By Chris Venvema, Michigan State University Extension
Freezing asparagus preserves the fresh flavor
Although spring has sprung, it is still pretty cold, but it is not too early to think about harvesting the first vegetable of spring, asparagus.
Officially named Asparagus officinalis, asparagus is actually a flowering perennial.
With its dark green color, asparagus is rich in vitamins A & B6, calcium, magnesium and zinc. Since it is 93% water, asparagus is low in calories and very low in sodium. Asparagus is a very good source of dietary fiber. When harvesting the asparagus, it is important to gather the tender young shoots. The larger and taller shoots are a woodier product. However, these older shoots should not be discarded, they can be peeled and enjoyed as well. Asparagus can be preserved for later use by freezing, canning, pickling or drying. The technique used depends upon the later intended use. For the fresh from the garden flavor, freezing is ideal.
To freeze asparagus it is necessary to blanch the young spears. To prepare the asparagus for freezing requires that young tender spears be selected. The stalks should be washed, trimmed and sorted according to size. Cut the spears to fit the containers for freezing. Water blanching requires the water to be boiling in a kettle. Tender small spears require a blanching time of two minutes, medium size spears need three minutes and large spears need four minutes. Cool quickly in ice water. Then drain and package leaving no airspace in the rigid container. A technique for individual size pieces is to drain and pat the spears dry. Next arrange the spears or pieces on a cookie sheet. Then place the cookie sheet in the freezer until the pieces are frozen. Finally put the frozen pieces in plastic bags, making sure there is no air trapped in the bag and put in the freezer.
Michigan State University Extension recommends canning asparagus because it is considered a low acid vegetable. Select tightly closed spears that are four to six inches in length. Wash thoroughly. Trim off the scales and tough ends. Then wash again. The spears can be cut into one inch pieces or left whole (4-6 inches).
For the raw pack technique, pack the asparagus tightly into hot jars, leaving one-inch headspace. If salt is desired put a ½ teaspoon of salt into pint jars or 1 teaspoon of salt into quart jars. Fill the jars with boiling water leaving one-inch headspace. Remove the air bubbles. Wipe the rim. Adjust the pretreated lids and process.
Processing can be done in a dial gauge pressure canner at 11 pounds of pressure OR in a weighted gauge pressure canner at 10 pounds of pressure. The processing times are 30 minutes for pints and 40 minutes for quarts.
It is spring time! Why not preserve spring’s first vegetable of the season, asparagus, today!
Resources:
http://nchfp.uga.edu/how/freeze/asparagus.html
http://nchfp.uga.edu/how/can_04/asparagus_spears.html
http://nchfp.uga.edu/how/can_06/pickled_asparagus.html
