Blanching is the process of scalding vegetables in boiling or steaming water for a short time. It is simple. Blanching helps retain the flavor, color and texture of vegetables that you plan to freeze.
- Place water in a large kettle or vegetable blancher and bring it to a rolling boil. Use a gallon of water per pound of vegetables, or approximately 2 cups of prepared vegetables.
- Clean and cut vegetables as needed.
- Place vegetables in a wire basket or the perforated blancher insert and immerse in boiling water. The water should return to a boil within one minute. If it takes longer to boil, vegetables will taste soggy.
- Cover and start counting blanching time as soon as water returns to a boil.
- Keep on high heat for the time given in the directions.
- Cool immediately in ice water for the same time used in blanching (corn-on-the-cob takes twice as long). Stir vegetables several times during cooling.
- Drain vegetables thoroughly.
- Pack the vegetables either by dry pack or tray pack.
- Dry pack: pack vegetable tightly into containers or freezer bags. Press out air and seal tightly.
- Tray pack: put a single layer of the vegetable on a shallow pan and put the pan into the freezer. As soon as the vegetable is frozen, put them into a freezer bag or container. Press out air and seal tightly.
- Freeze. Frozen vegetables will maintain high quality for 12 to 18 months at 0° F or lower.
If you have a steamer, you can use it but it will usually take 1-1/2 times longer to blanch the food. Steaming works best with broccoli, pumpkin, sweet potatoes and winter squash.
The microwave is not as efficient to use if you are preparing a large quantity of vegetables for the freezer.
You can use your microwave oven to blanch vegetables. However, blanching times are longer, and off flavors may occur as well as discoloration. You also have to work with only one or two cups of vegetables at a time. Therefore, the microwave is not as efficient to use if you are preparing a large quantity of vegetables for the freezer.
Blanch time depends on the vegetable and size. Under-blanching stimulates the activity of enzymes and is worse than no blanching. Overblanching causes loss of flavor, color, vitamins, and minerals.
Vegetable blanching times (water blanching)
|Vegetable||Blanching time (minutes)|
|Artichoke – globe hearts||7|
|Artichoke – Jerusalem||3 to 5|
|Asparagus – small stalk||2|
|Asparagus – medium stalk||3|
|Asparagus – large stalk||4|
|Beans – snap, green, or wax||3|
|Beans – lima, butter, or pinto - small||2|
|Beans – lima, butter, or pinto - medium||3|
|Beans – lima, butter, or pinto - large||4|
|Broccoli (flowerets 1 1/2 inches across)||3|
|Broccoli flowerets – steamed||5|
|Brussels sprouts – small heads||3|
|Brussels sprouts – medium heads||4|
|Brussels sprouts – large heads||5|
|Cabbage or Chinese cabbage – shredded||1 1/2|
|Cabbage or Chinese cabbage – wedges||3|
|Carrots – small, whole||5|
|Carrots – diced, sliced, or lengthwise strips||2|
|Cauliflower (flowerets, 1 inch across)||3|
|Corn-on-the-cob – small ears*||7|
|Corn-on-the-cob – medium ears*||9|
|Corn-on-the-cob – large ears*||11|
|Corn – whole kernel or cream style (ears blanched before cutting corn from the cob)||4|
|Greens – collards||3|
|Greens – all other||2|
|Kohlrabi – whole||3|
|Kohlrabi – cubes||1|
|Mushrooms – whole (steamed)||9|
|Mushrooms – buttons or quarters (steamed)||9|
|Mushrooms – slices (steamed)||5|
|Okra – small pods||3|
|Okra – large pods||4|
|Onions (blanch until center is heated)||3 to 7|
|Onion rings||10 to 15 seconds|
|Peas – edible pod||2 to 3|
|Peas – green||1 1/2 - 2 1/2|
|Peppers, sweet – halves||5|
|Peppers, sweet – strips or rings||3|
|Potatoes – Irish (new)||3 to 5|
|Soybeans – green||5|
|Squash – summer||3|
|* Cooling time for corn-on-the-cob is twice the time of blanching.|
As soon as blanching are completed, cool vegetables thoroughly by plunging in cold running water or ice. A properly blanched vegetable is brightly colored all the way through, when sliced with a knife. Cooling vegetables should take the same amount of time as blanching.
- Blanching vegetables, National Center for Home Food Preservation