Those of us who grow vegetables have all been faced at one time or another with too much of a good thing. It could be zucchini, that never seem to know when enough’s enough, green beans that seem to ripen the minute you turn your back, or tomatoes, those beautiful fruit that are worth growing if only for how much better they taste than the store-bought varieties.
I’ve developed a quick and easy way to can tomato puree which cuts the work time in half. It requires no dipping of tomatoes in boiling and cold water to remove the skins, which is to me the worst part of the process. All this involves is lots of tomatoes, a food processor, a very large kettle, quart canning jars and lids, and a canning kettle with a rack.
Start by washing your tomatoes and cutting out the stem ends. Run them through the food processor in batches, skin, seeds and all, until the mixture is completely pureed and no seeds are visible. Pour each batch into the large kettle until it’s about two-thirds full. Bring the tomato juice to a boil, then lower the heat to a simmer. The mixture should just be bubbling slightly. Cook for 2-3 hours UNCOVERED to evaporate as much of the liquid as possible. Stir frequently so the juice doesn’t stick to the bottom of the pan, more often as the mixture starts to thicken.
Turn off the heat and let the puree cool for about 30 minutes. Wash your quart canning jars, lids and rings in hot soapy water and rinse well. Fill each jar with puree, leaving about an inch of headroom at the top. Add a teaspoonful of canning, or non-iodized salt, to each jar. To assure the correct acidity level in the product, you should also add 2 tablespoons of lemon juice to each jar. Today’s tomato varieties aren’t as tart as old-fashioned types, so it’s best to add this bit of insurance to each jar. If you’re still in doubt or choose not to add the lemon juice, simply process the tomato sauce in a pressure canner.
Wipe the rims of the jars, place the lids on and screw the rings on just hand-tight. Place the jars on the rack in the water-bath canner, and pour warm water into the kettle to come up to about 2 inches over the tops of the jars. Cover the kettle, and bring to a rapid boil. Lower the heat just enough to keep the water at a steady boil, and process the quarts for 40-45 minutes. Turn off the heat and let the jars cool in the water before removing them. Place the processed jars on a clean towel and allow to cool completely. Listen for the distinctive pinging sound as the lids seal themselves, then tighten any loose rings before storing in a cool dark place. Be sure to mark the jars with the date they were processed.
You might notice that the sauce and water have separated in the jars. This is normal. You can either simply boil the sauce down more when you use it, or let the sauce cook longer before you process it. Very thin sauces can be thickened with a small can of store-bought tomato paste, if necessary.
University of Missouri Extension