What is oven spring?

scoring

Slashing the top of a shaped loaf just before baking with a sharp blade or razor. Controls where the loaf splits open during oven spring — without scoring, the trapped fermentation gas finds the weakest seam on its own and bursts there, often with an ugly tear or a flat split instead of a designed opening. Depth is the variable that matters most: about ¼ inch / 6mm at a 30-45° blade angle gives the dramatic raised “ear” that defines well-baked sourdough. Too shallow and the cut doesn't weaken the crust enough; too deep and the dough above the cut is too heavy to lift cleanly. Cold dough is dramatically easier to score than warm dough — one of the reasons the overnight cold retard exists. Patterns range from a single functional slash (most controlled rise) to decorative geometry (mostly visual). Boil-then-bake breads (bagels, pretzels) are not scored.

Maillard browning

The chemistry behind why baked surfaces turn brown and develop roasted, savory flavors. Named after French chemist Louis Camille Maillard, who described the reaction in 1912. Amino acids (protein) react with reducing sugars (glucose, fructose, but NOT sucrose directly) at temperatures starting around 280°F / 140°C, kicking into high gear at 310°F / 155°C and above. The reaction produces hundreds of flavor compounds — roasted notes, browning pigments, toasted aromas — that are responsible for the flavor of bread crust, brownie tops, seared meat, and roasted coffee. Distinct from caramelization (which is sugar breaking down on its own at higher temps, around 320-360°F / 160-180°C). Both reactions happen on a brownie surface during baking and combine to create the crackly mahogany top crust that defines a good fudge brownie.