Why are foods blanched

Tips on blanching for the best quality frozen vegetables. Blanching time is crucial and varies with the vegetable and size. Under-blanching stimulates the activity of enzymes, proteins that cause changes in color, texture, flavor and nutrients, and is worse than not blanching at all. Over-blanching causes loss of flavor, color, vitamins and minerals.

Follow these blanching tips for high quality frozen vegetables:. While most vegetables should be blanched prior to freezing, there are some exceptions: peppers do not need a blanching step, and some items such as potatoes are better prepared by par-cooking in an oven, rather than blanching, prior to freezing. Fruits do not need to be blanched heat treated prior to freezing.

The items that you freeze without blanching may look and taste bad, but omitting the blanching step is not a direct cause of foodborne illness. Stay food safe! We teach, learn, lead and serve, connecting people with the University of Wisconsin, and engaging with them in transforming lives and communities.

Connect with your County Extension Office ». Find an Extension employee in our staff directory ». Facebook Twitter. Feedback, questions or accessibility issues: info extension. Processing small quantities at a time, generally 1 pound of prepared vegetables, will mean that water returns to a boil quickly within 1 minute after vegetables are added.

Use either steam or hot water for blanching ; avoid microwave blanching. Follow stated blanching times. Use tested recipes for best quality; start timing the blanching process as soon as water is boiling or steam is being produced. Why blanch vegetables before freezing?

Blanching vegetables before freezing them is critical to their quality, but not their safety. Blanching is scalding vegetables in boiling water or steam for a short time. It is typically followed by quick, thorough cooling in very cold or ice water. Blanching stops enzyme actions which otherwise cause loss of flavor, color and texture. In addition, blanching removes some surface dirt and microorganisms, brightens color and helps slow vitamin losses.

It also wilts greens and softens some vegetables broccoli, asparagus and makes them easier to pack. It is critical to use the correct blanching time for the vegetable and size see table below. Under-blanching stimulates enzyme activity and thus is worse than no blanching.

Over-blanching leads to partial cooking and causes loss of flavor, color, vitamins and minerals. For home freezing, the most satisfactory way to blanch all vegetables is in boiling water. The water should return to boiling within a minute of adding the vegetables. As soon as water returns to a boil, the blanching countdown begins. Vegetables should be cooled quickly and thoroughly to stop the cooking process immediately after blanching. To do this, plunge the vegetables into a large bowl of cold water, 60 degrees Fahrenheit or below.

Change the water frequently or use one pound of ice for each pound of vegetables to help keep the water cold. It should take about the same amount of time to cool vegetables as it did to blanch them. Extra moisture can reduce quality when vegetables are frozen. Pack your blanched vegetables in food safe, plastic freezer bags or rigid containers before storing in the freezer. Allow some extra space in the container before sealing, as some items may expand when frozen.

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