UNIVERSITY PARK, Pa. -- Thinness may be a top quality for supermodels, but a vegetable expert in Penn State's College of Agricultural Sciences says when it comes to asparagus, thicker is better.
"In supermarkets, shoppers will see thin spears of asparagus bunched and marketed as 'tender gourmet' style," says Peter Ferretti, professor of vegetable crops. "In reality, spears that are larger than a half-inch in diameter are more tender and higher in soluble fiber and vitamins than the thinner spears."
Ferretti says two market trends might be responsible for the increasing interest in thinner spears.
First, restaurant chefs prefer thinner spears to create visually appealing recipes and garnishes.
Second, asparagus growers in the United States and other countries are picking their crops earlier, in order to stimulate the plant to produce spears more quickly.
"Asparagus is a perennial that can produce crops for 20 years or more if the plant remains free of disease and other pest problems," Ferretti explains. "In the past, growers would not pick or market the crop until the third or fourth year, when spears reached a salable thickness. Now, to stimulate growth, plants are harvested for two weeks in the second year when the spears are about a quarter-inch in diameter."
Ferretti says growers are reluctant to waste an entire crop when their management plan calls for harvesting thinner spears in the second growth year. Vegetable retailers found a marketable niche for this new crop by touting thinner asparagus as a gourmet item.
"Although many shoppers think 'younger and thinner' equals tenderness, the opposite is true for asparagus," Ferretti says. "A young asparagus plant is putting more of its energy into producing spears that will stand upright, so most of the plant material in the spears of younger asparagus plants is crude fiber."
Ferretti explains that crude fiber is the cellulose-based material found in the outer layers of celery and other vegetables. As the asparagus plant matures, less growth is dedicated to producing crude fiber and the spears thicken with soft, soluble fiber and other nutrients. "If you cut the end of a thin asparagus spear, you'll see a thin green outer ring with very little center mass," Ferretti explains. "A large spear will have the same thin green outer ring, but a much larger central mass containing the soluble fiber, plus nutrients."
Ferretti says there is little taste difference between thin and thick asparagus spears, but the thinner vegetables can be tougher to chew.
Ferretti also says asparagus is a nutritional bonanza, serving as a significant source of vitamins A and C. It also is high in folacin and potassium.
He says asparagus should either be prepared immediately or stored in a refrigerator set at about 35 degrees Fahrenheit. "The longer you let asparagus sit, the tougher it gets," Ferretti says. "Asparagus loses moisture very quickly, the sugars within the spear begin to turn to starch, and the spear develops woody tissue if left at room temperature. In thinner asparagus spears, this happens even faster."
Ferretti says asparagus is an exceptional plant for backyard gardeners because it is relatively expensive in grocery stores, and its perennial growth means the same plant will produce year after year. Ferretti recommends the Jersey Giant variety, which is available at most nurseries or large garden centers.
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EDITORS: For more information, contact Peter Ferretti at 814-863-2313.
Contacts: John Wall jtw3@psu.edu 814-863-2719 814-865-1068 fax