Goals of today's blog lesson
1.) State the main safety concerns of canning and how to mitigate risks.
2.) Find and research the national guidelines on safe canning
3.) Name the tooling and terminology used in the canning process
4.) Explain and perform the pressure canning process in correct order
5.) Correctly label, store, and rotate home-canned food
6.) Visually inspect home-canned food prior to consumption
Terminology
Cold or Raw pack- Method of canning where uncooked ingredients are placed into canning jars and cooked while being processed and sealed in the canner.
Hot Pack- Method of canning where ingredients are cooked or browned (ground meat) before placing in canning jars to be processed and sealed.
Pressure canner- Stovetop Pressure Vessel equipped with calibrated weights or gauges to ensure proper pressures are obtained in canning process. This is not the same as an Instapot or a stovetop pressure Cooker. (Pressure canner can be both a pressure cooker and canner but a pressure cooker is not necessarily suitable as a pressure canner.)
Tattler lids- Reusable canning lids. Tattler is the most common brand of approved reusable lids.
Processing- Refers to the time that canning jars and food is spent at the proper pressure in the pressure canner before removing heat source.
Altitude- The height above sea level that you are at. This is important as the pressure reading will be different at higher altitudes than at sea level to safely can food.
Non pressure canner- In high acid foods such as jams and jellies, it is not necessary to use a pressure canner to safely preserve food. In this case, a stock pot may be used to process the food.
Jiggler- This is the weight gauge system that many canners use to steadily release pressure. It “jiggles” back and forth letting air out.
Headspace- The predetermined gap between the top of the food level and the bottom of the lid. This will be mentioned in any approved recipes and is in place for expansion during heating.
Finding and researching the national guidelines on safe canning
Canning is potentially very dangerous and even deadly if done improperly due to bacteria called Botulism that thrives in negative pressure environments. This is why it is critical have a solid resource to ensure you are following good direction every time. Danger is present when incorrect tooling, process, or recipes are used.
The National Center for Home Food Preservation is the resource every person looking to learn how to can food must have. This is the canners “bible”, if you will. If using a recipe, first make sure that they reference this site. This is especially true for online platforms, but cookbooks as well. This site includes other forms of safe food preservation as well such as smoking and curing meat.
The dangers of canning
* Botulism
* Improper equipment (stove)
* Improper tooling (incorrect vessels used as canners, uncalibrated gauges, metallic tools, damaged canner seals, unapproved lids or jars)
* Not compensating for Altitude
* Under-processing
* Over-processing
* Skipping sterilization
* Inadequate jar load
* Poor Seals
* Pressure vessel explosions
* Unapproved recipes or adding ingredients
Botulism
The main issue with canning is introduction of deadly bacteria called Botulism. Most precautionary methods that we will list in the following slides are done to prevent the introduction of Botulism.
What is Botulism? “Botulism is a rare but serious condition caused by a toxin that attacks the body's nerves. Botulism may cause life-threatening symptoms. A type of bacteria called Clostridium botulinum produces the toxin. Botulism can occur as the result of food or wound contamination. The condition can also occur when bacterial spores grow in the intestines of infants. In rare cases, botulism can also be caused by medical treatment or bioterrorism.”- Mayoclinic
How can you detect Botulism? You cannot taste, see, or smell botulism in food.
How can you mitigate this risk? By using proper tooling, approved and tested recipes, and proper processes, and boiling canned food for 10 minutes prior to eating (optional but if you want to go the extra mile you can) you can minimize the risk of food-borne botulism illness.
Are there other forms of bacteria? If you have an improper seal or that seal gets damaged over time, you will introduce other bacteria which will present in cloudy or miscolored jars of food. This will probably also smell rancid and taste horrible. If a jar of food looks suspicious, throw it out!
Altitude
Altitude- Depending on your altitude, you may need to adjust your pressure of your canning processes. The NCFHP site will tell you in the charts and in recipes how to adjust your pressure due to altitude.
