How to Blanch Vegetables Before Freezing
Freezing is a great way to preserve fresh vegetables from a backyard garden or a local farmers' market when they are in season. And, by freezing vegetables that might not be available year round in the fresh produce section of your local supermarket, you'll be able to enjoy the flavor and health benefits of those vegetables all year round. But before you stash your favorite vegetables in the freezer, you'll need to know whether they should blanched first. To help you with that, you'll find below information about vegetables that need to be blanched, including a chart listing the recommended blanching times for those vegetables, as well as step-by-step instructions on how to blanch fresh vegetables before freezing them.
Why Should Vegetables Be Blanched Before Freezing?
Blanching, or cooking vegetables in boiling water or steam for a set period of time, inhibits the action of enzymes that cause vegetables to develop off-flavors and lose color and nutrients when stored in the freezer for a longer period of time. This process also helps remove dirt and organisms on fresh produce. Blanching time is crucial because underblanching stimulates the action of enzymes, while overblanching causes vegetables to lose color, flavor and nutrients.
Do All Vegetables Need to Be Blanched?
Blanching is recommended for almost all vegetables, but there are also some vegetables that will stay good in the freezer even without blanching. Vegetables that do not need to be blanched before freezing include sweet and hot peppers, ginger root, onions, turmeric root, and raw tomatoes. Also many fresh herbs, such as chives and dill, can be frozen successfully without blanching.
How Long Should Your Blanch Vegetables Before Freezing?
The ideal blanching time for vegetables generally varies from 30 seconds to 10 minutes, depending on the size and texture of the food and the blanching method you are using (water vs steam blanching). For detailed information about how long it takes to blanch a specific vegetables before freezing, have a look at the Blanching Times Chart provided below. Note that the times indicated are for water-blanching (boiling); if you want to steam-blanch your vegetables, multiply the times by 1.5.
Chart: Blanching Times for Common Vegetables
Please note that the following Blanching Times chart is intended as a general guide only – the actual blanching times may differ due to a number of factors.
| Vegetable | Preparation 1 | Blanching time 2 |
|---|---|---|
| Artichoke hearts | Leave the hearts whole | 7 minutes |
| Asparagus | Trim; leave whole or cut to your liking | 2 to 4 minutes |
| Beans, green | Trim off the hard ends | 2 to 4 minutes |
| Beans, snap | Trim off the hard ends | 2 to 4 minutes |
| Beans, wax | Trim off the hard ends | 2 to 4 minutes |
| Bell peppers 3 | Cut into strips | 2 minutes |
| Broccoli | Cut into 1½-inch pieces | 3 minutes |
| Brussels sprouts | Trim; leave whole | 3 to 5 minutes |
| Cabbage | Cut into coarse shreds or thin wedges | 1 1/2 minutes |
| Carrots | Cut into 1/4-inch slices | 2 minutes |
| Cauliflower | Cut into 1-inch florets (See also How to Freeze Cauliflower Rice) | 3 minutes |
| Celery | Cut into 1-inch lengths | 3 minutes |
| Chard | Chop or leave whole | 2 minutes |
| Chinese cabbage | Shred the cabbage | 1 1/2 minutes |
| Collard greens | Chop or leave whole | 3 minutes |
| Corn | Leave the ears whole | 7 to 10 minutes |
| Okra | Trim stem ends | 3 to 4 minutes |
| Jerusalem artichokes | Leave them whole | 3 to 5 minutes |
| Kale | Remove the tough stems by hand or using a kale trimmer | 2 minutes |
| Kohlrabi | Cut into 1/2-inch cubes | 1 minute |
| Mustard greens | Chop or leave whole | 2 minutes |
| Parsnips | Cut into 1/2-inch cubes | 2 minutes |
| Romanesco | 1-inch pieces | 3 minutes |
| Squash, summer | Cut into 1/2-inch slices | 3 minutes |
| Sunchokes | Leave them whole | 3 to 5 minutes |
| Tomatoes 3 | Leave whole; peel after blanching | 30 seconds |
| Turnips | Cut into 1/2-inch cubes | 2 minutes |
| Zucchini | Cut into 1/2-inch slices | 3 minutes |
1 In addition, the vegetables should be rinsed and/or peeled, as needed
2 The times indicated are for water-blanching (boiling). For steam-blanching, multiply the times shown in the chart by 1.5.
3 Can also be frozen without blanching
General Instructions for Blanching Vegetables
- Blanch trimmed, rinsed and cut vegetables for the time indicated in the Blanching Times Chart above.
- When the blanching time is up, quickly drain the vegetables. A flat stainless steel strainer that you can place over the top of the pot is great for this purpose, but you can also use a regular stainless steel colander.
- To stop any carryover cooking, plunge the vegetables into a large bowl filled with ice cubes and cold water, and let the vegetables chill in the ice-water bath for the same amount of time they were boiled or steamed.
- Drain thoroughly, and freeze using one of the two methods described below.
How to Freeze Blanched Vegetables
Method 1: Arrange the blanched vegetables in a single layer on a cookie sheet lined with a freezer-safe silicone baking mat or parchment paper, and put the sheet in the freezer. When the vegetables are frozen solid, transfer them to freezer-safe Ziploc bags or containers, and pop them back into the freezer for storage. The great thing about this method is that your blanched vegetables won't fuse together in the freezer, and you'll be able to grab just a few frozen pieces whenever you like.
Method 2: Divide the blanched vegetables into portions that work for your needs. Then, package the portions in freezer bags, leaving as little air inside as possible. A vacuum sealer is perfect for this purpose, but you can also use a straw tucked in the corner of the bag to suck out the air! This method works well if you have a good idea of how you're going to use your frozen vegetables so you are able to divide the vegetables into portions that are just the right size. This is also the preferred method for freezing leafy green vegetables such as kale or collards.
