Preserving produce by heat shocking before storing

The optimum time and temperature combination for the quick dip seems to depend on many factors, but the procedure is quite simple. Just let the water run from your tap until it gets hot, then fill a large pot of water about two-thirds full, and use a thermometer to measure the temperature. It will probably be between 105 F and 140 F; if not, a few minutes on the stove should do the trick. Submerge the produce and hold it there for several minutes (the hotter the water, the less time is needed), then drain, dry and refrigerate as you normally would.

Researchers still are working out the details of how heat-shocking works, but it appears to change the food in several ways at once. Many of the fruits and vegetables you bring home from the store are still alive and respiring; the quick heat treatment tends to slow the rate at which they respire and produce ethylene, a gas that plays a crucial role in the ripening of many kinds of produce. In leafy greens, the shock of the hot water also seems to turn down production of enzymes that cause browning around wounded leaves, and to turn up the production of heat-shock proteins, which can have preservative effects.