The life of a brewer isn’t a particularly glamorous one. Half the time you’re huffing, puffing, and sweating as you lug heavy materials around in a hot, steamy, environment, and the rest of the time is almost all spent cleaning. Cleaning is an amazingly important part of brewing, and to neglect it results in poor beer and broken equipment.
In this brief guide we’ll talk about the standard cleaning chemicals and processes a typical brewery will use.
Cleaning Substances for the Brewery
For most brewery equipment you need to rinse the heaviest dirt away, wash the remaining organic matter, rinse again, then sanitize. Here’s what you need.
Caustic soda (sodium hydroxide) is an aggressive alkaline cleaner that dissolves organic matter, making it ideal for cleaning brewhouse vessels, fermenters, and the plate heat exchanger. It dissolves easily in water, and formulated versions can be used hot or cold. It can cause severe chemical burns and must be handled with care.
The cheapest type is the raw, dry flakes, however this isn’t ideal for brewing as it’s quite rough, and can damage components and gaskets. Aside from that, it’s difficult to work with, and the dust can damage the respiratory system if breathed in, as well as eyes and skin. In brewing, it’s most commonly used in a formulated liquid form, with various additives added to improve cleaning, reduce foaming, and protect various materials.
It’s best used hot (up to 80℃) for hot side equipment, typically at a concentration of around 1% caustic to water, though for badly soiled equipment you can increase this to around 1.5%. For fermenters it can be used at colder temperatures, but is generally more effective when used hot or at least warm. It’s worth noting that caustic soda is neutralized by carbon dioxide (CO2), so be sure to fully vent and rinse your fermenters before proceeding with the caustic wash for best results.
When cleaning with caustic, it’s good to recirculate it through vessels via the spray ball to ensure complete cleaning of the interior. A weaker solution (around 0.3 – 1%) can also be left in pipes and in the heat exchange to soak, breaking down stubborn matter. To clean the heat exchanger, it should be recirculated (preferably in the opposite direction to the flow of beer), using a filter to catch any solids. For best results, recirculate in vessels, pipelines, heat exchange, etc. for 30 to 60 minutes.
Peracetic acid is a strong disinfectant and sanitizer that is frequently used by breweries to sanitize their equipment. In higher concentrations (up to 1% acid to water), it can be used to kill off stubborn bacterial and fungal infections. However, it’s typically used as a non-rinse sanitizer, at concentrations of around 0.1% acid to cold water. For best results, recirculate for around 30 minutes.
It’s a dangerous acid to work with, and care should be taken to avoid spilling it on the skin and eyes, as severe chemical burns can occur. It has a strong smell of vinegar, but don’t be tempted to give it a sniff, as it’s likely to knock you out!
Peracetic acid breaks down into acetic acid (vinegar) and oxygen. As such, it’s not an ideal choice for bottle washing or other post fermentation applications, as it can introduce oxygen into your finished beer.
Safe, no-rinse sanitizer is useful to have around the brewery and has several applications. The most well-known example is Star San, although Chemipro San is more or less the same. Made from food-grade phosphoric acid mixed with various agents common in detergents and cosmetic, it sanitizes surfaces and equipment.
It can be used for sanitizing bottles and packaging equipment, as unlike peracetic acid, it won’t break down into oxygen. Otherwise, it’s good to have a spray bottle which can be used for sanitizing gaskets and equipment prior to use.
This acid mix can be used to passivate stainless steel vessels, but is most commonly used to remove beer stone and other build-ups of mineral deposits. It doesn’t have to be used frequently, perhaps once or twice a year, and must be rinsed thoroughly.
On brewhouse vessels, use around a 1% mix of acid to water, between 60-70℃ to remove beer stone deposits. Recirculate for around 15 minutes. It can also be run through the pipework and heat exchanger.
For passivating fermenting vessels and other stainless steel vessels, use a 0.5% – 1.5% mix at room temperature and recirculate for around 15 – 20 minutes. Rinse thoroughly.
Brewery Cleaning Processes
Most modern brewery equipment uses ‘clean in place’ (CIP) systems to ensure a thorough wash across all surfaces. This means that cleaning solutions are pumped into a vessel via a spray ball, which sprays the interior in its entirety.
You can use a dedicated CIP station to do this, which consists of 2 or 3 vessels, each to hold a different solution. The CIP station is fitted with a pump, and the correct cleaning solution is pumped from the CIP into the vessel. From there, a hose at the exhaust valve of the vessel returns to the pump, allowing the cleaning solution to be recirculated via the spray ball.
Alternatively, mix your cleaning solution directly in the vessel and use a separate cleaning pump. In both cases, it’s important that the cleaning station is mobile (on wheels), to reduce hose lengths and increase cleaning pressure. When using CIP systems, high pressure is desirable, as this will ensure the cleaning solution is sprayed hard enough to reach every part of the vessel.
Cleaning the brewhouse
Ideally the brewhouse should be cleaned after use, but this isn’t always possible on the same day. However, once brewing is complete, it’s essential that the entire brewhouse system is at least rinsed.
- Rinse all organic matter washed away with a hose or pressure washer
- Spray hot water into the vessel to loosen any dirt, then spray again with hose or pressure washer
- Run hot water through all the pipework to remove any trace of wort, grain, etc.
