CASCO BAY — Tollef Olson turns a ratchet and lifts up a 24-foot-long section of line that has been suspended 7 feet underwater all winter. About 200 pounds of brown seaweed hang off the line.

“Look at the biomass we’ve created here,” he said, while standing on a barge about 500 feet from Little Chebeague Island. “Look at all this food!”

Oslon’s company, Portland-based Ocean Approved, has been working since 2009 to figure out how to farm kelp. Now the company, which has received a total of $470,000 in grants from the National Oceanic and Atmospheric Administration and the Maine Technology Institute, has completed its research and development and is focused on selling the product nationally through wholesalers. Its primary customers are restaurants, schools and institutions, such as hospitals.

In the past two years, sales have increased 400 percent, said Paul Dobbins, who manages the company’s business and operations, including a processing facility on Presumpscot Street. He declined to reveal the company’s revenue.

The company’s six owners, who include Dobbins and Olson, have yet to take a paycheck. Dobbins said they’re reinvesting earnings into the company because they want to build it up and increase its value.

“Our vision is that this will become big,” Dobbins said.

While other Maine companies harvest wild seaweed, Ocean Approved is the first company in the United States to grow it, Dobbins said. It’s also the only company in the world selling frozen kelp rather than kelp that is dried, reconstituted or salted.

The kelp is boiled briefly, until it’s green and soft, then frozen in plastic bags.

Dobbins said the potential market for the product is huge. Kelp is a $5 billion-a-year industry worldwide, and almost all of it is harvested and dried in Asia, where kelp farms are spread across entire bays. It is a staple of the Asian diet, a nutritious vegetable that doesn’t require any land, fresh water irrigation or fertilizer to produce.

Ocean Approved wants American consumers to think of kelp as a vegetable that can be served with a lot of mainstream dishes rather than just an ingredient in a sushi roll.

Olson, a kelp evangelist, said it’s an all-natural “super food” loaded with calcium and iodine, magnesium and iron.

Because it’s boiled and frozen, it tastes less salty than dried kelp, he said.

Culinary professionals are also fans. Elaine Cwynar, who teaches classes in American and Continental cuisine at Johnson & Wales University in Providence, Rhode Island, said kelp smoothies are especially tasty.

“People think it’s going to smell like the edge of the ocean, but it doesn’t,” she said. “It’s very pleasant.”

Portland’s Flatbread Co. puts kelp in salads served at its eight restaurants on the East Coast. Chefs simply thaw the kelp and toss it in, said the company’s regional manager, Jeanne Twomey.

She said Ocean Approved is benefiting from a cultural shift in which consumers want locally produced foods that have high nutritional value.

She said servers talk to customers about kelp being farmed on the coast of Maine. “The story is the best part of it,” she said.

The company sells three species of kelp and cuts them to create several products, including “sea slaw,” “sea rounds” and “kelp wraps.”

Consumers thaw and drain the product, then toss it directly it into a cold dish, like a salad, or put it in a hot dish at the last stage of cooking, Dobbins said.

Some of the company’s institutional customers include Mercy Hospital, Gould Academy, Portland Public Schools, Bowdoin College, the University of Maine, the University of New Hampshire and Dartmouth College.

While Ocean Approved views its processing methods as a trade secret, its methods for seeding and growing kelp are open to the public. The company intends to maintain its own farm in Casco Bay and buy farm-raised kelp from contractors. It currently has two contractors in Maine and one in Cape Cod.

Olson said the industry is well-suited for Maine because of the state’s clean, cold waters. Kelp in the natural environment is able to withstand being frozen twice a day, when it’s exposed to frigid air at low tide during the winter. As a result, its cell structure and chemical composition make it an ideal frozen product, Dobbins said.

Because the growing season is during the winter and early spring – just the opposite of the lobster season in Maine – there are plenty of lobstermen who could grow kelp in the winter, he said.

For those who own a boat, the investment is less than $20,000, Dobbins said. Except for a microscope, all the equipment can be bought at retail and pet stores, he said.

The company, which is entering the height of its harvesting season, has 15 people processing and three people working in the “nursery,” a laboratory at the Southern Maine Community College where it grows kelp spores. The company employs students who are studying marine biology.

People in other countries have expressed interest in the product, but the company is focused on the domestic market because it is so huge, Dobbins said.

The company’s biggest challenge now, Dobbins said, is managing its rapid growth. That means attracting new talent, creating new processes and systems that support the growth and developing new distribution channels.

Dobbins, who was part of the management team for three out-of-state startups, said that he and the company’s other owners have experience with starting, growing and selling companies.

“We have been through this before,” he said.

Tom Bell can be contacted at 791-6369 or at:

tbell@pressherald.com