A ptomaine is a nitrogen-containing organic compound produced when bacteria break down protein, typically during putrefaction. Chemically they are mostly amines and diamines, including putrescine and cadaverine, whose names betray their origin in decaying flesh. In the nineteenth century, before bacterial toxins were understood, ptomaines were blamed for food poisoning, and the idea lingered in popular language long after science moved on. Modern food safety recognises that the true culprits in spoiled food are pathogenic bacteria and the potent toxins some of them produce, not these relatively weak breakdown products. The term survives mainly as a historical curiosity, though biogenic amines such as histamine in spoiled fish remain a genuine and separate food safety concern.