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NCERT Solutions for Class 5th The World Around Us Chapter 3 Food Preservation — Mystery #3

Book page 43 Updated on2026-09-19

Q1.
Mystery #3: How do we save our food from spoilage?
Answer

We save food by keeping microbes away from it. We do that in five main ways, and Detective Disha found all of them in her own home.

  1. Drying and dehydration. Keep the food in the Sun until its water is gone. Chillies dried on a mat become chilli powder that lasts a whole year. Papads, badis, aam papad and dried fish are made this way.
  2. Pickling and oiling. Put the food in salt and spices and pour oil on top. The oil stops air from getting in — that is how Paati's mango pickle stayed good for two months.
  3. Refrigeration and freezing. Keep the food cold. A fridge is too cold for microbes to grow well, so milk, vegetables, butter and cake stay fresh in it. A freezer is colder still.
  4. Salt, sugar and spices. Disha's grandfather told her that people have long used salt, sugar and spices like black pepper to keep food from spoiling. Salt pulls the water out of the food. We still use these methods today — in murabba, in jam, in salted fish.
  5. Airtight cans and packaging. In food factories, food is sealed in cans and packets so that no air, and therefore no microbe, can reach it.
Take away moisture → drying
Take away air → oil, cans, sealed packets
Take away warmth → fridge, freezer
Add salt, sugar or spices → microbes cannot grow in them
Why we need to preserve at all: Fruits, vegetables, grain and fish are ready only at certain times of the year, and in certain places. Preserving lets a family eat mangoes in December, use chilli powder in June, and carry food on a journey — instead of throwing away what cannot be eaten at once.
Do you know? Matka as a cooler: we use clay pots (matkas) to keep water cool. Water seeps very slowly through the clay wall and evaporates from the outside, and evaporation takes heat away — so the water inside stays cool without any electricity.
Q2.
“Why are you drying these, Amma?”, she asked.
Answer

Amma answered, “To make chilli powder. This should last us for the entire year!” The chillies are dried so that they do not spoil, and so that they can be ground into powder and stored.

What drying does, step by step:

  1. Fresh green or red chillies are full of water. Water is exactly what microbes need.
  2. The chillies are spread on a mat, in a single layer, in strong sunlight.
  3. The Sun's heat makes the water inside them evaporate — it turns into water vapour and goes into the air.
  4. After some days the chillies become dry, light and brittle. They snap when you bend them.
  5. Now there is no moisture left, so microbes cannot grow. The dried chillies are ground into chilli powder and kept in a dry container for the whole year.

Finding #3: Drying in the Sun removes the moisture from the chillies. Without moisture, microbes cannot grow!

Why the Sun is enough: Water does not need to boil to leave a food. Gentle heat and moving air are enough — the same reason wet clothes dry on a line. Sun-drying costs nothing, needs no machine, and works in most parts of India for most of the year.
One rule while sun-drying: the food must be brought in before evening, when the air becomes damp. If it is left out at night it takes moisture back in, and then it can grow mould instead.
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