Two pots of water, one hot and one cold. A few seconds to a few minutes boiling time, then a cold plunge to "shock" the food and stop the cooking. Sounds straightforward, right? And yet the thermodynamics of what happens to fruits and veggies when they're blanched are actually pretty complex, and the results nothing short of amazing. Fruit, vegetable, and nut skins slide right off when peeled. Produce develops a brighter color and a crisp-tender texture that remain even after reheating, canning, or freezing. And summer recipes that start with blanched fruits and veggies retain all the fresh-picked flavors of the season.
4 Tips for Blanching Success
1. Maintain a rolling boil Start with 1 gallon (4 quarts) water for every pound of produce. Bring water to a rolling boil, not just a low simmer. Salt the boiling water with 1 to 2 teaspoons salt per gallon to increase the boiling point and "fix" bright colors.
2. Plunge in an ice-cold bath "Shocking" food to stop the cooking requires an immediate drop in temperature. Use 2 quarts water plus 2 quarts ice for every pound of produce. No actual ice for the ice water bath? Use the coldest tap water possible, and change it once or twice until the blanched fruits or vegetables are completely cooled.
3. Work in batches Tempting as it may be to toss all those fruits or veggies into a big pot of water, don't do it! You want the water (whether boiling or icy) to change the temperature of the food, not the other way around.
4. Use a timer Overblanched produce can lose its bright color and firm texture in a very short time, so leave the counting to a reliable kitchen gadget.
When to Blanch and Why
For easy peeling 10 to 60 seconds in boiling water loosens the skins of tomatoes, stone fruit (peaches, nectarines), garlic, onions, and nuts.
Before canning or freezing 2 to 5 minutes in boiling water halts enzyme activity so that foods won't discolor or lose their texture when preserved.
To speed up cooking Denser veggies, such as carrots, potatoes, and squash, can be blanched before they're added to stir-fries, salads, or casseroles.