Why Do You Need to Blanch (Treat in Boiling Water or Steam) Some Foods Before Freezing?

Have you ever stuck some springs of raw basil into a Ziplock bag and shoved it into your freezer?

When you took it out weeks or months later, it thawed into a blackened, slimy mess, right?

If you’d blanched the basil before freezing, it would have kept its emerald-green color and bright aroma and flavor.

Here’s why.

Although the temperatures in your freezer are too low for harmful bacteria to survive, they do not destroy the enzymes whose job it is to decay organic matter.

In other words, that raw basil did continue to slowly decompose even though it was frozen.

Blanching, which is simply a very brief treatment in boiling water or steam, kills off those enzymes.

To blanch foods for freezing, bring water to a boil in a large pot or underneath a steamer basket.

Drop in clean vegetables or herbs for just the amount of time specified (the water in the pot or steamer must be at a full boil before you start timing).

Once the time is up, immediately drain the blanched food in a colander and then either transfer it to a bowl of ice water or run it under very cold water.

This last step stops residual heat from continuing to cook the food.

Squeeze out or drain off as much water as possible before transferring the blanched vegetables or herbs to freezer containers and freezing.

Sweet and chile peppers, as well as onions, corn, and tomatoes, may be frozen without blanching with good results.

Most root vegetables, especially potatoes, do not freeze well even if they are blanched first; that includes carrots, despite the numerous commercial frozen vegetable combos that contain them.

Here are some ingredients, and their blanching times before freezing

Artichoke Hearts blanch for about 6 minutes
Asparagus blanch for about 2–4 minutes
Beans, green, or wax blanch for about 3 minutes
Broccoli (in 1-inch pieces or florets) blanch for about 2 minutes
Brussels sprouts blanch for about 3–5 minutes
Cauliflower (in 1-inch pieces or florets) blanch for about 3 minutes
Kohlrabi (in 1-inch cubes) blanch for about 1 minute
Leafy greens (including chard, collards, kale, spinach, etc.) blanch for about 1–2 minutes
Leafy herbs, fresh blanch for about 20–30 seconds
Okra blanch for about 2–3 minutes
Peas (in the pod) blanch for about 2–3 minutes
Peas (shelled, loose) blanch for about 1.5 minutes
Squash (summer, chayote, zucchini) blanch for about 3 minutes