Friday, May 18, 2012
One of spring’s favorite vegetables, asparagus, is so delicate that it requires special care. Start by selecting young tender spears that are firm, straight, uniformly sized and with closed, compact tips. If you grow your own asparagus, harvest spears when they are 4 to 10 inches long. Harvest spears at least every other day to prevent spears from becoming fibrous. It is best to cut asparagus spears below the soil level. Discontinue harvest when spear diameter becomes less than 3/8 of an inch.
White or blanched asparagus is grown by shading the spears with mounds of soil or mulch so that sunlight never reaches the plant. White asparagus is more fibrous than green asparagus and has a stronger, slightly bitter flavor.
Fresh asparagus needs to be kept cold to preserve its tenderness and natural sweetness. Asparagus is best eaten or preserved the day it is purchased or harvested but will keep up to 3 days if refrigerated. Wrap it in a damp cloth and store it in a perforated plastic bag in the refrigerator. Some people prefer to place bundled stalks upright in 1 inch of water in a glass or measuring cup in the refrigerator.
Prepare asparagus by washing thoroughly and sorting into sizes. Snap-off or trim at least ½ inch from the bottom of each spear—where the stem begins to toughen. Remove scales with a sharp knife.
To freeze asparagus, cut into even lengths to fit containers. Water blanch small spears for 2 minutes, medium spears 3 minutes, and large spears 4 minutes. Reduce blanching time for shorter pieces. Cool promptly, drain and package in plastic freezer bags, freezer jars, plastic freezer boxes, or vacuum package. No head space is necessary. Seal and freeze. Spears of asparagus may also be individually frozen before being packaged; this prevents it from freezing as one mass. In its fresh state, asparagus has a high water content. As it freezes, the water changes to ice crystals causing the cells to break down. As a result, frozen asparagus may seem less firm than other frozen vegetables.
Asparagus is a low acid vegetable and must be processed in a pressure canner to be safe. To can asparagus, prepare the asparagus as described above for freezing and cut into 1 inch pieces or leave whole. To hot pack, cover the asparagus with boiling water; boil 2 to 3 minutes. Pack hot into hot jars, leaving 1 inch head space. One-half teaspoon salt may be added per pint if desired. Fill jar to 1 inch from the top with boiling hot cooking liquid or water. Remove air bubbles. Wipe jar rims and adjust lids. For a raw pack, pack the raw asparagus tightly into hot jars, leaving 1 inch head space. Fill jars to 1 inch from the top with boiling water. Process hot or raw packed asparagus in a dial gauge pressure canner at 11 pounds pressure or a weighted gauge pressure canner at 10 pounds pressure for 30 minutes for pints and 40 minutes for quarts. (Make pressure adjustments for higher altitudes.) The long processing time and high temperature produces a softer product than fresh asparagus.
Many recipes for pickled asparagus are available in magazines and on the internet. Not all have been research tested. Keep in mind even pickled products will only be safe if enough vinegar has been added to increase the acidity. Pack the asparagus loosely so that adequate vinegar is in the jar. Avoid adding large amounts of other low acid flavoring ingredients such as onion, garlic, and peppers. Make sure you are using vinegar of 5% acidity. Asparagus pickles must be processed in a boiling water bath for safety. Use a scientifically tested recipe such as the one below.