Canning for Beginners Lesson 1: What is Canning?
- Anastasia Oxendine
- Aug 14
- 3 min read
Updated: Aug 16
Before you start canning, learn the basics of canning!
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The purpose of home canning is to extend the shelf life of your food. Whether it be homegrown food, locally grown food, or store bought, this article reviews the basics of home canning so you extend the shelf life and reap the benefits of your hard work!
So how does canning work?
If you’ve ever looked at a pantry shelf filled with colorful jars of home-preserved jams, pickles, or bone broth and felt a mix of inspiration and intimidation, you are in the right place.
Home canning isn't a lost art—it’s a simple, reliable science. Once you understand the core mechanics of how it works, the fear disappears, and the fun begins. Let's break down the absolute basics of food preservation so you can step into the kitchen with confidence.
What Actually Happens During the Canning Process?
At its core, home canning is about creating a safe environment where food can be stored at room temperature without spoiling.
When you process a jar of food in a canner, three critical things happen simultaneously:
Heat Kills Microorganisms: High temperatures destroy spoilage organisms—like molds, yeasts, and bacteria—that exist naturally on fresh food.
Air is Driven Out: As the jar heats up, the food and air inside expand, forcing oxygen out past the flexible flat lid.
A Vacuum Seal Forms: As the jar cools down after processing, the remaining steam condenses, creating a tight vacuum seal. This prevents ambient air and new bacteria from getting back in.
The Two Methods: High-Acid vs. Low-Acid Foods
Not all foods are canned the same way. The single most important rule in home canning is matching the acidity of your food to the correct canning method.
1. Water Bath Canning (High-Acid Foods)
Temperature: 212°F (100°C) — Boiling water.
How It Works: Jars are completely submerged in boiling water. Because high-acid foods naturally inhibit the growth of dangerous bacteria like Clostridium botulinum, the boiling temperature of water is all that's required to preserve them safely.
What You Can Process:
Fruits and fruit juices
Jams, jellies, and preserves
Pickles and fermented foods
Tomatoes (with added acid like lemon juice or citric acid)
2. Pressure Canning (Low-Acid Foods)
Temperature: 240°F – 250°F (115°C – 121°C).
How It Works: Low-acid foods require temperatures higher than boiling water to kill heat-resistant bacterial spores. A pressure canner uses trapped steam under pressure to reach these higher temperatures safely.
What You Can Process:
Plain vegetables (beans, corn, carrots)
Meats, poultry, and seafood
Soups, stews, and real bone broths
Dried beans and legumes
Safety Rule #1: You cannot safely preserve low-acid foods in a water bath canner. Pressure canning is non-negotiable for meats, plain vegetables, and un-pickled stock.
Essential Gear: What You Need to Get Started
You don't need a kitchen full of expensive gadgets to start canning, but having the right tools makes the process smooth and safe.
Essential Tool | What It's Used For |
Mason Jars & Lids | Glass canning jars (Ball, Kerr, etc.) designed for heat stress, paired with two-piece flat lids and screw bands. |
Heavy-duty, rubber-coated tongs designed to move hot jars safely in and out of boiling water. | |
Wide-mouth funnel that keeps jar rims clean while packing food or pouring hot liquids. | |
A non-metallic tool used to release trapped air bubbles and measure exact headspace before sealing. |
The Golden Rules of Safe Canning
Before diving into your first batch, keep these non-negotiable safety rules in mind:
Follow Tested Recipes: Always use recipes tested by reliable sources (such as the USDA Complete Guide to Home Canning or National Center for Home Food Preservation). Don't alter ratios, cook times, or thickeners on a whim.
Respect Headspace: The gap between the top of the food/liquid and the rim of the jar matters! Too little room causes food to siphon out; too much room keeps the jar from sealing properly.
Check Your Seals: After 12–24 hours of cooling, remove the screw bands and press the center of each lid. If it doesn't flex or pop back up, you’ve got a success!
What’s Next in Lesson 2?
Now that you know the basic science behind food preservation, you're ready to get your hands dirty! In Lesson 2, we’ll cover Essential Canning Equipment & Setting Up Your Kitchen so you're fully prepped for your very first batch.
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