Fermentation Tanks: Pollution Or Sustainable Solution?

Fermentation tanks are an essential component of the brewing process, providing an environment for yeast to convert sugar into alcohol. While they are crucial for fermentation, there are concerns about the potential pollution caused by these tanks during the fermentation process. This includes the risk of contamination from oxygen, wild yeasts, and bacteria, as well as the management of pollutant emissions, resource consumption, and energy consumption. Proper maintenance and precautions, such as sanitization, sterilization, and controlled tank pressure, are implemented to prevent pollution and ensure the purity and quality of the final product. The choice of tank material, such as stainless steel or concrete, also plays a role in minimizing environmental impact.

Do Fermentation Tanks Cause Pollution?

Fermenter sanitation and sterilization

Fermentation tanks are critical to ensuring the purity and quality of fermented products. To prevent pollution and contamination, tanks should be thoroughly cleaned and sanitized before and after use.

Sanitation involves cleaning the fermenter to remove debris, dirt, grime, and germs from the surface. Sanitization can be done in several ways, including:

• Using a soft brush to rinse the fermenter, avoiding scratching with a hard tool.
• Boiling water: filling a large pot with water and boiling all glass and metal implements for 5 minutes. For plastic or wooden items, avoid using boiling water and opt for sanitizers instead.
• Commercial sanitizers: filling the sink with a sanitizer mix and leaving it there while working in the kitchen. This is useful for sanitizing any equipment that may accidentally come into contact with the sink.
• Bleach: diluting 1 tablespoon of regular-strength bleach with no distinctive odour in 10 litres of cold water. Soak the equipment for 5 minutes, then rinse thoroughly with hot water at least 3 times and allow to air dry.

It is important to note that sanitation does not replace cleaning. Cleaning is essential before starting any fermentation process to minimize the risk of contamination and ensure the quality of the final product.

Additional Precautions

• Avoid using cleaners that leave a film on the surface of the fermenter, as it may interfere with the fermentation process or contaminate the brew.
• Be cautious with bleach: although it is a popular option, it can be dangerous to handle and requires thorough rinsing to avoid contamination.
• Always follow the instructions on sanitization products carefully and handle the fermenter correctly to avoid re-contamination.
• Ensure electrical equipment in the fermentation tank does not come into direct contact with water and steam to avoid moisture.
• During the cooling process, do not generate negative pressure in the fermentation tank to avoid pollution and potential damage to the equipment.
• Keep the pressure in the air pipeline higher than the tank pressure to prevent the liquid from flowing back into the filter.

Sterilization

Sterilization is the process of killing 100% of microorganisms and spores. While it is not necessary for all types of fermentation, it is a crucial step in the brewing process to ensure the success of the brew. Sterilization methods include:

• Steam sterilization.
• Hot water flushing.
• Chemical sterilization.

Airtight design and oxygen contact

The design of fermentation tanks plays a critical role in preventing pollution and ensuring the purity and quality of the final product. One key aspect is maintaining an airtight environment and minimising oxygen contact during the fermentation process.

Fermentation tanks are designed to be airtight and closed, creating a controlled and sterile environment. This design feature serves multiple purposes, including minimising the risk of airborne contaminants and preventing oxidation. By sealing the tank, the introduction of unwanted microorganisms, such as wild yeasts and bacteria, from the surrounding environment is reduced, preventing contamination. This is especially important in the brewing industry, where contaminants can alter the taste, fermentation, and stability of the final product.

To further enhance the airtight design, many fermenters are equipped with specialised air filtration systems. These systems filter incoming air, removing particles and microbes that could act as contaminants. This ensures that the air entering the tank is clean and sterile, reducing the risk of pollution during fermentation.

The airtight design of fermentation tanks also helps maintain the desired pressure levels during the fermentation process. It is crucial to maintain the tank pressure within a specific range, typically between 0.03 and 0.17 MPa, to avoid pollution and equipment damage. Additionally, during the cooling process, it is essential to avoid generating negative pressure in the tank, as this can lead to pollution and equipment damage.

The material used for fermentation tanks, such as stainless steel, also contributes to their airtight design and oxygen barrier properties. Stainless steel tanks are long-lasting and chemically stable, providing excellent corrosion resistance during the fermentation process. They can withstand the corrosive effects of acidic substances, alcohol, and other chemical reactions, resulting in a longer service life compared to other materials.

In summary, the airtight design and oxygen contact management in fermentation tanks are crucial for preventing pollution, ensuring product purity, and maintaining the desired pressure levels. By employing airtight seals, specialised air filtration systems, and materials like stainless steel, the risk of contamination and equipment damage is significantly reduced, resulting in a more controlled and efficient fermentation process.

