Submitted to: Journal of Chromatography
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 20, 1999
Publication Date: N/A
Interpretive Summary: Saffron, which is extracted from the female flower parts (stigmas) of the autumn crocus plant, is the world's most expensive spice. It retails for about $15.00 an ounce in the US. All of the saffron sold in the US is imported because there is no domestic industry to produce the spice. Saffron's high price in US markets occurs mainly because of costs associated with maintaining its quality. The determinants of saffron's spice quality are three naturally occurring compounds known as crocin which is responsible for color, picrocrocin which is responsible for taste, and safranal which is responsible for saffron's characteristic and desirable odor. Spice importers have had difficulty determining spice quality of saffron because crocin and picrocrocin degrade quite rapidly during the extraction and purification stages. Our laboratory has developed a new method known as high performance liquid chromatography or HPLC to determine the quality of saffron based on safranal content. The method is accurate and quantitative and can be used by spice companies to determine the quality of saffron imported from foreign markets. A supply of high quality saffron in retail stores would stabilize the price of this spice and ensure that consumers are getting the highest quality spice for the price they pay.
Technical Abstract: Saffron is a spice which is obtained from dried stigmas of plants of autumn crocus (Crocus sativus L.). An HPLC procedure was developed by which we could quantify the naturally occurring metabolite safranal which gives saffron its characteristic and desirable odor. Use of the method eliminates the degradation of other compounds in the stigma, such as crocin and picrocrocin to safranal. When ethanol-water extracts of stigmas were repeatedly injected into the HPLC the first injection revealed safranal and picrocrocin but after 2 hours no picrocrocin was found and the safranal concentration increased indicating that picrocrocin completely converted to safranal and other unidentified compounds. Stigmas extracted with acetonitrile showed no change in safranal concentration even after storage for one week. This finding indicated that acetonitrile selectively extracts safranal thus excluding the picrocrocin which converts to safranal when extracted with ethanol- water. The extraction of safranal from dry stigmas with 100% acetonitrile and the use of a 100% acetonitrile HPLC solvent system gave an estimate of the actual concentration of safranal in the stigma tissue at the time of extraction. The new and improved freeze-drying/HPLC method for extraction and quantification of safranal could be used by the spice industry to guarantee spice quality of saffron.