How to Soften Pasta That Hardens After Cooling

Pasta that hardens after being kept in the refrigerator does so because starch recrystallizes in the cold; the most practical fix is to briefly dip the pasta in boiling water or heat it in a covered pan with a little water, since starch regains some flexibility when it receives heat and moisture again. Why does pasta harden as it cools? During cooking, starch granules absorb water and swell, giving pasta its familiar soft texture. As pasta cools, these starch molecules rearrange, bond tightly together, and release some water; this process is called retrogradation and causes the same hardening in rice and bread. The cold temperature of the refrigerator speeds up this process, so pasta left overnight becomes noticeably harder than pasta left at room temperature. Still, do not leave cooked pasta out overnight; refrigerate it within 2 hours and use it within 3 to 4 days. Pasta stored mixed with sauce generally hardens less than plain pasta because the moisture in the sauce keeps the starch from drying out completely; for this reason, storing leftover pasta with sauce rather than without it is one of the first precautions. What are the most practical ways to soften it? The fastest way is to dip the pasta in boiling water for a few seconds using a strainer and remove it immediately; this method rehydrates the starch while preventing the pasta from becoming too soft and mushy. If you want to heat it in a pan, add a few tablespoons of water or sauce to the pasta, cover it, and steam it over medium heat for a few minutes; heating it uncovered quickly evaporates the moisture and dries the pasta out again. The same principle applies when reheating it in a microwave: if you drizzle a little water over the pasta and cover the container with a damp paper towel, the steam returns to the pasta and softens its texture evenly; when it is heated uncovered, the edges can harden while the center remains cold. How can you keep it from hardening again? If pasta is mixed with a little olive oil or sauce immediately after cooking and then stored, the starch on its surface retains moisture longer. Tightly closing the storage container also slows hardening by reducing evaporation; pasta left exposed dries out faster and absorbs odors more easily. Do all types of pasta respond in the same way? Thin pasta (such as spaghetti and vermicelli) hardens more quickly because it has more surface area and also responds more quickly to reheating; thick and stuffed pasta (such as penne and dumpling-like filled pasta) hardens more slowly, but because of its filling, it may take a little longer to heat evenly in a microwave. Whole-wheat pasta can leave a slightly firmer texture after cooling than white-flour pasta because it contains more fiber, so giving it a few extra seconds of steam while reheating makes a difference. If pasta is being prepared for a cold pasta salad, hardening is not really a problem; in this case, cook it from the start in less water until it is a little firmer (al dente), then cool it, because a slightly firm texture is what is desired in a salad. For pasta set aside for a hot dish, the goal is to preserve the softness of the original cooking, so reheating comes into play at this point.