Abstract
The production of saffron spice generates large quantities of plant by-products: over 90% of the plant material collected is discarded, and a consideration fraction of this waste is plant stamens. This work investigated the chemical composition and the antimicrobial activities of the non-polar fraction extracted from four different saffron flower stamens. The chemical composition of ethereal extracts of the saffron stamens was qualitatively assessed by means of gas–chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR) analyses. These analyses revealed ethereal extracts to possess a high polyunsaturated fatty acid content. In vitro antibacterial activity of stamen extracts showed no large differences between Gram-positive and Gram-negative bacteria in terms of minimal inhibitory concentration (MIC). In food matrix microbial analysis of the bacterial strains belonging to the main foodborne pathogen species, including Staphylococcus aureus DSM 20231, Escherichia coli DSM 30083, and Listeria monocytogenes DSM 20600, using low-fat UHT milk, revealed a statistically significant reduction in the number of cells (particularly for E. coli and S. aureus with a complete elimination of the population of the two target bacteria following incubation in diethyl ether extracts of saffron stamen (DES) at high concentrations tested, both at 37 °C and 6 °C (for 48 h and 7 days, respectively). A synergic effect was observed when the pathogens were incubated at 6 °C with DES. This work shows these by-products to be excellent sources of bioactive compounds, which could be exploited in high-added-value products, such as food, cosmetics, and drugs.
Highlights
The raw diethyl ether extract of saffron stamens was subjected to qualitative chemical analysis by nuclear magnetic resonance (NMR) spectroscopy: ethereal extracts were examined by 1 H, 31 P, HSQC, and 13 C
By referring to the detailed characterization of NMR signals relative to the main metabolites present in polar saffron extracts published by Sobolev and coworkers [26], we were able to confirm the presence of linoleic and linolenic fatty acids represented in the 1 H NMR by the signals for -CH3 at 0.95 ppm, -CH2 - at 1.6 ppm, and the double bond at 5.35 ppm
We show that the liposoluble fraction of saffron flower stamens—a part of the plant discarded during the production of saffron spice—is rich in linoleic, linolenic, and palmitic fatty acids, and exhibits strong antimicrobial activity, both in in vitro and in the food matrix, against some strains of the most common food-borne pathogenic bacterial species, including S. aureus and E. coli
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Saffron (Crocus sativus Linn.), of the family of Iridaceae, is commonly used for the production of the world’s most expensive spice, used for food flavoring, coloring, and preserving. The stigmas, which form a very small percentage of the total flower mass, are collected and processed for spice production. The production of saffron spice generates a number of by-products, with 1 kg of flowers yielding only 15 g of spice. This means that over 90% of the plant material collected ends up being discarded [5,6,7].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
