A cold water bath is a cooking technique that immediately arrests the process of whatever you are cooking by directly immersing it in cold or even ice water. The simplest cold water bath is to pour cold water on foods like pasta while it still sits in the colander. This can help keep your pasta al dente for recipes like pasta salad. Placing food in cold water is also common when you’re blanching, or lightly cooking, vegetables for use as a side and in salads.

The reason chefs employ a cold water bath is because food that is heated will continue to cook slightly, even after it is removed from the heat. When you are minimally cooking food and need it to retain a certain texture or firmness, you can still end up overcooking if you don’t use the cold water bath. This may also be called shocking the food, since its result is to immediately end the cooking process.

Sometimes people add salt to the cold water bath, about half a teaspoon for every quart of water used. This can help the food retain its natural sodium, though many skip this step with fine results. The simple cold water bath is composed of lots of ice covered in water. Some recipes recommend that you fill a bowl about two-thirds with ice, and then add enough water to cover the ice.

Food like blanched vegetables are then placed in the cold water bath and allowed to sit for a minute or two. They can then be removed and will not cook further. You can store most vegetables that have been shocked for a couple of days in the refrigerator. Consider placing them in airtight bags or lidded containers to keep them fresh. You’ll also want to dry them slightly if you plan to store them, so that excess moisture does not ruin them.

You should not employ the above cold water bath technique for pasta recipes where you want to keep the food hot and serve it immediately. In fact many recipes for pasta should not include a shock process, since even pouring cool water over pasta can remove the starchy coating pasta gets when it is cooking. This starch coating may be necessary when pasta is added directly to thin sauces, since it helps to thicken them. Similarly, if you are adding hot potatoes to thin sauces or soups to make them thicker, you should omit any type of rinsing or shocking.