Tomatoes, fresh from the garden or a local farm market, are a summer delight. If you’re a fan of preserving that summer goodness, you’ve probably wondered about a crucial step in home canning: adding lemon juice. So, do you really need lemon juice to can tomatoes? The short answer is a resounding yes!.
Why Acidify Tomatoes?
Tomatoes are unique because their acidity is borderline, walking the line between high- and low-acid foods. In simpler terms, some tomatoes aren’t acidic enough on their own to prevent the growth of harmful bacteria during the canning process.
Over the years, tomato varieties have evolved, and many now have a milder flavor and lower acidity than in the past. Testing has revealed that some modern tomato varieties have pH values at or above 4.6, and some even reach pH 5 or higher. A pH of 4.6 is the critical threshold; above this, nasty microorganisms like *Clostridium botulinum* can thrive, producing the toxin that causes botulism.
Adding lemon juice or citric acid lowers the pH of all tested tomato varieties enough to allow for safe water bath canning. Acidifying all whole, crushed, or juiced tomatoes is recommended because it ensures the safety of the canned product after processing in a water bath canner, and it also ensures a safe, short process in a pressure canner.
The Science Behind the Acidity
The primary reason for adding lemon juice to canned foods is to lower the pH level, creating an environment where harmful bacteria cannot thrive. This is especially important when canning low-acid foods like tomatoes and certain fruits.
How to Acidify Your Tomatoes
The acidification process is straightforward. Here’s how to do it:
- For quarts: Add two tablespoons of bottled lemon juice or ½ teaspoon of citric acid per quart of tomatoes.
- For pints: Use one tablespoon of bottled lemon juice or ¼ teaspoon of citric acid.
You can add the bottled lemon juice directly to the jars before filling them with the tomato product, or you can add it after filling. Just ensure you add the lemon juice to each jar and follow the recommended amounts precisely.
Why Bottled Lemon Juice?
It’s important to use bottled lemon juice rather than freshly squeezed. Bottled lemon juice has a standardized acidity level, while fresh-squeezed juice can have varying levels, making it unreliable for canning.
Can I Adjust the Taste?
If you’re concerned about the taste, you can add sugar to offset an acidic flavor after opening the jars that have been processed and sealed, if desired. However, don’t decrease the acid before canning.
Choosing the Right Tomatoes
- Regular tomatoes: These work well for juice and canning whole or crushed tomatoes.
- Italian and plum-type varieties: These are excellent for making sauce, salsa, catsup, and purees.
- Mixing: Feel free to mix the two types to achieve the desired flavor and consistency.
What About Low-Acid or Yellow Tomatoes?
Follow the same directions for canning low-acid or yellow tomatoes as you would for regular tomatoes. Although low-acid tomatoes might not taste as sour, their acidity is masked by the natural sweetness of the variety; no changes are needed in the recipe for safety.
High-Quality Tomatoes are Key
Always use high-quality tomatoes. Some growing conditions may cause tomatoes to be unsafe to can, even when they look fine. Tomatoes with blight and those from dead or frost-killed vines may be lower in acidity and are more likely to carry bacteria.
Methods to Avoid
- Open Kettle Method: Don’t just heat the tomatoes or tomato product and pour the hot product into the jars, add the lids, and wait for the lids to “pop” without further processing. Even though the jars may seal, the contents inside haven’t been heated adequately to destroy harmful spoilage organisms.
- Oven Canning: Avoid oven canning, as well as the use of so-called canning powders.
- Aspirin: Do not use aspirin.
Updated Guidelines
Canning recommendations for tomatoes have changed over the years, so be sure you follow the most up-to-date guidelines when canning tomatoes.
Safe Canning Practices
Acidifying tomatoes when recommended gives you confidence in knowing you have preserved safe tomatoes to enjoy all winter long. Michigan State University Extension reminds home food preservers to always use current, research-based recipes when canning tomatoes as well as any other produce. Recommendations and preservation methods have changed over the years, and it is critical to use current methods to have a safely preserved product for you to consume.
Additional Tips for Successful Canning
- Always use bottled lemon juice unless a recipe specifically calls for fresh.
- Avoid overfilling jars and ensure they are properly sealed to prevent contamination.
- Follow tested recipes and avoid altering the amount of lemon juice, as this can affect the pH and safety of the final product.
The Benefits of Organic Lemon Juice
Organic lemon juice offers several benefits over conventional options.
- It is free from synthetic pesticides and fertilizers, making it a healthier choice.
- Organic farming practices are more sustainable and environmentally friendly.
- The consistent acidity of organic bottled lemon juice ensures the safety and effectiveness of the canning process.
Final Thoughts
Using lemon juice in home canning is essential for both safety and quality. By following these guidelines, you can confidently preserve your tomatoes and enjoy the taste of summer all year round.