Summary
Chapter 3 of the Class 5 The World Around Us NCERT textbook (Our Wondrous World), "The Mystery of Food", follows detective Disha as she uncovers why food spoils, how microbes cause it, and the science behind traditional preservation methods — download the PDF and read a summary of food spoilage, drying, pickling, refrigeration, teeth, and oral hygiene as taught in the chapter.
- Microbes and Food Spoilage — Microbes are tiny living things found in soil, water, air, plants, animals, and inside us. They need moisture, air, and the right temperature to grow on food, causing it to smell foul and develop coloured patches (mould).
- Methods of Food Preservation — The chapter covers drying and dehydration (removing moisture so microbes cannot grow), pickling with oil (oil blocks air, stopping microbial growth), refrigeration (cold temperatures slow down microbes), and sealing food in airtight cans and packaging.
- Good Microbes and Fermentation — Not all microbes are harmful — microbes in the air help idli batter rise, and microbes in curd help good bacteria in the stomach aid digestion, making them useful when eating for an upset stomach.
- Teeth, Chewing, and Oral Hygiene — Humans have four types of teeth — incisors to cut, canines to tear, premolars to crush, and molars to grind. Chewing food properly releases saliva that helps digestion; regular brushing and dental check-ups prevent cavities and toothaches.
Key points & formulas
- 01Microbes are microscopic living things visible only under a microscope; a visible patch of mould is a colony of thousands of them.
- 02Microbes need moisture, air, and the right temperature to grow — removing any one of these stops spoilage.
- 03Drying in the sun removes moisture from foods like chillies, letting them last the whole year as chilli powder.
- 04Covering pickles with oil keeps air out and prevents microbial growth, which is why Paati's mango pickles stayed fresh for months.
- 05Cold temperatures in a refrigerator slow down microbes, preserving milk, vegetables, butter, and other perishables.
- 06Salt, sugar, and spices like black pepper have traditionally been used in India to preserve food from spoiling.
- 07Chewing food properly releases saliva that aids digestion, and eating slowly prevents choking — different teeth serve different roles in this process.
Frequently asked questions
01What is the main topic of Chapter 3 The Mystery of Food in Class 5 Our Wondrous World?
The chapter follows a curious girl named Disha who investigates why food spoils and how we can preserve it. It covers microbes, several food preservation methods, the role of good microbes, teeth and chewing, and oral hygiene.
02What are microbes and why do they cause food to spoil?
Microbes are tiny living things found everywhere — in soil, water, air, plants, animals, and inside us — that are so small they can only be seen through a microscope. They grow on food and change its taste, smell, and appearance, causing it to spoil.
03What three things do microbes need to grow on food?
According to Disha's brother Aditya, microbes need moisture, air, and the right temperature to grow. Removing any one of these three conditions can stop microbes from spoiling food.
04How does drying in sunlight preserve food like chillies?
Drying in the sun removes moisture from the chillies. Without moisture, microbes cannot grow, which is why dried chilli powder can last for an entire year.
05Why is oil added to pickles, and how does it preserve them?
Oil is added to pickles to stop air from getting in, because microbes need air to grow. Disha's Paati explained that covering pickled green mangoes with mustard oil kept them safe and delicious even after two months.
06How does refrigeration preserve food?
Fridges make the temperature too cold for microbes to grow, which slows them down. That is why items like milk, vegetables, butter, and cake are stored inside a refrigerator.
07What are the four types of teeth and what does each type do?
The four types are incisors (cut food), canines (tear food), premolars (crush food), and molars (grind food). Each type plays a different role in breaking down food before it is swallowed.
08Why is it important to chew food properly before swallowing?
Chewing food properly breaks it down into smaller pieces and releases saliva, which helps in digestion. Swallowing food too quickly without chewing can also lead to choking.
09How are good microbes helpful to our body?
Good microbes in curd and buttermilk join the good microbes already in our stomach and help in digestion. Microbes in the air also help make idli batter rise and become fluffy.
10What are some traditional methods used to preserve food in India?
The chapter mentions drying in sunlight, pickling with oil, refrigeration, and using salt, sugar, and spices like pepper to keep food from spoiling. Food factories also preserve food in airtight cans and packaging to keep microbes away.
11Why do seasonal fruits taste better and what example does the chapter give?
The chapter states that fruits taste best when eaten in their season and that waiting for them increases the joy. Lychee is given as an example of a seasonal fruit that Disha and her family eagerly enjoyed after almost a year.
12What dental advice does the dentist give Disha about oral hygiene?
The dentist tells Disha to rinse her mouth after eating, brush her teeth regularly, and eat fewer sweets. The chapter states that if a tooth is aching or a cavity develops, a visit to the dentist is necessary.
More chapters in Our Wondrous World
Read Chapter 3 of Our Wondrous World, the Class 5 The World Around Us NCERT textbook (2026-27 edition), online for free: the complete chapter as published by NCERT with every diagram, solved example and exercise, with step-by-step solutions, answers and revision notes. Open the NCERT PDF above, or browse all NCERT Class 5 textbooks.
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