Canning is a common method to preserve foods for very long periods, even years! Unfortunately, while home-canning has been steadily growing in popularity among homesteaders, it’s still considered too daunting to even try for many people.
Canning food is a science, not an art, and it has to be done perfectly and with care because there are risks involved. Yet, this doesn’t mean you have to miss out on the sheer joy of preserving your garden bounty!
I promise it gets easier the more you do it, and the results are completely worth the hassle.
If you want to learn how to can food, you first need to become familiar with the different canning methods, machines, equipment, and more. To help you with this, I’ve put together this extensive guide so that you can confidently try your hand at home canning.
Let’s jump in!
Canned foods are often considered not to be as nutritious as fresh or frozen foods, but the truth is that canning preserves most nutrients in a food. A study has found that fruits and vegetables are just as rich in dietary fiber and vitamins, whether fresh, frozen, or canned.
Moreover, it’s been determined that, in some cases, canned products are richer in nutrients than their fresh or frozen counterparts. For example, the heating process that the food items undergo during canning seems to make the dietary fiber more soluble, and thus, easier to digest.
However, any product you want to preserve has to be handled and canned properly, following specific instructions even for their harvest, because several factors can affect the overall quality of the items and promote the deterioration of flavor, color, texture, and nutrients.
The food items typically go through three major steps during the canning process:
Collectively, these steps remove oxygen, destroy enzymes in the food, and prevent the growth of bacteria, yeasts, and mold that are often the cause of spoilage.
If you’re a beginner and are just taking your first steps into the canning journey for the first time, then you’ll probably come across some new terminology you’ll need to understand to do things right, and more importantly, safely.
Here are some of the most common terms you’ll find:
Understanding the acidity (pH) of the food you’re processing is important because it determines the method you can use. It’s not a matter of preference but rather one of safety.
In canning, high-acid foods are those that have a pH less than 4.6 and a high concentration of hydrogen ions. These hydrogen ions prevent the growth of common spoilage agents like most bacteria, fungi, and yeast and make them easier to kill at the temperature of boiling water.
For those reasons, high acid foods such as fruits, juices, pickled and fermented items are safely processed in a boiling-water bath canner.
On the other hand, low-acid foods have a pH greater than 4.6 that creates the perfect environment for Botulinum spores to grow. Killing these spores is crucial to make the food safe to consume, but, unfortunately, they’re quite resistant to boiling water temperatures.
Because of that, low-acid foods like meat, fish, and vegetables should be properly processed in a pressure canner.
Avoid mixing high- and low-acid foods because it can result in an overall mixture with a pH greater than 4.6, making it unsafe.
There are two different canning methods: cold- or raw-packing and hot-packing. So, which one is right for you and your food? Well, let’s see the differences between both methods first.
Raw-packing involves filling your canning jars tightly with freshly prepared but unheated pieces of food. In other words, the food is left as is, no cooking or blanching required. You obviously have to peel it and cut it into smaller pieces, though.
Then, boiling liquid is poured over the contents before sealing the jars. There will be bubbles or trapped air around the food pieces that you will have to release to prevent discoloration while in storage.
Raw-packing is the more suitable method for vegetables processed in a pressure canner.
On the other hand, hot-packing is the practice of heating food to boiling, then letting it simmer for 2 to 5 minutes before filling the jars. Partially cooking the food before packing helps remove the air out of the jar and reduce food floating. This comes in handy when canning tomatoes and firm fruits like pears and peaches.
Hot-packing is the best pack style for foods processed in a boiling-water canner.
While you might notice that the color of hot-packed foods might look no better than that of raw-packed foods at first, both the color and flavor of hot-packed products will be superior within a short storage period.
Being cautious early on and taking the time to choose the right cans can save you a lot of frustration later. Always use jars that are approved for canning, and check each one for any cracks or chips. Cracks will always lead to broken jars in your canner, and even the smallest chip can cause a failed seal.
Mason jars are the most common choice when it comes to canning containers because, when used and handled carefully, they can be reused many times. However, they do require new lids each time.
The best choice are regular wide-mouth Mason-type home-canning jars with self-sealing lids like these ones here. Mason jars are usually available in ½ pint, pint, 1½ pint, quart, and ½ gallon sizes, with a standard jar mouth opening of about 2⅜ inches. On the other hand, Wide-mouth jars have openings of about 3 inches so that they can be easily filled and emptied.
Start with a careful and thorough examination of your jars, and discard any that have nicks, cracks, and rough edges. Such defects will prevent an airtight seal on the jar, leading to food spoilage. You can repurpose damaged jars for a craft project, but they’re not suitable for safe canning.
Then, wash your canning jars with soapy water, and rinse them well because detergent residues may affect the flavor and color of the food.
