Notes For All Chapters – General Science Class 7
Food Safety
1. Introduction
- Food is essential for growth, energy, and good health.
- It contains important nutrients such as carbohydrates, proteins, fats, vitamins, minerals, fiber, and water.
- However, if food gets spoiled, contaminated, or adulterated, it can cause serious health problems.
2. Food Spoilage
1. Food is spoiled when it changes in color, smell, texture, or taste.
2. Spoiled food loses nutrients and can cause illness if consumed.
3. Common causes of food spoilage:
- Microorganisms (bacteria, fungi, mold) grow on food.
- Chemical reactions change the food’s composition.
- Improper storage (damp places, wrong temperature).
- Physical damage (during transportation, handling).
Examples of Food Spoilage
| Food | Signs of Spoilage |
|---|---|
| Fruits & Vegetables | Change in color, bad smell, become soft |
| Bread & Cheese | Fungal growth (mold) |
| Milk | Becomes sour and curdles |
| Meat & Fish | Bad smell, slimy texture |
| Cooked food | Becomes sticky, develops bacteria |
3. Food Wastage
- Food wastage happens when edible food is thrown away or spoiled.
- Causes of food wastage:
- Improper farming methods.
- Overcooking or storing food incorrectly.
- Throwing away leftovers instead of reusing.
- Buying more than needed and letting food expire.
Ways to Reduce Food Wastage
- Take only as much food as needed.
- Store food properly in refrigerators and dry places.
- Reuse leftovers in creative ways.
- Buy fresh food in small quantities to prevent waste.
4. Food Storage and Preservation
- Food storage is keeping food safe and fresh for a longer time.
- Food preservation is preventing spoilage using various methods.
Methods of Food Storage & Preservation
| Method | Description | Examples |
|---|---|---|
| Freezing | Storing food at low temperatures to slow spoilage. | Ice cream, frozen vegetables |
| Drying | Removing water from food. | Dried fruits, grains |
| Boiling | Killing bacteria by heating food. | Milk, soup |
| Air-tight Packing | Prevents air from entering food packets. | Chips, biscuits |
| Pasteurization | Heating food to kill germs & cooling it quickly. | Milk, juices |
| Adding preservatives | Using natural or chemical preservatives. | Pickles, jams |
5. Food Protection and Food Preservation
- Food Protection: Preventing food spoilage due to pests and bacteria.
- Food Preservation: Using preservatives to increase shelf life.
Types of Preservatives
| Preservative Type | Examples |
|---|---|
| Natural Preservatives | Salt, sugar, oil (used in pickles, jams) |
| Chemical Preservatives | Vinegar, sodium benzoate (used in sauces, jellies) |
| Gas Packing | Nitrogen gas in chips packets |
| Irradiation | Using X-rays or gamma rays to kill microbes |
6. Food Adulteration (Unsafe Food Practices)
1. Food adulteration is mixing harmful or low-quality substances in food to increase quantity or make it look better.
2. Examples of food adulteration:
- Mixing water in milk.
- Adding chemicals to fruits to make them ripen faster.
- Mixing cheap powders in spices like turmeric or chili powder.
Effects of Adulterated Food
- Can cause food poisoning, stomach pain, long-term health issues.
- Some chemicals increase the risk of cancer.
7. How to Identify Adulterated Food?
| Food Item | Possible Adulterant | Test to Identify |
|---|---|---|
| Milk | Water | Drop milk on a smooth surface; if it spreads quickly, it contains water. |
| Chili Powder | Brick dust | Add water to chili powder, if red dust settles, it has brick powder. |
| Turmeric | Chemical dyes | Add acid; if it turns red, it has harmful chemicals. |
| Honey | Sugar syrup | If honey does not dissolve in water, it is pure. |
8. Government Regulations for Food Safety
- FSSAI (Food Safety and Standard Authority of India) checks food quality and sets safety standards.
- The Prevention of Food Adulteration Act (1954) punishes those who sell harmful food.
9. Safe Food Practices to Follow
- Check expiry dates on packaged food.
- Wash fruits and vegetables properly before eating.
- Avoid street food that is kept in unhygienic conditions.
- Do not buy food with unusual colors or smells.
- Store food properly to prevent spoilage.
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