Background. Saffron tepals are a by-product from the processing of Crocus sativus flowers, whose dried stigmas (saffron spice) are widely used both in the food and health sectors. Saffron tepals are rich in polyphenols, particularly flavonol glycosides and anthocyanins, which are considered to be potent antioxidants. Enzyme-assisted extraction of polyphenols offers several advantages in comparison to conventional methods. The present study evaluated the efficiency of enzyme-assisted extraction as a green technology for recovery of polyphenols from saffron tepals. Materials and methods. The by-product was obtained from a saffron producer in the region of Kozani, Greece. A simplex-centroid design was applied to select the enzyme preparations mixture required for aqueous extraction of polyphenolic antioxidants from dried saffron tepals. In addition, the parameters of enzymatic hydrolysis, enzyme dose and incubation time were optimised using response surface methodology. Results. The binary combination, comprising cellulolytic and hemicellulolytic preparations (1:1), led to the highest yield of total polyphenols (30.9 g GAE/kg saffron tepals) and total anthocyanins (2.0 g CGE/kg saffron tepals), reaching 45% and 38% higher values, respectively, as compared to the control sample (without enzymatic treatment). The experimental data regarding optimisation of the extraction conditions were fitted to second-degree regression models (R 2 = 0.85-0.98). Conclusion. The newly developed process may be applied as an environmentally friendly alternative to conventional organic solvent extraction, thus supporting valorisation of the saffron industry by-product. The polyphenols recovered could be used as biologically active substances or as natural food ingredients, replacing synthetic additives.

One main objective of this study was to increase the utilization of the raw material in the rose (Rosa damascena Mill.) essential oil industry by application of membrane technologies. A new ultrafiltration-based process for green recovery of polyphenols from distilled (de-aromatized) rose petals, the primary by-product in essential oil production, was created. The process includes enzyme-assisted extraction and subsequent membrane separation for partial concentration. Following a green membrane technology strategy, the newly developed process proposes an environmentally-friendly alternative to the conventional processing, comprising organic solvent ex-traction and adsorber resin purification. The results showed that the permeate flux decreased with volume reduction ratio’s rise and increased with the transmembrane pressure and feed flow rate rises. At the beginning of the process the highest flux was with UF1-PAN membrane, but at the end of the process with UF10-PAN membrane. Total polyphenols of the retentates in-creased by 27-39% and 26-67% during ultrafiltration with UF1-PAN and UF10-PAN membrane, respectively, with the highest value obtained for UF10-PAN membrane at VRR 6. The highest concentration factor and rejection of total solids, total polyphenols, redox-active antioxidants and radical scavenging antioxidants were obtained at VRR 6 with UF10-PAN membrane. This membrane and concentration level at transmembrane pressure of 0.4 MPa and feed flow rate of 330 dm3/h are recommended to be used for application of ultrafiltration of rose-petals by-product for potential use in the food industry.