Cooks often lump mushrooms into the category of vegetables, which, aside from being a taxonomy faux pas, can be problematic in the kitchen. While these fungi display characteristics of both meat (their savory flavor, for instance) and vegetables (their high water content) they are unique in important ways. Chief among these differences is their ability to maintain a pleasant texture over a wide range of cooking times. We set up the following experiment to illustrate how mushroom texture changes with cooking in relationship to a green vegetable and a cut of beef.

EXPERIMENT
We cut 1/2-inch-thick plans of portobello mushrooms, zucchini, and beef tenderloin and spaced them out evenly in a steamer basket. We set the basket over boiling water in a large Dutch oven, covered it with a lid, and steamed the samples for 40 minutes. At 5-minute intervals we used a CT3 Texture Analyzer to test the tenderness of each sample and then graphed the data as a function of tenderness over time.

RESULTS
After 5 minutes of steaming, the tenderloin, portobello, and zucchini required 186, 199, and 239 grams of force, respectively, to be compressed 3 millimeters. Tasters noted that all of these samples were tender. This picture changed rapidly with 5 more minutes of steaming: at the 10-minute mark, the tenderloin, portobello, and zucchini samples required 524, 195, and 109 grams of force, respectively. Tasters found the tenderloin to be tough and leathery, and the zucchini overly soft. The portobello, on the other hand, remained largely unchanged.

Over the course of the next 30 minutes, the tenderloin continued to toughen, eventually turning a whopping 293 percent tougher, while the zucchini decreased in firmness 83 percent and turned mushy and structure-less. The portobello, meanwhile, increased in firmness just 57 percent over the same period of time; after a full 40 minutes of cooking, tasters found the mushroom to be properly tender.

TAKEAWAY
While many foods we cook require precise attention to internal temperature and cook time, mushrooms are remarkably forgiving. The key to their resiliency lies in their cell walls, which are made of a polymer called chitin. Unlike the proteins in meat, or pectin in vegetables, chitin is very heat stable. This unique structure allows us to quickly sauté mushrooms for a few minutes or roast them for the better part of an hour, all the while achieving well-browned, perfectly tender specimens.