Keeping these rules in mind will help you create safe, tasty canned goods.
- Wash your hands, wash your tools, wash your food!
Your preserves won’t get cleaner in the jar. Wash everything that will touch the preserves right before you start – spoons, pots, funnels, jars/lids/screwbands, etc. Even if I think everything’s clean, it gives me peace of mind to do it again.
- When in doubt, throw it out!
If you open a jar and it looks off somehow, toss it! If the lid comes off easily, toss it! If the contents smell funny or have any mold, toss it (although a little discoloration is common and totally fine)!
if you follow the right procedure, this won’t happen very often, but it’s much better to waste a little food than to get sick. I’ve thrown out one jar (of about 100) and it was very obvious that it was bad.
- Follow trusted recipes.
Canning is a science and requires some precision. It is not safe to throw food in any old jar, stick it in boiling water for a bit, and store it on your shelf for a year. Water-bath canning can only be done with recipes that are acidic enough to prevent botulism spores.
Canning is hot right now, so there are lots and lots of bloggers posting recipes. Make sure that they know their stuff and have thought through any alterations they make to a trusted recipe. Even then, remember to follow Unbreakable Rule #2. See the references below for trusted sources and make sure to pay attention to the recommended:
- Jar size: A jar that’s too large may not allow the contents to be properly heated through and may result in spoilage due to micro-organisms. A jar that’s too small could result in an over-cooked product that won’t taste as good. Follow the recommendations.
- Processing time: This is the amount of time that the jars should be left in boiling water (see Process).
- Acidity: The vinegar used in canning is usually of 5% acidity, but some recipes call for a higher percentage. You can substitute different types of vinegar as long as you stick to the same acidity or higher.
I almost always use bottled lemon juice, rather than fresh. There’s some discussion about whether fresh is okay, but I find bottled more convenient and would rather not worry.
Don’t assume that you can make produce substitutions or add more of something. For example, white peaches are less acidic than yellow peaches, so you might not be able to use white peaches in a recipe that calls for yellow peaches. Adding more herbs to a pickle recipe, for example, will dilute the vinegar and may reduce the acidity to unsafe levels.
- Buy quality food!
In general, you should buy produce from farmers you know and preserve it at the peak of ripeness. Don’t use moldy or buggy produce. Don’t use produce that you wouldn’t otherwise eat. There are a few situations in which slightly under- or over-ripe produce is desired, but that should be specified in the recipe.
See our Canning page for more info.