Once clean, make sure to keep your jars hot until you’re ready to fill them to prevent breakage. There are two ways you can do this:
However, if you’re going to process your filled jars for less than 10 minutes in a boiling water bath canner, preheating them is not enough; the jars need to be sterilized.
To sterilize your canning jars, place the canning rack in the bottom of a boiling-water canner and submerge the jars with the right side up. Fill the canner with warm water until it’s 1 inch (2.5 cm) above the top of the jars. Boil them for 10 minutes at altitudes of less than 1,000 ft (305 m) and an extra minute for each additional 1,000 ft elevation.
Once sterilized, keep the jars in hot water until ready to fill. It’s recommended that you remove the jars and fill them one at a time.
Jars that are going to be used for vegetables, meats, fruits, and thus, processed in a pressure canner, don’t need to be sterilized. The same applies to jars for fruits, tomatoes, and fermented or pickled foods that will be processed in a boiling water bath canner for more than 10 minutes.
Supplies might vary depending on the type of food you want to preserve, but here are the most common ones:
As we’ve mentioned before, the canning method you choose will depend on the type of food you want to preserve. Remember to use a boiling-water bath canner for high-acid foods such as fruits, tomatoes, and pickles, and a pressure canner for low-acid foods like meat, fish, and vegetables.
If you’re in doubt, always verify that the recipe you’re following comes from a reliable source, or like I often do, double-check with the National Center for Home Food Preservation.
Most canners are designed to hold an average of 7 quart (1 L) jars or 8 to 9 pint-sized (500 ml) jars. Smaller pressure canners hold a load of 4 quart jars, whereas larger ones can hold 18 pint jars in two layers, and only 7 quart jars.
Before using your canner, whether it be a boiling-water or a pressure canner, take the time to read the manufacturer’s instructions because some of the steps can vary depending on each model.
Boiling-water bath canners are typically made of aluminum or porcelain-covered steel, and have perforated racks that can be removed at wish. The canner must be deep enough to ensure that at least 1 inch (2.5 cm) of boiling water remains over the top of the jars while processing.
You can use a boiling-water bath canner to preserve:
The specific steps for using a boiling-water canner might vary depending on the model you own and the type of food you want to process, but in most cases, this is what you have to do:
The jars will seal as they cool, and all you will have to do afterward is labeling and dating them before storing them.
Pressure canners are lightweight, thin-walled kettles with a jar rack, gasket, dial or weighted gauge, an automatic vent lock, a steam vent port, and a safety fuse.
Some people might think that it’s the pressure that kills the microorganisms in the food, but it’s the high temperatures the device can reach and maintain for a specific period. Pure steam, free of air, at sea level, can reach temperatures as high as 240°F (115 °C).
The canning recipe you follow should specify both the amount of time you have to leave the jars in the canner and the amount of pressure that’s required (in PSI, or pounds per square inch).
The process for using a pressure canner is similar to that of a boiling-water bath canner. The main difference is that, instead of being submerged, the jars will sit in just a few inches of water.
You can use a pressure canner to preserve:
To use a pressure canner to preserve your food, you usually have to follow these steps:
The sealing of the jars occurs while they cool. Once that’s done, you can finally label and date them before storing them.
When the jar lids are tightly vacuum sealed and the jars have cooled, you can remove the screw bands. Then, wash both the lids and jars under cool running water to remove any food residue. Finally, rinse and dry the jars.
Label and date your jars, and store them in a cool, dark, and dry place. They should never be stored in temperatures above 95 °F (35 °C), near hot pipes, a furnace, or under a sink. Avoid leaving your jars in an uninsulated attic or any place that gets direct sunlight as well.
All the conditions I’ve mentioned above will cause food to lose quality and spoil. Humidity can corrode metal lids, break seals, and even foster recontamination and spoilage.
While accidental freezing of the jars won’t spoil the food unless the seal is broken, freezing and thawing can soften the products. If you live in a cold climate, prevent jars from freezing by wrapping them in newspapers and covering them with more newspapers and blankets.
Like in any area of life, prevention is the key to ensuring safety. Here’s a summary of some of the potential dangers associated with home-canning, along with what to look out for and tips on how to prevent them.
While this type of food poisoning is rare, it can be fatal. This is actually a big reason why many homesteaders are wary of home-canning. Botulism is caused by the Clostridium botulinum bacteria, which produces a deadly toxin in canned goods that haven’t been processed or sealed correctly. This toxin attacks the nervous system, paralyzing the body and causing death.
What makes the toxin even more dangerous is that it’s quite resistant to heat and can’t be detected by sight or smell.
The best—and probably the only—way to ensure that your home-canned goods don’t have botulism is to follow the proper canning and storing methods. Pressure canning is your best ally in fighting against this deadly toxin because it produces enough heat to kill the bacteria. On the other hand, water bath canning methods can’t kill the bacteria in low-acid foods, which is why they’re not recommended.