Fermentation tank materials

Fermentation tanks are typically made from stainless steel, which is known for its durability, corrosion resistance, and excellent mechanical strength. Stainless steel tanks are designed to be airtight and closed, minimising the risk of airborne contaminants and providing an ideal environment for the fermentation process. They are widely used for brewing beer, wine, cider, vinegar, and other fermented drinks.

Stainless steel fermentation tanks offer precise temperature control, which is crucial for maintaining the desired yeast activity during the brewing process. They are often equipped with cooling systems such as jacket cooling or cooling coils to manage fermentation heat. The tanks can also be insulated with PUR foam or insulating wool to minimise heat loss and improve energy efficiency.

Another important feature of stainless steel tanks is their ability to withstand pressure. During the fermentation process, it is crucial to maintain the tank pressure within a specific range to avoid pollution and equipment damage. Stainless steel tanks are designed to handle overpressure and are equipped with relief valves for safety.

To maintain sanitary conditions, fermentation tanks should undergo thorough sanitisation procedures before each use. This includes cleaning the tank with soft brushes and rinsing it with steam sterilisation or hot water flushing to reduce potential contamination. Regular maintenance, such as checking the supporting surface of the tank and ensuring proper drainage, is also important to keep the tank in optimal condition.

Overall, the choice of stainless steel as the primary material for fermentation tanks plays a crucial role in ensuring the purity, quality, and stability of the final product, while also providing durability and ease of maintenance.

Tank pressure and temperature control

Fermentation tanks are designed to be airtight and closed, reducing the risk of airborne contaminants. They are critical to ensuring the purity and quality of fermented products. To maintain this purity, the tanks must be regularly cleaned and sanitised to prevent microbial contamination. This includes using approved cleaning agents and sanitizers, as well as adhering to proper procedures and industry regulations and guidelines.

Maintaining precise temperature control is crucial during fermentation. The temperature has a significant impact on yeast activity and the overall fermentation effect. Commercial fermentation tanks are often integrated with temperature sensors and heating/cooling mechanisms to ensure optimal fermentation conditions. This allows for precise control over the fermentation environment, promoting the growth and activity of the desired microorganisms.

Most stainless steel fermentation tanks are designed with a temperature control system that can maintain the temperature of the fermentation liquid within the ideal range of 18-22°C. This precise temperature control capability ensures that yeast activity is not affected by temperatures that are too high or too low, which could result in undesirable flavours or unstable alcohol content.

In addition to temperature control, it is important to monitor and control the pressure within the fermentation tank. Certain fermentation processes require specific pressure conditions, and the tank should be able to adjust internal pressure accordingly. Pressure relief valves and pressure monitoring systems are essential to prevent any unwanted pressure build-up that could compromise the fermentation process or the integrity of the tank. During the fermentation process, it is recommended that the tank pressure be maintained between 0.03 and 0.05MPa to avoid pollution.

Overall, the controlled environment within fermentation tanks, including optimised temperature and pressure parameters, leads to increased productivity, reduced batch-to-batch variations, and improved overall efficiency in the fermentation process.

Contamination and pollutants

Fermentation tanks are designed to prevent contamination and pollution. They are airtight and closed, reducing the risk of airborne contaminants and the introduction of unwanted microorganisms. Many are also equipped with specialised air filtration systems that remove particles and microbes that may act as contaminants.

Before the fermentation process, fermenters undergo a thorough sanitation procedure, including steam sterilisation, hot water flushing, or chemical sterilisation, to reduce potential contamination. During the process, parameters such as temperature, pH, and microbial activity are monitored to ensure they remain within desired ranges and to prevent deviations that could lead to contamination.

In the wine industry, the selection of fermentation tanks depends on various factors, including production volume, price, installation costs, maintenance costs, and monitorability. Environmental protection trends are also driving the industry to be more responsible for managing pollutant emissions, resource consumption, and energy consumption. For example, the OIV (International Organisation of Vine and Wine) helps winemakers produce an inventory to simplify production costs and increase transparency in calculating greenhouse gas emissions.

Stainless steel fermentation tanks are commonly used in the wine and beer industries due to their durability, manageability, and ability to monitor internal and external conditions. They are chemically stable and do not react significantly when in contact with wine, preserving flavour and aroma properties. Stainless steel is also corrosion-resistant, withstanding the acidic environment, alcohol, and other chemical reactions during fermentation without rusting or sustaining damage. This makes them more environmentally friendly than other materials, as they reduce waste generation and resource waste.

To avoid pollution during the fermentation process, it is crucial to maintain the correct tank pressure, usually between 0.03 and 0.05MPa. Additionally, the inlet steam pressure should not exceed the working pressure range of the equipment to prevent damage to the fermentation tank. Proper drainage of remaining water in the jacket of the tank is also essential to avoid equipment damage and the formation of pollution.

Frequently asked questions