Produce

Asparagus

Asparagus's distinctive smell some people notice in their urine after eating it is a genuine, harmless metabolic byproduct — some people can detect it and others genetically can't, unrelated to freshness or how it was cooked.

White asparagus, grown by mounding soil over the emerging spears to block sunlight and prevent chlorophyll production, is a genuinely different product from green asparagus, with a milder, less vegetal flavor prized especially in German and French cooking.

Thickness doesn't necessarily indicate age or toughness the way it might for some vegetables — thick and thin asparagus spears can be equally tender depending on the plant, though very thin spears generally cook faster.

White asparagus is grown by mounding soil over the emerging spears to block sunlight entirely, preventing the plant from producing the chlorophyll that turns a standard spear green, a labor-intensive technique especially prized in Germany and France, where a dedicated white asparagus (Spargel) season each spring draws significant seasonal menus and festivals.

Eating asparagus can cause a distinctive, sulfurous change in urine odor within a couple of hours, caused by asparagusic acid breaking down into sulfur-containing compounds during digestion — and genetics play a real role here too, since a meaningful portion of the population carries a genetic variation that makes them unable to smell the compound at all, regardless of whether their own body produces it.

Peru and the US (mainly California, Michigan, and Washington) are among the largest sources of asparagus sold in North America, with Peru's counter-seasonal growing calendar helping keep fresh asparagus available in US grocery stores through the winter months when domestic asparagus isn't in season.

Purple asparagus, a genuinely distinct variety bred for its anthocyanin pigment (the same compound class responsible for color in red cabbage and blueberries), tends to be slightly sweeter and less fibrous than green asparagus, though the purple color mostly cooks away to green once the spears hit heat.

Ancient Romans cultivated asparagus deliberately and valued it enough that Emperor Augustus reportedly coined the phrase "faster than cooking asparagus" to describe getting something done quickly, a detail suggesting the vegetable's fast cook time was already a recognized culinary trait roughly two thousand years ago.

Researchers at Philadelphia's Monell Chemical Senses Center have studied the asparagus-odor genetic variation directly, confirming through smell tests that a meaningful share of people carry a specific genetic variant that leaves them simply unable to detect the compound's smell, rather than everyone's body failing to produce it in the first place.

Asparagus was prized enough in the ancient world that surviving Egyptian tomb art depicts offerings of the vegetable, and Roman writers, including Cato the Elder, recorded specific cultivation instructions for it, evidence that asparagus has been treated as a valued, deliberately cultivated crop for thousands of years rather than a modern culinary discovery.

Snapping off the tough, woody end of an asparagus spear by bending it until it naturally breaks, rather than cutting it with a knife at a fixed point, is a commonly recommended technique because the spear tends to snap right where the fibrous, unpalatable base ends and the tender, edible portion begins.