Everyday Explained: Can you cut off the mouldy part of an onion and eat the rest?

Learn from a specialist on if it is safe to eat mouldy onions and if cooking kills the mould.

Onions are integral to everyday cooking. You will find them in everything from fresh salads and sandwiches to curries. They are practically a kitchen staple. But sometimes, when you reach for an onion, you may notice black, green, or fuzzy mould on its surface.

This may leave you thinking: should you throw away the entire onion or simply peel off the attached layers and use the rest? Can cooking, frying, or boiling make a mouldy onion safe to eat? ALSO READ: Everyday explained: Why do clothes smell musty after drying indoors?

In today's edition of Everyday Explained, let's hear from a specialist about whether it is safe to cook mouldy onions. Dr Ashok Kumar, senior consultant and head of medical gastroenterology at Dharmshila Narayana Superspecialty Hospital, Delhi, told HT Lifestyle that mould on an onion should not be treated as merely a surface-level problem that can be resolved by peeling or chopping away the affected part.

What should you do with mouldy onions?

Why? It turns out that mould may not be limited to the surface. He said, "It may look as though it is just growing on the surface; mould can form microscopic root-like structures that grow deeper into the food.”

Is it safe to eat cooked mouldy onions?

You may assume that cooking onions at a high temperature will destroy the mould and make them safe to eat. But the expert cautioned that onions cooked with mould on them are not necessarily safe to eat.

Dr Kumar said, “Heat may kill most mould-related toxins and other substances which may have formed in the food, but will not necessarily kill all such toxins. Cooking, frying or boiling should not be used to ‘neutralise' mould contamination.”

How to know your onion is dirty and not mouldy?

Not every dark or discoloured patch indicates mould. The doctor revealed that, in a dirty onion, only the outer skin may be discoloured due to dryness. Once you peel it, the discolouration should come off. But if the onion is mouldy, you will see that the inner edible layers may also be affected.

Who should be more cautious?

Dr Kumar advised people with allergies, asthma, or impaired immunity and other respiratory sensitivities to be careful when handling or smelling mouldy food, since the mould spores may cause respiratory or allergic reactions.