If you are putting food in a jar to keep on the shelf, you need to process it. It needs to be processed in either a hot water bath or in a pressure canner. Otherwise, keep food in the fridge or freezer. The only exception is food fermented in a salt brine which will last for several months if stored in cool storage, (i.e. a fridge or root cellar).
Canning preserves food by killing pathogens, stopping aging enzymes and removing oxygen to create a tight vacuum seal that prevents contaminants from re-entering food.
Two Forms of Safe Canning
There are two safe methods for canning food, hot water bath canning (including steam canning) and pressure canning.
Oven canning, open kettle canning, sun canning, microwave canning and canning in the dishwasher are NOT safe practices.
Hot Water Bath Canning
Hot Water Bath Canning is when jars are filled with food, sealed loosely with a lid, completely covered in boiling water and boiled for a set amount of time.
This method is only for high acid foods like fruits, fruit juice, jams, jellies, tomatoes with added acid and pickled vegetables.
Steam canning, according to new research (2017, 2020) by the National Center for Home Food Preservation (NCHFP) can be safely used for high acid foods in place of hot water bath canning.
When steam canning food and jars are prepared much like in hot water bath canning. The NCHFP says…
Jars must be preheated before filling with food and cooling prior to processing must be minimized. Processing times must be adjusted for altitude, and must also be 45 minutes or less, including any altitude modification. The processing time is limited by the amount of water the canner base will hold, and the canner cannot be opened to add water or for any reason at any time during the process. Finally, cooling of jars must take place in still, ambient air without any forced, more rapid cooling. The slow cooling of processed jars is important to the overall food safety of the whole canning procedure.
Pressure canning uses a special canner that seals tightly and cans food under high pressure. There are different types of pressure canners which are different than pressure cookers. Be sure to read Commonly Asked Questions about Pressure Canners. The pressure in the canner raises the temperature above boiling which is high enough to kill tough bacteria like Clostridium Botulinum and their spores.
Jars are filled with food, sealed loosely with a lid and put in a pressure canner (not a pressure cooker) with only a liter or two of water. The canner is sealed with a tight-fitting lid and brought up to the correct pressure and jars are processed for a set time. After the time is up, the canner cools and naturally releases its pressure before the lid is removed and jars are taken out. The amount of water to add to the canner, what pressure to use and for how long to process jars varies depending on the food in the jars and is included in tested, trusted recipes. Adjusting for altitude is important when pressure canning.
This method is for low acid foods like vegetables, meat, fish, poultry and mixed foods like soups and sauces. Low acid foods cannot be processed by hot water bath canning because some bacteria and their spores can live in low acid foods, particularly Clostridium Botulinum, one of the most dangerous bacteria. Low acid foods must be canned by pressure canning.
Which Method To Use?
The acid level in the food determines which method to use. You cannot safely switch between hot water bath canning and pressure canning. It is not safe to can low acid foods using a hot water bath and you will get poor texture, colour and quality if you can high acid foods in a pressure canner.
Can I Use My Instant Pot or Pressure Cooker to Pressure Can Food?
Electric pressure cookers like the Instant Pot are different than pressure canners. Pressure cookers work differently than canners and do not reach the necessary temperatures needed for safe canning. There is not enough research to know the exact time and process to use with pressure cookers; they are not recommended for pressure canning.
You can use your pressure cooker for hot water bath canning high acid foods by using it like a big pot and not using any pressure.
Where Can I find Safe Recipes?
Just like in every industry, there is always new research, information and recommendations regarding safe canning practices. What we did 25 years ago, is often not the best method today. It’s likely that your great-grandmother’s recipe or instructions for canning do not follow current practices.
To be sure you are getting current, safe and nutritious information, follow recipes and instructions from trusted, credible sources. The leading source of credible information and the organization regularly doing testing on safe canning practices is the US National Centre for Home Food Preservation. Other sources I trust include:
Healthy Canning – recipes and tips
Certo – Home of Kraft – makers of Certo Pectin
Canadian Living – shares approved recipes
If you come across cookbook or blog authors, read their credentials, look at their general tone and how they write about canning and preserving. Anyone who has credible canning information should be referring to national standards and safe canning practices.
Quick Resources to Home Canning
Hot Water Bath Canning Recipes
Pressure Canning Recipes
I would love to hear about what you’re canning this year. If you have a question or want to share info, leave a comment below or tag me on Instagram at #getgettys or Facebook @GettyStewart.HomeEconomist.
Getty Stewart is an engaging speaker and writer providing tasty recipes, time-saving tips, and helpful kitchen ideas to make home cooking easy and enjoyable. She is a Professional Home Economist, author of Manitoba’s best-selling Prairie Fruit Cookbook, Founder of Fruit Share, mom and veggie gardener.