Las Cruces – New Mexico State University Department of Plant and Environmental Sciences faculty members have come up with a new, "green" method for extracting red dyes used in foods and cosmetics from chile peppers.
The red pigments extracted from chile are added to many processed foods and to some cosmetics to enhance their appearance. They are also believed to be a healthier, more economical coloring agent than synthetic red dyes. About five years ago, NMSU faculty members Mary A. O'Connell and Laura Hernandez began the research process to find a more environment-friendly method to extract the pigment using more varieties of chile.
The old extraction method, using the chemical hexane, only allowed for mild, non-pungent varieties of chile to be used. Capsaicinoids, the compounds responsible for the heat or pungency of chile, are readily soluble in hexane. To produce a pigment sample with no pungency, only mild, non-pungent red-pigmented fruit can be used.
The new method, included in the research published in the online publication HortScience by O'Connell, Hernandez, Richard D. Richins, Barry Dungan, Shane Hambly and F. Omar Holguin, is the supercritical fluid extractions method, which uses the non-hazardous materials ethanol and carbon dioxide. The SFE method is more environment-friendly and allows pungent or hot varieties of chile to be used for pigment extraction.
"Being able to use more chile varieties is one of the really neat advantages of this new method," said Richins, laboratory manager for the Department of Plant and Environmental Sciences.
The SFE method may present new opportunities for local farmers and add to its importance as a staple crop in New Mexico, Richins said.
"It's challenging anymore for farmers to make much of a profit from chile, and a lot of it is being imported from other countries," Richins said. "The overall chile acreage in the state has been declining. These findings may open up more options for farmers."
O'Connell, Regents Professor for the Department of Plant and Environmental Sciences, said the new method also reduces contamination from dried leaves that may be mixed in during the harvesting and drying processes.
"It's a 'green' approach and doesn't generate hazardous waste," O'Connell said. "The fewer noxious materials you have to use, the better off everyone is."
The research, "A 'Green' Extraction Protocol to Recover Red Pigments from Hot Capsicum Fruit," is published in the July edition of HortScience, a publication by The American Society for Horticulture Science.
"We hope this research will help ensure that chile continues to be an important crop in New Mexico and helps extend the uses for chile," O'Connell said.
For more information, contact the Department of Plant and Environmental Sciences at 575-646-3405.