Fresh fruits and vegetables can do some alarming things. They can crack open and change colors, sport tiny - or really big - scars, and even start trying to make new produce, right there on your kitchen counter.
"When in doubt, throw it out," you might tell yourself as you approach your garbage can, suspicious produce in hand.
But hold on. Americans dump an estimated 150,000 tons of food every day, most of which is landfilled and generates methane, a potent greenhouse gas. You're also squandering the resources used to produce that food. A 2018 study by researchers at the U.S. Department of Agriculture and two universities found that every year, more than 30 million acres of cropland and 4.2 trillion gallons of water are dedicated to producing food that Americans throw away.
So before you curse your overly ambitious farmers market run, consider taking a second look at that scarred tomato on your counter or the sprouting onion in your pantry. Because while sometimes "off-looking" fruits and veggies are telling you that they're no longer good to eat, often they're simply showcasing harmless science lessons.
Here's what you might see in your fresh produce haul and what to make of it.
A sprouting onion
The onion looked fine when you took it home, but, now, it has sprouted green shoots. Is your stir-fry doomed? Not at all. The onion, prompted by factors such as age and temperature, simply moved to its next stage of life.
"It's certainly not dangerous to eat," said Elizabeth Mitcham, of the University of California Postharvest Technology Center, noting that it just won't be optimal quality. "If it's in my cabinet, I'm not going to throw it away."
Having sent sugars and water to the sprout, the onion may taste a little bitter and possibly more fibrous; you're more likely to notice this if you eat the onion raw. I've sauteed onions and garlic with small sprouts and haven't noticed unpleasant flavors in the final dish. In fact, I usually forget about the sprouting by the time I sit down to eat my meal.
As for the sprout itself, the "Waste-Free Kitchen Handbook" urges treating it like a green onion, though Cook's Illustrated taste testers found the green shoots unpleasant. Give it a try and decide for yourself. And, of course, potato sprouts are an entirely different story. We'll get to that in a moment.
A green potato
A number of vegetables, including potatoes, garlic, onions and carrots, will develop green patches if exposed to light - the better to photosynthesize. But in potatoes, something a little extra, and a little dangerous, happens, too. Natural or artificial light prompts the creation of defensive toxins called glycoalkaloids that can cause digestive distress, headaches and neurological issues if consumed in significant volumes.
But before you pitch your potatoes at the first hint of green, consider that such glycoalkaloids naturally occur in potatoes at harmless levels and even contribute to flavor. Additionally, the human body tends to excrete the toxins quickly, without incident, and you'll probably notice a bitter taste on the first bite of any seriously glycoalkaloid-riddled tubers.
When Nora Olsen, potato specialist for the University of Idaho, encounters a green potato, her first concern is flavor, not poisoning her family. Noting that potatoes in the United States are bred for low glycoalkaloid content and that you need to ingest quite a lot to get sick, she advises cutting off lightly greened patches and pitching any potatoes with large green areas. If serving young children, err on the conservative side.
Potato sprouts also pack higher levels of glycoalkaloids. Olsen doesn't worry much about pen-tip-sized sprouts and suggests just rubbing them off when you wash your potatoes. Bigger sprouts, along with the "eye" they sprouted from, should be cut off, but the potato itself may be dehydrated and not worth salvaging.
A scarred tomato
Like us, when fruits and vegetables suffer scrapes, they naturally seal up the wounds. Unlike us, however, they don't form scabs that fall off to reveal new tissue. So, the scars, made up of a woody material with pathogen-fighting properties, stick around on tomatoes and other types of produce.
Seeing a big scar? That's likely evidence of an injury that dates back to the tomato's early days; the scar just grew with the tomato. Tiny scratches might tell a story of rough handling during harvest. If you see an asterisk pattern on top of your tomato, or concentric rings, you're probably looking at the tomato's answer to stretch marks. It likely got an unexpected influx of water in the field, grew too fast, cracked open and then healed the cracks. Many heirloom tomatoes, not bred for aesthetic perfection, are more likely to develop scars.
No matter the cause, if the scar is dry and not showing mold or rot, the tomato is safe to eat.
At the store, I deliberately select tomatoes with dry scars because I worry others will pick over them and they'll go to waste. I don't notice small scars once I've made my sandwich or shakshuka. In my kitchen I do, however, cut around big, thick scars; they'll likely have an unappealing texture.
An apple with patches of brown, corky skin
A number of factors can cause apples to develop rough, brown skin, but excessive moisture is a common culprit, especially amid the wet springs of the East Coast. Known as russeting, the rough brown skin often starts around the little dip where the stem attaches and radiates outward. The pattern makes perfect sense when you consider how water might collect and drip down the apple.
Certain varieties, such as Golden Delicious, are more susceptible to russeting. While the appearance may be off-putting, it doesn't negatively impact flavor. In fact, some people swear they taste better.
A moldy peach
Aside from not tasting very good, moldy and rotting food sometimes harbors pathogens and toxins that can make you sick. What if it's just a little mold? For soft foods, such as peaches, the USDA recommends discarding the entire item because the mold could have penetrated it thoroughly. For harder foods, such as carrots or bell peppers, cut off the affected area and eat the rest. Mitcham, with the UC Postharvest Technology Center, said that one moldy strawberry doesn't doom the entire carton.
"I will take it out as quickly as possible because otherwise it might spread to others in the container," she said. And, of course, as with all produce, you'll want to give the fruit a good rinse before eating it.