L12. Food Additives Lesson Outcomes How I did Targets APP: AF2, AF4 How I did Targets Task 1: Recall the main types of food additives and describe their function. Grade C Task 2: Describe what emulsifiers are. Grade B Task 3: Describe how emulsifiers work. Grade A/A* Connector: (Grade D) Describe what do you know about food additives

Homework Homework task: 1. Research food additives and some of the issues concerned with their uses. Example: allergies and hyperactivity in some children are associated with some food colourings like tartrazine. Due date: Criteria for Grade C: Criteria for Grade B: Criteria for Grade A/A*:

BIG picture What skills will you be developing this lesson? Numeracy Literacy  Team work Self management  Creative thinking Independent enquiry  Participation  Reflection  How is this lesson relevant to every day life? (WRL/CIT)

Extension: can you group the food additives in categorise. Task 1 (Grade C) Keywords for Task 1: Food additive Food colour Task 1: Paired work-Identify the additives on each food label given to you. Extension: can you group the food additives in categorise.

Task 1 Now write down in no more than four words, what comes to mind when you think of food additives. Share your answer in small groups. Pairs feed back one of their answers to the rest of the class, ‘passing’ if their answer has already been given. Use student book pages 64-64 to explain what food additives are, the main types and what they do.

Task 1 Practical: To investigate the effect of sulfur dioxide on browning in apple slices. While you are doing the practical here is something you should do: Thinking about Sodium hydrogensulfite solution releases sulfur dioxide. Why should the solution affect the browning reaction in apples? Asking questions 1 What effect did crushing have on the rate of browning? Suggest why it should have this effect. 2 What effect did sodium hydrogensulfite solution have on the rate of browning? Suggest why it should have this effect. Spreading the word Describe what you did and what you found out.

Answers 1 The crushed apple should go brown fastest; more of it is exposed to the air 2 The apple from the water should go brown fastest; the sodium hydrogensulfite solution releases sulfur dioxide, which acts as an antioxidant.

How can I improve on task 1? Task 1: Review Go back to your lesson outcome grid and fill out the ‘How I did’ and the ‘Targets’ column. Lesson Outcomes How I did Targets Task 1: Recall the main types of food additives and describe their function. Grade C Met? Partly met? Not met? How can I improve on task 1?

Emulsion An emulsion is a mixture of two immiscible (unblendable) substances. One substance is dispersed in the other. Examples of emulsions include butter and margarine, milk and cream, espresso, mayonnaise, the photo-sensitive side of photographic film, magmas and paint.

Emulsification Emulsion is two LIQUIDS that will not mix (IMMISCIBLE for example: oil and water) but have been made to mix together through the addition of another chemical called Emulsifier. Write down the immiscible substances used in making mayonnaise.

How an emulsifier works? What keeps vinegar trapped in oil?

How an emulsifier works?

How an emulsifier works? Let’s go deep inside mayonnaise Where am I found? What is my role? Where is my dear WATER? VINEGAR is a weak solution of ethanoic acid in water.

egg emulsifiers emulsion mayonnaise mix oil Summary Oil and vinegar do not usually __________ . If you shake them up, they soon separate, the __________ floating on the surface. But if you shake them up with egg yolk you get __________ . Mayonnaise is a thick __________ , with tiny vinegar droplets trapped in the oil. They do not separate out because lecithin molecules from the __________ yolk bind them in place. Chemicals that do this are called __________ . mix oil emulsion mix egg emulsifiers egg emulsifiers emulsion mayonnaise mix oil

How can I improve on task 2? Task 2: Review Go back to your lesson outcome grid and fill out the ‘How I did’ and the ‘Targets’ column. Lesson Outcomes How I did Targets Task 2: Describe what emulsifiers are. Grade B Met? Partly met? Not met? How can I improve on task 2?

Demonstration : Effect of an emulsifier on an oil-water mixture. Task 3: (Grade A/A*) Task 3: Demonstration : Effect of an emulsifier on an oil-water mixture. Video_001

Emulsifiers An emulsifier is a substance which stabilizes an emulsion, frequently a surfactant. Detergents are another class of surfactant, and will chemically interact with both oil and water, thus stabilising the interface between oil or water droplets in suspension. This principle is exploited in soap to remove grease for the purpose of cleaning. A wide variety of emulsifiers are used in pharmacy to prepare emulsions such as creams and lotions.

Task 3: (Grade A/A*) Task 3: Emulsifiers 1. Emulsifiers help oil and water to mix, and then not separate. a Name a food that contains emulsifiers. b Describe the structure of an emulsifier molecule. Include these words in your answer: hydrophilic, hydrophobic

Extension Monosodium glutamate, MSG, is a flavour enhancer added to processed foods like soups and sauces. Some people report feeling sick after eating food containing MSG. Others suffer from a burning feeling and chest pains. MSG is an approved food additive, E621. a In scientific studies, some people reported similar symptoms when they thought the food contained MSG, even when it did not. Suggest why this observation is important. b Some effects on nerves have been observed in laboratory animals when large doses of MSG are injected under their skin. Discuss the extent to which this observation is important when deciding if it is safe to add MSG to food. c Glutamate, released from MSG, is found naturally in the body. Suggest how this might affect the view of MSG as being safe.

How can I improve on task 3? Task 3: Review Go back to your lesson outcome grid and fill out the ‘How I did’ and the ‘Targets’ column. Lesson Outcomes How I did Targets Task 3: Describe how emulsifiers work. Grade A/A* Met? Partly met? Not met? How can I improve on task 3?

- A world without additives. Review of lesson Interactive_001, a drag and drop activity: Match additive type to why it is used. Describe: - A world without additives.

Technicians’ notes Student Activity 1.12 Eye protection Two boiling tubes Cork borer Knife or safety blade Pestle and mortar Stopclock Teat pipette Test tube rack White tile Apple 0.1m sodium hydrogensulfite solution – the solution itself is low hazard but liberates sulfur dioxide gas, which is toxic

Technicians’ notes Student Activity 1.12 In the apple browning practical ensure there is adequate ventilation and make sure that you know who has asthma or similar breathing difficulties – sulfur dioxide can exacerbate these. The students do not need to know details of the mechanism of browning, just that it involves the apple reacting with oxygen in the air. Sulfur dioxide acts as an antioxidant and will increase the time taken for browning to happen.

Technicians’ notes Demonstration 2 Two boiling tubes with bungs Stop clock Three teat pipettes Test tube rack Cooking oil Whisked egg yolk Whisk the yolk of one egg shortly before the demonstration.

Demonstration: Notes 1 In the demonstration, to each boiling tube add water to a depth of 2 cm and cooking oil to a depth of 2 cm. Add whisked egg yolk to one boiling tube to a depth of 1 cm. Note the appearance of the contents of both boiling tubes. Insert the bungs and shake vigorously for 30 seconds. Leave the boiling tubes in the test tube rack and note the appearance of each one at various times during the rest of the lesson. Ensure that students understand that oil and water do not mix, and that emulsifiers help them to mix without separating again. All students need to know that emulsifier molecules have a hydrophilic end and a hydrophobic end. Higher Tier students also must be able to describe how they bond to water molecules or oil molecules.