Equipment considerations- the stove and canner
Your Stove is the biggest piece of equipment you will need to concern yourself with. Gas stoves are the best for canning, wood stoves are also possible to can on. Glass top electric stoves are problematic as the suction caused between the bottom of the canner and the top of the glass can cause the glass to break. If you do not have the right stove, maybe you can invite yourself to a friend that is also interested in canning. Getting a new stove is not always the cheapest option.
The next critically important piece is your Pressure canner.
A pressure canner is a stovetop pressure vessel (that can hold at least 4 quart sized jars) with removable weight(s) or a gauge on top that reads the pressure. A pressure canner is NOT electric. There are pressure cookers that are electric, such as everyone’s Christmas gift two years ago, the instant pot. This will NOT work for pressure canning. It can be used for jams and jellies though. A pressure cooker is also different from a pressure canner. But sometimes they are multi-functional. The main difference between a cooker and a canner is the way the weight works. The canner weight rocks back and forth to keep an even steady release of air to maintain the proper pressure. A pressure cooker weighted gauge lifts off suddenly and for a long time, making a very loud release and then goes back down until pressure comes up enough. It is not as sensitive to added pressure. I made the mistake of using this my first couple times and it ended in overprocessing my food. I believe it was getting a little too much pressure each time, causing excessive boiling. I had to throw out some of my jars because the water level was less than halfway up the jar. Some were filthy and didn’t seal. Anyways, its not recommended. I couldn’t find anything online about pressure cooker vs canner until I tried it and found out for myself.
Here is the culprit..
I have now a presto brand Canner with a weight gauge and I love it. Very easy to use, it has a weight stack system which makes it easy to change weights if needed. They are highly rated by most people who can.
Maintenance- Keep an eye on your canner seal. They will eventually fail and need to be replaced otherwise the pressure may not build or stay constant and will result in under-processing.
Approved Jars- You may be tempted to reuse old pickle or jelly jars for canning. Unfortunately, these are not approved for reuse. You can find canning jars in packs at Walmart, hardware stores, etc. in the canning section. You can also find them online or at your second-hand stores. Make sure they are a name brand such as Ball or Kerr. If buying used, check for cracks or chips on the sealing surface. There are wide mouth and regular jars. For ease of filling, I ALWAYS buy the wide mouth jars. If you are canning liquid it might be preferred to buy the standard jars.
Approved one-time-use lids- These are sold with the jars and in small boxes with lids only or lids and rings. The rings last indefinitely so usually you just want to box of lids only. These lids are one-time use only. You may use them to store refrigerated food like you would use Tupperware, but not for canning.
The photo below is a used lid. Notice how there is a noticeable groove all the way around. This won’t seal properly again.
This is a new lid. You can see the rubberized material is in good shape.
Approved reusable lids-
The main brand for these are Tattler. They take a little getting used to and are more expensive and harder to find. You can find them online though. If you plan to can every year though, they are worth the extra investment.
Canning Rack- There needs to be separation between the surface of the bottom of the canner and the surface of the bottom of the jars as they can get too hot on the bottom, or create a small suction and break the jar. Canning racks are often bought with the canner and are easy to find online.
Debubbler- You will want to use a debubbler tool that preferrably also measures your headspace (distance between the top of the food to the lid). Can be purchased at stores with a small canning section. You can find these even at safeway or QFC usually.
Jar lifter- This is a special type of tong-like tool that wraps around the jar to pull it out of the canner. These are often sold in a kit with the debubbler in any canning section in a store (Walmart, safeway, hardware stores)
Funnel- A funnel is nice to have to prevent spillage and additional cleaning and just to make it easier to fill in general. Often sold in a canning kit at a store with a basic canning section.
A note on metallic items- You do not want to place metallic tooling inside your jars. Iron-containing metal spatulas, etc. can rust and cause botulism to be introduced.
Equipment- Gauges
Dial gauge -If you opt for a readable gauge, you will need to ensure you get it calibrated each year. It is recommended to do this before the canning season begins at your local extension office. I would also recommend right after the canning season. If your gauge fails mid-canning season, it would be nice to know there was failure before you eat your improperly processed food that winter
Weight gauge - This may seem less “exact” than a dial gauge as you can’t really watch the pressure come up and hold, etc. I much prefer the weighted gauge personally. No calibration concerns as it would take some serious and obvious damage to compromise the weights. A dial gauge will fail after so much use or may get smacked and something internal can break and fail. I love the simplicity of the weighted gauge and don’t feel I have to monitor it constantly. Just passively listen for the rocking and releasing of steam while I’m doing other things in the house.
