Cake
A cake is a race between two clocks: the leavener makes gas while the egg and the starch build the structure meant to hold it. Set the structure too early and it never rises; too late and it rises and falls. The oven temperature is what referees the race.
Change them and see
Balanced
Roughly a teaspoon to every 125 grams of flour. Gas production and structure setting land in the same window: it rises in the oven and stays where it rose.
In order, minute by minute
Not a list of steps but a timeline: each one carries the minute it happens at and the temperature it happens at. Changing the order changes the result, and this shape is why the engine can say so.
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0 minutes
Beat the room-temperature fat with the sugar until it lightens and grows.
The sharp edges of the sugar crystals open air bubbles in the fat. Those bubbles have to exist before the leavener works, because the gas does not create bubbles, it inflates the ones already there. Melted fat cannot hold them and fridge-cold fat will not open them.
What to look for It pales and visibly grows.
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5 minutes
Add the eggs one at a time, waiting for each to disappear.
Egg is mostly water and fat does not take water kindly. All at once splits the emulsion, and a split batter releases the air it was holding, which does not come back.
What to look for It should stay smooth; a spoonful of the flour brings a split batter back.
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8 minutes
Sift in the flour and the leavener and mix ONLY until the flour disappears.
Gluten starts forming the moment flour meets liquid. A cake does not want it: the same network that traps gas in bread makes a cake tough and opens long tunnels in the crumb. A minute of extra mixing moves a cake towards a biscuit.
What to look for A few streaks of flour left is right; perfectly smooth is too far.
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10 minutes 175 °CCritical point
Into an ALREADY HOT oven straight away, and do not open the door for twenty minutes.
This is where the race is run. The leavener begins making gas the moment it is wet, and spends some of it standing on the counter. In the oven the egg proteins coagulate between 62 and 70 °C and the starch gelatinises at 62; the structure is built at those two temperatures and locks the gas inside. Too cool an oven and the gas escapes before the structure exists; too hot and the crust sets early while the inside is still expanding, and splits the top open.
What to look for Middle shelf, 170–180 °C. A skewer should come out with moist crumb on it, not wet batter.
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45 minutes 60 °C
Ten minutes in the tin, then onto a rack.
A hot cake is still fragile: the starch gel firms as it cools and that is where the structure gains its real strength. Leaving it in the tin much longer works the other way, as trapped steam soaks the base.
What to look for The edges should have pulled slightly away from the tin.
The numbers that decide it
Balanced
Read off leavener against flour. Too little gives a low cake and too much a fallen one: two ends of the same curve.
125
Fat gets between the gluten strands and stops them lengthening. More fat means a more tender crumb, and past a point a structure too weak to carry the gas.
200
Colour comes from caramelisation and Maillard, both of which need the sugar. Cutting it takes away colour and moisture as well as sweetness, because sugar also holds water.
What is happening in the pot
- 62–70 °C · no way back Starch gelatinised The granules soaked up water, swelled and burst into a network. It has thickened, and it will firm further as it cools. Held in the system
- white 62 °C · set 82 °C The egg is setting Proteins unfold and link up, binding everything together. This is where creaminess comes from. Held in the system
What happened, why, and what to do
Some of these can be saved and some cannot. Writing up the second kind as though it were the first costs somebody another twenty minutes.
01 The middle sank ⌄
Why
The structure was not set before the gas finished expanding: too much leavener, too cool an oven, or the door opened early.
Cannot be saved
A fallen cake does not rise again. Cut the middle out and use it as a trifle layer: the taste is intact and only the structure is lost.
02 Long tunnels inside, and a tough crumb ⌄
Why
Over-mixed after the flour went in. A gluten network formed and gathered the gas into channels instead of an even crumb.
Cannot be saved
Not recoverable. Next time fold the flour in by hand and stop early.
03 A soapy, metallic taste ⌄
Why
Too much leavener: what did not react stays in the crumb and covers everything else.
Cannot be saved
The taste cannot be removed. Keep the leavener between 1.5 and 4.5 per cent of the flour.
04 It came out dry ⌄
Why
Overbaked, or the sugar was cut. Sugar binds water, so less of it means a drier cake as well as a less sweet one.
Can be saved
Brush it with syrup or diluted juice: a cake takes this well and genuinely recovers.
05 The batter split and looks curdled ⌄
Why
The eggs went in too fast or too cold and the fat-and-water emulsion broke.
Can be saved
Beat in a spoonful of the measured flour. It comes back together, a little denser but saved.
The safety check does not know the following. That is not the same as nothing being wrong — it means nobody looked, and anything meant to keep at room temperature has to be measured rather than assumed.
- Water activity
This is a model estimate rather than a measurement. How far each threshold behind it has been checked is below; fourteen of the fifteen still have no source on file, and saying so is better than not.
engine 1.0.0 · ruleset 2026.09.1 · confidence medium
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