Blanching: What it is, Why to blanch before freezing and drying vegetables and fruits, and How to blanch!

This month's notes: August 2014: Blueberries, blackberries, raspberries tomatoes, corn and most vegetables are being picked in most places; strawberries are finishing or done; Peaches are in and early apples will start in late July. Find a local blueberry festival and blueberry picking tips here. See how easy it is to make strawberry jam or strawberry-rhubarb jam! Make your own homemade strawberry ice cream including low fat, low sugar and other flavors))  Have fun, eat healthier and better tasting, and save money by picking your own locally grown fruit and vegetables, and then using our easy canning and freezing directions!

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Blanching is scalding vegetables in boiling water or steam for a short time as an important step prior to vegetables being frozen. Blanching stops enzyme actions which can cause loss of flavor, color and texture.  Up until harvest time, enzymes cause vegetables to grow and mature. If vegetables are not blanched, or blanching is not long enough, the enzymes continue to be active during frozen storage causing off-colors, off-flavors and toughening.

Blanching

  • Slows or stops enzymatic action, preserving flavor, color and texture,
  • cleanses the surface of dirt, bacteria, molds and other organisms,
  • brightens the color,
  • helps retard loss of vitamins and
  •  softens vegetables and makes them easier to pack and less susceptible to freezer burn

Blanching time is crucial and varies with the vegetable and size. Under-blanching actually stimulates the activity of enzymes and is worse than no blanching. Over-blanching causes loss of flavor, color, vitamins and minerals. Follow recommended blanching times below or attaches to each relevant recipe (blanching applies to freezing and many drying recipes, but not to canning; since canned foods are effectively blanched during the heat treatment in the canner)

How to Blanch vegetables and fruits

Water Blanching

For home freezing, the most satisfactory way to heat all vegetables is in boiling water. Use a blancher which has a blanching basket and cover, or fit a wire basket into a large pot with a lid.

Use one gallon water per pound of prepared vegetables.

  1. Put the vegetable in a blanching basket and lower into vigorously boiling water over high heat. Place a lid on the blancher. If you don't have a basket, just dump them into the pot as shown in the photo.
  2. The water should return to boiling within 1 minute, or you are using too much vegetable for the amount of boiling water. Start counting the blanching time as soon as the water returns to a boil. Keep heat high for the time given in the directions for the vegetable you are freezing. (See further down the page for blanching times)
  3. As soon as blanching is complete, vegetables should be cooled quickly and thoroughly to stop the cooking process. To cool, plnge the basket of vegetables immediately into a large quantity of ice water, 60ºF or below. If you didn't use a basket, just pour the pot into a colander in the sink then dump the strained vegetables into the ice water. If ice is used, about one pound of ice for each pound of vegetable is needed. Cool the vegetables for the same length of time that you blanched them; or longer if they are still warm..
  4. Drain vegetables thoroughly after cooling. Extra moisture can cause a loss of quality when vegetables are frozen. Simply pouring them into a strainer or colander in your sink and leting them drain for 2 or 3 minutes is fine.

Steam Blanching

Heating in steam is recommended for a few vegetables. For broccoli, pumpkin, sweet potatoes and winter squash, both steaming and boiling are satisfactory methods. Steam blanching takes about 1½ times longer than water blanching.

To steam, use a pot with a tight lid and a basket that holds the food at least three inches above the bottom of the pot. Put an inch or two of water in the pot and bring the water to a boil.

Put the vegetables in the basket in a single layer so that steam reaches all parts quickly. Cover the pot and keep heat high. Start counting steaming time as soon as the lid is on. See steam blanching times recommended for the vegetables listed below.

Microwave Blanching

Microwave blanching may not be effective, since research shows that some enzymes may not be inactivated. This could result in off-flavors and loss of texture and color. Those choosing to run the risk of low quality vegetables by microwave blanching should be sure to work in small quantities, using the directions for their specific microwave oven. Microwave blanching will not save time or energy.

Blanching Times*

Vegetable Blanching Time
(minutes)
Artichoke-Globe
(Hearts)

7
Artichoke-Jerusalem 3-5
Asparagus
Small Stalk
Medium Stalk
Large Stalk

2
3
4
Beans-Snap, Green, or Wax 3
Beans-Lima, Butter, or Pinto
Small
Medium
Large

2
3
4
Beets cook
Broccoli
(flowerets 11/2 inches across)
Steamed

3
5
Brussel Sprouts
Small Heads
Medium Heads
Large Heads


3
4
5
Cabbage or Chinese Cabbage
(shredded)

1 1/2
Carrots
Small
Diced, Sliced or Lengthwise Strips

5
2
Cauliflower
(flowerets, 1 inch across)

3
Celery 3
Corn
Corn-on-the-cob
Small Ears
Medium Ears
Large Ears
Whole Kernel or Cream Style
(ears blanched before cutting corn from cob)


7
9
11

4
Eggplant 4
Greens
Collards
All Other

3
2
Kohlrabi
Whole
Cubes

3
1
Mushrooms
Whole (steamed)
Buttons or Quarters (steamed)
Slices steamed)

5
3 1/2
3
Okra
Small Pods
Large Pods

3
4
Onions
(blanch until center is heated)
Rings

3-7
10-15 seconds
Peas-Edible Pod 1 1/2-3
Peas-Field (blackeye) 2
Peas-Green 1 1/2
Peppers-Sweet
Halves
Strips or Rings

3
2
Potatoes-Irish (New) 3-5
Pumpkin cook
Rutabagas 3
Soybeans-Green 5
Squash-Chayote 2
Squash-Summer 3
Squash-Winter cook
Sweet Potatoes cook
Turnips or Parsnips
Cubes

2

*blanching times are for water blanching unless otherwise indicated.

 

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