The
Science of
Cooking
A kitchen is a chemistry lab where you get to eat the results. Heat moves, sugars and proteins transform, oil and water make peace, gas bubbles lift dough, and invisible microbes decide what’s safe.
- 00First Principlesp.2
- 01Heat on the movep.4
- 02Browning reactionsp.5
- 03Emulsions & glutenp.6
- 04Rising & settingp.7
- 05Boiling, salt & microbesp.8
- 06Pancake labp.10
- ✦Self-check · Make it · 5 Questions · Side Questp.9
You'll need: a few spoons (metal, wood, plastic), butter, bread and a toaster, a jar, oil and vinegar, yeast, a balloon and a bottle, a food thermometer, pancake ingredients.
Principles
A first principle is a basic truth you can build on. Cooking science rests on a few ideas: heat moves from hot to cold, molecules change when heated (proteins unfold, sugars brown), gases expand, and microbes grow fastest at warm temperatures.
What do I already know?
What is necessary?
Everything in this module is built from four bricks. Rate yourself on each one, then check the example to see if your rating holds up.
What is the objective?
By the end, you’ll be able to explain the science behind browning, rising, mixing, boiling and keeping food safe.
- 01Tell conduction, convection and radiation apart in the kitchen.
- 02Explain the Maillard reaction and caramelization.
- 03Explain how emulsions and gluten work.
- 04Compare yeast, baking soda and baking powder.
- 05Explain why water boils cooler at altitude.
- 06Use the danger zone to keep food safe.
The list on the left is ours. Now make it yours. What do you want out of this?
How much do you know about the science of cooking right now? Shade the boxes in pencil. You'll come back at the end (p.9) and shade it again in pen.
Why start this way? When you know what you already have (1), what you need (2) and where you're going (3), you learn faster and you notice the gaps. Every module on the Cooking Path starts with these same three questions.
Heat on the move
Every recipe is really a set of instructions for moving heat into food at the right speed.
Every cooking method uses them
| Type | How | Kitchen example |
|---|---|---|
| Conduction | direct touch, molecule to molecule | pan → steak; hot handle |
| Convection | hot fluid (air, water, oil) flows | boiling pasta; convection oven fan |
| Radiation | energy travels as waves (infrared, microwaves) | broiler, toaster, campfire glow |
Why pans are metal
Metals like copper, aluminum and steel conduct heat fast, so pans heat food evenly. Wood, silicone and plastic are insulators, which is why spoons and handles are often made of them.
Which method is which?
Butter spoon race
Put a tiny dab of butter on the handle ends of a metal, a wooden and a plastic spoon. Stand them in a mug of hot tap water (an adult can help). Whose butter melts first?Why do cooks rest a steak or roast before slicing?
Heat safety: use oven mitts, turn pot handles inward, and keep a lid nearby for small pan fires (never water on a grease fire). If you’re under 18, cook on the stove or in the oven only with an adult nearby.
Maillard vs caramelization
Brown means flavour. Two different reactions make it happen, and cooks use both.
Proteins + sugars + heat
When food’s surface gets hot and dry, amino acids (from proteins) react with certain sugars, making hundreds of new flavour and aroma molecules and a brown colour. It’s named for French chemist Louis-Camille Maillard, who described it in 1912.
Think toast, seared meat, roasted coffee, golden bannock and the crust on bread. It speeds up a lot above about 140 °C.
Sugar on its own
Caramelization happens when sugar alone breaks down under heat. Table sugar (sucrose) starts to caramelize at roughly 160–170 °C, turning from clear to gold to amber, and bitter if pushed too far.
Caramel sauce, crème brûlée’s top and dulce de leche’s colour (partly Maillard, thanks to milk protein).
Water is the speed limit
Water can’t get hotter than its boiling point (100 °C at sea level) in an open pot. That’s too cool for fast browning, so boiled potatoes stay pale while roasted ones go golden. To brown food: dry the surface, use high heat, and don’t crowd the pan (crowding makes steam).
