New insight in the saffron quality characterization: the NMR based approach

In the last years several efforts have been driven to food authentication and new analytical techniques have been applied in the view of a deeper characterization. The growth of a new discipline, called "Food-omics" evidenced the need of a larger exploration of different aspects related to food. From the chemical point of view, a food is considered a complex matrix containing different chemical compounds widely ranging in concentration and in chemical properties. In this context NMR (Nuclear Magnetic Resonance) spectroscopy represents a valid and powerful technique allowing the analysis of different classes of chemical compounds with high -medium abundance, within a single experiment, using a limited experimental time and no chemical treatment of sample. In this work, the NMR analysis is presented to assess the quality of saffron, nowadays defined by the specifications and methods described in the ISO 3632 trade standard. A particular emphasis will be dedicated to the results achieved during the STSMs approved by COST Action FA 1101 "SaffronOmics". The use of multivariate statistical analysis on 1H NMR data obtained from DMSO extracts of saffron, allowed to evaluate different quality aspects: the geographical discrimination between Greek and Iranian saffron of the same harvest, the definition of the storage period during which saffron can be considered yet fresh, irrespectively from the origin, and the identification of possible bio-adulterants such as C. sativus stamens, safflower, turmeric, and gardenia. These findings highlight the potentiality of NMR spectroscopy in quality assessment of the most expensive spice worldwide, protecting both producers and consumers.