It is that time of year where tomatoes are abundant. Perhaps you are growing them in your garden? Or perhaps you find them by the case at your local farmer’s market? But regardless of where they come from, do you know which tomatoes to avoid for canning purposes?
According to NCHFP, “Select only disease-free, preferably vine-ripened, firm fruit for canning”. That sounds easy right? But what if you harvest or buy tomatoes that don’t look picture perfect?
Iowa State University Extension and Outreach offers a little more information with this statement: “Overripe and infected tomatoes may be low enough in acid to support Clostridium botulinum. Use only firm, ripe tomatoes that have no spoiled parts or mold. Tomatoes harvested from dead vines are low in acid. They can be eaten fresh or frozen, but do not can tomatoes from dead vines”.
To give you a better understanding of which tomatoes to skip when it comes to canning, a photo is worth a thousand words (or at the very least a photo with a brief description).
Anthracnose is a tomato disease (fungus). Symptoms of this appear on ripe fruit, starting as small, sunken, and water-soaked lesions. These lesions will then increase in size and the center will darken (and contain a fungal structure from which spores are released) and the tomato begins to soften.
Internal black mold may be caused by a couple of diseases. The first is anthracnose as listed above. The second culprit could be blossom end rot. Mold may simply enter through hole (caused by animal or insect) or a crack in the tomato skin. If you purchase tomato ‘seconds’ at a market or farm or using ones from your own garden that appear to have some damage, it is prudent to cut open the tomato to make sure the tomato does not have internal black mold like the one in the photo above. Sunscale may also cause internal black mold, though in this case, the damaged tomato is allowed to stay on the plant too long and the tomato begins to rot.
Sunscald. Now with this issue, the tomato itself is exposed to direct sunlight during periods of hot weather. If the damage is just a tan, papery blemish, that can be cut away. However, if the affected tomato is allowed to stay on the vine, internal mold may develop.
Tomatoes that have an off aroma should not be used. A healthy tomato should smell like… well… a tomato. If the fruit smells sour or moldy (even if mold is not visible), discard the tomato.
Diseased tomatoes and those with internal black mold should not be used for canning purposes. The act of canning will not remove the disease or repair the mold. These tomatoes could spoil in the jar and ruin your batch regardless if you canned them for juice, stew tomatoes, or even pasta sauce.
For the best possible canning results, use vine-ripened fruit that is firm to the touch. As the saying goes, “If in doubt, toss it out” should apply when it comes to this summertime fruit. So keep in mind, what not to can when it comes to tomatoes. Your health will thank you for it.
now that is something I never knew–thank you for sharing:-) I won’t feel guility throwing them away!
You are welcome. While we all want to use as much of our harvested or purchased produce as possible, sometimes the best thing we can do is toss out the ones with an off aroma or are diseased.
I think you are wise + I am glad you wrote about this
Oh.. thank you. I felt that this is something that not everyone knows about.
This makes a lot of sense. Thanks!
You are welcome. Sometimes I think we feel compelled to use everything when in reality, we are better off just tossing some of the produce.
Sue Dreamwalker says
I have never experienced internal black mould.. I have had several split this year with lines running around the top.. Which I have cut away and used these tomatoes for fresh soup making.. in fact I made fresh tomato soup today… I add a a Red or green pepper in too.. ( not the hot variety ).. Roast them in quarters in the oven then blend in blender with veg stock.. delicious 🙂 Thank you for this post.. 🙂
This year, I bought cases of tomatoes as ours (in the garden) have been slow to ripen. This is the first time that I encountered it, but knew that mold could develop from various tomato diseases. (Your soup sounds wonderful).
Sue Dreamwalker says
It is… and nice and you make it as thick or thin as you like it by just adding more or less veggie stock.. .. My recipe is here if you are interested.. I add just one pepper sliced and roasted and around 3 to 4 gloves of garlic depending on size… Enjoy
Oh… thank you for the link to the recipe. We love tomato soup and we turn it into a childhood favorite by making grilled cheese sandwiches to go along with it.
Sue Dreamwalker says
Great Minds think alike.. Me too 🙂