Cooks often lump mushrooms into the category of vegetables (they’re actually a fungus). While mushrooms display characteristics of vegetables (high water content) as well as meat (savory flavor), they are unique in their ability to maintain a pleasant texture over a wide range of cooking times. We set up the following experiment to illustrate how a mushroom’s texture changes with cooking as compared with that of a green vegetable and a cut of beef.
We cut ½-inch-thick planks of portobello mushroom, zucchini, and beef tenderloin and steamed them in a basket in a large Dutch oven for 40 minutes. At 5-minute intervals we used a piece of equipment called a CT3 Texture Analyzer to determine how much force was required to “bite” into each piece of food.
After 5 minutes of steaming, the tenderloin, portobello, and zucchini required 186, 199, and 239 grams of force, respectively, to be compressed (or “bite”) 3 millimeters into the food. Tasters noted that all of these samples were tender.
This picture changed rapidly after 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 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 structureless. 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 still be properly tender.
While many foods we cook require precise attention to internal temperature and cooking 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 the 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.