How do you strain tomatoes for canning?

Canning tomatoes is a great way to preserve the fresh flavor of summer tomatoes to enjoy all year long. Properly straining tomatoes is an important step when canning tomato products like sauce, salsa, or whole peeled tomatoes. Here’s a guide on how to properly strain tomatoes for canning using the right equipment and technique.

Why Strain Tomatoes for Canning

Straining tomatoes when canning achieves two main goals:

• Removes skins and seeds – Tomato skins and seeds can add unwanted texture and bitterness to canned tomato products. Straining removes most skins and seeds for a smoother finished product.
• Thickens the tomato liquid – Straining concentrates the tomato flesh and results in a thicker, less watery product. This is especially important for canning tomato sauce or paste.

While some small tomato seeds may remain, straining tomatoes helps give you the best quality and consistency for canned tomato goods.

Equipment for Straining Tomatoes

To separate tomato skins, seeds, and excess liquid from the tomato flesh, you’ll need the following equipment:

• Large stock pot – Use a 6-8 quart pot so you can cook and strain several pounds of tomatoes at once.
• Slotted spoon – A large slotted spoon allows you to scoop out skins and seeds.
• Mesh strainer – A medium or large mesh strainer will catch skins and seeds while allowing tomato liquid to pass through.
• Food mill (optional) – A food mill finely strains tomatoes, removing even tiny seeds and bits of skin.
• Cheesecloth (optional)- Cheesecloth can be used to line a mesh strainer for an extra-smooth product.
• Kitchen tongs – Helpful for handling hot cooked tomatoes.

Preparing Raw Tomatoes for Straining

Always start with ripe, undamaged fresh tomatoes when canning. To prepare them for straining:

1. Wash tomatoes and remove cores, stems, and any bruised or soft spots. Leave tomatoes whole.
2. Dip tomatoes in boiling water for 1 minute to loosen skins. Use a slotted spoon to transfer to ice water bath.
3. Peel off loosened skins. A paring knife may be needed to remove any pieces still clinging.
4. Chop peeled tomatoes into chunks to make straining easier. Keep juice from the chopped tomatoes.

Straining Methods

There are a few different ways to strain peeled and chopped tomatoes. The method used depends on whether you want a smooth pureed product or something more rustic with small bits of skin and seed.

For Rustic Tomato Products

If you want a product like tomato sauce with some texture, you can strain as follows:

1. Add tomatoes and their juices to a large pot. Crush tomatoes lightly with a potato masher or large spoon if they are large pieces.
2. Bring tomatoes to a boil over high heat. Reduce heat and simmer for 5 minutes, stirring frequently.
3. Once tomatoes are softened from cooking, remove from heat.
4. Set a mesh strainer over a large bowl. Use a slotted spoon to transfer tomatoes into the strainer, pressing with the back of the spoon to extract as much liquid as possible.
5. Discard skins and seeds left in the strainer. Reserve liquid in bowl.
6. For a thicker end product, return strained tomatoes to pot and simmer over low heat, stirring frequently, until reduced to desired consistency.

For Smooth Pureed Products

For a smoother tomato puree or sauce, use a food mill:

1. Cook tomatoes as above until softened, 5-10 minutes.
2. Set food mill over large bowl and ladle cooked tomatoes into the mill.
3. Turn handle to work tomatoes through mill. The screen will separate seeds and skin from tomato flesh and juice.
4. Discard skins and seeds left in mill. Reserve pureed tomato liquid in bowl.
5. For even smoother sauce, pass puree through a mesh strainer lined with cheesecloth.
6. Return strained puree to pot and simmer until desired consistency is reached.

Tips for Straining Tomato Products

• Use a gentle hand when straining. Pressing too hard can push some skin and seeds through the strainer.
• Work in small batches so pulp does not overflow the strainer.
• Keep tomato liquid from straining to use for thinning sauces or making juice.
• Let sauce simmer uncovered to reduce and thicken it after straining.
• Add seasonings like garlic, basil, or salt after straining so they aren’t removed.
• Freeze extra homemade tomato puree in one cup portions to add to soups or stews.

Straining Tomatoes for Specific Canned Products

Beyond basic tomato sauce, straining is also important when canning products like salsa, tomato paste, or whole peeled tomatoes.

Salsa

Use the rustic straining method to remove skins and large seeds, but leave plenty of chunky tomato pieces for texture and mix with other ingredients like onions, peppers, and spices after straining.

Tomato Paste

Cook tomatoes down until mushy and deep red, then pass through a food mill and simmer for an hour or more, until reduced by 75-80%, for a thick concentrated paste.

Whole Peeled Tomatoes

After peeling raw tomatoes, gently simmer until soft and use a food mill to remove skins and seeds. Leave tomatoes whole or cut into pieces and pack into jars in strained tomato liquid.

Storing and Canning Strained Tomato Products

When canning strained tomatoes, follow these tips:

• Use boiling water bath canning method for high acid foods like tomatoes. Do not pressure can.
• Only can tomato products in vented standard mason jars, not square-shouldered jars.
• Adjust lids and rings according to manufacturer’s guidelines.
• Process pint or quart jars in a boiling water bath for the appropriate time based on your altitude.

Here are some basic boiling water bath processing times for strained tomatoes:

Product	Jar Size	0-1,000 ft	1,001-6,000 ft	Above 6,000 ft
Tomato Juice	Pints or Quarts	40 min	45 min	50 min
Tomato Sauce	Pints	35 min	40 min	45 min
Tomato Sauce	Quarts	40 min	45 min	50 min
Whole or Halved Tomatoes	Pints or Quarts	85 min	90 min	95 min

Once canned, store jars in a cool, dark place and use within a year for best quality.

Conclusion

Properly straining tomatoes by removing skins, seeds, and excess liquid is the key to fresh tasting canned tomato products. With the right equipment and technique, you can make smooth purees or retain some texture, depending on your preference. Always use current guidelines for high-acid boiling water bath canning to store your homemade tomato creations safely.