Science of Cooking: Ask the Inquisitive Cooks! (2024)


" Why are the ends of even farm-fresh asparagus always tough? " Dear Anne and Sue, Why are the ends of even farm-fresh asparagus always tough? And how can I keep its vibrant green color? From Suzanne Fingold		Still have more questions? You'll find more answers in our archived monthly feature articles by the Inquisitive Cooks. ( Meet the Inquisitive Cooks )

Hello Suzanne, Asparagus contains an enzyme that creates a woody compound called "lignin," at the end of each spear. Lignin is not softened by heat, so it remains fibrous and tough after cooking. To eliminate lignin, snap (don't cut) the end of each spear just before cooking. It will break right at the point where the stalk becomes tender. Do this just before cooking so you leave no time for asparagus to accumulate yet more lignin. The enzyme responsible for creating lignin is destroyed during cooking.

Like other green vegetables, the color of asparagus comes from chlorophyll, one of the most sensitive pigments found in food. When vegetables are raw, their pigments are isolated from the natural plant acids within each cell. But as cell walls soften during cooking, plant acids diffuse, coming in contact with chlorophyll. The acid reacts with the chlorophyll and chemically changes the bright green pigment in chlorophyll to a drabber form. You'll notice that the longer asparagus cooks, the more unappetizing its color becomes. Keeping chlorophyll vibrant means cooking green vegetables quickly. Asparagus is delicious steamed, grilled, or stir-fried. If you are cooking it in boiling water, bring the water to the boil, add the asparagus and cook just a few minutes. Leave the lid ajar to allow some plant acids to escape with the steam and other to dissolve in the water. Asparagus in season—tender and succulent, with flavors at their prime—is a wonderful reminder of the benefits of buying locally, when produce is at its best. Anne and Sue