How to Sterilize a Fermenter

Virtually everything relating to home brewing is fun, from developing new recipes through to sampling the finished product. However, there are a couple of steps in the process which can be tedious for even the keenest brewer — like sterilizing brewing equipment. 

Despite sterilization being mundane, it is a crucial step in the brewing process which cannot be skipped if you want your brew to succeed. In this guide, I’ll explain why sterilization is essential and share the best method for sterilizing your fermenter. 

Anvil Stainless Steel Bucket Fermenter - 7.5 gallon
  • 304 Stainless Steel
  • Coned Bottom
  • Rotating Racking Arm

Cleaning Vs Sterilization

Although brewers use the terms “cleaning” and “sanitization” interchangeably, they are two separate processes. 

Cleaning removes debris, dirt, grime, and germs from the surface of the fermenter. It can be performed with a general cleaning solution. Sanitization involves using a specialized solution with bacteria killing properties.

Cleaning removes material that can become host to, or fuel for, living organisms like bacteria, viruses, and protozoa. The best time to perform cleaning is immediately after you have used it. This ensures the material in the fermenter doesn’t have a chance to embed itself in any nooks and crannies.

If your fermenter won’t be used for a while, you will need to clean it again before sterilization, to remove any dust, mold, and other materials which have accumulated during storage.

Regardless of how well you clean, it’s impossible to completely eliminate the stubborn microorganisms that lurk in the crevices of a fermenter. The sanitization step will remove any germs lurking in the fermenter before brewing — ensuring your brew is a success.

What Happens If You Don’t Sanitize?

If an unwanted bacteria, fungi, or wild yeast remains present in your fermenter, it can lead to major problems including:

  • The beer becomes unsafe to drink
  • There are significant changes in the flavor of the finished beer
  • The aroma of the beer changes
  • Additional compounds make the beer cloudy or change its color
  • The alcohol content of the beer changes
  • Wild yeast consumes all of the available sugar and preventing the fermentation process  from occurring

The Best Way To Sterilize A Fermenter 

Step 1: Clean throughly 

It is best practice to clean your fermenter before sterilization. It doesn’t take long and ensures there is no debris hiding in the nooks and crannies of the vessel. 

There are several products and tools suitable for fermenter cleaning. One of the easiest options is to use a liquid dish determent and a soft sponge. Liquid dish detergents are a great choice because they are non-toxic, foam up quickly, and can be bought in any store. If you use a liquid detergent, find one that is free of perfumes and dyes. 

A better option is to use a specialized cleaning solution like Five Star PBW, B-Brite Cleanser, Craft Meister Alkaline Wash, or One Step No-rinse cleaner. These products are specifically designed for cleaning brewing equipment, so you can be certain they are safe for your fermenter. 

Five Star P.B.W. Cleanser - 4 Pounds
  • PBW is an alkaline, non-caustic, environmentally and user friendly cleaner
  • Cleaner is very effective in removing thick, difficult, and caked-on organic soils
  • Effective substitute for caustic soda cleaners and household cleaners

Specialized fermenter cleaners are non-toxic, biodegradable and capable of getting into any small cracks inside the fermenter. They are also safe to use on a wide range of materials including plastics, stainless steel and glass. 

When using these types of cleaners, you won’t have to worry about stains or corrosive pitting in metals (which can occur with some caustic household cleaners). 

Another advantage of using a specialized cleaner is you won’t need to use rough scrubbing tools. This avoids the risk of creating scratches in the fermenter’s surface which become the perfect place for bacteria to hide.

It’s always best to clean your fermenter immediately after using it, so any yeast byproduct, sugars, and bacteria cannot attach itself to the fermenter’s walls. If the fermenter has been sitting for more than a couple of weeks since its last cleaning, clean it again before sterilization.

Cleaning procedure

  1. Rinse the fermenter out with hot water (multiple times if very dirty)
  2. Add the cleanser and water according to instructions
  3. Agitate the solution by shaking the fermenter 
  4. If the fermenter is very dirty, leave it to soak for 10 to 15 minutes 
  5. Use a soft cloth or soft cleaning brush to clean inside the fermenter
  6. If you have a glass fermenter, you can also use a carboy brush to remove stubborn material
  7. Airlocks, lids, and bungs can be cleaned with hot water. If they are particularly dirty, let them soak in a cleanser solution
  8. After cleaning, rinse with cool water then let the equipment dry fully before storage

Notes:

  • Avoid using any sharp or abrasive tools if you have a plastic fermenter as it may cause scratches
  • Avoid using any cleaners that leave a film on the surface of the fermenter, as it may interfere with the fermentation process or contaminate your brew
  • Be careful with products containing bleach. Although bleach cleaning products have been a popular option with brewers for many years, these chemicals can be dangerous to handle and you will need to rinse your fermenter thoroughly to avoid contamination. Modern cleaning solutions are a safer option. 

Step 2: Sanitization 

After your equipment has been thoroughly cleaned, it is time for sanitization. Ideally, use a no-rinse sanitizer like One Step, Five Star Star San or B-T-F Iodophor. As the name suggests, no-rinse sanitizers don’t require a water rinse after use. This removes the risk of the water you use reintroducing unwanted bacteria or other germs. 

Five Star - Star San - 16 Ounce - Brew Sanitizer High Foaming Acid Anionic
  • STAR SAN is a high foaming, acid anionic, no-rinse sanitizer
  • Self-foaming acid sanitizer ideal for brewing, dairy and other food and beverage equipment
  • Extremely effective bactericide and fungicide and is not affected by excessive organic soils

No-rinse sanitizers are odorless, tasteless, and completely safe for human consumption. They won’t change the flavor or aroma of your beer in any way, so don’t hesitate to use them.

It’s important to note that the way you use your sanitizer is just as important as the type of sanitizer being used. You must follow the instructions carefully and handle the fermenter in the right way to avoid any re-contamination.

Although chemicals like bleach and hydrogen peroxide can be used to sterilize fermenters, there are drawbacks associated with their use. For starters, it can be dangerous to handle these chemicals and sterilization can take longer to achieve. 

The fermenter also needs to be thoroughly rinsed out after use, which can reintroduce contaminants if your water supply is not clean. So, opt for specialized brewing sanitization agents if they are available.

Sanitization Procedure: 

  1. Fill your fermenter with the mixture of sterilizer and water as specified on the product’s directions
  2. Close the fermenter lid and shake the fermenter so the solution comes in contact with all of the inside surfaces
  3. Open the lid and insert any additional brewing equipment which needs to be sanitized, including the airlock, additional lids, and bungs.  
  4. Leave the sanitizer in contact with the additional equipment for at least 3-5 minutes (check instructions to confirm the appropriate contact time)
  5. Remove the additional brewing equipment and set aside. Drain the sanitizer from the fermenter. DO NOT RINSE if you are using a no-rinse sanitizer.

Although cleaning and sterilization is a chore, both procedures are essential if you want to be a successful home brewer. Avoid cutting corners, as you may ruin a batch of beer, which is absolutely heartbreaking. Thanks for reading!