Cleaning stainless steel tanks and wine barrels

With its many different production steps, viticulture is one of the most complex challenges in agriculture. Each individual step requires different measures in terms of hygiene. Only meticulous cleaning prevents the wines getting contaminated and therefore a reduction in the quality of the end product – this is especially the case around the barrels and tanks in which the wine is stored and matures.

Removing residues from wine barrels and tanks

An important step in viticulture is the fermentation and aging phase. Fermentation and ripening allow the aromas created in the vineyard to come to the fore and give the wines their unique flavour. It is therefore all the more important to prevent germs from disrupting the delicate fermentation and ripening process. This is why it is so important to thoroughly clean wooden wine barrels as well as stainless steel tanks, and where the grapes are stored.

What needs to be cleaned from wine barrels and stainless steel tanks?

Contaminants in viticulture are mostly organic residues, inorganic deposits, salts, carbohydrates, tannins and dyes, or microbial contaminants. In addition to the type, quantity and age of the residues and the nature of the surface that required cleaning, it is really the correct cleaning method that makes all the difference.

To effectively remove grape residues, fermentation foam or wine scale from the tanks, the right cleaning equipment can make a big difference. Climbing into the barrels and tanks is ill-advised and to be avoided.

When is the right time to clean the inside of a wine tank or wooden barrel?

In winemaking, wines must be decanted, filtered and put through other processes several times. Before each bottle filling or before each variety change, the inside of the container needs to be cleaned and prepared for the new contents as quickly as possible. Afterwards it is advisable to check the barrel in case of lingering odours or residues.

To clean a freshly emptied wine barrel, 1 to a maximum of 2 cleaning cycles are usually recommended. With things such as a barrel cleaner in combination with a high-pressure device, cleaning can be completed within a few minutes.

For cleaning, the barrels can be taken out of the cellar into the open air and processed in the yard. Large wine barrels or tanks that are not so easy to transport can be cleaned directly in the cellar with the right tools.

Cleaning oak wine barrels

Special considerations for cleaning the inside of a wooden barrel

Some wines ferment and age in oak barrels, called barriques. In addition to the origin of the wood, the size and age of a barrel affect the style and flavour of the wine.

Some wines also age in larger oak barrels called “tonneau” that hold either 300 or 500 litres. These barrels have thicker wooden walls and can be used for many years. The smaller barriques wear more quickly, but can usually be used 3 to 4 times if they are gently cleaned.

Above all, the organic material of the wooden barrels must be meticulously clean, because wine absorb unwanted things like a leftover residue skin on the wooden surface. Barrel sterility and careful work minimise microorganisms in the finished wine from the outset, so that it does not become undrinkable.

Cleaning wooden wine barrels: manually or mechanically?

Traditionally, barrel brushes are used for cleaning oak barrels. The inner wall is scrubbed by hand either dry or with anhydrous soda. Afterwards, the barrel should be thoroughly rinsed again with hot and cold fresh water before it is filled again.

For more efficient cleaning, a barrel cleaner can be used as an alternative. The spraying device is particularly suitable in combination with a pressure cleanercleaner washing the interior of oak barrels with a volume of between 225 and 600 litres.

The barrel cleaner is connected to the high-pressure device with a hose. Cold or hot water pressure cleaners can be used here.

Among other things, hot water devices are characterised by their sterilising effect and short drying and cleaning times. Especially when it comes to removing stubborn dirt such as tartar build ups, hot water devices make cleaning much easier and faster. The use of cleaning agents is not necessary in this case.

Wine barrel cleaning with a Kärcher pressure cleaner

Advantages of hot water high-pressure cleaners

Cleaning with hot water: High-pressure cleaners clean even better at a constant pressure. Alongside improved results and faster cleaning and drying times, hot water high-pressure cleaners also have a measurable germ-reducing effect. When the steam stage is used, even delicate surfaces can be gently cleaned with temperatures of up to 155 °C. Furthermore, the machines allow for a reduction in the working pressure, the time required and the volume of cleaning agent that is used. This means that cleaning with hot water offers a number of advantages and various possibilities for optimising the cleaning process.

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The head of the barrel cleaner is inserted into the interior of the barrel via the bunghole. The depth of immersion for the cleaning head can be varied depending on the size of the barrel. A rubber cone located on the carrier tube seals the opening. Cleaning is best done with pure water - this is particularly gentle on wood and the environment. Both the cleaning head itself and its nozzles rotate. The high-pressure jet can therefore reach every spot and can clean the wine barrel thoroughly. At the same time, a suction tube mounted at the lower end of the cleaner permanently absorbs the water thanks to the suction function.

