Bakery Ingredients and Their Functions
Domain 2 tests what each ingredient contributes, how much is used, and what goes wrong when it is wrong. Expect short questions linking an ingredient to a function or a fault: “which ingredient gives crust colour”, “why did the dough not rise”.
Flour
Gluten forms from gliadin (extensibility) and glutenin (elasticity) when flour is hydrated and worked. Maida is a low-ash refined flour for cakes and pastries; bread flour carries roughly 11–13 % protein; atta is whole wheat with higher ash and water absorption; sooji and besan are used in Indian products.
Sugar, fat, eggs, milk
- Sugar tenderises, holds moisture (hygroscopic), feeds yeast, and browns through caramelisation and Maillard reaction.
- Fat shortens gluten, traps air during creaming and carries flavour. Butter is about 80 % fat and 15–16 % water, so it is not a 1:1 swap with oil.
- Eggs coagulate at 70–80 °C, aerate when whisked, and emulsify through lecithin in the yolk.
- Milk adds lactose (browning), water and tenderness.
Leavening agents and salt
Baking powder is soda plus acid plus starch, single- or double-acting; baking soda releases carbon dioxide only when an acid is present. Yeast is biological: active near 25–30 °C and killed above about 55 °C. Salt gives flavour, tightens gluten and controls yeast, typically 1.8–2.2 % of flour weight in bread.
Worked example
A cookie formula needs 200 g butter, but only oil is available. Butter is 80 % fat, so 200 × 0.80 = 160 g fat → use 160 g oil. The missing 32 g is water, so add roughly 32 g milk to keep the dough consistency. Oil is 100 % fat and does not cream, so expect a flatter, softer cookie - chill the dough before baking.
Traps that cost marks
- Treating a cup of flour as fixed; a scooped cup can exceed 150 g while a spooned cup is nearer 120 g.
- Using baking soda without added acid.
- Putting salt directly onto yeast, which slows it.
- Assuming all flours absorb the same water.