Calories in Onions, white

What makes onions so powerful?

White onions have a higher water content and shorter shelf life than yellow onions, meaning they historically served as a seasonal crop in many regions before modern storage technologies. When you cut an onion, you break open cells that release an enzyme called alliinase. This enzyme converts amino acid sulfoxides into sulfenic acid, which rapidly rearranges into syn-propanethial-S-oxide, a volatile gas. This gas wafts upward and stimulates sensory neurons in the eyes, triggering the lacrimal glands to produce tears to wash away the irritant. White onions, known for their papery white skin and sharper, more pungent flavor compared to yellow or red varieties, typically contain higher concentrations of these sulfur compounds. This is why they are favored in Latin American cuisines for raw applications like salsas, where their crisp bite and sharp acidity can stand up to bright cilantro and lime. Cooking them breaks down these volatile compounds, transforming the pungent sulfur into sweet, mild sugars through the Maillard reaction and caramelization.