All Form Two Food and Nutrition Chapters
- Chapter 1Food AdditivesRead below · Free
- Chapter 2CerealsContinue in the app
- Chapter 3MalnutritionContinue in the app
- Chapter 4Meal PlanningContinue in the app
Lesson Objectives
By the end of this chapter, students should be able to:
- Define food additive and related key terms.
- Explain why food additives are used.
- Distinguish between natural and artificial additives.
- State the guidelines for using food additives.
- Identify the main categories of food additives with examples.
1. Key Words and Concepts
Before we begin, let us understand the following terms:
2. Concept of Food Additives
Food additives are substances added to food in small amounts on purpose. They are not food themselves but do a particular job, such as:
- Keeping food safe and fresh for longer.
- Improving taste, colour or appearance.
- Improving texture (mouthfeel).
- Replacing nutrients lost during processing.
Why Are Food Additives Important?
- Preserve food: stop mould, bacteria and yeast, which reduces food poisoning.
- Maintain nutritional quality: vitamins and minerals can be added (fortification).
- Improve sensory qualities: make food look, smell and taste better.
- Aid processing: help ingredients mix, keep powders free-flowing and make bread rise.
- Give convenience: make ready-to-eat meals and long-life products possible.
Natural and Artificial Additives
| Type | Source | Examples |
|---|---|---|
| Natural | Plants or animals | Beetroot juice (red colour), lemon juice or citric acid (preservative), pectin from fruit (jam) |
| Artificial (synthetic) | Made in a laboratory | Tartrazine (yellow colour), saccharin (sweetener), sodium benzoate (preservative) |
Both types must be thoroughly tested and approved before use in food.
🔦 Spotlight — Did You Know?
Salt (sodium chloride) is one of the oldest food additives. Ancient Egyptians used it to preserve fish and meat more than 4,000 years ago. Many Tanzanian families still preserve fish by salting and drying.
🗣️ Classroom Activity 1: Label Detective
Bring the label from a packet of biscuits, juice, noodles or sweets.
- List every additive named on the label.
- Put each into a category (preservative, colour, sweetener and so on).
- Decide which are natural and which are artificial, then share with the class.
3. Guidelines for Using Food Additives
Strict rules protect our health, and food manufacturers must follow them:
| Guideline | Meaning |
|---|---|
| Permitted list only | Use only tested and approved additives; unapproved additives are illegal and dangerous. |
| Correct purpose | Use the right additive for its approved job (a preservative must not be used just to change colour). |
| Maximum level | Do not use more than the safe limit; too much can be toxic. |
| Label declaration | State additives clearly on the package, by name or E-number. |
| No deception | Never hide poor quality or spoilage with additives. |
| Minimal amount | Use as little as necessary (Good Manufacturing Practice). |
Take special care with vulnerable groups: some colours may affect children's behaviour and sulphites can trigger asthma.
🧠 Jog Your Brain — Check Your Understanding
Answer the questions. Click “View Answer” to reveal the correct response.
1. A substance added to food on purpose to improve keeping quality or appearance is a:
2. Which additive stops the growth of bacteria, yeast and moulds?
3. An emulsifier helps to:
4. The highest safe amount of an additive in a food is the:
5. Why must additives be declared on the label?
4. Categories of Food Additives
1. Preservatives
Stop spoilage by microorganisms and give food a longer shelf life.
- Sodium benzoate: soft drinks, sauces, margarine.
- Sulphur dioxide: dried fruits, sausages.
- Sorbic acid: cheese, yoghurt, baked goods.
- Nitrates and nitrites: cured meats such as bacon and ham (they also give a pink colour).
2. Antioxidants
Prevent fats and oils from reacting with oxygen and becoming rancid. They also stop cut fruit turning brown.
- Vitamin C (ascorbic acid, E300): fruit juices, canned fruit.
- Vitamin E (tocopherols): vegetable oils, margarine.
- BHA and BHT: snacks, butter, cereals.
3. Emulsifiers, Stabilisers and Thickeners
- Emulsifiers help oil and water mix (lecithin in chocolate and mayonnaise).
- Stabilisers keep the mixture even (pectin in jam, guar gum in ice cream).
- Thickeners make food thicker (corn flour, gelatine in soups and puddings).
4. Food Colourings
- Natural: caramel (cola, brown bread), beetroot red (sweets), turmeric (curry powder).
- Artificial: tartrazine (E102, yellow), Sunset Yellow (E110), Allura Red (E129).
5. Flavourings and Flavour Enhancers
- Flavourings add a taste or smell (vanilla extract, lemon oil, artificial vanillin).
- Flavour enhancers bring out existing flavour (MSG, E621, in soups, noodles and stock cubes).
6. Sweeteners
- Nutritive (give energy): sucrose, glucose, fructose.
- Non-nutritive (little or no energy): saccharin, aspartame, sucralose, used in “sugar-free” products.
7. Other Categories
- Acids or acidity regulators: citric acid, phosphoric acid.
- Anti-caking agents: keep powders free-flowing (calcium silicate in table salt).
- Raising agents: baking powder helps cakes and bread rise.
- Fortificants: vitamins and minerals added to improve nutrition (iodine in salt, vitamin A in oil, iron in flour).
🔦 Spotlight — Why Is Ham Pink?
The pink colour of bacon and ham comes from nitrites. Without them the meat would look grey-brown. The same additives also help prevent the growth of the bacterium that causes botulism.
✏️ Classroom Activity 2: Sort the Additives
In groups, copy these additives onto cards: citric acid, tartrazine, aspartame, lecithin, vitamin C, baking powder, iodine in salt, sodium benzoate.
- Sort the cards into the categories above.
- Give one food in which each is used.
5. Chapter Summary
- Food additives are substances added on purpose to food for a specific job such as preserving, colouring, thickening or enhancing flavour.
- They can be natural or artificial, and both must be tested for safety.
- Guidelines: permitted list only, correct purpose, maximum levels, label declaration, no deception and minimal use.
- Main categories: preservatives, antioxidants, emulsifiers, stabilisers and thickeners, colourings, flavourings and enhancers, sweeteners, and others (acids, raising agents, fortificants).
- Reading labels carefully helps us make informed and healthy food choices.
📝 End-of-Chapter Assessment — Suggested Answers
Complete the questions, then click the buttons to check your answers.
Part A — Multiple Choice (10)
1. Sodium benzoate is used as a:
2. Which is a natural food colouring?
3. Saccharin is a:
4. MSG is a:
5. Lecithin in chocolate acts as an:
6. Iodine added to salt is an example of a:
7. Baking powder is a:
8. Which stops fats and oils going rancid?
9. Corn flour in soup acts as a:
10. E-numbers show that an additive has been:
Part B — Short Answer (8)
1. Explain the difference between a preservative and an antioxidant. Give one example of each.
2. State three reasons why food additives are used in the food industry.
3. A label on an orange drink lists “Sunset Yellow (E110)”. (a) What category is it? (b) Why should a buyer know its E-number?
4. List three guidelines a manufacturer must follow when using additives.
5. Name one natural and one artificial food colouring.
6. What is the main job of an emulsifier?
7. A home-baked cake and a factory cake are left for a week. Which is likely to spoil first and why?
8. Why might a person prefer a home-baked cake even if it spoils faster?
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