Application of Ultrafiltration for Recovery of Polyphenols from Rose Petal Byproduct.

One main objective of this study was to increase the utilization of raw material in the rose (Rosa damascena Mill.) essential oil industry by the application of membrane technologies. In this research, distilled (dearomatized) rose petals, the primary byproduct in essential oil production, were subjected to an enzyme-assisted extraction and subsequent membrane separation for partial concentration at different levels using UF1-PAN and UF10-PAN membranes. The results show that the permeate flux decreased with a rise in volume reduction ratio and increased with a rise in transmembrane pressure and feed flow rate. At the beginning of the process, the highest flux was with the UF1-PAN membrane, but at the end of the process, it was with the UF10-PAN membrane. Total polyphenols of the retentates increased by 27-39% and 26-67% during ultrafiltration with the UF1-PAN and UF10-PAN membranes, respectively, with the highest value obtained for the 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 the UF10-PAN membrane. The use of green technology based on enzyme-assisted extraction and ultrafiltration for recovery and concentration of polyphenols from rose petal byproduct solves practical environmental problems for the treatment and utilization of byproducts from the rose oil industry. The retentate obtained could be used in the food production, cosmetic, and pharmaceutical industries.

Concentration of Polyphenolic Antioxidants in Apple Juice and Extract Using Ultrafiltration.

The aim of the present work was to study the potential of ultrafiltration with three polyacrylonitrile membranes (1, 10, and 25 kDa) to concentrate polyphenolic antioxidants in apple juice and extract. The permeate flux, total polyphenols, polyphenolic profile, phenolic acid content, and total antioxidant capacity were determined using the FRAP and DPPH tests, the content of water-soluble proteins during ultrafiltration was established, and the concentration factors and rejections were determined. The permeate flux decreased by increasing the volume reduction ratio and decreasing the molecular weight cut-off of the membranes. The concentration factor and rejection of polyphenolics increased with the increase in the volume reduction ratio (VRR) for all membranes and both liquids. The concentration and rejection effectiveness of the 1 kDa membrane was higher than those observed for 10 and 25 kDa during the ultrafiltration of the apple extract, while these values were comparable for 1 and 10 kDa during the ultrafiltration of the apple juice. The concentration factors and rejections of total polyphenols were higher in the extract than in the juice. Chlorogenic acid was the main compound in the polyphenol profile of apple juice. The total content of phenolic acids, determined by using HPLC, increased by 15-20% as a result of the membrane concentration, but the separation process did not significantly change the ratio between the individual compounds.

Optimisation of the enzyme-assisted extraction of polyphenols from saffron (Crocus sativus L.) petals.

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. 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 (R2 = 0.85-0.98). CONCLUSIONS: 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.

Near-Infrared Spectroscopic Analysis of Total Phenolic Content and Antioxidant Activity of Berry Fruits.

This study evaluates the feasibility of using near-infrared (NIR) spectroscopy as a rapid and environmentally friendly technique for validation and prediction of the total phenolic content (TPC) and antioxidant activity (AOA) indices (as 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, inhibition time (IT) of the Briggs-Rauscher oscillating reaction, and relative antioxidant capacity (RAC)) of berry fruit extracts. The analysed berry samples originated from Croatia (blackberries, wild blueberries, raspberries, red currants and strawberries) and Bulgaria (wild blueberries, raspberries and strawberries). Principal component analysis and partial least squares (PLS) regression were used from the set of chemometric tools in distinguishing and validating the measured berry fruit extract. ANOVA and PCA showed no significant impact of the origin and freshness of the samples. PLS models were developed to validate the relationship of NIR spectra with TPC and AOA of berry fruits. Representativeness of the models was expressed with the R2 and the ratio of performance to deviation. Calculated R2 values were above 0.84 and the ratio of performance to deviation was between 1.8 and 3.1, indicating adequacy of the PLS models.

Heat stability of strawberry anthocyanins in model solutions containing natural copigments extracted from rose (Rosa damascena Mill.) petals.

Thermal degradation and color changes of purified strawberry anthocyanins in model solutions were studied upon heating at 85 degrees C by HPLC-DAD analyses and CIELCh measurements, respectively. The anthocyanin half-life values increased significantly due to the addition of rose (Rosa damascena Mill.) petal extracts enriched in natural copigments. Correspondingly, the color stability increased as the total color difference values were smaller for anthocyanins upon copigment addition, especially after extended heating. Furthermore, the stabilizing effect of rose petal polyphenols was compared with that of well-known copigments such as isolated kaempferol, quercetin, and sinapic acid. The purified rose petal extract was found to be a most effective anthocyanin-stabilizing agent at a molar pigment/copigment ratio of 1:2. The results obtained demonstrate that the addition of rose petal polyphenols slows the thermal degradation of strawberry anthocyanins, thus resulting in improved color retention without affecting the gustatory quality of the product.

Flavonol glycosides from distilled petals of Rosa damascena Mill.

Flavonol glycosides were extracted from petals of Rosa damascena Mill. after industrial distillation for essential oil recovery and characterized by high-performance liquid chromatography-electrospray ionization mass spectrometry. Among the 22 major compounds analyzed, only kaempferol and quercetin glycosides were detected. To the best of our knowledge, the presence of quercetin 3-O-galactoside and quercetin 3-O-xyloside has so far not been reported within the genus Rosa. In addition, based on their fragmentation patterns, several acylated quercetin and kaempferol glycosides, some of them being disaccharides, were identified for the first time. The kaempferol glycosides, along with the kaempferol aglycone, accounted for 80% of the total compounds that were quantified, with kaempferol 3-O-glucoside being the predominant component. The high flavonol content of approximately 16 g/kg on a dry weight basis revealed that distilled rose petals represent a promising source of phenolic compounds which might be used as functional food ingredients, as natural antioxidants or as color enhancers.

Effect of mash maceration on the polyphenolic content and visual quality attributes of cloudy apple juice.

The effects of enzymatic mash treatments on yield, turbidity, color, and polyphenolic content of cloudy apple juice were studied. Using HPLC-ESI-MS, cryptochlorogenic acid was identified in cv. Brettacher cloudy apple juice for the first time. Commercial pectolytic enzyme preparations with different levels of secondary protease activity were tested under both oxidative and nonoxidative conditions. Without the addition of ascorbic acid, oxidation substantially decreased chlorogenic acid, epicatechin, and procyanidin B2 contents due to enzymatic browning. The content of chlorogenic acid as the major polyphenolic compound was also influenced by the composition of pectolytic enzyme preparations because the presence of secondary protease activity resulted in a rise of chlorogenic acid. The latter effect was probably due to the inhibited protein-polyphenol interactions, which prevented binding of polyphenolic compounds to the matrix, thus increasing their antioxidative potential. The results obtained clearly demonstrate the advantage of the nonoxidative mash maceration for the production of cloud-stable apple juice with a high polyphenolic content, particularly in a premature processing campaign.