Malt is barley (occasionally wheat or other cereals) that has been deliberately sprouted and then dried in a kiln — a controlled, arrested germination that unlocks the grain's own enzymes and rewrites its flavour into something sweet, biscuity and toasty. It is one of the great hidden ingredients of the food world: the fermentable sugar-source and flavour backbone of virtually all beer and whisky, the "malt" of malted milkshakes, Ovaltine and Horlicks, the boost that browns bagels and pretzels, and, boiled down, the dark treacly malt extract and malt syrup used as a natural sweetener. Pale malts taste of honey, biscuit and fresh bread; crystal, chocolate and black malts, kilned far hotter, turn caramel, coffee, nutty and burnt.