Often when fruits and vegetables look dangerous to eat, they could in fact just be showcasing some harmless science lessons. Picture: The Washington Post
Often when fruits and vegetables look dangerous to eat, they could in fact just be showcasing some harmless science lessons. Picture: The Washington Post

Manky looking fruit and veg: How to tell if it's safe to eat

By Rachael Jackson Time of article published Jul 30, 2019

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Fresh fruit and vegetables can do some alarming things. They can crack open, change colour, sport scars, and try to make new produce on your kitchen counter. 

“When in doubt, throw it out,” you might tell yourself. But hold on. Consider taking a second look at that scarred tomato or sprouting onion. 

While sometimes “off-looking” fruits and veggies are telling you that they’re no longer good to eat, they’re often just 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 has sprouted green shoots. Is your stir-fry doomed? Not at all. The onion, prompted by factors such as age and temperature, moved to its next stage of life.

“It’s not dangerous to eat,” said Elizabeth Mitcham, of the University of California Postharvest Technology Centre. “I’m not going to throw it away.” Having sent sugars and water to the sprout, the onion might taste a little bitter and more fibrous.

I’ve sautéed onions and garlic with small sprouts and haven’t noticed unpleasant flavours.

A green potato

Many vegetables will develop green patches if exposed to light - the better to photosynthesise. But in potatoes, something 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.

Such glycoalkaloids naturally occur in potatoes at harmless levels and contribute to flavour. Additionally, the human body tends to excrete the toxins quickly, without incident, and you’ll probably notice a bitter taste on the first bite.

When Nora Olsen, a potato specialist for the University of Idaho, encounters a green potato, her first concern is flavour, not poisoning her family. 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 have higher levels of glycoalkaloids. Olsen doesn’t worry much about pen-tip-sized sprouts and suggests rubbing them off when you wash your potatoes. Bigger sprouts, along with the “eye” they sprouted from, should be cut off, but the potato might be dehydrated and not worth salvaging.

A scarred tomato

Like us, when fruits and vegetables suffer scrapes, they seal the wounds. Unlike us, they don’t form scabs. The scars, made up of a woody material with pathogen-fighting properties, stick around on tomatoes and other types of produce.

A big scar is probably evidence of an injury that dates from 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 probably got an unexpected influx of water in the field, grew too fast, cracked open and then healed the cracks. No matter the cause, if the scar is dry and not showing mould or rot, the tomato is safe to eat. In my kitchen, I cut around big, thick scars; they’ll probably have an unappealing texture.

An apple with patches of brown, corky skin

Many factors can cause apples to develop rough, brown skin, but excessive moisture is a common culprit. 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.

While the appearance might be off-putting, it doesn’t affect flavour.

A mouldy peach

Apart from not tasting good, mouldy and rotting food sometimes harbours pathogens and toxins that can make you sick. What if it’s just a little mould?

For soft foods, such as peaches, the US Department of Agriculture recommends discarding it because the mould could have penetrated the entire fruit. 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, says one mouldy strawberry doesn’t doom the entire carton - just take it out as quickly as possible before it spreads to the others. 

The Washington Post

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