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Gardening season is here! With this will come much growth and hopefully a fruitful yield of homegrown fruit and veggies for you and your family. An important consideration to make is how you plan on preserving the fruits of your labor, and for some, canning is the preferred method. In this blog, we will discuss the fundamentals of canning, as the best way to safely preserve foods long-term is to gain an understanding of the craft.


The History of Canning

Canning dates to the Napoleonic War era, starting in 1803. Napoleon was losing the war due to his men starving without food. This food shortage was because when fresh foods would make their way to the front lines, they would be rotten, which would leave the soliders no choice but to search around or purchase goods from the country that they were fighting in. In an effort to find a solution, Napoleon turned to his people, through the Society for the Encouragement of the Industry, and offered a 12,000-franc reward to whoever could find a way to preserve large quantities of food for his soldiers. A chef by the of Nicolas Appert won the reward after discovering that food cooked within a glass jar would not spoil unless exposed to oxygen, after 14 years of experimentation. With his reward money, Appert developed the first commercial cannery, the House of Appert, which was in operation from 1812-1933. Since Appert, modern scientists have made many advancements in canning, including pressure canning, which have allowed households all over the world to preserve sustainable foods for the long term.


Benefits of Canning

It saves time – although it may be more time initially, it saves time for meal prep later.

It can extend deals – if you find foods that are sale or available fresh at a farmer’s market, canning allows you to buy in bulk and preserve the freshness, rather than only buying a little and being worried that it will spoil/rot before consumption.

It saves money – preserving some goods in bulk through canning can help to save money when comparing to buying the same things at the grocery store.

You know where your food came from – if you can, you either grew or know first-hand the source of everything going into your jars.

It reduces waste – rather than tossing out excess veggies from your garden because you cannot eat them fast enough, canning allows you to preserve the freshness to enjoy later.


The Three Pillars of Canning

Acidic Value

All food naturally has a pH level. On the pH scale, numbers are what tells us the acidic value – the higher the numbers are on the scale, the lower the acidic value is (4.6-8), whereas the lower the numbers are on the sale, the higher the acidic value is (1-4.6). The reason that food’s acidic value matters, especially when it comes to canning, is because without the presence of acid, harmful bacteria will grow in our foods. This is an important consideration to make when determining which kind of canning needs to be done for a certain type of food (water bathing or pressure canning – which we will discuss shortly). It is also important to remember that if you have multiple ingredients going into a jar, like salsa for example, than the pH value is the sum of all of the foods in the recipe, not just the pH value for one ingredient. For example, tomatoes have a generally high pH level (~4.3-4.9), but when you add in onions, jalapenos, corn, and black beans to your salsa, the pH becomes neutralized because those vegetables having lower pH levels. When this happens, if you want to water bath can your salsa, you will need to add a pH increasing agent, such as vinegar or lemon/lime juice, or pressure can the salsa (as pressure canning controls itself for lower-acid foods).


The time required for a recipe is dictated by the foods in which you are canning and the acidic value in which those food have.


The typical water bath temperature is 212 degrees Fahrenheit, whereas the pressure canning temperature is greater than 250 degrees Fahrenheit. The method of canning that is used (water bath vs. pressure) is determined by the acidic value of what you are canning.


Canning Methods

There are two methods when it comes to canning – water bath canning or pressure canning. Water bathing is used for high-acid foods (pH of 4.6 and lower). Pressure canning is used for low-acid foods (pH of 4.6 or higher).


What Can Be Pressure Canned?

–          Broths/stocks

–          Casseroles

–          Fish

–          Fruits and chutney

–          Legumes/beans

–          Meat


What Should NOT be Pressure Canned

–          Dense foods, like mashed potatoes (heat cannot adequately penetrate the food)

–          Milk and milk-based creams

–          Delicate/soft-skin berries and fruits (they will turn brown)



I hope that this blog provided some insight to you on the fundamentals of canning and gets you excited for the preservation process for your own food!




Information source: “The Complete Guide to Pressure Canning”, by Diane Devereaux