So you decided to start a garden! But you suddenly realized that the amount of produce you have will not be eaten in a timely fashion. This is when the process of canning begins. This article is going to be a guide on how to can anything. And specifically the science of canning different fruits, vegetables and even meats based on a few basic principles.
For many years our ancestors used to use food preservation as a way for survival. Food preservation in any Northern climate is essential to daily living. This is why canning in Canada is particularly common. Using canning allows for the preservation of all different sorts of edible foods without drying them out.
With canning we avoid the loss in colour we typically see with freezing. And with canning we also avoid the potential of frost burn from the freezer. Let’s look at a few basic principles that we need to consider when looking at preserving food in jars.
How Does Canning Work
The counting process involves placing food in jars or containers that are able to be heated at a temperature that will destroy any microorganisms. Microorganisms such as bacteria, fungi and enzymes are all responsible for causing foodborne illness. In the canning process the heating of both the Char and in some cases the contents helps drive the air out of the jar which then causes a vacuum seal once the heat dissipates.
The combination of high heat and lack of oxygen is the perfect combination to destroy any harmful microorganisms. However and some cases this may not be enough if the food is not acidic. This is why when canning we need to identify if our food is acidic or alkaline. If the food we are planning is alkaline in nature and is below the acidic range needed we have to add acids. Acids can come in the form of things such as vinegar and even lemon juice.
The low acidic foods include:
- Dairy products
- All vegetables
The low acidic Foods listed above have a pH value that is close to you 4.6. This means we have to add acid to our recipe for canning. One of the best ways to make this happen is through recipes on the internet. You have to keep in mind that if a recipe is not used and acid does need to be introduced. It is not safe to use the boiling water bath method without an acid.
The high acidic foods include:
Safe Canning Methods
There are two safe ways of processing jars; the boiling water bath method and the pressure canner method.
Boiling Water Bath Method
This is safe for tomatoes, pickles, salsa, jams/jellies & preserves. This method is very simple to follow. You want to either follow a recipe you find on the internet or the recipe on the back of the pickling or preserve packet. you’ll simply cut up your produce. Add in all your ingredients and be sure not to overfill the jars.
From there he will heat boiling water to the required temperature based on your recipe. You will place your cans with the lids on into the boiling water ensuring that the entire top is covered. Now you simply leave your jars boiling in the bath water for the required amount of time.
This is the only safe method of preserving vegetables, meats & poultry. The glass jars are filled with the recipe and then placed into 2-3 inches of water. The pressure cooker which is heated to a temperature of at least 240° F. This temperature can only be reached using the pressure method.
Canning Methods To Avoid
Canning methods that are considered potentially unsafe can include a microwave method, open kettle methods and oven / steam canning. This is because the methods do not get to a heat high enough to destroy dangerous microbes.
Common Canning Mistakes
With anything new there can be mistakes. Some of these mistakes I still make to this day and in some cases it’s just the luck of the draw. Let’s go over how to identify mistakes that can be dangerous in the canning process. I will also include some tips and tricks to help prevent these mistakes from happening.
During the canning process it’s not uncommon for some of our recipes to end up on the lip of the jar. If we end up with food on the lip of the jar we can have an improper seal. This is why when we are done filling the glass jars we want to wipe the rim with a sterile cloth.
You will also want to check the rim of your jar for crack, nicks and even manufacturer defects. All three of these things can result in an improper seal. If you are using a reusable lid be sure that the seal is not damaged.
Remember improper sealing means oxygen can get into the jar and cause bacterial growth. If the top “button” is still poppable it is not yet sealed.
Improper heating is probably one of the easiest to diagnose. If we do not have our water up to temperature for a long enough period of time this would be considered improper heating. However, one thing we don’t think about when heating are bubbles. Air bubbles within our jars are actually a poor heat conductor.
Oddly enough the air bubbles within our jars can act as an insulator. This means our jar is not properly heated throughout the entire mixture. This leaves the potential for microbes such as harmful bacteria to colonize.
Removing the air bubbles from our jars are pretty simple. It is a quick fix that involves using a spoon to stir the contents of the mixture around lifting all the bubbles to the surface. Which will eventually release them into the atmosphere.
Cracking jars is admittedly the most common issue I encounter. This is because I am an impatient person when it comes to processing food. You want to and first check your jars for any cracks or scratches that may have developed.
After that you want to ensure that the jars are not exposed to incredibly cold temperatures or hot temperatures too quickly. This is the most common reason for why are charged crack. The best way to prevent this is actually by putting your jars in a dishwasher cycle prior to canning.
Once the cycle has finished the jars will be very warm. This warm jar can then be placed into the boiling water or pressure cooker. Because the jars are at a higher temperature you are less likely to have breaking. However if we wash our jars in cold water and then place them into boiling water we will end up with breakage.
There you have it, the science of canning. Always remember kenning is a science experiment in your kitchen. The ultimate goal of the science experiment is to eliminate any potentially harmful microbes through the use of heat and lack of oxygen. So long as you’re following the recipe you will be just fine. Remember to label your jars with the date of processing to help you give an idea of when it may expire. Be sure to tag us in your photos of canning or on Instagram or Facebook.