The mystery lumps are almost always just solidified pork fat, not mold. Spam is made from ground pork and ham, including both lean meat and fat, plus salt, water, sugar, modified potato starch, and sodium nitrite. When chilled, pork fat turns white and firm, so you’ll see scattered pale bits throughout the loaf. That’s normal—and it’s part of what keeps Spam moist, sliceable, and flavorful instead of dry and crumbly.
Mold, by contrast, usually appears only on the surface, looks fuzzy or powdery, and tends to be green, blue, gray, or black, often with a sour or rotten odor. If the can is bulging, leaking, badly rusted or dented at the seams, or the meat smells off, throw it out. But if the can is intact and the Spam smells and looks typical aside from those white specks, heat it up and watch them melt away into crispy, salty, perfectly safe slices.
