Maillard Browning (oven)
Bread Rising (yeast CO₂)
Emulsion Stability
Maillard Rate vs Temperature (Arrhenius curve)
The kitchen is a chemistry laboratory in disguise. Everyday cooking and baking involve acid-base reactions (vinegar and baking soda fizzing), Maillard browning reactions (the complex cascade that creates the flavour and colour of toasted bread and grilled meat), fermentation (yeast converting sugars to carbon dioxide and ethanol in bread and beer), emulsification (oil and water held together by egg yolk lecithin in mayonnaise), and phase transitions (water melting chocolate and dissolving sugar).
The baking soda and vinegar reaction is a classic acid-base neutralisation: acetic acid (CH₃COOH) reacts with sodium bicarbonate (NaHCO₃) to produce sodium acetate, water, and carbon dioxide gas — the dramatic fizz. This same reaction is used in baking: when baking soda meets an acidic ingredient (buttermilk, yoghurt, lemon juice), CO₂ bubbles form and expand in the heat of the oven, causing baked goods to rise. Baking powder contains both baking soda and dry acid, releasing CO₂ in two stages for even leavening.
The Maillard reaction, occurring above 140°C, is a non-enzymatic browning reaction between amino acids and reducing sugars that produces hundreds of new flavour compounds, aroma molecules, and the characteristic brown colour of cooked food. It is distinct from caramelisation (pure sugar decomposition at higher temperatures). Understanding kitchen chemistry allows cooks to make deliberate choices — the temperature, pH, and moisture content all determine which reactions occur and what flavours develop.
Baking soda (sodium bicarbonate) reacts with acids in the batter (buttermilk, yoghurt, brown sugar, cocoa) to produce carbon dioxide gas. These bubbles are trapped in the batter's gluten network and expand in the oven's heat, causing the batter to rise and giving the cake a light texture. Too little baking soda produces a dense cake; too much leaves a soapy or metallic aftertaste.
The Maillard reaction is a chemical reaction between amino acids (from proteins) and reducing sugars (glucose, fructose) that occurs above about 140°C. It produces hundreds of flavour, aroma, and colour compounds — the brown crust on bread, the seared crust on a steak, roasted coffee aroma. It is not caramelisation (which involves only sugar) and requires both protein and sugar to be present.
Water is polar (molecules have separated positive and negative regions) and forms hydrogen bonds; oil is nonpolar. Polar and nonpolar molecules do not mix because the energy cost of disrupting their respective bonding networks exceeds the gains from mixing. Mayonnaise holds together because egg yolk contains lecithin, an emulsifier with a water-loving head and oil-loving tail that sits at the oil-water interface, stabilising tiny oil droplets in water.
Yeast in bread dough ferments sugars, producing carbon dioxide and ethanol. The CO₂ is trapped by gluten (a network of wheat proteins developed by kneading), causing the dough to expand and develop a light, airy texture. The initial rise (bulk fermentation) and second rise (proofing) allow the gluten network to relax and the yeast to generate enough CO₂ for good texture. Heat in the oven kills the yeast and sets the structure.
Raw egg white contains proteins (ovalbumin, ovotransferrin, lysozyme) folded into compact 3D structures. Heat (above ~60–70°C) provides enough energy to break the weak bonds holding these structures together, causing proteins to unfold (denature) and then randomly tangle together, forming a solid network that traps water. This is irreversible — you cannot uncook an egg — because the protein network is stabilised by new disulphide bonds and hydrophobic interactions.