Determination of Saffron Flower Metabolites by Near-Infrared Spectroscopy for Quality Control

Abstract

Saffron, obtained by dehydrating the stigmas of the Crocus sativus flower, is a spice of great importance. In saffron, the flower emerges before leaf formation, thanks to the nutritional reserves of the corm. Early knowledge of metabolite levels such as crocins, picrocrocin, safranal, anthocyanins, or kaempferols in flowers serves as a guide to evaluate the quality of the corm (coloring power, flavor, aroma, or antioxidant capacity, among others). In this study, near-infrared spectroscopy (NIR) was calibrated and validated to determine the main saffron metabolites, both in stigmas and in floral residue. To achieve this, saffron flowers from different locations of the Denomination of Origin (D.O.) “Azafrán de La Mancha” (Castilla-La Mancha, Spain) were analyzed using NIR spectroscopy. Prior to this, samples were analyzed by RP-HPLC-DAD, where the concentration of all cited metabolites was determined. The development of a predictive model through NIR calibration and validation was successful, achieving high R2 values, especially in the case of the sum of crocins and kaempferol-3-O-β-sophoroside. Using these predictive models, it is possible to determine the quality of saffron corm by analyzing the flower.