If the unit has a suction mode, the last water residues can be completely removed from the bottom of the drum. After cleaning, all that is needed to immediately switch the unit from high-pressure cleaning to suction mode is a handle, and this will make the drum or container ready for use again.

Wine barrel cleaning with high pressure is extremely efficient. Even in with cold water, using a barrel cleaner meets hygiene requirements.

Cleaning a wooden barrel with a barrel cleaner

Tip - don't forget pumps, hoses etc:

Comprehensive hygiene in wine cellars does not only include cleaning wine barrels. Pumps, hoses, equipment, filters and fittings also need to be meticulously cleaned.

Cleaning stainless steel tanks

Many winemakers use stainless steel tanks to ferment and store wine. A major advantage of these over classic wooden barrels is that stainless steel is airtight and watertight, so no oxygen gets into the wine. This means that the wine's inherent flavour is not distorted, as is the case with wooden barrels, for example. Another advantage is that stainless steel tanks are much easier to clean. Tartar is easier to remove from these tanks, for example.

Stainless steel tanks are therefore increasingly used in wineries due to these properties. Due to their size, however, they are often difficult to transport, which is why cleaning them directly in the wine cellar is recommended. In this case, mobile pressure cleaners can be used alone or in combination with internal cleaning heads.

Cleaning stainless steel tank with high pressure cleaners or steam

Effective tank cleaning and removal of stubborn dirt like tartar can be achieved with a pressure cleaner. To get into all corners of smaller tanks or when working in confined spaces, use a short jet pipe.

In contrast to wooden barrels, cleaning agents can be used for cleaning stainless steel tanks. Alkaline cleaners are suitable for dissolving organic residues and the concentration can be adjusted depending on the degree of contamination. Appropriate cleaning agents can be applied, for example, with using a cup foam lance connected to a pressure cleaner. The cleaning foam is so stable that it adheres to surfaces for longer and can therefore act on the surface for a long time. After a good exposure time, the foam is rinsed off again with water.

Step by step:

Pre-rinse: Pre-rinse the container with water.
Cleaning with alkaline agents: Apply cleaning agent (alkaline) and allow it to react with the surface.
Intermediate rinsing: The water can be collected and used for pre-rinsing/pre-soaking other tanks.
Neutralisation: Clean the tank with an acidic detergent to completely remove any alkaline film.
Rinse out: Thoroughly rinse out the tank with clean water.

Cleaning with steam is particularly efficient and hygienic, too. Hot water high-pressure cleaners that have a steam stage or professional steam cleaners are beneficial here. By steaming and then rinsing with cold water, stubborn dirt can be easily removed and germs are killed.

Wine containers will have been successfully cleaned when no rough residues can be seen. Particular attention should be paid to the corners and weld seams – dirt can hide here. A greasy surface usually indicates that lye residues have remained on the surface. It is imperative that these get removed as they affect the taste of the wine.

Clean large stainless steel tanks even more effectively with high pressure cleaners and internal cleaning heads

Tank cleaning with internal cleaning heads

An internal cleaning head is recommended for larger tanks or if there are a large number of tanks to be cleaned. Connected to a high-pressure cleaner, this is inserted into the tank from above. Propelled by the liquid jet it emits, the head rotates so that the jet reaches all corners.

Depending on use and container size, cleaning can be individually adapted. So, for large or particularly dirty containers, a slower rotation speed and a fine spray pattern can be selected. When cleaning smaller or less dirty containers, faster rotation and a coarse spray pattern are used.

In addition to the correct procedure, the cleaning outcome depends on the choice of the right cleaning agent and the right concentration, as well as on the appropriate mechanics, time and temperature.

Cleaning tank or wine barrel externally

High-pressure cleaners are also usually used for cleaning the outside of wine barrels and tanks. Telescopic rod systems can provide support for high tanks. In combination with suitable cleaning agents, this ensures that no contaminants enter the tank or barrel from the outside.

The excess water and cleaning agent residues are drained off via a channel in the floor. The drainage system ensures controlled drainage of the water during barrel and tank cleaning in wine cellars. If this kind of system is not available, the water can be absorbed with the help of a wet and dry vacuum cleaner.

Tip – pay attention to the right work clothes:

When working with cleaning agents, the required personal protective equipment must be worn. In addition to safety goggles and pH resistant footwear, it is also advisable to wear protective gloves.