The Science of Food

Nothing in cooking happens by luck

A sauce goes lumpy. A cake comes out flat. Toast browns but bread does not. It is tempting to file all of that under bad luck or lack of skill. It is neither. ⭐ Every change food makes has a trigger condition: something that has to be true before the change will happen at all. Starch does not thicken a sauce because you stirred it hopefully. It thickens when it is heated with enough liquid. An egg does not set because it was in the pan a while. It sets once it is hot enough for its proteins to unfold and join up. ⚠️ So a cooking failure is a condition that was wrong, not a mistake in your character. And that is very good news, because a condition is something you can change one at a time and test, which is exactly what the food investigation task asks you to do.

Three ways heat reaches food

Before any of those changes can start, heat has to arrive. It gets in by three routes, and most real cooking uses more than one at once. Which route dominates decides where a food heats first, which is why some things brown on the outside long before the middle is done.

Order what happens in a thickening sauce

A starchy liquid is heated and stirred until it thickens. Put the five stages in order.

• Starch grains sit whole in the cold liquid and settle if left
• Heating begins and the grains start to absorb liquid
• The grains swell as they take in more
• The swollen grains burst and release starch into the liquid
• The freed starch spreads through the liquid and thickens it

What happens to an egg white

An egg white goes from clear and runny to white and firm as it cooks. In the right order, what has happened to its proteins?

• They unfolded, then joined together and set
• They melted and then hardened again as they cooled
• The water evaporated and left the solid behind
• The sugars in it browned and changed colour

Words for what heat does

Five changes, each with its own trigger. Learn the trigger with the word, because the trigger is what an examiner is really asking about.

Find the condition that went wrong

A student describes making a sauce that failed. Select the ONE sentence that names the condition responsible.

• I weighed out the flour and the butter carefully and melted the butter in the pan.
• I stirred the flour into the butter and cooked it gently for a minute.
• I then tipped all the cold milk in at once and turned the heat up high straight away.
• I stirred it hard with a wooden spoon the whole time.
• It went lumpy and I had to throw it away, which was annoying.

Which changes need dry heat

Three of these five changes need DRY heat rather than plenty of liquid. Choose the three.

• Starch at the surface of bread breaking down and browning as it toasts
• Sugar turning brown and changing flavour in a hot dry pan
• The surface of a pastry case going golden in the oven
• A starchy liquid thickening as it is heated and stirred
• An egg setting firm in simmering water

One question to ask of any result

Whenever food does something, wanted or not, ask one question. ⭐ What condition caused that? Not what did I do wrong, and not what should I have done. What was true at that moment: how much heat, how much liquid, how much air beaten in, how much acid, how long. That question is also the whole method of the food investigation task, because a condition is something you can change one at a time while keeping everything else the same.

Match the change to the condition that triggers it

The window that mists up

Leave the kitchen for a moment and look at a window on a cold morning. The inside of the glass is running with water. Somebody always says the window is faulty, or that the house is damp, or that it is simply what old windows do. ⭐ None of that is an explanation. Here is one. Air holds an amount of water you cannot see, and how much it can hold depends on how warm it is. Warm air holds plenty. Cool it down and it can hold less, and what it can no longer hold has to go somewhere. The glass is the coldest surface in the room. Air touching it is chilled, drops below the point where it can keep its water, and puts the difference on the glass. ⚠️ So the mist is not a fault. It is a condition being met. And once you can say WHICH condition, you know exactly what would change it: warm the glass, dry the air, or stop making so much water indoors. Three different fixes, all from one sentence of explanation. ⭐⭐ Now put that habit back in the kitchen, because it is the same habit. A result you did not want is telling you that some condition was met, or was not met. Name it and the fix names itself.

Complete the food science facts

Starch grains swell and burst in hot liquid and thicken it, which is called _____. Under dry heat a protein first unfolds, which is called _____, and the unfolded proteins then join and set. Sugar browning and changing flavour in a hot dry pan is _____, and air beaten into a mixture is _____. Oil and water are held together in one mixture by _____, and useful bacteria change a food such as yoghurt by _____.

Build the explanation sentence

A cake made with a fat that was too soft and beaten too little comes out heavy. Complete the explanation.

Find the food science words

Six words from this module are hidden in the grid. Each clue describes one of them.

Food science quick-fire

Five quick decisions. Three lives.

Diagnose and test a failure

A batch of shortcrust pastry comes out tough and chewy instead of crumbly. Work out what to do.

• First, what is the most likely condition behind a tough pastry?
• You want to test that. How should you set up the comparison?
• The batches are baked. How do you judge the result?

Explain a change in your own words

A cook makes a sauce that stays thin and watery however long it is heated. Explain what has gone wrong and how you would test your explanation.

• Name the change that was supposed to happen and what it needs in order to happen
• Give one condition that could have stopped it, and say why that condition matters
• Say what you would change, and what you would deliberately keep the same
• Say how you would judge whether the sauce was thicker, without relying on opinion