The Truth about Blanching

PeppersDuring a recent food preservation class, the topic of freezing vegetables came up. The big question of the day was “do you really always have to blanch vegetables before freezing them?”

Today I want to share my answer to that question with you.

But first, a quick review.

Blanching is the process of quickly heating fresh vegetables in boiling water or steam. This process is recommended for almost all vegetables when you’re going to stash them in the freezer. The amount of time that you need in order to heat a vegetable depends on the type of vegetable, its shape, and its size. Visit the homepage for the National Center for Home Food Preservation to find a complete list of recommended blanching times. A quick dip in boiling water or steam is followed by an immediate ice bath, which stops the cooking process. And that’s blanching in a nutshell.

Now, is this step necessary? Can’t you just throw raw vegetables into the freezer?

For best flavor and texture, the answer is no. Blanching improves the quality of the frozen vegetables. Vegetables that have been blanched before freezing will have better color, texture, flavor, and nutrition over the long haul than ones that have not been blanched.

So, what about vegetables that aren’t blanched? Are they safe to eat?

There is nothing mysterious or dangerous about vegetables that have not been blanched before freezing. These vegetables are safe to eat. To blanch or not to blanch is a quality issue, not a food safety issue.

TomatoesThat being said, there are some foods that seem to freeze very well without blanching. Want to know what they are? The short list features tomatoes, onions, and peppers.

  • Tomatoes can be frozen raw, either cut-up or whole. You can remove the skins, but if that feels like too much work, you can also freeze whole and well-washed tomatoes with their skins on. Thaw the frozen tomatoes under warm running water and the skins will slip right off. The texture of thawed tomatoes will be soft, but they can still be used for cooking.
  • Do you have too many leftover chopped onions? I like to pack them up in ½ cup portions that are just right for soup or that work well as an addition to ground meat. Like tomatoes, frozen onions will have a softer texture, but they’re still good in cooked foods.
  • Peppers can also be frozen without blanching. I like to freeze them in quarters or strips in single layers on a tray and then, once they’re solid, put them into freezer bags. This allows me to grab as many as I need for a recipe. If you have enough freezer space, raw peppers can be frozen whole and thawed just slightly to be used for stuffed peppers. Be sure to use freezer-quality bags or packaging — this helps keep the quality top notch (and it also keeps the pepper odors from transferring throughout the freezer).

Time is a critical component here. The longer an unblanched food is kept in the freezer, the lower its quality will be. Unblanched items should be used within 6 to 8 months of freezing.

By Cheryle Jones Syracuse, MS, Professor Emeritus at The Ohio State University

Here’s a free blanching handout that you can offer your clients today!


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Frost on the tomatoes


My tomato plants didn’t do too good this year.  My husband currently has it calculated that each cherry tomato we ate cost 33 cents. But there are still a couple  little green tomatoes on the plants, if they ripen that will bring my cost per tomato down a little.

But other people had better luck than I did with their tomato plants. As the days are getting shorter and the nights colder, they are looking for ways to use up or save tomatoes on their plants that haven’t quite ripened.  With special care, green tomatoes will ripen indoors and can be stored 4-6 weeks.  But, it’s important to remember that not all tomatoes can be saved, they must have reached a certain stage of maturity on the vine or they will never ripen.

Obviously, the best way to ripen tomatoes is to leave them on the vine as long as possible. However, as the temperatures cool and there is a risk of frost, it is important to pick the tomatoes. When the temperature goes below 45 degrees for several days, the tomatoes may not ripen satisfactorily or may rot and decay before ripening.

For best results, select the largest, blemish-free tomatoes from healthy plants.  Mature green tomatoes are greenish white on the blossom end, these are the one you’ll have the most luck with ripening.  Hard bright green tomatoes will never ripen.

After harvesting, remove the stems to prevent them from puncturing each other, rinse and let them dry before storage.  Just wiping the soil from the tomatoes is not recommended as it may cause damage which may lead to decay.

Sort by degree of ripeness, this way you can store then in the order in which they will ripen. To reduce bruising, wrap the tomatoes individually in newspaper. This also helps trap some of the ethylene gasses that the tomatoes give off which helps them to ripen.  Pack the green tomatoes one or two layers deep in shallow boxes or trays.

The tomatoes should be stored in moderately moist airy place.  Too much dampness will promote decay and if the room is too dry the tomatoes will shrivel and dry out before they ripen.  Since homes and garages vary in humidity levels and temperatures, you’ll need to learn by trial and error which works best.


Mature green tomatoes reach an eating-ripe state in 14 days if held at 65-70 degrees Fahrenheit.  Ripening can be slowed down by holding the tomatoes at 55 degrees.  Storage at temperatures below 50 degrees will slow ripening, but result in poor quality.

Home refrigerators should be set at 40 degrees or slightly lower.  This is too cold for green tomatoes.  Tomatoes held at that temperature for more than a few days will never ripen. Tomatoes may be kept in the refrigerator after they are fully ripe but they may become watery after a couple of days.

Be sure to check your stored tomatoes frequently and remove any damaged one, as one spoiled tomato can ruin the entire batch. 

If your supply of green tomatoes is plentiful you might try then in a green tomato salsa, grill them or oven fry. Nutritionally, according to the USDA data base, a green tomato has slightly more calories– 41 calories— than a raw ripe red tomato at 32 calories per cup (180 grams).  Green tomatoes also have  a little more Vitamin C (70% DV vs. 38% DV) and a little more sugar (7 grams vs. 5 grams.)

With some special care you might be able to have fresh tomatoes for Thanksgiving.

Cheryle Jones Syracuse, MS

Professor Emeritus, The Ohio State University