- Start Prepping
- Finance & Tech
- How To Guides
- Bug Out Bag
One of the most common problems that canners of all levels encounter is being knowledgeable about foods that can and can’t be canned in one way or another.
But that’s just part and parcel of the joy of preserving your own food – there’s just so much to learn along the way.
While there are obviously certain types of foods that aren’t really suitable for canning, they can be preserved through other variations of preservation.
This is primarily the reason why we find it important to share what we know about foods that are best left not canned – so that we can contribute to the existing body of knowledge for canners, novice or otherwise, towards a safer canning experience.
As the number of canners grows in number, so does the need to provide relevant information and advice as to how to be safe. Here’s what we know about discerning the proper type of foods to can as well as the foods that you cannot can:
Much of what determines foods that can and can’t be processed for canning is their acidity – that is, their pH level. Acidic foods possessing a pH level of 4.6 and below may be processed with a boiling water bath canner. On the other hand, lower acidity foods with pH levels of above 4.6 generally need to be processed with a pressure canner.
The main reason why low-acid foods need to be pressure canned is due to the existence of Clostridium botulinum. This type of bacterium can potentially produce the dangerous neurotoxin botulinum, which is the most potent toxin known to humans. It is the same bacterium that causes foodborne botulism.
Worse, C. botulinum can survive adverse conditions such as boiling temperatures, and grow in sealed jars or cans – and trust us, this is something you do NOT want in your food.
Using a pressure canner allows you to increase the heat above the boiling point (212 ºF) towards the prescribed temperature of around 250 ºF, which effectively kills off C. botulinum spores and sterilizes your finished product when you process low-acid foods.
We know that acidic foods contain pH levels of 4.6 and below. Conversely, we know that low-acid foods contain pH levels upwards of 4.6. But do you know which foods fall under both acid and low-acid classifications? While there exists substantial variation among varieties of fruits and vegetables as well as processing and growing, it’s easier than you think. Here are some examples to guide you.
Acid foods (4.6 pH and below): apples, blackberries, cherries, gooseberries, muscadine grapes, nectarines, oranges, peaches, pears, pineapples, plums, raspberries, and strawberries.
As the name implies, these foods contain enough acid, in most cases naturally occurring, to prevent the growth of potentially harmful bacteria. These foods also tend to destroy such bacteria faster when heated. Acid foods can be safely processed using a boiling water bath canner.
Special mention must be made for tomatoes and figs. While these foods are generally considered acidic, they contain pH levels just above 4.6. If you plan to can them as though they were acid foods (that is, using a boiling water bath canner), you will need to add some lemon juice or citric acid to reduce their pH level to 4.6 or below.
Low acid foods (above 4.6 pH): red meats, poultry, seafood, dairy products (not recommended for home canning), and fresh vegetables.
Low acid foods, as discussed earlier, require the use of a pressure canner to ensure safe processing. Use a tested recipe when canning low acid foods to ensure safety. Avoid canning dairy products – if you wish to process dairy, try freeze-drying it instead of using conventional canning methods.
Combinations of acid and low acid foods require canning with a pressure canner, unless enough acid is added to lower the pH level to 4.6 and below.
If you do not own a boiling water bath canner or a pressure canner, you may opt to use a pressure cooker. While conventional pressure cookers are generally not recommended for canning due to size limitations, if want to start your canning journey there is one pressure cooker we can recommend before you invest in a pressure canner: the Power Pressure Cooker XL. Its size and versatility have made it universally regarded as the best pressure cooker for this purpose.
Regardless of what device you choose to use, make sure to follow its manufacturer’s instructions to the letter as pressure canners and cookers pose the risk of fire or explosion when used improperly.
Short of literally testing each and every food product with a pH meter (which can be very expensive and tedious to do), one of the best ways to easily discern foods for canning is to simply use a recipe that works from a trusted source. This way, you know that what you’re canning is a safe product that has been tested by many others before you.
Finally, there are a multitude of sources you can refer to for recipes: the National Center for Home Food Preservation of the University of Georgia is one of the foremost sources on preserving foods, among many other reliable academic sources, while the Clemson University Cooperative Extension Service offers a list of literary sources on canning recipes online. Be sure to check them out.