Toast colour chart
With an adult’s OK, toast 4 slices of bread at 4 settings (or for 1, 2, 3 and 4 minutes). Line them up and describe smell, colour and taste. Which has the best flavour, and when does it turn bitter?Why do recipes say to pat chicken or tofu dry before searing?
Watch the toaster: never put a knife or fork into it, and unplug it before shaking out crumbs. Sugar for caramel gets far hotter than boiling water and sticks to skin, so caramel making is an adult-supervised job.
Emulsions & gluten
Two kinds of structure: tiny droplets that stay mixed, and protein nets that hold bubbles.
Making oil and water mix
Oil and water don’t mix; shake them and they separate. An emulsion breaks one into tiny droplets spread through the other. An emulsifier has one end that likes water and one that likes oil, so it holds the droplets apart.
- Mustard and honey help hold a vinaigrette together.
- Egg yolk (lecithin) makes mayonnaise and hollandaise.
- Milk is a natural emulsion of butterfat in water.
The stretchy network
Wheat flour has two proteins, glutenin and gliadin. Add water and knead, and they link into stretchy, springy gluten that traps gas so bread can rise.
- Knead more → chewier (bread, bagels).
- Mix less → tender (muffins, cakes, pancakes).
- Rye and barley also contain related proteins.
People with celiac disease must avoid gluten completely; even crumbs matter.
Mayonnaise without the risk
Homemade mayonnaise uses raw egg yolk, which can carry Salmonella. Health Canada advises using pasteurized eggs for any recipe with raw or lightly cooked egg. Commercial mayonnaise is generally made with pasteurized egg. In this book we stick to egg-free emulsions you can taste safely: mustard vinaigrette or an aquafaba (chickpea-can liquid) mayo.
Shake-off
Make two small jars of 3 : 1 oil and vinegar. Add ½ tsp mustard to one only. Shake both for 20 s and time how long each takes to separate.Why should muffin batter be stirred “just until combined”?
Allergen note: wheat, egg, mustard and milk are all priority food allergens in Canada, and gluten matters for people with celiac disease. Always check before you share food.
Rising & setting
Light, fluffy food is a gas trapped in a protein-and-starch cage.
Three ways to make bubbles
| Leavener | How it makes gas | Used in |
|---|---|---|
| Yeast | living fungus eats sugar → CO₂ + alcohol (the alcohol bakes off) | bread, pizza, cinnamon buns |
| Baking soda | a base: needs an acid (buttermilk, yogurt, lemon, brown sugar) to release CO₂ | cookies, soda bread |
| Baking powder | baking soda + a dry acid in one can; most is “double-acting” | muffins, pancakes, bannock |
English chemist Alfred Bird made an early baking powder in 1843, reportedly because his wife was allergic to eggs and yeast.
Why eggs go solid
Proteins are long chains folded into shapes. Heat makes them unfold (denature) and tangle together (coagulate), so a runny egg turns solid. Egg white starts to set at roughly 62–65 °C and the yolk a little higher.
For food safety, Health Canada says egg dishes should reach 74 °C.
Teamwork in a muffin
Gas bubbles from the leavener expand in the oven’s heat, and steam adds more lift. Then egg proteins set and starch firms up, locking the bubbles in place. Open the oven too early and the structure isn’t set yet: the bubbles can collapse.
Balloon of life
Mix 1 packet (about 8 g) of yeast, 1 tbsp sugar and 250 mL warm water (like a warm bath, not hot) in a bottle. Stretch a balloon over the top. Check every 10 minutes. What blows it up?A recipe uses baking soda but you swap the buttermilk for plain milk. What might happen?
Boiling, salt & microbes
The same science that changes boiling points also decides how long food stays safe.
