How to tell if food has really gone bad

Four checks, in the order that actually works — and the five myths that send people to the hospital.

Smell

The most reliable everyday test.

Sour, sharp or 'cheesy' where it shouldn't be — dairy, cooked rice, sauces.
Ammonia or strong fishy smell on seafood and deli meat.
Rancid, crayon-like or putty smell on oils, nuts and whole-grain flour.
Yeasty, boozy or fermented smell on fruit, juice and yogurt.

Texture

Trust your fingers before your eyes.

Slime or a sticky film on meat, poultry or deli slices that won't rinse off.
Greens that go dark and translucent, then wet.
Fruit that leaks or collapses under light pressure.
Ropey, stringy sauces or soups.

Look

Useful, but easy to misread.

Fuzzy mold of any color — white, green, black, pink.
Grey-green tint on meat, iridescent sheen on deli meat.
Cloudiness or a film floating on liquids.
Brown inside ground beef alone is normal oxygen exposure, not spoilage.

The package

Sometimes the container tells you first.

Bulging or puffed lids and pouches — pressure means gas from bacteria.
A hiss or fizz on opening something that isn't carbonated.
Leaking, dented seams or rust on cans.
Frost inside a freezer bag means thaw-refreeze cycles: safe, but quality is gone.

Five myths worth unlearning

“I can just scrape the mold off.”

Only for hard cheese, firm carrots or cabbage — cut 2.5 cm (1 inch) around and below. Soft food, bread, jam, yogurt and cooked dishes go in the bin whole, because the roots run invisibly through them.

“It smells fine, so it's fine.”

The bacteria that make you ill — salmonella, listeria, E. coli — don't smell, look or taste like anything. Smell catches spoilage, not danger. Use the time limits too.

“The date on it has passed, so it's dangerous.”

'Best before' is about quality. 'Use by' is the safety one, and it matters most for meat, fish, ready meals and unpasteurised dairy.

“I'll just taste a tiny bit.”

A tiny bit is enough. There is no safe tasting test — ever.

“It was only out overnight and the room was cool.”

Two hours at room temperature is the limit for anything perishable (one hour above 32°C / 90°F). Reheating does not undo it — some toxins survive boiling.

Checking one specific food?

Every food page lists its own spoilage signs alongside fridge and freezer times.

Look up a food