How to Freeze Kohlrabi: A Comprehensive Guide to Preserving This Underrated Vegetable

Kohlrabi, often called a German turnip, is a cruciferous vegetable with a mild, slightly sweet flavor and a crisp texture. While readily available in the fall and winter months, you might find yourself with an abundance of it, or perhaps you want to enjoy its unique taste year-round. Freezing kohlrabi is an excellent way to preserve its flavor and nutrients for future use. This comprehensive guide will walk you through every step, from selecting the best kohlrabi for freezing to properly storing it for optimal quality.

Table of Contents

Understanding Kohlrabi: A Brief Introduction

Before we delve into the freezing process, let’s briefly understand what makes kohlrabi so special. This unassuming vegetable, related to cabbage, broccoli, and cauliflower, boasts a bulbous stem that grows above ground. Both the bulb and the leaves are edible, offering a range of culinary possibilities.

The flavor of kohlrabi is often described as a cross between a turnip and a cabbage, but milder and sweeter. Young, smaller kohlrabi bulbs tend to be more tender and flavorful, while larger ones can become woody. The leaves taste similar to collard greens or kale.

Kohlrabi is also a nutritional powerhouse, packed with vitamin C, fiber, potassium, and other essential nutrients. Freezing allows you to enjoy these benefits even when fresh kohlrabi isn’t in season.

Why Freeze Kohlrabi? The Benefits of Preservation

Freezing is a time-tested method of food preservation that offers several key advantages. For kohlrabi, these advantages are particularly appealing.

Extending Shelf Life: Fresh kohlrabi, when stored properly in the refrigerator, can last for several weeks. However, freezing extends its shelf life significantly, allowing you to enjoy it for months.
Reducing Food Waste: If you have more kohlrabi than you can consume before it spoils, freezing prevents it from going to waste.
Maintaining Nutritional Value: While some nutrient loss can occur during freezing and thawing, the majority of vitamins and minerals are retained.
Convenience: Frozen kohlrabi is readily available for use in soups, stews, stir-fries, and other dishes, saving you time and effort.

Selecting and Preparing Kohlrabi for Freezing

The success of freezing kohlrabi hinges on selecting the right bulbs and preparing them properly. Follow these guidelines for the best results.

Choosing the Right Kohlrabi

Look for Firmness: Select kohlrabi bulbs that are firm to the touch and free from blemishes, bruises, or soft spots.
Consider Size: Smaller to medium-sized bulbs (about 2-3 inches in diameter) are generally more tender and flavorful than larger ones.
Check the Leaves: If the leaves are still attached, they should be fresh, green, and crisp, indicating a recently harvested bulb.

Cleaning and Peeling Kohlrabi

Wash Thoroughly: Rinse the kohlrabi bulbs under cold running water to remove any dirt or debris. Use a vegetable brush to scrub the surface if necessary.
Peel the Skin: Use a sharp vegetable peeler or paring knife to remove the tough outer skin. The skin can be quite thick, especially on larger bulbs. Be sure to remove all traces of the outer layer.

Cutting and Preparing for Blanching

Choose Your Cut: Decide how you want to use the kohlrabi after freezing. Common options include cubes, slices, or matchstick cuts. Cut the kohlrabi into uniform pieces for even blanching and freezing.
Leaf Preparation (Optional): If you want to freeze the kohlrabi leaves, wash and chop them as you would other leafy greens. They can be frozen separately or mixed with the bulb pieces. Keep in mind that the texture of the leaves will change after freezing, becoming softer. They are best used in cooked dishes.

Blanching: The Key to Preserving Quality

Blanching is a crucial step in preparing kohlrabi for freezing. It involves briefly cooking the vegetables in boiling water or steam, followed by a rapid cooling in ice water.

Why Blanch? The Benefits of the Process

Inactivates Enzymes: Blanching deactivates enzymes that can cause deterioration in color, flavor, and texture during frozen storage.
Reduces Microorganisms: It helps to reduce the number of microorganisms present on the surface of the kohlrabi.
Preserves Color and Flavor: Blanching helps to maintain the vibrant color and fresh flavor of the kohlrabi.
Softens Texture: It slightly softens the texture, making it more palatable after freezing and thawing.

Blanching Methods: Water Blanching vs. Steam Blanching

Water Blanching: Bring a large pot of water to a rolling boil. Add the prepared kohlrabi pieces and blanch for the recommended time (see table below). Use a slotted spoon to remove the kohlrabi from the boiling water.
Steam Blanching: Place the kohlrabi pieces in a steamer basket over a pot of boiling water. Cover and steam for the recommended time.

The time depends on the form.

Choose the blanching method that works best for you. Water blanching is generally faster, while steam blanching may retain more nutrients.

Cooling and Draining

Ice Water Bath: Immediately transfer the blanched kohlrabi to a bowl of ice water. This stops the cooking process and prevents the kohlrabi from becoming overcooked.
Cool Completely: Ensure the kohlrabi is completely cooled in the ice water bath for the same amount of time as it was blanched.
Drain Thoroughly: Drain the cooled kohlrabi well. Excess water can lead to ice crystal formation and freezer burn. You can spread the kohlrabi on a clean kitchen towel or paper towels to absorb excess moisture.

Freezing Kohlrabi: Techniques and Best Practices

Once the kohlrabi is properly blanched, cooled, and drained, it’s time to freeze it. Here are a few techniques to consider.

Flash Freezing (Open Tray Freezing)

Spread in a Single Layer: Arrange the blanched kohlrabi pieces in a single layer on a baking sheet lined with parchment paper. This prevents the pieces from sticking together during freezing.
Freeze Until Solid: Place the baking sheet in the freezer and freeze until the kohlrabi pieces are solid, usually for 2-3 hours.
Transfer to Freezer Bags or Containers: Once frozen solid, transfer the kohlrabi pieces to airtight freezer bags or containers.

Flash freezing is ideal for preventing clumping and allowing you to use only the amount of kohlrabi you need at a time.

Packaging for Freezing

Choose the Right Containers: Use freezer-safe bags or containers that are designed to withstand the low temperatures of the freezer and prevent freezer burn.
Remove Air: Press out as much air as possible from freezer bags before sealing them. You can use a vacuum sealer for optimal air removal. For containers, leave a small amount of headspace to allow for expansion during freezing.
Label and Date: Label each bag or container with the contents and the date of freezing. This helps you keep track of how long the kohlrabi has been stored.

Storage Time and Temperature

Optimal Temperature: Store frozen kohlrabi at 0°F (-18°C) or lower for best quality.
Storage Time: Properly frozen kohlrabi can maintain good quality for 8-12 months. After this time, it may still be safe to eat, but the flavor and texture may deteriorate.

Thawing and Using Frozen Kohlrabi

When you’re ready to use your frozen kohlrabi, there are several thawing methods you can choose from.

Thawing Methods

In the Refrigerator: The safest way to thaw frozen kohlrabi is in the refrigerator. This can take several hours, so plan ahead.
In Cold Water: Place the freezer bag or container in a bowl of cold water. Change the water every 30 minutes to ensure it stays cold.
In the Microwave: Use the defrost setting on your microwave to thaw the kohlrabi. Be careful not to overheat it, as this can affect the texture.
Directly in Cooking: In many cases, you can add frozen kohlrabi directly to soups, stews, or stir-fries without thawing.

Using Frozen Kohlrabi

Texture Changes: Keep in mind that frozen and thawed kohlrabi will have a softer texture than fresh kohlrabi. It is best used in cooked dishes where a crisp texture is not essential.
Cooking Applications: Frozen kohlrabi is excellent in soups, stews, stir-fries, gratins, and casseroles. It can also be mashed or pureed.
Avoid Raw Consumption: Due to the change in texture, frozen kohlrabi is not recommended for raw consumption in salads or slaws.

Troubleshooting: Common Problems and Solutions

Even with careful preparation, you might encounter some challenges when freezing kohlrabi. Here are some common problems and solutions.

Freezer Burn: This occurs when moisture evaporates from the surface of the food, leaving dry, discolored patches. To prevent freezer burn, ensure the kohlrabi is properly packaged in airtight containers or freezer bags, and remove as much air as possible.
Loss of Texture: Freezing can affect the texture of kohlrabi, making it softer. Blanching helps to minimize this effect. Also, avoid overcooking the kohlrabi after thawing.
Off-Flavors: If the kohlrabi is not blanched properly, it may develop off-flavors during frozen storage. Ensure you blanch the kohlrabi for the recommended time.

Beyond the Bulb: Freezing Kohlrabi Greens

Don’t forget about the kohlrabi greens! These leafy tops are also nutritious and flavorful and can be frozen using a similar method.

Wash and Chop: Wash the kohlrabi greens thoroughly and chop them into smaller pieces.
Blanch: Blanch the greens in boiling water for 2 minutes or steam them for 3 minutes.
Cool and Drain: Cool the blanched greens in ice water and drain them thoroughly.
Freeze: Pack the greens into freezer bags or containers and freeze.

Frozen kohlrabi greens are a great addition to soups, stews, and smoothies.

Freezing kohlrabi is a simple and effective way to preserve this versatile vegetable and enjoy its unique flavor and nutritional benefits year-round. By following these guidelines, you can ensure that your frozen kohlrabi retains its quality and flavor for months to come. Enjoy!

Can I freeze kohlrabi raw, or does it need to be blanched first?

No, you cannot freeze kohlrabi raw without compromising its texture and flavor. Freezing raw kohlrabi causes cell walls to rupture, resulting in a mushy and less palatable product upon thawing. Blanching is a crucial step that deactivates enzymes responsible for deterioration, preserving the vegetable’s quality during freezing and subsequent thawing.

Blanching helps retain the kohlrabi’s crispness, color, and nutritional value. Properly blanched kohlrabi will hold its shape better when thawed and cooked, making it suitable for a wider range of culinary applications. Skipping the blanching step will lead to a significant decline in the overall quality and taste of your frozen kohlrabi.

How long should I blanch kohlrabi before freezing it?

The ideal blanching time for kohlrabi depends on how it’s prepared. If you’re freezing kohlrabi cubes or slices, blanch them for 3 minutes. If you’re freezing whole, small kohlrabi bulbs, blanch them for approximately 4 minutes. Ensure the water is at a rolling boil before adding the kohlrabi.

After blanching, immediately transfer the kohlrabi to an ice bath to stop the cooking process. This prevents overcooking and helps maintain the vegetable’s bright color and crisp texture. Leaving the kohlrabi in the ice bath for the same duration as the blanching time is generally recommended.

What’s the best way to package kohlrabi for freezing?

The best packaging for freezing kohlrabi involves airtight containers or freezer-safe bags. Ensure that the kohlrabi is completely cooled after the ice bath before packaging to prevent ice crystals from forming excessively. Squeeze out any excess air from freezer bags to further protect the vegetable from freezer burn.

Consider portioning the kohlrabi into serving sizes that match your typical usage. This makes it easier to thaw only the amount you need, preventing unnecessary thawing and refreezing. Label each container or bag with the date and contents to keep track of your frozen kohlrabi supply.

How long does frozen kohlrabi last in the freezer?

Properly blanched and frozen kohlrabi can last in the freezer for 8 to 12 months without significant loss of quality. While it might still be safe to eat after this time, the texture, flavor, and nutritional value may start to decline noticeably. Regularly check your frozen kohlrabi for signs of freezer burn, such as discoloration or ice crystals.

Maintaining a consistent freezer temperature of 0°F (-18°C) or lower is crucial for optimal preservation. Fluctuations in temperature can lead to faster deterioration of the frozen kohlrabi. Consuming the kohlrabi within the recommended timeframe ensures you’re enjoying it at its best.

How do I thaw frozen kohlrabi?

There are several ways to thaw frozen kohlrabi, depending on your intended use. You can thaw it in the refrigerator overnight, which is the safest method and helps maintain its texture. Alternatively, you can thaw it under cold running water for a faster, albeit less ideal, approach.

In some cases, you can even cook frozen kohlrabi directly without thawing, especially if you’re adding it to soups, stews, or stir-fries. Keep in mind that cooking times may need to be slightly adjusted to account for the frozen state. Avoid thawing at room temperature, as this can promote bacterial growth.

Can I freeze kohlrabi greens as well as the bulb?

Yes, you can freeze kohlrabi greens similarly to other leafy greens like spinach or kale. The process involves washing them thoroughly, removing any tough stems, and blanching them briefly for 2-3 minutes to preserve their color and nutrients. Remember to cool them quickly in an ice bath after blanching.

After cooling and draining well, squeeze out any excess water from the blanched greens. This helps prevent ice crystals from forming during freezing. Package the greens in airtight containers or freezer bags, removing as much air as possible, and freeze them for later use in soups, stews, or other cooked dishes.

What are some good ways to use frozen kohlrabi after thawing?

Frozen kohlrabi, once thawed, can be used in a variety of culinary applications. It’s excellent in soups, stews, and stir-fries, adding a mild and slightly sweet flavor. Consider adding it to gratins or roasting it alongside other root vegetables for a hearty side dish.

Due to the slight change in texture after freezing and thawing, it may not be ideal for raw applications like salads. However, it still works well in cooked dishes where the texture difference is less noticeable. Experiment with different recipes to discover your favorite ways to incorporate this versatile vegetable into your meals.