- Tom Green
- December 9, 2020
Using a yeast starter makes better beer. Healthy yeast leads to tastier beer and quicker fermentations. But sometimes life gets in the way and you can’t find the time to boil the wort, cool it, and pitch the yeast. What if you could have premade, sterilized wort, ready to go in minutes?
Wort can be canned – just like jams, preserves, and pickles – using a pressure canner or a boiling water bath. Through the process of heat sterilization, wort becomes shelf stable for months, even years. Canned work is amazing for quick, ready-to-pitch starter wort. Using a pressure canner is the best and most efficient way to ensure safe and high quality wort. But, you can also reduce the pH of wort and use the water bath canning technique.
There are a few advantages to using canned wort:
- Ready-to-go wort for quickly made starters
- Makes enough wort for five to ten starters, saving hours of time
- Saves money by making it easy to harvest and reuse yeast
Before you start – a warningCanning is the process of sterilizing food products for stable, long-term storage. For low acid products – like wort – a temperature of 250°F is required to ensure sterilization. That’s why pressure canners are used. For high acid products (i.e. low pH) – like most pickles and fruit – a temperature of 212°F is sufficient.
Toxins from a bacteria called Clostridium botulinum can appear in low-oxygen, non-sterile environments. This can cause a rare, but very deadly disease, called botulism. When canning wort, it’s imperative to eliminate this possibility.
There are two methods to can wort:
- Pressure canning standard wort (recommended)
- Water bath canning wort with a pH adjusted to 4.3 and below
Pressure canning is by far the preferred method for great quality and safe starter wort. If using the water bath canning method, the pH of the wort must be lowered. The downside to that is that the low pH can have adverse effects when it comes time to propagating yeast starters.
Always be safe when making canned wort – botulism is no joke. If you’re serious about canning wort, it’s definitely the best idea to invest in a pressure canner.
Preparing wort to be cannedFor the starter wort, aim for an original gravity (OG) of 1.040. This is a good gravity for most types of yeast starters.
You have a few options on how to make the wort:
ExtractUsing dried malt extract (DME) is the easiest and quickest way to make starter wort.
Use the following ratios to make the wort. You can just add the DME, water, and yeast nutrient directly to the jar. Shake well to make a homogenous mixture.
The heat from the canning process will dissolve everything and sterilize so you don’t have to pre-boil DME starters. There’s no risk of dimethyl sulfide (DMS) as the DME has already been boiled during the extract production process.
Imperial Units
- ½ cup of dry malt extract
- ½ teaspoon of yeast nutrient
- 1 quart of hot water
Metric Units
- 100 grams of dry malt extract (DME)
- 2.2 grams of yeast nutrient
- 1 liter of hot water
All GrainIf you’re an all grain brewer, you can easily brew a batch of 1.040 wort using some 2-row. Boil the wort for at least 15 minutes to eliminate DMS.
Alternatively, you can make a bit more volume of wort on your next brew day (if brewing a pale beer). Dilute (or boil down) to reach a gravity of 1.040.
How to can wort with a pressure cannerThe most consistent and easiest way to produce canned wort is using a pressure canner.
A pressure canner is (usually) a stove top pot that operates under high pressure and high temperature. There is a difference between a pressure canner and a common pressure cooker. Pressure cookers do not always reach the required temperature and pressures to sterilize canned wort.
*Your pressure canner or cooker must be capable of reaching and holding 15 PSI to safely can wort*
Equipment neededFor this method, you’ll need the following items:
- Pressure canner (or pressure cooker if it can hold 15 PSI)
- Pint or quart size mason jars
- Jar lids
- Lid rings
- Jar tongs
Every pressure canner is different. Make sure you read the instructions for your model very carefully. Pressure canners operate under high heat and high pressure, which can be dangerous if handled improperly.
They also vary in size and volume. Do not overfill your pressure canner. Boil only the recommended number of jars at a time.
Step 1: Make the wortMake the wort as per the ratios above and fill each jar. Leave about ¼” of space to the top of the jar. It’s always a good idea to add some yeast nutrient – about ½ teaspoon nutrient per quart of wort.
Step 2: Prepare jars to be sterilizedPlace the lid on the filled jar and lightly screw on the ring. You’re not looking for a tight fit. It should be secured but loose enough to move a bit. Pressure will need to escape from the jar during the canning process.
Never reuse jar lids. They are designed for one-time use only.
Step 3: Prepare the pressure cannerCarefully follow your pressure canner’s instructions.
Usually, the first step is to add the water to the canner. Use the specified amount. If your canner has a rack, make sure that’s in place before adding the water.
Next, place the jars inside the pressure cooker and secure the lid, as per the instructions.
Step 4: Heat up the pressure cannerCarefully following your pressure canner’s instructions, it’s time to heat it up. For most canners, you start heating on your stovetop with the relief pipe open. Once steam starts to release from the pipe and the locking valve initiates, put the pressure regulator on it.
Allow the pressure canner to reach 15 PSI on the pressure gauge. This means that the canner is operating at the correct pressure, at the correct temperature – around 250°F – to completely sterilize the contents.
Step 5: Allow pressure canner to operate for 20 minutesSet a timer for 20 minutes and let the pressure canner operate at a constant 15 PSI.
Step 6: Remove from heat and allow to cool to room temperatureAfter 20 minutes, turn off the heat. The pressure canner will be hot and pressurized. It will take an hour or two to cool and naturally depressurize. Don’t force it to cool using an ice bath or another method – the slow cooling time is important for the sterilization process.
Once the pressure canner is depressurized, the locking valve will open. At this time, it is safe to remove the lid.
