Blanching is the process of immersing fruit and vegetables first in boiling water, or steam, and then in very cold water to preserve or freeze the produce. It cleans produce and also helps reduce any bitter flavors. It makes peeling produce, such as tomatoes and peaches, easier and helps them retain their nutrients, color and flavor even when they are frozen.
For boiling water blanching, put the fruit or vegetables into a wire basket, and lower it into a pot of boiling water. The produce must be completely immersed in the water, which must continue to boil. Typically, one gallon of water is used per pound of produce. Follow the blanching times specified for different fruits and vegetables.
For steam blanching, use a pot with a tight lid and a basket that holds the produce at least three inches above the water. Steam blanching is best for sweet potatoes, broccoli and pumpkin. This process takes one-and-a-half times longer than water blanching. For best results, lay the produce in a single layer, and keep the heat on high.
As soon as the vegetables are heated, they must be thoroughly and quickly cooled under cold running water or ice water. The cooling time should be equal to the heating time.