The process of rose oil distillation generates a huge amount of waste byproducts, which often remain unused, and poses serious environmental challenges; at the same time, they contain polyphenols with antioxidant, antimicrobial, and therapeutic properties. The purpose of this work is to investigate the possible application of ultrafiltration using three polyacrylonitrile membranes (molecular weight cut-off 1 kDa, 10 kDa, and 25 kDa) to recover the total polyphenolic compounds, phenolic acids, and flavonoids from rose wastewater. The permeate flux, energy demand, contents of total polyphenolic compounds, phenolic acids, and flavonoid phenolic compounds were determined during ultrafiltration at a volume reduction ratio of 2, 4, 6 and 8, and the rejections and concentration factors were established. The optimal operation conditions for permeate flux, energy demand, rejection, concentration factor, and antioxidant activity were established at a volume reduction ratio of 8, transmembrane pressure of 0.5 MPa, and 1 kDa membrane. These working conditions will be used in our future investigations to obtain extrudates from rice semolina enriched with ultrafiltered rose wastewater. Protocatechuic and vanillic acid, determined by HPLC, increased in the retentate when the 1 kDa membrane was used, while gallic acid, catechin, p-coumaric acid, rutin, hesperidin, and rosmarinic acid decreased.

The purpose of this work was to investigate the posibilties of ultrafiltration with three polyacrylonitrile membranes (molecular weight cut-off 1 kDa, 10 kDa, and 25 kDa) to recover the total polyphenolic compounds, phenolic acids and flavonoids from rose wastewater. The permeate flux, energy demand, contents of total polyphenolic compounds, phenolic acids and flavonoid phenolic compounds were determined during ultrafiltration at volume reduction ratio of 2, 4, 6 and 8, and the rejections and concentration factors were established. The permeate flux decreased with the rise in the volume reduction ratio, and with the decrease in the transmembrane pressure and the molecular weight cut-off of the membranes. Inverse relationship was observed between the permeate flux and the energy demand at the same operating conditions. The rejections and concentration factors of total polyphenolic compounds, phenolic acids and flavonoid phenolic compounds rose with the increase in the volume reduction ratio for all membranes. The 1 kDa membrane had higher concentration and rejection effectiveness than 10 and 25 kDa membranes. Protocatehuic and vanillic acid, determined by using HPLC, increased in the retentate when 1 kDa membrane was used, while gallic acid, catechin, p-coumaric acid, rutin, hesperidin, rosmarinic acid decreased.

This study investigates the possibilities for application of ultrafiltration for utilization of rose waste water obtained from water-steam distillation of rose petals from Rosa damascena Mill. Ultrafiltration was conducted using an UF1-PAN membrane up to volume reduction ratio of 5. The effects of frontal filtration prior to ultrafiltration and temperature (20°C and 50°C) during membrane process were examined. The obtained retentates and permeates were analyzed according to the following parameters: total phenolic content, phenolic acids, flavonoid phenolic content and spectral characteristics. The flux and energy demand were determined during ultrafiltration. The results showed that there was no statistically significant difference between the flux during ultrafiltration with and without frontal filtration, as well as for energy demand at the same working conditions. The temperature rise led to an increase in the flux and a decrease in the energy demand. The total phenolic content, phenolic acids, and total flavonoid content were found to increase in the retentate, while they decreased in the permeate. The principal component analysis was made for all parameters measured and revealed that the samples can be separated into three groups. In further investigations, the retentate will be added to rice grits in order to obtain enriched extruded products.

In this study, the potential of extrusion for producing functional food from corn semolina enriched with an ultrafiltration (UF) retentate obtained from rose wastewater was investigated. Extrudates were produced using a single-screw laboratory extruder (Brabender 20DN), and their physical (expansion ratio, bulk density, and moisture content), functional (water absorption and solubility indices), and process characteristics (specific mechanical energy and mass flow rate) and phenolic content were investigated. The effect of the UF retentate’s amount (4 or 11%), the temperature in the third zone of the extruder (150 or 170 °C), and the working screw speed (180 or 220 min⁻¹) on the physical, functional and process characteristics was examined using a full factorial design. Increasing the retentate’s amount led to a decrease in the expansion, water solubility index, specific mechanical energy, and mass flow rate, as well as an increase in the bulk density, moisture content, and water absorption index of extrudates. The augmentation of temperature led to a decrease in the bulk density, water solubility index, specific mechanical energy, and mass flow rate and had no significant effect on the other characteristics. The increase in the screw speed resulted in extrudates with a lower water solubility index, water absorption index, and specific mechanical energy and a higher expansion and moisture content, while it had no significant effect on the density and mass flow rate. The UF retentate enhanced the total phenolic, phenolic acid, and flavonoid contents of the extrudates. Optimal conditions for producing high-quality extrudates were found at 5.02% UF retentate, 150 °C, and 207.8 min⁻¹.

The moisture sorption isotherms of corn extrudates fortified with ultrafiltration (UF) concentrate derived from rose wastewater (RWW) were examined. Two formulations containing 4 g (sample S4) and 11 g (sample S11) of retentate, respectively, per 100 g of semolina were prepared and subsequently extruded. Adsorption and desorption isotherms of both samples were determined at 10 °C, 25 °C and 40 °C using the static gravimetric method within a water activity range of 0.11–0.85. The experimental data of equilibrium moisture content (EMC) were fitted using modified GAB, modified Oswin, and modified Halsey equations. The monolayer moisture content of the samples was determined using the BET model. The results showed that the sorption isotherms exhibited a typical sigmoidal (Type II) shape and a pronounced hysteresis effect between adsorption and desorption. The hysteresis effect decreased with increasing temperature. Based on the combined evaluation of error analysis and residual distribution, the modified Oswin model provided the most balanced overall performance and was determined as suitable for the description of the sorption isotherms of the extrudates studied. The effect of UF-retentate level on EMC was not uniform and depended on temperature, water activity, and sorption direction. The monolayer moisture content of the extrudates varied from 4.08 to 8.39% d.b. The higher retentate level was generally associated with higher monolayer moisture values. Packaging and storage at the theoretically estimated range of water activities from 0.09 to 0.24 may be expected to maintain EMCs close to the monolayer.