Onion

Allium cepa

Onions are a long-keeping Northeast storage vegetable with a balance of sweetness, sharpness, and sulfurous aroma. Variety and maturity make a real difference: spring onions are green and mild, while cured onions are denser and sweeter.¹

Cutting an onion breaks cells and allows previously separated chemicals to react. Thiosulfinates and related sulfur compounds shape both its pungency and its eye-watering effect.²

The degree of damage changes the flavor: chopping, pounding, and pureeing expose different amounts of tissue and produce different mixtures of sulfur compounds. For onion that will be eaten raw, rinsing the cut pieces removes reactive compounds from the damaged surfaces before they become harsher in the air.³

Onion and leek both need a long seedling phase in Maine: Extension lists globe onions at 6–8 weeks indoors and leeks at 10–12 weeks.⁴

An onion bulb is a compressed underground shoot, not a swollen root. Its fleshy scales are enlarged leaf bases wrapped around a short stem, and the dry papery skin is made from outer layers that have stopped growing and dehydrated. The bulb’s storage life depends on variety, maturity, and curing: after harvest, the neck and outer scales need to dry so they form a barrier against moisture loss and decay. UMaine Extension notes that varieties differ markedly in how long they keep, so a sweet onion and a storage onion should not be treated as interchangeable pantry crops.⁵

The pungency of a fresh onion is also a defense system that only becomes obvious when the bulb is damaged. Cutting mixes enzymes with sulfur-containing precursors in separate cell compartments, producing unstable compounds that irritate the eyes and quickly change as the cut surfaces sit. Heat rearranges and softens that chemistry, which is why the same bulb can move from sharp and sulfurous to sweet and rounded without changing its identity.