Martin's and Giant started carrying Giant Food Stores' Simply Enjoy brand onion jam and red pepper jelly in March.
While most people associate fruit with jelly, the U.S. Food and Drug Administration doesn't limit the terms "jam," "jelly" or "preserves," to things that contain fruit, said FDA spokeswoman Veronica Castro.
Also, jam, jelly and preserves aren't the same, said avid jam maker Annette Ipsan, executive coordinator for horticulture at Maryland Cooperative Extension in Washington County.
"Jellies are clear and have no seeds," Ipsan said. "Preserves and jams tend to be thicker, often with chunks of fruit."
Regardless of flavor, most spreads undergo a similar process, Ipsan said.
Using fruit as an example, Ipsan said fruit picked at the peak of its ripeness is crushed and cooked with sugar and pectin, the ingredient that gives the spread its gel-like consistency.
The mixture is then placed in sterile jars, which are either submerged in hot water or placed inside a pressure canner.
Bonnie Senay, who makes fresh hot pepper jam from her Sharpsburg home, said she's recently noticed more interest in flavors such as onion jelly, though she has yet to make onion jelly herself.
Senay, 48, who's been "jamming" for 20 years, used to sell homemade hot pepper jam, which she made from produce she bought at local farm stands.
"They're so pretty," Senay said of pepper jams. "They make for good presentation."
While they aren't the kind of jams you'd want to spread on your breakfast toast, the divergent spreads are finding a place in pantries, food experts say.
It's part of a broader trend in which specialty foods - including nonfruit jams and jellies - are growing in popularity.
As the U.S. population grows more diverse and more people are seeking ways to put a twist traditional foods, consumers are venturing out in search of new products at the grocery store, according to information from food and beverage marketing research firm, Mintel International.
In October 2006, Mintel surveyed 1,838 adults about their purchasing habits and found that 64 percent of them purchased some sort of specialty item in the six months prior to the study.
Spokespeople from Martin's and Giant said the retailers started selling specialty foods such as onion jam and pepper jelly after examining industry trends.
While they would not disclose sales figures, Jaime Miller, spokesman for Giant Food, said the onion and pepper spreads are available at the 700 retailers along the East Coast owned by Ahold USA, the parent company of Giant Food Stores and Martins Food Markets and Giant Food.
Not all retailers are seeing an increase in specialty spread sales.
Vanessa McCutcheon Smith, vice president of sales for the Frederick, Md., based McCutcheon Apple Producers Inc., said she hasn't noticed a dramatic increase in the sale of specialty spreads since the jam makers started offering them in the '80s.
In addition to fruit flavors, McCutcheon sells hot pepper jelly and jellies made from quince and currants, Smith said. McCutcheon has been in the jelly and jam-making business since 1938.
"We've seen more of an interest in our combination flavors," said Smith, of jams and jellies that contain multiple fruits.
Hot Pepper Jam
4 cups finely chopped peppers (See cook's note)
4 cups vinegar
6 teaspoons calcium water (1/2 teaspoon of calcium powder and 1/2 cup of water, mixed)
4 1/2 teaspoon pectin (See notes)
7 cups sugar
12 (8-ounce) jars
Notes: Bonnie Senay uses red bell peppers in combination with jabaero or Caribbean red peppers. Use as little as 1 teaspoon of the jabaero or Caribbean red peppers for mild jam, but no more than one cup for spicy jam. Use gloves to remove the seeds and membranes from the hot peppers. For pectin, Senay uses Pomona's Universal Pectin. Calcium powder comes packaged with Pomona's Universal Pectin.
Bring to a boil the peppers, vinegar and calcium water. Add the pectin and the sugar, and boil for another 1 to 2 minutes, making sure that the pectin and sugar have dissolved. Remove from heat.
Fill jars 1/2 inch from the top, and wipe the rims clean. Screw on the lids, and submerge the filled jars in boiling water for 10 minutes. Allow jars to cool.
- Recipe courtesy of Bonnie Senay