This program is designed for students studying: Year 10 Food Technology Year 11 Food and Technology Year 12 Food and Technology

Transcription

1 Page 2 Page 3 Teacher's Notes Chemistry of Cooking Duration: 19 min Years: 8-12 A H 2 O CO 3 Na Timing information Set counter at zero at beginning of program Minutes Topic 01:06 Title 02:30 06:31 Denaturation 07:19 Coagulation 08:11 Raising 11:02 Gelatinisation 13:19 Browing reactions 15:53 16:42 Crystallisation 18:19 Credits Program Outline This program is designed for students studying: Year 10 Food Technology Year 11 Food and Technology Year 12 Food and Technology It is a combination of animation (30 %) and live action where food is prepared and the chemical reaction of the ingredients is explained. It involves making a simple sponge with trimmings to explain how and why particular methods are used to produce a perfect sponge. The basic physical and chemical changes which occur when a sponge is prepared and baked are identified and clear scientific explanations for these changes are defined. The physical and chemical changes referred to in this video are: Denaturation Coagulation Gelatinisation Browning reactions Crystallisation Introduction The video is divided into clearly defined sections, which can be easily used as a series of lessons. Good cooking is not based on mysterious skills possessed by the few. Anyone can develop the knowledge and skills by understanding: What happens to food as it s cooked? How do techniques like beating change food? How cooking changes food. Simple sponge ingredients are illustrated and their physical and chemical properties discussed. is explained in relation to the beating of eggs. Protein denaturation is explained in simple terms through animation. This enables students to understand the actual chemical properties of protein and why this knowledge is important when making a sponge. They can then expand this knowledge to other cooking techniques such as bread making and biscuits. Denaturation and Coagulation The link between denaturation and coagulation is explained using animation again to reinforce the chemical reaction which is unseen but the result is evident. The importance of foams are highlighted by a series of questions: why too little, or too much, beating won t lead to a good foam, why eggs straight out of the refrigerator won t fluff up so well why it s important to retain air in the mixture through the whole process. The role of sugar and flour in sponge making is discussed with emphasis on their physical and chemical properties.

2 Page 4 Page 5 Page 6 Baking Process The chemical composition of raising agents is comprehensively discussed allowing the student to see what effects the cooking process has on the overall mixture with emphasis on: physical and chemical changes produced by heat. effect of raising agents changes to starch grains and other substances in flour. browning reactions Gelatinisation,Coagulation and Dextrinisation Gelatinisation,Coagulation and Dextrinisation, which occur during cooking, are illustrated through animation and clearly explains to the students why these processes are important in the manufacture of the perfect sponge. The chemical change which occurs to the protein and sugars in the mixture are emphasised to reinforce the importance of understanding the chemical composition of the nutrients present in the ingredients. Browning Reactions Varying browning reactions are discussed introducing students to the French term Mallard Reaction, a reaction between carbohydrates and proteins, producing browning on scones, bread, cakes and potatoes. It is also seen when milk and egg are used in glazes. The term emulsification is explored through the whipping of the cream. The chemical components of the cream are analysed and the emulsification processed explained using animation and practical demonstration. Irreversibility of the beating process is discussed and the overbeating end result of butter is mentioned. Crystallised Crystallised or candied fruit is the last process to be discussed on this video. It details the procedure and the chemical reaction of the sugar, which produces a clear solid saturated sugar solution. The video ends with a summary of these terms Denaturation Coagulation Gelatinisation Raising Browning reactions Crystallisation It reinforces their importance in the preparation cooking and decoration of a simple egg sponge. The activity sheets are designed to be done in sections also. The senior students would be expected to expand on the information provided in each activity. Year 10 students could be shown the video in sections as they start exploring the chemical reaction of different processes other than sponge making. CREDITS Writer/Producer Rod Rees Camera Tim Mummery Editor Dominique Fusy Sound Brendon Maher Online Editor Roddy Balle Teachers notes Mary Gabrielle Fitzgerald Executive Producer John Davis Copyright CLASSROOM VIDEO (2000) and Orders: Classroom Video 1/1 Vuko Place Warriewood, NSW, 2102 Ph: (02) Fax: (02) orders@classroomvideo.com.au UK: Phone: (01454) Fax: (01454) Canada: Phone: (604) Fax: (604)

3 Activity Sheet 1 1. What are the ingredients for a simple egg sponge? 2. Name the physical and chemical properties of eggs Physical properties Chemical properties 3. What happens when you beat eggs? 4. Define aeration. 5. The volume increases up to times when the air bubbles are trapped to form froth. 6. Adding and stabilises the foam. 7. Explain what is meant by the term denaturation. 8. When the protein molecule chains unravel it is called and when they link with each other it is called. 9. Coagulation and the foam. 10. Why does too little, or too much beating lead to poor foam? 11. Why don t eggs, straight out of the refrigerator, fluff up well? 12. Why is it important to retain air in the mixture throughout the process of sponge making? 13. Name the chemical properties of sugar? 14. What part does sugar play in the structure of the sponge? 15. Name the chemical properties of flour. 16. Why is flour used in sponge making? 17. Give two reasons for sifting flour. 18. Name the raising agents in the sponge mixture and explain how they reacte during the cooking process. a. b. c. Page 7

4 Activity Sheet 1 (Cont'd) 19. What happens to the flour during cooking? 20. As the mixture is heated, penetrates and the grains swell. They eventually and the starch to form a gel. 21. Why is flour used to thicken sauces, gravies and custards? 22. Does this gelatinisation process also contribute to the texture and strength of the sponge? 22. At degrees C, the protein coagulates; the protein strands together. 23. What is gluten? 24. How is the shape of the cake fixed? 25. How does the cake rise evenly? 26. How is the crust formed on the sponge? 27. What is meant by the term dextrinisation? 28. What nutrient causes caremelisation? 29. What is meant by the term Mallard Reaction? 30. Explain how milk and egg create a glaze. 31. What is meant by the term emulsification? 32. What is the chemical reaction of protein when cream is whipped? 33. Is the whipping process reversible? Explain your answer. 34. If you continue to beat cream what is the end result? 35. The basic process of crystallisation involves: The fruit peel is cooked with a. The of sugar is gradually increased until the fruit flesh is with the sugar. When it cools, the sugar. 36. Why does food go stale? 37. What are the best conditions for storing a sponge? Page 8

5 Activity Sheet 2 Explain the following terms using the your knowledge of how the physical and chemical properties of the follow ingredients of a sponge react to one another and to the process involved in sponge making. 2 eggs 1/3 cup castor sugar 1/3 cup flour ½ teaspoon baking soda Denaturation Coagulation Gelatinisation Browning Reaction Crystallisation Page 9