For centuries cottonseed was considered more a liability than an asset, an attitude that has changed as cottonseed became the heart of a multimillion-dollar industry.
According to historians, cottonseed has been around for millennia. However, cottonseed had little or no value until machines to remove hulls and linters were invented in the 1800s. These machines made it feasible to extract oil from cottonseed.
“Early extraction methods removed only about one-half the oil contained in the seed; modern mills can extract 98 percent to 99 percent of the oil. Approximately 320 pounds of oil can be extracted from a ton of cottonseed,” says Gail Kring, president of PYCO (Plains Yazoo Cotton Oil), the largest federated cottonseed cooperative in the Southern United States.
The Lubbock-based corporation owns two oil mills in Lubbock and one in Greenwood, Mississippi, and has a total work force of 221 employees.
“We built our first oil mill in Lubbock in 1936, our second here in 1997. And we acquired the Greenwood mill in 1999,” Kring said. “The combined processing capacity of the three mills is 2,625 tons per day.”
The mills truck in cottonseed from gins as distant as 200 miles. And during cotton harvest season trucks bring in cottonseed around the clock. It is off-loaded onto one of several piles, each of which can contain up to 50,000 tons.
“To get the maximum benefit from cottonseed we put it through an elaborate milling process, which results in four major components: oil, linters, hulls, and meal,” Kring said.
Processing begins with a cleaning procedure that removes all foreign material from the cottonseed.
The cottonseed is then “re-ginned” to remove the linters; hulls are mechanically removed to expose the “meats,” which are cooked at 170 degrees Fahrenheit, pressed into paper-thin flakes, and subjected to live steam and high pressure. The oil is extracted by hexane, and subsequent processing produces hexane-free meal and oil.
“Economically, oil is the most important of the four major cottonseed components,” Kring said.
“Prime Bleachable Summer Yellow oil produced by the crushing operation is further processed into Refined Bleached Deodorized (RBD) oil, used in the snack food industry for cooking and frying. We also refine the RBD oil a bit further to produce Refined Bleached Winterized Deodorized oil, a high quality, all-purpose cooking and salad oil,” Kring said.
Linters produced by re-ginning are packaged into neat, uniform, universal-density bales and sold to both mechanical and chemical cellulose markets.
Kring said products made by mechanical conversion include high quality papers, mattresses, upholstery padding, yarns, and medical-grade cotton products.
Chemical conversion of linters contributes to many products, including solid rocket propellants, gunpowder, food casings, ice cream, plastics, and high quality films.
“The hulls produced during seed cotton processing are used in rations for cattle feeding and dairy operations. They are also used in making oil-well drilling mud, rubber, and plastics,” Kring said.
“The meal produced during the milling process is about 41 percent protein, and can be used as fertilizer and for feeding livestock, fish, and shrimp.
“Every component of the cottonseed is completely utilized. Nothing is wasted,” Kring said.