Question 1: Define the term 'gelatinisation' as it relates to starch in cooking. Explain what happens to the starch molecules during this process.

Answer: Gelatinisation is the process where starch granules absorb water and swell when heated, leading to thickening of the mixture. During this process, the starch molecules, mainly amylose and amylopectin, absorb water, swell, and eventually burst, releasing starch into the mixture which thickens it.

Question 2: Describe the role of emulsifiers in food products such as mayonnaise or salad dressings.

Answer: Emulsifiers help mix oil and water by reducing surface tension, creating a stable emulsion. They enable ingredients that normally separate, like oil and water, to stay combined, resulting in a smooth, uniform product.

Question 3: Explain how the functional property of foaming is used in making sponge cakes. Include the role of air in this process.

Answer: Foaming involves trapping air within a mixture, creating a foam. In sponge cakes, whisked eggs or egg whites create a foam of air bubbles that expand during baking, giving the cake its light and airy texture.

Question 4: Identify two ingredients commonly used as thickeners and describe how they work to increase the viscosity of a sauce or soup.

Answer: Common thickeners include flour and cornstarch. They work by absorbing water and swelling, which increases the viscosity of the liquid, making it thicker and more stable.

Question 5: Draw a simple diagram illustrating the process of coagulation in egg proteins. Label the key parts of your diagram.

Answer: A correct sketch would show liquid egg whites turning into a solid mass when heated, with protein molecules denaturing and forming new bonds. Labels should include 'protein molecules,' 'heat,' 'denaturation,' and 'coagulated mass.'

Question 6: Describe how heat affects the functional property of dextrinisation in bread crust formation.

Answer: Dextrinisation occurs when dry heat breaks down starch into dextrin, which contributes to the browning and crispness of the bread crust. Higher temperatures accelerate this process, enhancing colour and texture.

Question 7: Explain the difference between absorption and adsorption in relation to food science, providing an example of each.

Answer: Absorption involves a substance being taken into the interior of another (e.g., a sponge absorbing water). Adsorption is when molecules adhere to the surface of a material (e.g., salt adhering to the surface of meat).

Question 8: Sketch a diagram to show how heat transfer occurs during cooking, including conduction, convection, and radiation. Label each method clearly.

Answer: A correct diagram should depict a pan on a stove (conduction), hot air circulating around food (convection), and radiant heat from an oven or flame (radiation). Labels should identify each method.

Question 9: Discuss why the functional property of enzymatic browning is undesirable in certain foods and suggest a method to prevent it.

Answer: Enzymatic browning causes foods like apples and potatoes to turn brown, which can reduce visual appeal and perceived freshness. To prevent it, foods can be treated with acids like lemon juice, which inhibit enzymatic activity.

Question 10: Describe the process of retrogradation in starchy foods and how it affects the texture of cooked food when cooled.

Answer: Retrogradation occurs when gelatinised starch molecules realign and crystallize as the food cools, leading to staling or firming, as seen in cooled bread or cooked rice becoming hard or chewy.