Onions

Onions are the underground bulbs of Allium cepa, composed of fleshy leaf bases that store nutrients for the plant, and they vary in size, shape, colour, and flavour according to variety. Beyond their culinary role as the aromatic foundation of cuisines worldwide, they supply flavonols such as quercetin, sulphur compounds responsible for their pungency and tear-inducing effect, and prebiotic fructans. They are eaten raw, caramelised, fried, or pickled, and dehydrated onion powders season countless processed foods. Proper curing and dry, ventilated storage prevent sprouting and rot, while their antimicrobial sulphur chemistry contributes modest preservative effects in traditional preparations.