By Diane Wright Hirsch
UConn Extension Educator/Food Safety
It has been a wonderful year for growing fruits and vegetables in Connecticut. A trip to your backyard vegetable garden, local farmers’ market or maybe the nearby pick-your-own orchard, even late in the season, will attest to this: bins and shelves are still overflowing with beautiful tomatoes, raspberries, green beans and corn. But, soon it will all be gone and we will be wishing that we had stashed some away for the long winter.
There is a way to fix this–without turning to imports from China or Chile or even the well-traveled produce from California, which begins to lose nutritional value as soon as it is picked. Freeze your local produce, whether it is from your garden or the farmer down the road. If done right, freezing can preserve the flavor and health-giving benefits of summer fresh fruits and vegetables. IF DONE RIGHT.
Freezing is easy, requires no special equipment and is often the home food preservation method of choice. Many people do not want to use a canner or pressure canner. It can be a little scary if you do not know what you are doing. Keep in mind, though, that freezing can be a more costly way of preserving than canning. It requires that you have a freezer that can hold all of the food you want to freeze at 0°F and, if you choose single use plastic freezer bags, they can be expensive. But, it is less time consuming and most folks prefer the flavor and texture of frozen foods.
Another thing to keep in mind is that you may not be able to reproduce the commercially frozen products that you are used to. Unless you have a blast freezer in the basement! The frozen foods you buy in the grocery store is often picked and processed the same day. This is always best, though not always possible when you are waiting for your garden to produce enough green beans to make the job worth it. Also, they are freezing food very fast at very low temperatures that create very small crystals and prevent mushiness and texture changes that may occur during home freezing.
Freezing produce at home
You can’t just wash your produce, cut it up and throw it in the freezer without much thought. Well you can, but the result will be just as tasteless as a January tomato. People need to know that while the temperature of a freezer keeps food safe, it will not preserve the quality of your produce without some help.
After harvest, fruits and vegetables undergo chemical changes which can cause spoilage and deterioration of the product. This is why these products should be frozen as soon after harvest as possible and at their peak degree of ripeness. Fresh produce contains chemical compounds called enzymes which can cause flavor, color and texture changes, and the loss of vitamins and minerals even while stored in the freezer. These enzymes must be inactivated to prevent these reactions.
When freezing vegetables, you can inactivate the enzymes by blanching—or dropping them into boiling water or steaming for a short time. Cool the vegetable quickly in ice water to keep it from cooking. Even though blanching can be a bother, in most cases it is absolutely essential for producing quality frozen vegetables. The exceptions to this rule are peppers, onions and herbs, which do not need to be blanched.
Fruits are a bit different. The major problem associated with enzymes in fruits is the development of brown colors and loss of vitamin C. Because fruits are usually served raw, they cannot be blanched like vegetables. Instead, home food preservers control the browning and loss of vitamins with ascorbic acid (vitamin C), an anti-oxidant. Ascorbic acid may be used in its pure form or in commercial mixtures (such as “Fruit Fresh”). This is more effective than the use of lemon juice.
Often you will see recipes that suggest that you freeze fruits with sugar or in a light sugar syrup. Though many folks today are sugar phobic, keep in mind that the quality of many fruits (peaches, apples) is not as good when packed without sugar. Sugar helps to preserve both the flavor and texture of frozen fruits. If you are planning to use the fruits to make jams or preserves later on, or, if there are health concerns such as diabetes, then, of course, freeze in plain water or dry.
Frozen fruits and vegetables can also suffer a variety of changes—flavor and texture—when the product is not well protected from the air. You might have heard it referred to as freezer burn. You can control this problem by using materials for packaging that are made specifically for the freezer—plastic wraps, plastic bags, hard sided plastic containers or even glass. You should not consider this an opportunity to re-use plastic containers that may have once held cottage cheese, yogurt or other non-frozen foods. Economically and environmentally speaking, you may want to invest in re-usable freezer containers that may be found in grocery, farm supply or department stores next to the home canning supplies. Glass works well, too, but special care must be taken to avoid breakage, including leaving enough space for the food to expand while freezing.
Keep in mind also that while freezing preserves safety and quality, there are some foods that will simply be different after you freeze them. Some fruits and vegetables are naturally high in moisture. When frozen, the moisture freezes and causes the cells of the plant to burst. Once thawed, these products will be softer than when fresh—no matter how careful you are. So, tomatoes, many fruits, summer squash and greens once frozen will be better suited to mixed dishes, sauces or soups. It doesn’t make much sense to freeze cabbage (develops off flavors), celery, cucumbers, endive, lettuce, or radishes.
Frozen fruits and vegetables will maintain good quality for one year if packed well and kept in a freezer at 0°F.
Freezing Green or Yellow Beans
Pick young tender beans that snap when broken. Harvest while seeds are small and tender. Wash, snip off tips and sort for size. Cut or break into suitable pieces or freeze small beans whole. Blanch 3½ minutes. Chill in ice water. Drain, pack in freezer container.
Choose well ripened fruit of good quality. Wash in cold water and sort. Dip 3 or 4 peaches into boiling water until skins loosen—15-20 seconds. Peel and slice peaches into containers one-third full of syrup (3 cups sugar to 1 quart water with 1⁄2 teaspoon ascorbic acid). Make sure to leave a head-space of at least ½ inch to allow for expansion of the liquid during freezing.
For specific instructions for freezing fruits and vegetables, contact the UConn Home and Garden Education Center by phone at (877) 486-6271 or by email to firstname.lastname@example.org contact the National Center for Home Food Preparation at: http://www.uga.edu/nchfp.