The term "blanching" refers to the
technique of plunging a food, usually a vegetable or fruit,
into boiling water until either its color has set or the food
has softened slightly. This takes anywhere from a few seconds
to several minutes, depending on what is being blanched.
Then the food is removed to an ice
bath to "shock," or stop the cooking process and to set color.
Why do you use this technique? It
makes it easier to peel the skin of fruits like tomatoes and
peaches. It also enhances the color of vegetables like green
beans or broccoli. That is why the blanched green beans shown
here look so vivid.
It's also a good idea to blanch
vegetables you intend to freeze, because blanching inactivates
the enzymes that promote spoilage.
Parboiling is a technique that is
similar to blanching, but takes a bit longer. Parboiled food
is actually partially cooked. This technique is especially
useful when you are stir-frying foods that take different
amounts of time to cook. If you parboil a dense food, such as
broccoli, you can add it to your wok at the last minute to
cook along with a quicker-cooking food, such as shrimp.