Blanching and freezing vegetables.
Fresh, tender vegetables are the best for freezing, but there are some of them difficult to can-corn, peas, and green lima beans. Tomatoes become soft and flabby,
as do salad vegetables, such as celery, lettuce, green onions, and radishes. Tomato juice can be frozen satisfactorily but is so easy to can that you probably won't
want to use premium freezer space for it. Vegetables high in starch content, such as potatoes and mature lima beans, do not freeze well. Over-mature vegetables
neither do.
Steps to blanche and freeze
- Washing and Sorting
Washing in cold water is the first step in preparing most vegetables for freezing. Lift them out of the water because grit settles to the bottom of the pan. Sort
vegetables according to size for heating and packing unless they are to be cut into pieces of uniform size. Broccoli and cauliflower may be soaked for 30 minutes
in 1 tablespoon of salt per gallon of water to remove insects before blanching.
- Heating before Packing
With the exception of green pepper, vegetables maintain a better quality in frozen storage if they are heated before packaging, so they must be blanched.
Blanching slows or stops the action of enzymes that help vegetables grow and mature. After maturity, enzymes cause loss of flavor and color. If vegetables are not
heated enough, the enzymes continue to be active during frozen storage. Then the vegetables may develop off-flavors, discolor or toughen, and lose nutritional value.
Heating also wilts or softens vegetables and makes them easier to pack.
The most satisfactory way to blanch most vegetables is in boiling water. Use a blancher, which has a blanching basket and cover, or fit a wire basket into a large
kettle and add the cover. Using at least 1 gallon of boiling water for each pound of prepared vegetables, follow the blanching directions given for the vegetable
you are freezing.
Broccoli, pumpkin, sweet potatoes, and winter squash can be either boiled or steamed. To steam, use a kettle with a tight lid and a rack that holds a steaming basket
at least 3 inches above the bottom of the kettle. Put 1 or 2 inches of water in the kettle and bring the water to a boil. Put the vegetables in the basket in a
single layer so that steam reaches all parts quickly. Cover the kettle and keep the heat high. Follow the directions given for the vegetable you are freezing.
- Cooling
After heating vegetables, they should be cooled quickly and thoroughly to stop the cooking. Plunge the basket of vegetables immediately into a large quantity of
cold water (60°F or below). Change the water frequently, or use cold running water or ice water. If ice is used, you'll need about 1 pound of ice for each pound
of vegetables. It will take as long to cool the food as it does to heat it. When the vegetables are cool, remove them from the water and drain thoroughly.
- Packaging
Package vegetables in suitable freezer containers. Vegetables that package loosely, such as asparagus, Brussels sprouts, cauliflower, corn-on-the-cob, and hot peppers,
need no headspace. Tomato juice and sections, as well as sweet potatoes, need a 1-inch headspace. All other vegetables need a ½-inch head-space. Seal, label, and
freeze immediately.
HRS Spiratube technology
This is explained in the enclosed schematic.
Advantages of HRS Spiratube's solution:
- No water consumption.
- High energy recovery.
- Vegetables are never exposed to the atmosphere.
- Can be cleaned by CIP.
- Low cooling temperatures are allowed.
Schematic of HRS' blanching and freezing vegetables