While you can always reuse canning jars and rings, lids must be replaced each time you want to can food. Each jar should have a brand new lid that includes a rubber ring around the inside bottom edge and helps to ensure a proper seal.
A reused lid won’t seal properly, and it can ruin your canned food and allow bacteria and toxins to enter the jar. Once you finish the contents of a jar, I recommend that you mark the lid so that you won’t get confused on which lid is new or old next time you want to can.
Old lids can either be recycled or used for crafts or to top other jars that will be kept in the fridge but never reused for canning.
Safe canning practices require that canning jars are sterile before filling for ultimate safety. Sorry, grandma, simply washing and drying the glass jars isn’t enough anymore. A completely sterile environment will minimize the risk of toxin or bacteria growth.
Clean and sterilize the jars, just as I’ve mentioned in the article’s section “Preparing the Canning Jars and Lids.” In short, you have to run them through a dishwasher cycle or submerge them in a stockpot or boiling-water canner if you’re going to process them for more than 10 minutes.
Otherwise, place the jars on the canning rack in the bottom of a boiling-water canner and submerge them with the right side up. Boil the canning jars for 10 minutes at altitudes of less than 1,000 ft (305 m) and an extra minute for each additional 1,000 ft elevation.
Make sure to keep the jars warm right until they’re ready to be filled to avoid compromising their sterile condition.
Many people often forget to ensure that the work area and other canning tools are sterile as well. Simply dipping your jar lifter and other tools into boiling water for a few seconds to avoid cross-contamination will do.
I’ve mentioned this many times already, I know, but it’s worth repeating once more: boiling-water bath canners should be used for high-acid foods, whereas pressure canners are ideal for low-acid foods, but these can be used for both.
What you should never, ever use is an electric, multi-cooker appliance. It doesn’t matter if it has a “canning” or “steam canning” button on the front panel.
Why? Because while electric multi-cooker manufacturers claim that their cooker reaches the pressure required for canning, it’s the temperature—not the pressure—that matters. The temperature in the canner has to stay at a constant minimum throughout the entire process time to ensure the safety of the final product.
With a canner placed on a stovetop, this is easy to control, but what happens with electric appliances during power surges or drops? Does the temperature stay constant? Hard to know, really.
If you want to know more about why it’s not safe to use an electric multi-cooker as a canning device, check the NCHPF’s article on the topic.
It’s important to know what to look for when checking your canned products for spoilage. Examine the jars closely before opening and don’t taste or use any that shows any of the following signs:
Low-acid foods may not show any signs of spoilage, but if you even suspect the jars might have been compromised, you should treat them as having produced the botulinum toxin and should handle them carefully in one of two ways:
The botulinum toxin can be fatal even if it enters through the skin, so be extremely careful not to contact the suspect food or liquid. Always wear disposable rubber or heavy plastic gloves, an apron, and long-sleeved clothes. Said apron and clothes, if contaminated, have to be bleached or thrown out.
Be mindful of where you leave the jars to cool and keep them away from children and pets!
Contaminated surfaces include any countertop and equipment (including can openers and clothing) that could have come in contact with suspect foods or liquids. Do the following to clean them up:
If you’ve reached this far, I’m impressed! It means you’re really invested in learning how to properly can your food. So, as a reward, I will make a quick summary of the most important aspects of home-canning, along with some personal tips to achieve the best results.
Food is typically canned in glass jars, but you can also use metal containers. The difference is that metal containers are usually expensive, can be used only once, and require special sealing equipment. Honestly? They’re not worth it. Glass jars are much more convenient for home-canning purposes.
After allowing the jars to cool for 12 to 24 hours, you can test the seals in three different ways:
Properly canned and stored foods can last several years, but they start to lose nutrients and flavor after a year in storage. But if you’re preparing for a zombie apocalypse and don’t care about taste, then you can confidently stock up on canned foods for about 10 years!
Don’t worry; a failed seal on a jar is not the end of the world. Simply remove the lid and check the rim of the container for tiny nicks or cracks. If you notice any, change the jar and lid, prepare them, and reprocess the food using the same processing time within 24 hours.
Another option involves adjusting the headspace in unsealed jars to 1½ inches (4 cm) to freeze them instead of reprocessing them. You could also store single unsealed jars in the refrigerator as long as you consume them within a week.
As you can hopefully see by now, home-canning is not that difficult! However, knowledge is power, and knowing precisely the dangers involved in canning your food and how to prevent them is the first step to successful canning.
I’ve guided you through everything you need to know about this wonderful method for food preservation, from the benefits and specific terminology you’ll come across in recipes to how to choose the right containers, operate the different canners, and check for signs of spoilage.
All that’s left now is for you to try your hand at it and share your experience with me!
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