Stew

Stew keeps 3–4 days refrigerated and 2–3 months frozen. As with soup, the difficulty is cooling rather than the window.

Stew is worse than soup in this respect because it is thicker and denser, so heat moves through it by conduction rather than convection — there is very little internal circulation to carry heat to the surface. A thick stew can hold its center above 100°F for hours in a refrigerator.

Divide it into shallow containers no more than two inches deep and refrigerate within two hours. For a large batch, cool the pot in an ice-water bath first, stirring often to move the hot interior outward.

Most stews freeze well and many improve, as the flavors continue to combine. Potatoes are the exception — they turn grainy and mealy when frozen, so leave them out and add fresh on reheating if you plan to freeze.

Reheat stew to a full boil, stirring so the center actually reaches temperature.

Stew is the classic vehicle for Clostridium perfringens, an organism sometimes called the "cafeteria germ" and one of the most common causes of foodborne illness in the United States.

The reason is a precise match between the organism's requirements and how stew is made. C. perfringens forms heat-resistant spores that survive long simmering. It is anaerobic, preferring low-oxygen environments — which is exactly what the interior of a thick, dense pot provides. And it grows extraordinarily fast in the 70–125°F range, faster than almost any foodborne bacterium, so a slowly cooling pot gives it an ideal window.

Meat and poultry stews are the highest-risk combination, and large-batch cooking is the classic setting: church suppers, holiday meals, catered events. The illness that follows is usually cramps and diarrhea beginning 6–24 hours later.

Reheating to a full boil kills the vegetative cells, which is a real benefit — but it is far better not to let them grow in the first place, since some strains also produce a toxin during the process.

The signals for stew that has gone are a sour or fermented smell, bubbling or fizzing without heat, a slimy or ropy texture in the liquid, and surface mold. Reheating cannot rescue any of those.