3.3.2.5.2 Mechanical raising agents and steam Quiz: AQA Food Preparation and Nutrition, Unit 2

The 20 questions

1. Which mechanical methods incorporate air into a mixture?

   • Boiling, steaming, poaching and simmering in liquid
   • Whisking, beating, folding, sieving, creaming and rubbing in
   • Baking, roasting, grilling and frying in dry heat
   • Marinating, curing, pickling and brining in acid

2. When is steam produced as a raising agent in a mixture?

   • When the sugar in a mixture reaches caramelisation and turns brown
   • When the protein in a mixture is denatured by the addition of acid
   • When the water in a moist mixture reaches boiling point and turns to vapour
   • When the fat in a mixture melts and separates from the liquid part

3. Choux pastry is made by cooking flour and water, then beating in egg. What mainly lifts it in the oven?

   • Yeast fermentation during a long proving period before baking
   • Air trapped by rubbing fat into the flour in the mixture
   • Carbon dioxide released by bicarbonate of soda in the paste
   • Steam formed from the water in the paste

4. Why does a Yorkshire pudding batter need a very hot oven or hot fat?

   • So the protein denatures slowly and the batter stays runny in the tin
   • So the sugar caramelises quickly and seals the surface of the batter
   • So the yeast is killed before it can ferment the batter too quickly
   • So the water in the batter turns to steam quickly and lifts the batter as it sets

5. Which mechanical method is used to beat air into egg whites?

   • Sieving
   • Rubbing in
   • Marinating
   • Whisking

6. A cook sieves dry ingredients before mixing a sponge. What does this do for the raising?

   • It emulsifies the flour into the fat before the fat is creamed
   • It removes all the air from the flour so that the sponge is dense
   • It adds air to the dry mix and spreads the raising agent evenly
   • It caramelises the sugar in the flour as it passes through the sieve

7. Why does a sponge made from whisked eggs alone rise without any chemical raising agent?

   • Fat melts and emulsifies with air to make a larger volume in the tin
   • Air whisked into the eggs expands as it heats and lifts the batter
   • Starch dissolves in the egg and releases a gas as the sponge cooks
   • Sugar caramelises in the oven and releases carbon dioxide into the cake

8. Why does puff pastry lift in layers in the oven?

   • Starch in the layers turns to steam and pushes the pastry layers apart
   • Sugar in the layers turns to steam and caramelises the surface of the pastry
   • Water in the layers turns to steam and pushes the pastry layers apart
   • Yeast in the layers turns to steam and ferments the pastry from within

9. At what temperature does water turn into steam at normal atmospheric pressure?

   • Freezing point, 0°C
   • Room temperature, around 20°C
   • Body temperature, around 37°C
   • Boiling point, 100°C

10. A sponge is mixed with a whisk but the flour is folded in carelessly, and it sinks after baking. Why?

    • Starch was over-gelatinised, so the sponge became too heavy and dense
    • Air was knocked out during heavy mixing, so the batter has less lift
    • Sugar was caramelised, so the sponge became too dry in the middle
    • Fat was emulsified too tightly, so the sponge became too dense overall

11. What happens to the flour's gluten if a sponge batter is over-mixed after the flour is added?

    • It dies off and the sponge stops rising altogether in the tin
    • It caramelises in the mix and the sponge turns brown inside
    • It coagulates in the bowl and the batter sets before baking
    • It develops and the sponge becomes tougher, with less lift

12. Which equipment helps a cook trap the most air in a whisked foam?

    • A wet bowl with a wooden spoon for gentle stirring of the mix
    • A clean, dry, grease-free bowl with a balloon whisk
    • A hot pan placed over a flame so the eggs boil quickly
    • A plastic bag rubbed between the hands to pop the mixture

13. Why does steam contribute little lift to a very dry biscuit dough?

    • The dough is too wet, so steam escapes before any lift can form
    • The dough is too cold, so steam condenses straight back into water on the tray
    • The dough has little water to turn into steam, so there is little lift
    • The dough is too hot, so steam is trapped and burns the surface

14. Which statement about steam as a raising agent is correct?

    • Steam forms only when sugar syrup reaches a high temperature in a pan
    • Steam forms only in cold mixtures that have been chilled thoroughly in the fridge before they are baked
    • Water shrinks as it turns to vapour, so steam pulls the mixture down
    • Water expands greatly as it turns to vapour, so steam lifts the mixture

15. What role does egg play in choux pastry raising?

    • It adds fat that emulsifies and binds the choux paste together in the mixing bowl
    • It adds starch that dextrinises and forms a hard, dry shell
    • It adds moisture and protein that trap the steam and set around it
    • It adds sugar that caramelises and holds the steam in place

16. A choux bun collapses if it is removed from the oven too early. Why?

    • The steam has gelatinised the starch and made the case dense and gluey
    • The steam has emulsified the fat so the case slips out of shape
    • The steam has not yet set the structure, so the case falls as it cools
    • The steam has caramelised the sugar and made the case brittle and hard

17. A pancake batter is left to rest before cooking. What does resting allow?

    • Starch hydrates and air bubbles settle, giving a more even texture
    • Sugar caramelises slowly and turns the batter a brown colour
    • Yeast ferments and raises the batter for a fluffy, lifted pancake
    • Fat emulsifies and separates into a clear layer on top of the batter

18. What kind of raising agent is steam?

    • A physical raising agent, which expands when water turns to vapour
    • A chemical raising agent that releases carbon dioxide when heated
    • A protein raising agent that sets around air bubbles in the mixture
    • A biological raising agent produced by yeast cells in the dough

19. Which raising effects are at work in a scone made with baking powder and milk?

    • Biological gas from yeast, with some steam from the milk
    • Mechanical air from creaming, with alcohol produced from the milk
    • Chemical gas from baking powder, with some steam from the moist milk
    • Chemical gas from bicarbonate alone, with no steam at all in the oven

20. A cook adds a splash of extra water to a scone mix. Which raising effect increases?

    • Steam from the water, which adds lift during baking
    • Caramelisation of the sugar, which makes the scone sticky on top
    • Yeast activity, which slows down as the mixture becomes wetter
    • Emulsification of the fat, which makes the scone firmer in texture

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