The pineapple (Ananas comosus) is the multiple fruit of a tropical bromeliad — a spiky, barrel-shaped cylinder of golden flesh sheathed in a tough, diamond-patterned rind and crowned with a tuft of stiff leaves. Bright, intensely sweet and mouth-pricklingly acidic, it carries an enzyme that digests protein — and your tongue — making it one of the few fruits that quite literally bites back.