The apricot kernel is the seed that sits inside the woody stone of the apricot (Prunus armeniaca), a flat, pale-tan, almond-shaped nut freed by cracking the pit. It comes in two culinary forms: a mild, marzipan-sweet type — the nan xing of Chinese cooking and the source of amaretto and amaretti flavour — and an intensely bitter type whose almond-and-marzipan aroma is the classic base of noyaux, persipan and bitter-almond essence. The bitter kernel owes both its scent and its toxicity to the same compound, amygdalin, which releases cyanide when the seed is chewed.