Disheartened to see our garden tomatoes infected with blight this year, but determined to salvage something, I took the least-damaged green fruits (nothing ripened this year!), cut off the blemishes and proceeded to can twenty 500-ml jars of green tomato pickle.
It was only after the last lid snapped, that I began to wonder: even if consuming blighted tomatoes does not pose any human health risk, are they safe for canning?
It turns out this is a frequently asked question for staff with Penn State University Co-operative Extension. When I spoke with associate professor of food science Luke LaBorde last week, he had this to say: while the pathogen that causes the blight won’t make humans sick, the fungus infestation may have raised the pH of the tomato flesh to a level that does make it unsafe for canning. The other concern is that blighted tomatoes’ surfaces are damaged, so other types of moulds and pathogens may have infiltrated the tomato.
Bottom line: don’t can blighted tomatoes. That’s red tomatoes.
It may be a different story, however, if we’re talking green tomatoes made into pickles. Green tomatoes tend to be more acidic than red tomatoes, LaBorde points out. So making a green tomato pickle with a recipe calling for plenty of vinegar and using only the non-diseased parts of the fruit (cut off a generous part of the tomato showing any signs of blight) should produce a safe finished product. The vinegar addition likely will address the issue of the potentially higher pH level, said LaBorde.
But, then again, we just can’t be sure.
In an article published on the Penn State Co-operative Extension website LaBorde writes: “our specific recommendation is that tomatoes showing signs of late blight disease should not be used for canning. This applies even to tomatoes with only minor lesions since we cannot be sure that the infestation has spread to the interior of the fruit and the extent of internal infestation is not always clearly visible.”
The concern is that the tissue damage and rise in pH that occurs can create conditions that promote the growth of other potentially harmful microorganisms.
“Some may say that this is an unnecessary waste of food,” LaBorde writes. “But anytime you are unsure of the safety of food, remember this saying: “when in doubt, throw it out.”
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