If you’ve spent time canning, you’ve heard all about acid levels and why it determines if you can safely water bath can food. Acidity for canning is truly important!
While canning jellies and jams are one of my favorite activities, it is important to understand how to do so correctly. There are a lot of misunderstandings about what is safe for canning, and it’s important to know why acidity for canning matters so much.
Related: 8 Canning Mistakes You Are Making
The Role of Acidity for Canning
I get a lot of questions from friends and family about canning. Many people don’t understand the role of acidity for canning. The fact is that you cannot can every single fruit out there if you plan to use a water bath canner.
To be considered safe, the fruit you selected must have a pH scale of 4.6 or lower. The lower the number, the more acidic!
Why is Acid So Important for Canning?
Botulism cannot grow and thrive in an acidic environment. To safely can your fruits in a water bath canner, the acid must be present. The presence of acid stops the germination of botulism spores; botulism only grows and develops in low acid, oxygen-free environments.
If you use a water bath canner, the jars and contents are heated to the boiling point, around 212 degrees F depending on your elevation. This heat kills off most microorganisms that lead to mold, spoilage, or fermentation, but it’s not hot enough to kill off botulism spores.
Killing off botulism requires much higher temperatures.
Foods that are lower in acids, such as meat or vegetables, must be canned in a pressure canner. Their pH level is higher than 4.6. A pressure canner heats the food to a higher pressure, ensuring all bacteria spores are killed, including botulism.
When canning jellies and jams, acid plays another role. It helps to set and gel. If you want to have an enjoyable, safe jelly or jam, you need acid!
What Foods Have High Acid Levels?
Most fruits have high levels of acid that make them safe for canning. Feel free to water bath can fruits such as:
- Yellow Peaches
Some fruits have acid levels that are slightly above 4.6; these can be water bath canned if you add acid to your canning recipes – we’ll talk about that in a minute.
A few fruits with lower acidity levels include:
- Asian Pears
- White Peaches
- White Nectarines
Tomatoes Have Questionable Acidity Levels
Something that surprises a lot of canner is that tomatoes have a questionable acidity level. As more gardeners use heirloom tomatoes, the lower the acidity levels become. Many tomato varieties are prized for their low acid levels.
If you take a look at the tomato pH table created by NDSU, you’ll see that many tomatoes have a pH level between 4.9 and 5.2. 4.6 is the cut off for safe water bath canning.
The best way to ensure your tomatoes are safe to water bath can is to add lemon juice. This will push your acidity levels into an appropriate level.
The Acidity of the Entire Jar Counts
Here is something that canners often forget – the pH level of the entire jar counts. That’s why following trusted recipes matters, especially for tomato sauce and salsa.
You have to balance out the acid in these recipes. The tomatoes might have enough acid, depending on the type of tomatoes you grew, but once you add things like onions, garlic, basil, and other spices, the acidity level continues to decrease.
That’s why many tomato sauce recipes and salsa recipes including bottled lemon juice and vinegar.
How to Increase The Acidity Levels in Foods for Canning
If you’re canning food that varies in acidity or is borderline, you can increase the acidity for canning by adding vinegar or lemon juice. These are the two most common acids used in home canning; lemon juice has a higher level of acid but might change the flavor.
If you’re using vinegar, make sure you use vinegar that is at least 5% acid.
That being said, there are other ways to increase acidity for canning. Here are a few suggestions to try.
Add Lemon Juice
As I mentioned, the most common way to increase acidity levels is by adding lemon juice. It’s recommended that you use 1 TBSP of lemon juice for each cup of fruit.
Using a 5% vinegar in your recipe is another way to increase the acid level.
Add Under Ripe Fruit to Recipes
Some fruits have more acid when they’re under ripe, such as apples. If you’re making something like strawberry jam, try adding some under ripe strawberries. Not only do under ripe strawberries have more acid, but they contain more natural pectin.
This isn’t tested like lemon juice and vinegar but in other areas of the world, tamarind is used. This has a lower pH range than vinegar – around 3.0. It’s super acidic!
Add Some Wine
You also can try adding wine, but this isn’t as tested method. It’s not uncommon to find home canning recipes that use wine because wine has a natural pH range between 3.0 to 4.0.
The only problem with using wine is that the range varies so much. While wine makers have a a goal that they follow, it doesn’t guarantee that will happen.
Some Foods Cannot Be Water Bath Canned – Period
No matter how much acid you add, some foods have to be pressure canned. Adding some vinegar or lemon juice to these foods will do absolutely nothing.
For example, you cannot water bath can green beans if you add a vinegar to the recipe. The only time you can water bath these veggies is by pickling, which is a totally different product but delicious as well.
Some foods that you absolutely cannot water bath include:
- Green beans
If you are curious about the pH level of your selected fruit, click here for my free chart! It contains the pH level of most fruits.