LightMySky

Why Food Goes Bad and How to Stop It

Food spoils because microbes grow in it, and every preserving method is an attack on one of the things they need: warmth, water, air or time. Cooking, chilling, drying, salting and canning are the same idea applied differently.

No account needed. Progress saves in this browser.

What a learner can do afterwards

  • Name what microbes need to grow and match each preserving method to the thing it removes
  • Explain why the fridge slows spoiling but does not stop it
  • Say what cross-contamination is and give one habit that prevents it
  • Explain the difference between a use-by date and a best-before date, and which one matters for safety

1 · Read

Food spoils because tiny microbes grow in it. They need warmth, water, air, and time to multiply. Every preserving method attacks at least one of those needs.

Try it together

Chilling in the fridge slows microbes down, but it does not stop them, so old leftovers still turn. Drying takes their water away, salting draws water out, and canning seals air out with heat. That is why dried fruit, salty ham, and sealed cans all keep longer.

Microbes also hitch rides, which is called cross-contamination. Juices from raw chicken can carry them onto salad, hands, and boards. Wash fruit like melon before cutting, and keep raw and ready foods apart with clean hands and tools.

Good to know

Read packet dates with care. A use-by date is about safety, so do not eat the food after it passes. A best-before date is about quality, so the taste may fade but the food can still be safe.

Starve microbes of warmth, water, air, or time, block their rides between foods, and respect the use-by date.

2 · Watch

Take it off screen

Print a worksheetA4 with an answer key page for grown-ups. No screen, no internet.

Where it sits

Where this leads

Jobs that lean on this skill. Follow one to see everything it is built on.

Then practise

8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.

Spotted a problem on this page? Tell us
Why Food Goes Bad and How to Stop It · Design & Technology, ages 12 to 14 · LightMySky