From saffron residues to natural safranal : Valorization of waste through a β-glucosidase

Saffron (Crocus sativus L.) spice, traditionally used as food additive for its coloring and flavoring properties, has shown great potential to promote health. Among the main constituents of saffron spice, safranal has been shown to alleviate and prevent gastric disorders, cardiovascular diseases and to exert anticonvulsant, anxiolytic, antidepressive and neuroprotective activities. In this work, we recovered picrocrocin from saffron residues and efficiently biotransformed it using a halo-thermophilic β-glucosidase from Alicyclobacillus acidophilus (Aac), which gave the corresponding aglycone 4-hydroxysafranal with complete conversion (>99%) and rapid reaction times (15 min). After a thermic treatment, safranal was obtained in excellent yields. To make the process even more efficient and sustainable a one-pot, 2-step chemo-enzymatic transformation was set up, yielding a marketable natural safranal as final product.