Why Edmonton boils cooler
Water boils when its vapour pressure matches the air pressure. Higher up, there’s less air pressing down, so water boils at a lower temperature.
| Place | Typical air pressure | Water boils at about |
|---|---|---|
| Vancouver (sea level) | 101 kPa | 100.0 °C |
| Edmonton (about 670 m) | 94 kPa | 97.8 °C |
| Calgary (about 1,045 m) | 89 kPa | 96.5 °C |
| Banff (about 1,400 m) | 86 kPa | 95.4 °C |
Calculated from a standard-atmosphere model; real values shift a little with the weather. Pasta and beans take a bit longer at altitude.
Flavour and myth
- Salt boosts flavour and can make bitterness taste weaker.
- Myth: salt in pasta water makes it boil much hotter. A tablespoon (15 g) in 4 L raises the boiling point by only about 0.07 °C.
- It’s there for taste, not temperature.
The danger zone is 4–60 °C (40–140 °F). In that range, bacteria that cause food poisoning can multiply quickly; some can double about every 20 minutes in ideal conditions (so 1 becomes 8 in an hour). Health Canada’s rules: keep cold food at 4 °C or below and hot food at 60 °C or above, refrigerate leftovers within 2 hours, and cook to safe internal temperatures checked with a digital food thermometer (e.g. 74 °C for poultry pieces and leftovers, 71 °C for ground beef). Wash hands with soap for at least 20 seconds, and keep raw meat away from ready-to-eat food.
Boil test
With an adult, bring a pot of water to a rolling boil and measure its temperature with a food thermometer (don’t touch the pot bottom). Compare with the table. Note today’s weather.Why does a pressure cooker cook beans faster?
Quick self-check
Six questions, covering every stop. Show your thinking. Answers are upside down at the bottom; no peeking till you're done.
1 · Name the three ways heat moves, with a kitchen example of each.
2 · What’s the difference between the Maillard reaction and caramelization?
3 · What does an emulsifier do? Name one.
4 · Why does baking soda need an acid?
5 · Why does water boil below 100 °C in Edmonton?
6 · What is the danger zone, and what are the two Health Canada temperatures that bound it?
Re-shade your knowledge meter
How much do you know about the science of cooking now? Flip back to p.3 and shade the meter again in pen (or shade this one). Did any of the four bricks on p.2 move from "Not yet" to "Got it"?
The great pancake lift-off
Cook three mini pancakes with different leaveners and measure which rises highest, then eat your data.
1 · My question
Which leavener makes the fluffiest pancake: baking powder, baking soda + lemon, or none?
2 · Base batter (makes 3 small bowls)
- 375 mL (1½ cups) all-purpose flour, 2 tbsp sugar, a pinch of salt
- 375 mL (1½ cups) milk, 1 egg, 2 tbsp melted butter or oil
- Split into 3 bowls (about 250 mL each)
3 · The test
- Bowl A: add ½ tsp baking powder
- Bowl B: add ¼ tsp baking soda + 1 tsp lemon juice
- Bowl C: add nothing (the control)
- Same pan, same heat, same 60 mL scoop for each
4 · Results
| Bowl | Height (mm) | Bubbles? | Taste 1–5 |
|---|---|---|---|
| A | |||
| B | |||
| C |
Prediction (and why):
Draw a cut pancake from each bowl:
5 · Must-haves
- A control (bowl C)
- Height measured with a ruler, cut through the middle
- Cooked until set in the centre, no wet batter
- One science reason for each result
6 · What I found
Which rose most? Which tasted best? Was the soda pancake soapy or just right?
Stove time: if you’re under 18, cook with an adult nearby, keep handles turned in and use a flipper, not fingers. No tasting raw batter: it contains raw flour and raw egg. Wash hands after cracking the egg. Allergens: wheat, egg and milk are priority allergens; ask before sharing (a plant milk and egg replacer can work for some).
5 Questions
I Still Have
This module didn't answer everything. Good. Write 5 new questions it didn't answer, one of each type below. There are no wrong questions, only ones nobody's asked yet.
★ Star the one question you'd most like answered. You'll need it on the next page.
1What I'll find out
Break your big question into 2 or 3 smaller ones you could actually answer.
2Where I'll look
3How I'll share it
Who I'll share it with:
Done by: