Preserving Food: A Guide to Freezing Vegetables

If your vegetable garden is like mine, it goes into overdrive around mid-summer producing overwhelming amounts of produce.  Those seeds and tiny transplants that we planted in spring magically morph into monster-sized plants producing gallons of tomatoes, beans, peppers, and corn.  And don’t get me started on those overachieving summer squash and zucchini plants!

Naturally, if your garden plot produces enough produce to share with others, the local food banks and your friends and neighbors will appreciate your generosity.  Any produce you don’t eat fresh from the garden or share with others can be preserved by canning, dehydrating, brining, etc.  While these methods of preserving food bring us a deep sense of accomplishment, they also require a commitment of time and effort.  But what if you don’t have the time, energy, or equipment these methods require? Under those circumstances, freezing your surplus veggies may be the answer.  The point is not to let any food go to waste.

WHY FREEZE VEGETABLES

Several excellent reasons come to mind for freezing vegetables:

• Convenience. Preserving vegetables by freezing them is quick, simple, and doesn’t require any special equipment.  Also, produce can be prepared for freezing in small quantities of a pound or two at a time, which most people can easily manage.
• Cut down on Food Waste. American consumers waste an alarming amount of food daily.  If the vegetables in your crisper drawer routinely wither, go limp or turn moldy, then consider freezing them before they go bad.
• Extend “Shelf life.” Blanching (more on that later) and freezing vegetables is a good way to enjoy them all year long and not just when they are at peak in the summer months. If kept frozen at 0°F or lower, most vegetables will maintain high quality for up to 12 months or more.
• Retain nutritional value. Clemson University Extension’s Factsheet HGIC 3063 states that freezing is “the method of food preservation that preserves the greatest quantity of nutrients.”  For best overall quality, produce should be frozen when it is young, tender, and at its peak of flavor.  Ideally, it should be frozen as soon as possible after it is harvested – preferably within hours.

Even if you don’t grow your own vegetables, you can buy them from grocery stores or farmer’s markets when they are in season, freeze them, and enjoy them all year long.

FREEZING BASICS

Although you can freeze just about any vegetable, some hold up better than others to being frozen and thawed.   You can’t, for example, expect to achieve the same crisp results using thawed vegetables as you would get from roasting fresh ones.  You can, however, expect excellent results using previously frozen vegetables in cooked foods such as soups, stews, casseroles, and frittatas.

Vegetables with a low moisture content generally hold up well to being frozen.  Some examples include broccoli, carrots, cauliflower, corn, green beans, peas, squash, and sturdy greens such as chard, collards, kale, and spinach.  Other vegetables such as onions, peppers, and celery may also be frozen, but the results are generally not as good as those vegetables having a lower moisture content.  Vegetables with a high moisture content such as cucumbers, green onions, lettuce, and radishes do not freeze well.  Once they are thawed, the texture can be mushy and watery.  Whole tomatoes also don’t freeze well because of their high moisture content.  However, they freeze quite well if they are first processed into tomato juice, puree, sauce, or paste.

Before you start prepping your produce for freezing, decide how you want to use it in future meals.  Vegetables that are cut into a small or medium dice work well in soups. Ones cut into large dice or chunks are suitable for stews or casseroles that will be simmered or baked for a long time.  Vegetables that will be layered in casseroles generally work best sliced into rounds. By making those decisions now, you are basically doing all the prep work for meals up front as you prepare to freeze your produce.

BLANCHING BASICS

With some exceptions, most vegetables should be blanched before they are frozen.  Blanching is a quick and simple process.  It involves briefly plunging small quantities of vegetables into a pot of boiling water to:

• Deactivate natural enzymes that cause food to deteriorate.
• Set or brighten the color of the food.
• Clean dirt and microbes from the surface of the food.
• Help slow the loss of vitamins and minerals.  
• Soften food, which makes it easier to pack into containers.
• Loosen the skins of tomatoes to make them easier to peel.

To blanch vegetables, you will need the following equipment:

• A large saucepan with lid
• A wire basket, perforated metal strainer, or cheesecloth bag for submerging the vegetables into the pot of boiling water.
• A large bowl filled with cold water and ice for rapidly cooling the cooked vegetables.
• A slotted spoon for removing the cooled vegetables from the ice water bath.
• Freezer-safe storage containers such as plastic freezer bags, rigid plastic containers, or tempered (freezer-safe) glass jars.
• A marker or pen for labeling the contents of the containers and the date.

Timing the blanching process:

Timing is very important for overall high quality of blanched vegetables.  If vegetables aren’t blanched long enough, enzyme activity may continue during frozen storage, resulting in off flavors, off colors, and toughening. Vegetables that are blanched too long may lose some of their flavor, texture, and color.

The length of time needed for blanching depends on the vegetable being blanched and the size of the pieces.  The National Center for Home Food Preservation recommends the time needed to blanch the following selected vegetables:

• Asparagus: 2 minutes for small, 3 minutes for medium, and 4 minutes for large stalks
• Beans (green, snap or wax): 3 minutes
• Broccoli flowerets (1.5” across): 3 minutes
• Brussels Sprouts: 3 to 5 minutes depending on the size of the sprouts
• Cabbage (shredded): 5 minutes
• Carrots: 2 minutes for diced or sliced; 5 minutes for whole or small
• Cauliflower flowerets (1.5” across): 3 minutes
• Celery (diced or sliced): 3 minutes
• Collards: 3 minutes
• Corn kernels: 4 minutes (blanch on the cob, cool and cut off kernels); 7-11 minutes for corn on the cob depending on whether the ear is small, medium, or large
• Eggplant (cut into 1/3-inch slices): 4 minutes
• Kale: 2 minutes
• Okra: 3 to 4 minutes
• Peas (shelled): 5 to 2.5 minutes
• Potatoes: 3 to 5 minutes
• Spinach: 2 minutes
• Summer squash (cut into 1/2-inch slices): 3 minutes.

Steps for blanching vegetables:

• Wash vegetables thoroughly and rinse several times before cutting them to remove dirt, debris, pesticide residue, and bacteria.
• Cut vegetables into a uniform size suitable for use later in recipes.
• For each pound of firm vegetables (about 4 cups), bring one gallon of water to a boil in a large pot or two gallons of water for each pound of leafy greens (about 8 cups).
• While water is coming to a boil, fill a large bowl with cold water and ice cubes and set aside.
• Place the prepared vegetables in the wire basket and lower it into the vigorously boiling water. Cover the pot.  If the water stops boiling, wait until it comes back to a boil before you start timing the blanching process.
• After the vegetables are finished blanching, remove them from the boiling water and immediately dip them into the bowl of ice water until they are completely cool.
• Remove the cooled vegetables from the water and pat them as dry as possible. Any extra moisture can decrease the quality of the frozen vegetables.

Steaming as an alternative to blanching

Some vegetables, such as broccoli, winter squash, sweet potatoes, and pumpkin, may be blanched using steam as opposed to boiling water.  Either method will work, but steaming takes about 1-1/2 times longer than water blanching.

To steam vegetables, bring 1” to 2” of water to a rapid boil in a saucepan that can accommodate a steamer basket.  The steamer basket must hold the food at least 3” above the bottom of the pan. Arrange cut up vegetables in a single layer in the steamer basket.  Place the basket over the boiling water and cover the pan with a tight-fitting lid.  Start counting the steaming time as soon as the lid is in place.

Packing vegetables for freezer storage

After blanched vegetables are cooled and dried off, you have two choices for packing them for freezer storage:

• Packing Choice # 1: Quickly package them into freezer containers.  If using plastic freezer bags, press out as much air as possible to prevent freezer burn and to keep the food from drying out.   Leave ½” to 1” of headroom space at the top of the bag (to allow for any expansion during the freezing process). Seal the container tightly, label it, and store it in the freezer at 0°F or below.
• Packing Choice # 2: This is a two-step process, which takes more time and effort but may make your life easier later.  Arrange the cooled and dried off vegetables in a single layer on a shallow tray (or sheet pan).  Place the tray in the freezer just long enough to freeze the vegetables firm but no longer than that.  Otherwise, the exposure to the dry freezer air will affect the quality of the produce. Remove the frozen produce from the freezer and promptly package it for storage (without headspace, since the produce is already frozen).  Tightly seal the container, label it, and store in the freezer.  This approach prevents the vegetable pieces from freezing into a solid block, which makes it easy to remove a portion of the vegetables from a container and return the rest to the freezer.

  

TIP:  For best results, avoid stacking containers of vegetables on top of one another.  Place them in several areas of the freezer so that they freeze faster.

FREEZING HERBS

Herbs may be frozen but they become limp as they thaw. However, the limp herbs are perfectly suitable for adding flavor to cooked foods.  To freeze herbs, simply wash, drain, and pat them dry to remove excess moisture. They don’t need to be blanched before being frozen. Trim, chop, and bag for freezing.   The frozen herbs may be added directly to food that is being cooked.

An alternative method for freezing herbs is to cover them in water and freeze them as ice cubes. For this method:

• De-stem and chop herbs just as you would if you were using them fresh.
• Partially fill an ice cube tray with water and place about a tablespoon of chopped herbs in each section.
• Push the herbs under the water and place the tray in the freezer.
• After the cubes are solidly frozen, add additional water to top off each cube and return the tray to the freezer.
• After the cubes are completely frozen, pop them out of the tray and transfer them to a freezer bag.
• Add the frozen ice cubes directly to soups, stews, sauces, or other cooked foods.

A FINAL THOUGHT ON FREEZING VEGETABLES

The thought of filling my freezer with produce from my garden gives me great satisfaction. However, it’s all too easy to lose track of what’s in the freezer.  Vegetables will last a good long time when frozen but they do eventually lose flavor, color and texture if not used within a year or so.  A simple way to keep track of your freezer contents is to tape a list of them to the freezer door. List oldest items first and newest items last.   As you use each item, cross it off the list. That way, you have a visual reminder of what is in the freezer, the date each item was frozen, and a reminder to use the oldest items while they are still at maximum flavor and texture.

SUMMARY

As gardeners, we derive a great deal of satisfaction from the vegetables we grow in our gardens every year.  But unless we are disciplined about the quantities we grow, it’s easy to become overwhelmed by too much produce in our gardens.  Donating some of the surplus to local food banks and sharing it with friends and neighbors are great ways to share the bounty and avoid wasting food.  But if we still have more than we can use right away, freezing is a quick, easy, convenient way to preserve the surplus.  You’ll be happy you did when you find yourself enjoying corn on the cob from your freezer in January.

FEATURE PHOTO: Frozen vegetables from author’s garden.  Photo:  Pat Chadwick        

SOURCES

“Blue Book Guide to Preserving,” (Ball Corporation, 2012)

Freezing/Blanching, National Center for Home Food Preservation, University of Georgia Extension.

Freezing Fruits and Vegetables, Clemson University Factsheet HGIC 3063

Freezing Fruits and Vegetables, Virginia Cooperative Extension Publication 348-596

Freezing Herbs, Pennsylvania State University Extension

Freezing and Food Safety, United States Department of Agriculture

How to Freeze Vegetables, University of Missouri Extension