written by: Lindsay Evans•edited by: Donna Cosmato•updated: 7/6/2011
What is blanching? Is blanching necessary when freezing vegetables? Which vegetables need to be blanched? Learn all about the recommended way to freeze fresh vegetables for storage.
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All About Blanching
Freezing food is one simple method of preserving food at home. However, sometimes its not as simple as throwing a ziploc bag of veggies in the freezer. This is when blanching comes in as a way of preserving and cleaning the food.
According to the National Center for Home Food Preservation (NCHFP), blanching vegetables refers to "scalding vegetables in boiling water or steam for a short time." Blanching vegetables prior to freezing is necessary because the process "stops enzyme actions which can cause loss of flavor, color and texture." Not only that, blanching also removes any small particles of dirt or microorganisms from the surface of the food that may remain after washing. Additionally, blanching veggies before freezing can actually help your food retain vitamins and minerals.
The NCHFP recommends following their chart for blanching times when preparing vegetables for freezing. "Underblanching stimulates the activity of enzymes and is worse than no blanching," their site reports. "Overblanching causes loss of flavor, color, vitamins and minerals."
All vegetables, from green beans to carrots to okra, should be blanched before they are frozen for storage. Not only will the texture of your vegetables be improved when eaten out of the freezer, you can be sure that bacteria, fungus, and mold have not spoiled your frozen food. Although they move and multiply very slowly, remember that microorganisms can still live on your veggies in the freezer.
Blanching vegetables in the microwave is not recommended by the NCHFP. Follow the instructions below on boiling water blanching and steam blanching.
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How to Blanch with Boiling Water
Boiling water blanching is the method recommended by the NCHFP. To blanch vegetables in boiling water, bring a large lidded stock pot of water to a rolling boil over high heat. If you have a wire basket that fits the stock pot, place vegetables in the basket, lower into the boiling water, and put on the lid. Once the water returns to a boil (it should be one minute or less) begin blanching time according to the NCHFP chart.
If you do not have a wire basket you may use a large slotted spoon to scoop vegetables out of the boiling water after the recommended time.
You must thoroughly cool the vegetables after blanching. Submerge them in a clean sinkful of ice water or use cold running water. Quick cooling ensures that the blanching process stops and avoids overcooking your food.
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How to Steam Blanch Vegetables
According the NCHFP recommendations, steam can be used to blanch mushrooms and broccoli or to cook sweet potatoes, pumpkin, and winter squash prior to freezing. All other vegetables should be blanched in boiling water.
To steam blanch, use a steamer basket that holds the food a few inches off the bottom of the pan. Place an inch or two of water in the pan and bring to a boil over high heat. Don't overcrowd the steam basket, use only enough food to cover the basket in a single layer. Begin steam blanching time after the food is placed in the basket and the lid is on.
Cool blanched vegetables in ice water or under cold running water.
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Freezing Your Veggies
Your food is now ready to be frozen! Be sure your vegetables are well drained after blanching and cooling. Pack your blanched vegetables in plastic zip-top freezer bags or plastic freezer containers. Label with the date, place in the freezer, and you're done!