Canning and freezing fruits and veggies from your garden can sound intimidating, but it’s as simple as this formula: Time + Science = Preserved Food.
Okay, okay. I know you didn’t come here for a science lesson, but hear me out.
When you can and freeze, your main goal is to remove air and microorganisms from your container. Canning achieves this with heat, while freezing — obviously — does it through cold.
Freezing doesn’t kill microorganisms like canning does, instead their growth is prevented by reducing the temperature to the point they become inactive, according to the Purdue Extension Office. As a reminder, once you thaw your frozen fruit or vegetables the microorganisms will begin to grow again.
It’s important to also blanch your food prior to freezing. Blanching will improve the color, texture and flavor of the food, as well as help cleanse it from dirt and microorganisms. Syrups can be added when freezing fruits to also help with color, texture and flavor, but it won’t prevent spoilage.
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The heat from canning sanitizes the food you’re preserving by killing any microorganisms that may be living on the skin of the food. As the food cools in the jar after processing, the hot air inside the jar rushes out and creates a vacuum. When the vacuum is high enough the jar will seal, creating a noticeable “pop.”
There are two types of canning methods to use, and they type you use depends on what you’re canning, according to the extension office.
Foods that are high in acid — apples, cherries, peaches — are ideal for canning in a simple water bath. The acids in the food help to destroy any microorganisms that are killed at the boiling point of water (212 F).
Low acid foods — peppers, beans, carrots — must be processed in a pressure canner. The addition of pressure alters the boiling point of water to 240 F, which effectively kills any microorganisms on the food.
In both methods, it’s vital to clean and sanitize your jars and lids to prevent any bacterial contamination.
Whether you’re freezing or canning, timing is critical when processing. When freezing, blanching the correct amount of time is vital to preserving quality. When canning, proper timing is important to prevent spoilage.
Always remember to use canning recipes that have been scientifically tested to prevent spoilage.
Often, if your preserved food is spoiled you’ll be able to detect it through sight or smell. But, food can spoil without any visual signs; if you think a can or bag may be compromised, toss it out to be safe.
As a bonus, here are the guidelines set out by the Purdue Extension Office on canning and freezing different types of fruits and vegetables.
- Snap beans
- Peaches, apricots and nectarines
- Jams, jellies and spreads