Valorisation of saffron floral by-products through fermentation: a focus on the antimicrobial activity

Saffron is obtained from the stigmas of Crocus sativus L. flowers, and after their removal, the remaining 80 % of the flower, including stamens and tepals, are discarded. Therefore, this work aimed to investigate the fermentability of saffron by-products and their valorisation through the recovery of antimicrobial extracts. To evaluate the fermentability of saffron by-products, a Design of Experiment was applied and the growth ability of 20 microbial strains, mainly lactic acid bacteria and one yeast, was tested. The best-adapted strains ( Limosilactobacillus fermentum , Lacticaseibacillus rhamnosus, Lacticaseibacillus paracasei and Pediococcus acidilactici ) were selected, and the antimicrobial activity of extracts from the fermented matrices was evaluated against Salmonella enterica, Listeria monocytogenes, Staphylococcus aureus and Escherichia coli . After the extraction process, especially the extracts obtained from the fermented matrices showed antimicrobial activity (Minimum Inhibitory Concentration values ranged between 50 and 25 mg/mL). To test the reproducibility of the fermentation and the antimicrobial activity of fermented matrices, by-products from different Mediterranean countries, collected in different years and subjected to different post-harvest treatments, were evaluated. The growth ability observed in the different matrices was comparable and in line with the predicted model as the antimicrobial activity. • Saffron floral by-products are an ideal substrate for lactic acid fermentation. • The fermented matrices exhibited antimicrobial activity not present in the unfermented material. • The fermentation of various saffron floral by-products results in a constant antimicrobial activity.