Step 7: Take out the jars and allow to coolCarefully remove the jars from the pressure canner. They will still be very hot. Use tongs or heat proof gloves.
During the cooling process, the jars will start to self-seal.
Step 8: Remove the rings from the jarsOnce all of the lids have sealed – or “popped” – remove the rings from the jars. Rings can be reused for future canning sessions (but the lids are one-use only).
A vacuum seal keeps the lid in place. Over time, if the lid comes loose, it’s an indication that a yeast or bacteria has grown in the wort, and it should be discarded.
Step 9: Store at room temperature or in the fridge or cellarThe high temperature and high pressure canner has completely sterilized the wort. The jars can be safely stored at room temperature, or in your cellar or fridge, for years.
When you’re ready to make a starter, simply bring your premade wort to room temperature and make a starter as usual.
How to can wort without a pressure cannerWithout a pressure canner, it’s still possible to can wort. In order to eliminate the potential for botulism, you’ll need to ensure the wort has a low enough pH to inhibit bacterial growth. For that reason, a good quality pH meter is absolutely necessary. You’ll be adjusting the wort with phosphoric or lactic acid to a pH of below 4.3.
Note: A normal starter wort has a pH of 5.4 to 5.5. Using a wort with lower pH could affect the growth and health of certain yeast strains. If this is a concern for you, it is not advised to use this method for canning wort.
Equipment needed
- Large pot with canning rack
- Pint or quart size mason jars
- Jar lids
- Lid rings
- Jar handling tongs
- pH meter (not paper strips)
- Food grade phosphoric or lactic acid
- Graduated cylinder with 1mL divisions
Step 1: Make the wortMake the wort as per the guidelines above. If using DME, you should mix the water and extract in a large pot with warm water (instead of in each jar). This makes it easier to adjust the pH in the next step.
Step 2: Lower the pH of the wort to 4.3 (DO NOT SKIP THIS STEP)Add enough phosphoric or lactic acid to drop the wort’s pH to 4.3 or lower. As wort chemistry can differ significantly, there is no easy rule for the amount of acid to add.
A good starting point is to add about 1 mL per gallon of wort. After each addition, test the wort with your pH meter. Depending on your meter, you may need to measure the wort at room temperature.
Step 3: Prepare jars to be sterilizedFill each jar with your pH adjusted wort. Leave about ¼” of space to the top of the jar. It’s always a good idea to add some yeast nutrient – about ½ teaspoon of nutrient per quart of wort.
Place the lid on the jar and lightly screw on the ring. It should not be a tight fit. Pressure will need to escape from the jar during the canning process.
Never reuse jar lids. They are designed for one-time use only.
Step 4: Prepare the potAdd the rack to the canning pot and add enough cold water to cover a jar halfway. Bring the water to a simmer.
Bring more water to a boil in another pot or kettle. You’ll need enough to cover the jars once they’re in place.
Step 5: Add jars to pot and cover with waterPlace all the jars of wort inside the canning pot, upright onto the rack. Leave about ½” spacing between each jar. Add enough boiling water to cover the jars.
Cover the pot and bring water to a rolling boil.
Step 6: Boil jars for 20 minutesSet a timer for 20 minutes to let the boiling water bath sterilize the wort.
Step 7: Remove pot from heat and carefully remove the jarsAfter 20 minutes, turn off the heat. Using the tongs, carefully move the jars from the water onto a heat proof surface.
Allow them to cool and leave them, undisturbed, for 12 hours. During this time, the lids should have all sealed and “popped”. If the lids have not sealed, you can try the process again, or refrigerate and use the wort within 24 hours.
Step 8: Remove the rings from the jarsOnce all of the lids have sealed – or “popped” – remove the rings from the jars. Rings can be reused for future canning sessions (but the lids are one-use only).
A vacuum seal keeps the lid in place. Over time, if the lid comes loose, it’s an indication that a yeast or bacteria has grown in the wort, and it should be discarded.
Step 9: Store in the fridge or cellarFor canned wort made with the water bath technique, we recommend storing the wort in a cold place, ideally below 38°F. This is an added safety to ensure that no harmful bacteria is able to grow in the wort.
When you’re ready to make a starter, simply bring your premade wort to room temperature and make a starter as usual.
Final ThoughtsHaving canned wort is a quick and convenient way to make yeast starters. Pitching the right amount of healthy yeast is vital for a strong fermentation to limit any off-flavors. Taking the time and hassle out of making a starter will make it a lot easier for you to always prepare a starter before you brew.
Using a pressure canner is straightforward, but make sure you follow the instructions for safe operation. If you try canning using the boiling water bath method, it is absolutely necessary that you pay close attention to the pH of the wort. Canned wort must be completely sterile to eliminate the risk of harmful bacterial growth.
Because of this, we highly recommend that you stick to the pressure canning method to can wort.
Frequently Asked QuestionsDo you need a pressure canner to can wort?The most efficient and safest way to can wort is using a pressure canner. The high pressure and high temperature sufficiently kills all bacteria in the wort. This is what makes it suitable for long term, shelf-stable storage.
Simply boiling jars of wort is not sufficient to completely eliminate the risk of botulism. In order to safely can wort using the boiling method, it is essential to reduce the pH of the wort below 4.3, using lactic or phosphoric acid, before canning. It’s also recommended to store this type of canned wort in the fridge below 38°F.
How do you make a starter with canned wort?To make a start with canned wort, you simply need to add the canned wort and yeast to a sanitized bottle or flask and let it ferment, as usual. Follow our guide on making a yeast starter to help get the healthiest yeast possible.
Do you need to re-boil canned wort?No – canned wort is sterile from the canning process. Consider it like starter wort that has already been boiled and cooled.
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