Wash and soak in salt water (1 tablespoon of salt per quart of water) for about 30 minutes to flush out any insects or worms. Trim outer leaves and sort according to size.
Blanch in boiling water; boil small heads for 3 minutes, medium heads 4 minutes and large heads for 5 minutes. Cool quickly.
No headspace required.
1 pounds of Brussels sprouts = approximately 1 pint frozen.
Page 1 - Vegetable Freezing Guide: Blanching and Packing
Page 2 - Preparation and Blanching Times for Specific Vegetables
Page 3 - Cooking Frozen Vegetables