke mentality of “I will kill it completely next time”. Here is an analysis of the links that are more likely to contaminate miscellaneous bacteria such as lactic acid bacteria:

• Cooling of mashed wort sheet and subsequent pipeline

After each thin plate is used, if it cannot be thoroughly cleaned and disinfected, the cooled wort residue is a good medium for miscellaneous bacteria such as lactic acid bacteria because it contains rich nutrients. When necessary, the thin plate needs to be disassembled for cleaning and descaling.

• Passaging yeast

The hygienic condition of the yeast determines whether it can be passaged. Before the cold wort is connected to the yeast, a microscopic examination should be done to check the hygiene of the yeast. If there are bacteria such as bacilli in the above picture, do not pass it.

• Filling

Beer filling has the highest hygienic requirements in the brewing process. It belongs to the clean operation area. Pay attention to the sterilization and disinfection of space, containers and contact surfaces. What is easy to ignore is the packaging container used, such as cans, which many people think have no nutrient medium and no bacteria to grow. In fact, after the microbial smear test, if it is stored in a bad environment for a long time, it will also bring pollution, especially when making fresh beer, you need to pay attention.

• Operators

According to the long-term production experience and the results of sanitation testing, personnel are one of the main ways to cause the pollution of lactic acid bacteria. Especially after April every year, when the weather gets warmer, if operators do not wash their hands and disinfect regularly (normally no less than once an hour, and wash hands and disinfect at any time when they touch other unclean surfaces), a large number of lactic acid bacteria will grow and be brought into beer, especially It is the direct harm caused by the manual operation of the brewery.

There are many reasons for beer acid, which need to be systematically analyzed from the aspects of man, machine, material, method, environment and measurement, and comprehensive prevention and control should be adopted.

The quality of beer, “three points of craftsmanship, seven points of hygiene”, when the hygiene is done, the taste is pure. As winemakers, we want to practice good hygiene.