Please note that the following information is based on guidelines provided by the National Center for Home Food Preservation (USDA). People in countries other than the USA sometimes can using different procedures and processing. Just because a recipe isn’t tested by the USDA, does not mean it is not safe. You are responsible for your own health and safety. Use your own discretion when canning.
The Science of Canning
Canning is the process in which food inside of a glass jar (or metal can) is heated to the temperature needed to kill food borne bacteria and harmful micro-organisms.
The process of canning also removes all oxygen from the inside of the jar as it cools and creates a vacuum seal so no oxygen can get to the food, keeping it protected from future micro-organisms.
There are 2 types of food you will be canning – low acid and high acid. The acidity of a food is determined by its pH level. A low pH is a more acidic food. A higher pH is a less acidic food.
Which brings us to our next point:
Pressure Canning vs. Water Bath
Pressure Canner (PC) – A pressurized pot that raises the temperature of the food in jars well above boiling for a certain amount of time at a specific pressure. The internal temperature of the food in the jar reaches 240° Fahrenheit. Pressure canning is ideal for low-acid foods (pH level higher than 4.6) such as meats and beans.
Pressure canners either have a dial (geared steam) gauge, weighted gauge, or both (dual gauge). A dial gauge can measure the pressure, but cannot control it. A weighted gauge controls the pressure, but cannot measure it. How to Pressure Can
Water Bath (WB) – The process of fully submerging the jars in boiling water in a large pot for a certain amount of time. This is a shorter and lower temperature process than pressure canning. Ideal for high-acid foods (pH level of 4.6 or lower) such as fruits and pickles. How to Water Bath Can
Is Canning Safe?
YES!!! As long as you follow instructions and use common sense, canning is very safe.
Pressure canners now-a-days have so many fail-safes to prevent explosions and other mishaps, so there is no need to be timid. Just be sure to inspect all parts to make sure they are still in good condition and fully functional before each use and ALWAYS follow your equipment’s manual.
But What About Botulism?
First, let me tell you what botulism is: Botulism is a rare and potentially fatal illness caused by a toxin, produced by the bacterium Clostridium botulinum.
Clostridium botulinum thrives in environments where oxygen is not present (i.e., canned jars).
How often do people get botulism from home canned foods? In the United States, an average of 15% of the cases of botulism are canning related. And of that 15%, 11% is from commercially canned products and 4% is from home canning. These percents are based off an average of 145 cases a year.
The latest report from CDC National Botulism Surveillance, 2014: 177 cases of botulism. 6 from home canning. View Full 2014 Report
(2001-2014 CDC Botulism Surveillance Reports can be viewed here)
As you can see, botulism is rare overall, regardless of the cause. When you consider the even smaller numbers from home canning, you can bet that as long as you use safe canning methods and storage, you are not likely to contract botulism.
If you want to exert extra caution, boil your canned food after opening for 10 minutes before consuming. This will kill the botulism toxin.
What do I need to get started?
- Jars with lids
- Jar lifter to lift jars in and out of pot
- Funnel for filling jars
- Head space tool (measures the distance from the top of the jar to the top of the contents inside the jar)
- Bubble remover (can use a butter knife)
- Towel (to put hot jars on after you heat in pot or pressure canner)
- Large pot with lid for water bath OR a pressure canner for pressure canning (NOTE: Pressure cookers should NOT be used for pressure canning)
- Rack to put on bottom of pot/canner so jars don’t directly touch the bottom of the pot.
Helpful Tips & Tricks
- If you are pressure canning for the first time, do a test run without any jars to get used to your new equipment.
- If your pressure canner has a dial gauge and you are not sure if it is working properly, you can get it tested at your local Extension Office. The manufacturer may also test it for free.
- NEVER place hot jars out of the WB or PC directly on your countertop. This can damage your countertop and break the jars. Place on a towel on your counter instead.
- ALWAYS have your jars and food the same temperature as the water in your pot. If the water is cold, do cold pack (cold contents inside the jar) and heat everything up together after putting jars in the pot. If water in pot is hot, do a hot pack (hot jars with hot contents in the jars) then place in hot water in the pot. This will prevent jar breakage.
- If you are using Ball® or Kerr® lids, you do not need to boil them before canning.
- If you have hard water, add a dash of vinegar to the water in your pot/canner to avoid water spots on your finished jars.
- When cooking acidic foods, use a non-reactive pot or pan. Reactive metals will make your food taste metallic and discolor the food. (exceptions are copper and well-seasoned cast iron)