Scientists, Firms Find New Uses For Crab Shells
RALEIGH, N.C. — FIBER scientist Sam Hudson shows off his tricks one by one, starting with a vial filled with tiny bits of rose-colored crab shells. "We take crab shells from a fish processing plant and turn it into this," he says, bringing out a clear cellophane-like material that crackles when touched.
Then, he takes a metal pin and pulls threads from another vial filled with something that looks and stretches like airplane glue.
Welcome to the chitin revolution.
Chitin (the first syllable sounds like "kite") is an old material that is gaining new respect from industry. It's a substance that crabs, shrimp, and other mollusks use to build their shells - nature's second most common organic compound after cellulose. For centuries, chitin has lived in the shadow of cellulose derivatives like cotton and wood, which man has used to make everything from cloth to tools.
Now, chitin is slowly moving out on its own.
The Japanese, who are leaders in the field, use a derivative of chitin (called chitosan) for wastewater treatment. Here in the United States, Vanson Chemical Company markets Sea-Klear, which can be used to purify anything from a swimming pool to a food processor's wastewater. One advantage: the chitosan-treated sludge of, say, a cheese factory can be fed to animals. Chemically treated sludge has to be disposed of.
A Japanese company, Asahi Chemical Industry, is coating artificial cotton clothing with chitosan to improve the fabric's dyeing characteristics. A Norwegian company called Protan A/S is selling chitosan-based creams and lotions for cosmetic and medical purposes. Other companies are experimenting with chitosan to enhance the growth and yields of wheat, soybeans, and other crops.
"It's really a rather amazing material," says John Vercellotti, a food-flavor research chemist with the US Department of Agriculture in New Orleans.
Much of the research is taking place along the coasts because that is where the chitin is. Seafood processors are anxious to get rid of the tons of shells that pile up outside their plants. (By one estimate, Louisiana alone produces tens of millions of pounds of crawfish carcasses each year.)
Two years ago, Technical Insights Inc. of Englewood, N.J., forecast that the market for chitin-based products would reach $1.9 billion by 1999 worldwide, $710 million in the US. But several Japanese and US chitin companies have gone out of business since the prediction.
"I hope they're right," says Joel Van Ornum, president of Vanson Chemical. He says the forecast is very optimistic.
According to analysts and scientists, health-care products will make up the bulk of the chitin market for the next several years, followed by agriculture and wastewater treatment.
As companies push out new chitin products, laboratories are dreaming up new uses for the stuff. Dr. Vercellotti, for example, is using a derivative of chitosan to preserve the flavor of meat. (The substance keeps the iron in meat from reacting with the fatty acids, which causes a leftover or even rancid taste.) Earlier this year in Britain, researchers presented evidence that apples coated with a similar material could be kept fresh for six months.
Vercellotti says several large food companies are interested in the idea but that it could take five to 10 years before products show up on the grocery shelf.
Stronger fibers than steel
Other researchers are looking at coating paper with the material. Here at North Carolina State University's textile college, Mr. Hudson is thinking threads. Theoretically, a suit made of chitosan thread would be stronger than steel.
Some basic research problems remain, however. For one thing, chitosan tends to weaken in water, which isn't too helpful for a chitosan bandage or protective film. Hudson is working on coming up with better solvents to turn chitosan into better and stronger fibers.
None of this means that chitin will replace polyesters and wool.
"The really exciting discovery would be to find an extraordinarily strong fiber," he says.
But such chitin-based items, if they ever are discovered, are most likely decades away from the department store in the mall, he adds.