Age evaluation of commercial saffron by means of FT-IR and 1H NMR-based metabolomic approaches

The trade standard ISO 3632 is widely applied to saffron commercial transactions to classify samples according to their quality characteristics, e.g. coloring strength, expressed as E1%at 440 nm values. The results of these methods do not provide information about the "age" of the traded products, that is, the elapsed period from the initial processing. In the frame of "Saffron-OMICS" objectives we developed two spectroscopic databases using FT-IR and 1H NMR metabolomic data. The present study is a follow up work, aiming to evaluate the age of various saffron samples (n =17) purchased from open markets and retail shops in major saffron-consuming countries and checked for purity. For most of these samples, information about the packaging and expiration dates was available. FT-IR metabolomics indicated that most of the samples could not be considered as fresh (i.e. <= 4 years after processing) . However a clear classification into groups was not feasible. The information obtained from the 1H NMR metabolomics was more conclusive. Indeed, most of the samples that were analysed close to their expiration date were classified as non-fresh (>= 4 years). Considering that, to the best of our knowledge, the product to be packed comes from the latest two harvests and that most of the manufacturers of the studied samples declared a period of usage of two-years on the label, scientific findings support empirical practices. Data from UV-Vis (E1% values) and HPLC-DAD analyses (contents of total crocetin esters and picrocrocin) of aqueous/methanolic extracts at the time of purchase and soon after the FT-IR and NMR analyses enrich the overall discussion about the potential to evaluate the age of commercial saffron samples through metabolomics approach.