Blanch and freeze
Blanch and freeze means boiling vegetables briefly, chilling them in ice water, then freezing them. It keeps their color, flavor and texture for months.
Blanch and freeze is the standard way to freeze most vegetables at home. You blanch them in boiling water for a set time, cool them fast in ice water, dry them and freeze them. Blanching stops the natural enzymes that otherwise keep working in the freezer and turn vegetables dull, tough and off-tasting.
How to do it
- Wash, trim and cut the vegetables into even pieces.
- Bring at least 4 liters (1 gallon) of water to a rolling boil for every 450 g (1 lb) of vegetables.
- Add the vegetables. Start timing when the water comes back to a boil, which should take no more than a minute. If it takes longer, use fewer vegetables per batch.
- Lift them out and shock them in ice water for about as long as they boiled.
- Drain well and pat dry.
- Flash freeze on a tray, then pack into freezer bags or containers. Press out the air, label with the name and date, and freeze at -18°C (0°F) or below.
These are typical blanching times from US home-preserving guidance:
| Vegetable | Blanching time |
|---|---|
| Peas | 1 1/2 minutes |
| Spinach and other soft greens | 2 minutes |
| Sliced carrots | 2 minutes |
| Green beans | 3 minutes |
| Broccoli florets | 3 minutes |
| Cauliflower florets | 3 minutes |
| Sliced zucchini (courgette) | 3 minutes |
Why it works
Heat stops the enzymes that cause loss of color, flavor and nutrients. It also cleans the surface and wilts leafy vegetables so they pack more tightly. Cooling at once stops the vegetables from cooking through.
How to store it
Most blanched vegetables keep their best quality for 8 to 12 months at -18°C (0°F). They stay safe longer, but texture and flavor slowly fade. Cook them from frozen.
Common mistakes
- Blanching too briefly. Short blanching can make enzymes more active than none at all.
- Blanching too long, which leaves soft, overcooked vegetables.
- Putting in too much at once, so the water stops boiling.
- Freezing wet vegetables, which clump and build up ice.
- Leaving air in the bag, which causes freezer burn.
Related terms
- BlanchBlanching is cooking food for a short time in boiling water, then stopping the cooking in ice water. It sets color and loosens skins.
- ShockTo shock is to plunge just-cooked food into ice water so it stops cooking at once. It keeps vegetables bright and crisp and makes eggs easier to peel.
- Flash freezeFlash freezing means freezing food in a single layer on a tray before bagging it, so berries, dumplings and cookie dough stay loose and easy to portion.
- Freezer burnFreezer burn is the dry, grayish, leathery patches on frozen food left exposed to air. It is safe to eat but tastes and feels worse, so trim it off.
- Vacuum sealVacuum sealing removes air from a plastic bag and seals it shut. It slows freezer burn and spoilage but does not make food safe at room temperature.
- HeadspaceHeadspace is the empty gap between the food and the lid of a jar or container. The right amount helps canning jars seal and stops frozen jars cracking.