Below are photos of a stackable weight gauge.
SEALING
Sealing is the creation of negative pressure or vacuum inside the jars. When you load your canning jars into your canner, you loosely tighten down on your sealing rings. (If you tighten too tight, the lid may not be able to move up slightly to let air out, causing jar explosions or lid buckling. Too loose, and there is not enough downward pressure to help create an initial vacuum seal.) As the food is heated up, the air expands and is able to push past the lid to escape. As your cans cool down after processing, the air contracts, causing a negative pressure inside the jar which preserves your food and prevents bacteria from being able to grow inside. The air cannot come back in because the lid and seal is in place and “suctioned down” to the top of the can.
The correct tooling, clean sealing surface, and processes used is what we count on the create and keep a proper seal.
Tooling- The lid and jar are the important tooling pieces here. The reusable tattler lids may be used until they are no longer effective. Then the gaskets may be reordered instead of whole new sets. Normally, people are using the one-time lids. When a lid is new, there is a good sealing surface. As it heats up, the rubberized sealing surface is able to move to form a seal around the glass. Once the lid is opened, there is a permanent deformation where the lid had sealed to the jar. In addition to that, the lid usually is buckled during opening with a tool, causing the whole lid to often be deformed. Some have reused lids for low-risk applications such as canning emergency water. If the seal does not pass the seal check after processing, little has been lost with plain drinking water.
*The reusable tattler style lids often need to be a finger tight when loading, and retightened to quite tight when you remove the jars from the canner to ensure proper sealing occurs. *
Clean sealing surface- After loading the recipe into the jars, it is recommended to apply white vinegar to a clean rag and clean around the rim of the jar as food usually spills on the rim during food loading. If oils or small particles of food or spices are on the rim, it will interrupt the seal and not seal properly.
Process- If the jars are not tightened down slightly, it may not lead to an effective seal. If the food is overprocessed and boils inside the jar excessively, the juices will leak out and cause the sealing surface not to be clean. It will also be unsafe if the “water level” inside the jars is less than half way up the jar. Overprocessing is what typically causes this.
Underprocessing is when the food has not reached the right temperature and pressure for the right amount of time. This not only results in unkilled bacteria such as botulism, potentially uncooked food and introduction of other bacteria, but also a poor seal as the temperature difference inside the jar as it cools down is what causes the vacuum.
CHECKING THE SEAL
Ensuring a proper seal is obtained with each canning jar after the processing is complete is critical.
* Check for seal by attempting to open the jar manually. If you are unable to open the jar without the use of tools, you know you have a good seal.
* Check for seal again after storage, prior to use. Sometimes a seal can be lost, and bacteria is introduced to your food.
* You can check for some bacteria by looking for cloudiness or discoloration in the jar. There is no way to see, smell, or taste botulism though. The best prevention is using good tooling and proper processing.
PROCESSING TIMES
The proper processing times, elevation, and pressures are stated in the National food preservation recipe cards. These directions shall be followed to ensure safe canning of food. If done improperly, this will result in underprocessing or overprocessing.
Underprocessing is when the proper pressure or time has not been reached to complete your canning process. This can be caused by operator error, a gauge that reads high, damaged seals, or bad process such as not waiting for pressure to build adequately before starting the timer. You must wait for steam to escape from the opened release valve for 10 minutes before placing the jiggler on the stem and setting the processing timer. Lifting the jiggler to quickly depressurize the canner and not processing for the full time are other ways underprocessing will happen. This will result in unsafe food that may be difficult to detect.
Overprocessing is when the proper time or pressure has been exceeded. This can be caused by a gauge that reads low, using a pressure cooker instead of a pressure canner, forgetting to set a timer or ignoring the timer. This will result in over-boiling of liquids in jars. (If over half the liquid boils out, it is not shelf-stable) This will also result in a big mess and potentially mushy food.
