Blanching Vegetables

Blanching is a process where food is plunged first into hot boiling water and then cooled rapidly in ice water to stop the cooking process. When done properly, this destroys the enzymes that cause vegetables to ripen, which causes undesirable changes in food flavour, colour, and texture. Almost all vegetables require blanching before freezing or dehydrating, with a few exceptions.  Make sure to follow exact blanching times for each type of vegetable. Under-blanching does not destroy all the enzymes, while over-blanching reduces flavour, texture, and nutrient content. 

 

Equipment needed: 

• Large pot with a cover (4 L water to about 500 g vegetables or 8 L for leafy greens)
• Wire basket or cheesecloth bag 
• Large bowl
• Ice
• Colander 

Instructions:

1. Fill the large bowl with very cold water.
2. Set aside. 
3. Fill pot with 3/4 full of water and bring to a boil.
4. Place vegetables in wire basket or tie loosely in cheesecloth bag leaving length of string for ease of handling
5. Lower vegetables into vigorously boiling water, cover and immediately start counting blanching time. Keep heat on high so water quickly returns to a boil.
6. Once blanching time is up, chill vegetables immediately in cold running water. If water is not cold enough add ice.
7. Leave vegetables in cooling water for the same time used in blanching but no longer than necessary. 
8. Drain cooled vegetables thoroughly and freeze or dehydrate according to the instructions on each page.

Vegetable	How to Prepare	Blanching Time
Asparagus	Remove tough ends. Cut in uniform lengths	Med – 3 min Lrg – 4 min
Beans (green/wax)	Trim ends. Leave whole or cut in 3 cm pieces	Cut – 3 min Whole – 4 min
Broccoli	Remove woody stems and trim. Cut through stalks so that pieces are not more than 3 cm across	Med – 3 min Lrg – 4 min
Brussel Sprouts	Trim stems and outer leaves	Sm – 3 min Med – 4 min Lrg – 5 min
Cabbage	Trim outer leaves and core. Cut in wedges or shred coarsely	Wedges – 2 min Shredded – 1 min
Carrots	Remove tops and scrape or peel. Leave small carrots whole. Cut larger carrots in 1 cm slices or dice or cut lengthwise in fingers	Cut – 3 min Whole – 5 min
Cauliflower	Break heads into small flowerets about 3 cm in diameter	3 min
Corn	Whole kernel If on cobs, remove husks and trim cobs to even lengths	4 min On Cob: Sm – 7 min Med – 9 min Lrg – 11 min
Parsnips	Remove stem and root ends. Peel. Cut in 2 cm fingers or 1 cm slices	Fingers – 1 min Slices – 1 min
Peas	Shell	2 min
Spinach, Chard	Wash thoroughly. Cut chard in 3 cm pieces or separate leafy parts from stalks and cut stalks in 10 cm lengths	2 min
Summer squash	Cut in 1 cm slices	2 min
Winter squash (butternut)	Peel and dice (butternut)	2 min
Turnip	Peel and dice	2 min

Ref: Ontario Ministry of Agriculture and Food. (1990). Freezing Foods. Food Advisory Services. Canada Department of Agriculture.