All for Joomla All for Webmasters
Tim: (19) 982360493   This email address is being protected from spambots. You need JavaScript enabled to view it.

Controlled process

22 December 2017
(0 votes)
Author :  

Controlled process


Proper control of the various steps to make a quality beer

By Michael Trommer

Physicochemical control

In order to keep the high standard of the beer, physicochemical control is essential. Various items in the beer production must be controlled:

     accurate analysis of primitive extract, apparent extract, alcohol content, degree of fermentation (complete fermentation), pH value, among others;

     determination of diacetyl content, bitterness value, dissolved oxygen, and colloidal stability, via forcing tests and other analyses.

Beer analysis

It is known that the apparent measurement of the beer extract is not correct, because the alcohol present in the product can alter the final result.

In order to obtain the real measurement of the original extract (or primitive extract), the alcohol must be removed via distillation. This evaporated volume is then replaced with water before measuring the extract. This determination can be performed through refraction or distillation.


In this method, the beer color is assessed subjectively by using a spectrophotometer, rather than with the naked eye.

pH level

The pH value influences the stages of enzymatic decomposition in the wort and determines protein solubility and wort color during boil.

Beers with high pH are always beers in which few nitrogen compounds coagulated, were precipitated, and got removed from the medium through wort boil. For that reason, their protein stability is usually reduced. The optimum pH value is 5.2 to 5.6 during mashing and 4.0 to 4.3 in the finished beer.

Determination of oxygen in the beer

It is a great challenge to avoid air/oxygen pickup in the stages of filtration and filling of the finished beer. There are many methods to measure the oxygen.

In efficient filling systems, it is possible to obtain 0.10 mg O2/l. Most beer filling systems have an air pickup value of 0.5 mg O2/l.


medição de oxigênio.png

Determination of diacetyl content in the beer

In most breweries, diacetyl is controlled in the fermentation stage. The cold phase must only be started when the diacetyl content reaches 0.10 mg/kg. The lower the value, the better. Nowadays, this control is performed in a gas chromatograph most of the time.

Determination of foam stability

The most important criterion is foam stability (head retention). The most used method for that analysis is the NIBEM.

Determination of bitterness (IBU)

Determining the bitterness of the beer is an important parameter. It is performed using a spectrophotometer.


Carbon dioxide

The concentration of carbon dioxide content dissolved in the beer is also an important item of quality control:

-        Low fermentation beers: the concentration must be between 0.40 and 0.60%;

-        High fermentation beers: the concentration must be between 0.40 and 1.00%.

Determination of turbidity

Another very important analysis is the determination of turbidity. Certain methods are capable of providing results (about whether or not the beer will become turbid in a short period of time) in only a few days. The most important method is the forcing test, which goes as follows:

  •         start values at 20°C (turbidity must be measured using a turbidimeter);

  •         bottles are stored for 24 to 40 hours (stabilized at 60°C);

  •         cool down to room temperature and store at 0°C for 24 hours;
  •         measure turbidity as above;

  •         repeat hot and cold phase as above until obtaining a turbidity value of 2 EBC (visual opalescence in the beer).

There are alternative methods, but the principle is always the same.

Biological control of the process

It is possible to find foreign microorganisms along the wort and beer path until obtaining the finished beer.

When these microorganisms propagate in the beer, they leave a fine sediment on the bottom, before making the beer cloudy. After that, the metabolic process of the foreign microorganisms affects the taste of the beer, making it unpleasant or undrinkable.

Not all microorganisms that somehow propagate in the wort or beer are harmful. It is possible to determine the health risk level as follows:

1- Microorganism flora that is non-harmful to the beer and humans;

2- Microorganism flora that is potentially harmful to the beer and humans;

3- Microorganism flora that is necessarily harmful to the beer.

A non-harmful flora consists of mold spores and many bacteria and yeasts. They cannot propagate in the beer.

A potentially harmful flora can only propagate in the beer if the latter presents appropriate characteristics for such contamination, such as:

  •         high pH level (above 4.3);
  •         oxygen absorption;
  •         CIP performed in concentrations below what is recommended, e.g. circulation time below the minimum required.

Those bacteria are:

  •         Lactobacillus casei;

  •        Lactobacillus lactis (formerly Streptococcus lactis);

  •         Pectinatus cerevisiiphilus;

  •         Megasphaera cerevisiae;

  •         Enterobacteriaceae.

Some of those bacteria, such as Lactobacillus lactis, produce lactic acid. Pectinatus cerevisiiphilus and Megasphaera cerevisiae develop a strong smell of sewage.

The necessarily harmful flora propagates in oxygen-free beers with a low pH level. Over time, it also propagates in the bottled beer.

This group includes the following bacteria:

  •         Lactobacillus lindneri;

  •        Lactobacillus brevis;


  •         Lactobacillus frigidus;

  •         Pediococcus damnosus and Sarcina (Sarcina bacteria produce diacetyl and butyric acid).

Microbiological control of the process

The role of microbiological control is to collect and analyze previously established points of the process to determine in which of them the wort and the beer are being contaminated.

It is important to take samples only from significant points. A data collection plan must be devised.

With special focus on maintaining sterility, the samples must be collected and then placed on Petri dishes containing nutrients for propagation of the microorganisms. In an incubator, the dishes with the sample material are maintained at 37°C – at this temperature, the contaminant spores propagate and form visible cells colonies. Under a microscope, the type of contaminant can be recognized from the colony formation.

Out of every batch of beer, one sample (transparent bottle) is taken and placed in a stability chamber at 26°C. This sample must not present sediment nor turbidity during the shelf life of this batch.

Microbiological control is of utmost importance in detecting any contamination before it can affect the shelf life of the product.

With these physico-chemical analyses, it is possible to achieve constancy of product quality. In order to provide this quality in all senses, it is ideal to perform microbiological control and standardize the entire process.

Automation is a very strong ally, which, along with standardization, prevents flaws in the process that may affect the finished beer.

In order to ensure constant quality, it is necessary to work using preventive and predictive maintenance.

By applying these points in the brewing process, we can raise a toast to a product with guaranteed quality.


KUNZE, Wolfgang. Technologie Brauer und Mälzer. Berlin, Germany: VLB.

ANGER, H.-M.. Brautechnische Analysenmethoden. Freising, Germany: Self-published by MEBAK.

Michael Trommer

This email address is being protected from spambots. You need JavaScript enabled to view it.

0 Comment 2494 Views
Michael Trommer

Michael Trommer, descendente de pais alemães que vieram para colonização do norte do Paraná e posteriormente migraram para São Paulo.

Com 28 anos de experiência profissional na área de bebidas (cervejas e sucos). Contudo, sua maior atuação foi na indústria cervejeira, onde atuou na área de produção, laboratório, desenvolvimento de produtos maltados e não maltados, padronização de processos (sistema da qualidade) e implantação de manutenção preventiva e preditiva. Presta serviços para empresas de pequeno, médio e grande porte do segmento de bebidas.

Leave your comment

Online Now


Free counters!