STERILIZATION
Sterilizing is the process of heating up your jars and lids prior to filling them and processing them. Some people do this by running a dishwasher load and pulling the clean hot jars out. Others have the jars heat up inside the preheating pressure canner and allow the jars and lids to steam for 10 minutes. Sterilizing helps kill bacteria prior to starting and it helps regulate the glass temperature so that it does not get shocked and break when loading.
INADEQUATE JAR LOAD
Enough jars must be loaded in your pressure canner in order to ensure even temperature distribution throughout. If you do not have enough recipe to fill the jars, it is acceptable to fill jars with water and place them in there. You can even can the water (this is the only situation I’d re-use one-time use lids for) for emergency drinking water. You must have at least 2 quart jars or 4 pint jars in your canner to ensure proper heat distribution.
The canner you use must be large enough to hold 4 quart jars sitting upright on the rack.
PRESSURE VESSEL EXPLOSIONS
Though not as common as in older canners, being contentious of canner explosion hazards is important. Canner explosions can occur for the following reasons:
* Clogged Vents
* Canner malfunction/ cracks in the canner
* Improper use of oil (if using as a pressure cooker for a meal)
* Overfilling while using as a pressure cooker for a meal, causing vent clogging.
APPROVED RECIPES
Approved recipes are recipes that have been tested by professionals repeatedly and passed safety tests for food preservation. While there are many recipes that are “tried and true” they still could cause illness and in severe cases, death. Heat density is a huge part of approving recipes. Such as, only ground beef that is browned thoroughly first may be canned but strips of beef is ok to raw pack. Recipes that incorporate several ingredients such as beef stew must be processed according to the ingredient that takes the longest to process. Larger containers will take longer to process.
You may subtract an ingredient in a recipe though, but you want to keep the proportions of the ingredients close. Do not add anything that is not in the recipe for risk of improper canning method.
You can find all kinds of great meals such as this beef stew. It feels AWESOME to have shelf stable healthy meals ready to go and there in case of food shortages or power outages. (The gas stove will still work in this case)
THE BASIC CANNING PROCESS
Following along with your approved canning recipe, the basic canning process consists of the following;
Tooling:
Clean jars and lids, white vinegar and clean cloth, towel, debubbler, jar lifter, pair of tongs, canner
Process:
1. Fill the canner with 2-3 inches of water, place on stove and begin to boil. Put the lid on but do not fasten it. Fill clean jars with water and place in the canner. Place the lids in the canner as well. Allow jars and lids to steam for 10 minutes.
2. Lay out a towel on the counter for hot jars.
3. After 10 minutes, lift 1 hot jar and lid out and place on towel. Fill jar with hot food until the level is up to the predetermined headspace. Using debubbler, scrape all sides of the inside of the jar all the way down. Wipe rim with clean cloth dipped in vinegar. Place lid on jar and screw down “finger tight”.
4. Place back in the canner and repeat with all jars.
5. Fasten canning lid to the canner and remove the weights. When steam begins to escape out of vent visibly, set a timer for 10 minutes. When the timer ends, place the weights on the stem. Wait for the jiggler to lift once and set timer for processing.
6. When processing timer goes off, shut off stove and wait 10 minutes. Allow all the pressure to release naturally.
7. Open the lid and allow a few minutes for cool-off.
8. Using the lifter, remove the jars from the canner and place on the towel. After a few minutes you should hear the pinging of the lids sealing. Should also see internal boiling for a while.
9. When the jars are completely cooled down, lift up on the lids and attempt to open the lids without using tools. If they open, store them in refrigerator and use within 3 days. If the seals are good, wipe the jars clean and label with recipe and date.
10. Store in a cool, dark place and ensure you are able to rotate oldest cans first by putting them in the front, using a system, or going in a left to right or right to left filling method.
My filing method is to go from the back to the front, working right to left. I know to pull canned food from the right since it will be the oldest.
Thank you for reading and I wish you the best in your canning adventures!-
Steph
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