- Run hot water through the heat exchanger to dislodge any solids. If possible, run hot water backwards through the heat exchanger for best results.
The next step is to give the vessels a quick caustic wash. This will remove the more stubborn dirt. Recirculate a hot caustic wash (up to 80℃) through any dirty vessels, giving each one at least 30 minutes. If the vessels have been well rinsed and there’s not too much organic matter to begin with, you can reuse the same cleaning solution on each vessel.
Run the caustic cleaning solution through the pipes and let it soak for around 30 minutes. Rinse everything well.
Cleaning the heat exchanger
This is one of the most important tasks, as it is here that the wort loses the protection of heat, and becomes susceptible to infection. After a hot rinse, recirculate a hot caustic wash through the heat exchanger, using a filter to catch the worst of the debris.
Recirculate for at least 30 minutes, and then let soak for another 30 before rinsing thoroughly. For best results, backwash the heat exchange, making sure to rinse out both ways.
Before the next use, some brewers run a sanitizing acid solution through the heat exchange to kill off any potential threats, and let it soak until ready to use. Alternatively, run boiling (or higher than 75℃) water or even wort through the heat exchanger to sterilize it with heat.
Cleaning fermenting vessels and conditioning tanks
Fermenting vessels and conditioning tanks should be cleaned out after being emptied. The sooner you do this, the easier they are to clean, as dried foam and yeast can stick to the edges.
To empty the vessel, you should first start depressurizing it by opening the spray ball valve. Be sure to turn on any extractors or open the doors and windows to vent the CO2 – and if you start to feel dizzy, head outside for some fresh air immediately.
Next, hook a hose to the exhaust valve, and open it slowly. Sometimes, especially after high dry-hop doses, the valve can become clogged. Pump hot water back into the valve to dislodge the blockage. Empty the yeast, trub, and whatever’s left of the beer into the drain if allowed. Once it’s empty, open up all the valves and the manhole and allow it to vent.
First of all, give the vessel a good rinse with hot water via the spray ball – this should dislodge the worst of the dirt. Next, open up the manhole and valves, and take a look inside – be careful not to breathe in the CO2. Use a hose to rinse off any stubborn parts, but don’t spend too much time doing so. Leave the valves and manhole open and vent for at least an hour before the caustic wash. This releases the CO2 from the vessel, which would otherwise neutralize the caustic soda, or in severe situations, cause a vacuum failure and implode your vessel.
Close the manhole and all valves, and hook the vessel up to your CIP station or cleaning pump. Fill with a caustic soda/warm water solution at 1%, and recirculate for at least 30 minutes. In most cases, this is enough to clean the worst organic matter off.
Empty the caustic, and rinse thoroughly with hot water. You can use a pH metre to check that the caustic has been completely rinsed away. Never rinse out a hot caustic wash with a cold rinse – this can cause a vacuum failure and lead to tank implosion! In most cases, a vacuum safety valve should stop this from happening, but prevention is the best cure.
After a good hot rinse, carefully remove all the valves, racking arms, carbonation stones (wear gloves when handling the carbonation stone, as the oils from your skin can block the pores), etc. from the vessel. Check the openings and scrub or rinse out any dirt that remains. Often, deposits of yeast can build up in these areas, and will need to be cleaned by hand. Wash all of the pieces (including clamps and gaskets) by hand and let soak in hot water. Rinse off and reattach everything, ready for an acid wash.
Allow the vessel to cool down fully before giving it a rinse with acid. Normally, you should only do the acid rinse on the same day that you’ll fill the tank. This offers the best protection. Simply hook the vessel up to your cleaning station and recirculate a mix of peracetic acid and water (0.1% acid to water) for around 30 minutes. At this concentration, you won’t need to rinse the tank out after emptying it.
Cleaning new equipment
Before using your new equipment you’ll need to give it a good clean. First of all, carry out a visual inspection of the interior surfaces, taking note of oil stains, dust, and welding debris. Most new equipment is passivated and pickled prior to shipping, so it should be in good condition – but be sure to verify this with your supplier in advance.
New equipment will normally just need a good hot rinse via the CIP system, followed by a light caustic wash and a final hot rinse. To be sure it’s in the best condition it can be, you can follow the following steps as well.
Passivating your vessels
Stainless steel surfaces are coated in a thin, transparent film, which creates a layer of protection against corrosion. Over time, this can wear down, although for the most part it is able to repair itself, as long as it’s exposed to oxygen/oxidizing elements. However it’s good to help the process along, a process known as passivation.
Use a 1.5% nitric and phosphoric acid mix to water at around 50℃ – be sure not to exceed 60℃. Recirculate for 15 to 20 minutes, and then drain, but don’t rinse. Next, recirculate a non-caustic alkaline cleaner at a dilution of 1.5% in water at 50℃, for around 15 to 30 minutes.
Rinse well, and you’re finished. The vessel is now ready for use, and can be used sanitized immediately if required – there’s no need to wait 24 hours to air-dry with this method.
If you notice any surface rust, it can be removed with citric acid. Recirculate 1.5% citric acid to water at around 50℃, for around 15 to 30 minutes and rinse well. This process is only necessary if rust is present and shouldn’t be carried out otherwise.