Concentration of bioactive compounds from grape marc using pressurized liquid extraction followed by integrated membrane processes

Ultrasound-assisted extraction and concentration of phenolic compounds from jabuticaba sabará (Plinia peruviana (Poir.) Govaerts) peel by nanofiltration membrane

Jabuticaba peel, rich in antioxidants, offering health benefits. In this study, the extraction of phenolic compounds from jabuticaba peel using ultrasound-assisted (UA) and their subsequent concentration by nanofiltration (NF) employing a polyamide 200 Da membrane was evaluated. The UA extractions were conducted using the Central Composite Rotatable Design (CCRD) 22 methodology, with independent variables extraction time (11.55 to 138 min) and temperature (16.87 to 53.3 °C), and fixed variables mass to ethanol solution concentration at pH 1.0 (1:25 g/mL), granulometry (1 mm), and ultrasonic power (52.8 W). The maximum concentrations obtained were 700.94 mg CE/100 g for anthocyanins, 945.21 mg QE/100 g for flavonoids, 133.19 mg GAE/g for phenols, and an antioxidant activity IC50 of 24.36 μg/mL. Key phenolic compounds identified included cyanidin-3-glucoside, delphinidin-3-glucoside, and various acids like syringic and gallic. NF successfully concentrated these compounds, enhancing their yield by up to 45%. UA and NF integrate for sustainable extraction.

Can Storage Stability and Simulated Gastrointestinal Behavior Change the Cytotoxic Effects of Concentrated Guava Leaves Extract against Human Lung Cancer Cells?

The influence of storage stability and simulated gastrointestinal behavior of different extracts of guava leaves extracts (NC: not concentrated, and C10 and C20: concentrated by nanofiltration) was evaluated based on their total phenolic compound (TPC) contents and antioxidant activity as well as on their cytotoxic effects on A549 and Vero cells. The results showed that C10 and C20 presented high stability for 125 days probably due to their high TPC contents and antioxidant activity. The simulated gastrointestinal behavior modified their TPC contents; however, after all digestion steps, the TPC values were higher than 70%, which means that they were still available to exert their bioactivities. Additionally, the cytotoxic effects of these extracts were evaluated before and after the simulated gastrointestinal behavior or under different storage conditions. C10 presented the best selectivity indices (SI) values (IC50 Vero cells/IC50 A549 cells) at both conditions suggesting that it can be considered a potential extract to be developed as a functional food due to its resistance to the gastrointestinal digestion and storage conditions tested.

Integrated Membrane Process in Organic Media: Combining Organic Solvent Ultrafiltration, Nanofiltration, and Reverse Osmosis to Purify and Concentrate the Phenolic Compounds from Wet Olive Pomace

Phenolic compounds from a hydroalcoholic extract of wet olive pomace were purified and concentrated by an integrated membrane process in organic media. First, UF010104 (Solsep BV) and UP005 (Microdyn Nadir) membranes were tested to be implemented in the ultrafiltration stage, with the aim of purifying the extract and obtaining a permeate enriched in phenolic compounds. Despite the high flux observed with the UF010104 membrane (20.4 ± 0.7 L·h-1·m-2, at 2 bar), the UP005 membrane was selected because of a more suitable selectivity. Even though some secoiridoids were rejected, the permeate stream obtained with this membrane contained high concentrations of valuable simple phenols and phenolic acids, whereas sugars and macromolecules were retained. Then, the ultrafiltration permeate was subjected to a nanofiltration step employing an NF270 membrane (DuPont) for a further purification and fractionation of the phenolic compounds. The permeate flux was 50.2 ± 0.2 L·h-1·m-2, working at 15 bar. Hydroxytyrosol and some phenolic acids (such as vanillic acid, caffeic acid, and ferulic acid) were recovered in the permeate, which was later concentrated by reverse osmosis employing an NF90 membrane. The permeate flux obtained with this membrane was 15.3 ± 0.3 L·h-1·m-2. The concentrated phenolic mixture that was obtained may have important applications as a powerful antioxidant and for the prevention of diabetes and neurodegenerative diseases.

Recovery of Oleuropein from Olive Leaf Extract Using Zinc Oxide Coated by Polyaniline Nanoparticle Mixed Matrix Membranes

This study explores the integration of zinc oxide coated with polyaniline (ZnO-PANI) nanoparticles into a poly(ether sulfone) (PES) matrix to concurrently enhance permeate flux and oleuropein (OLP) rejection during the filtration of olive leaf extract (OLE). The effect of ZnO-PANI content on porosity, pore size, surface hydrophilicity, and pure water flux (PWF) was studied. The results indicate that an increase in ZnO-PANI content (0-0.2%) leads to a 3-fold increase in mean pore size, permeability (1.29-7.18 L/m2 h bar), porosity (72.2-77.8%), and improved surface hydrophilicity of the prepared membranes. Membrane performance was tested for OLE permeate flux of the OLE and total phenolic compounds (TPC) rejection at various pressures (10-30 bar), the performance of the OLP rejection at 30 bar, and fouling resistance. The 0.2 wt % ZnO-PANI membrane exhibits the highest permeate flux, while the 0.4 wt % ZnO-PANI membrane offers the highest rejection values (90-97% for TPC and 100% for OLP). Bare PES demonstrated the best fouling resistance. Strategic ZnO-PANI incorporation achieves a balance, enhancing both the flux and rejection efficiency. The 0.2 wt % ZnO-PANI membrane emerges as particularly favorable, striking a beneficial equilibrium between permeate flux and OLP rejection. Intriguingly, the use of these membranes for OLE filtration, postpretreatment with ultrafiltration (UF), results in a remarkable 100% rejection of OLP. This discovery underscores the significant and specific separation of OLP from OLE facilitated by a ZnO-PANI-based mixed matrix membrane (MMM). The study contributes valuable insights into the development of advanced membranes with enhanced filtration capabilities for high-added value phenolic compound separation.

The Optimization of Operating Conditions in the Cross-Flow Microfiltration of Grape Marc Extract by Response Surface Methodology

The recovery of valuable compounds like phenolic compounds and sugars from grape marc extracts implies different steps, including clarification. In this study, a response surface methodology (RSM) was used as a statistical tool to study the effects of operating conditions such as transmembrane pressure (TMP), temperature and feed flow rate on the performance of a microfiltration (MF) monotubular ceramic membrane with a pore size of 0.14 μm in the clarification of grape marc extract from the Carménère variety, as well to optimize the process conditions by implementing the Box-Behnken statistical design. The desirability function approach was applied to analyze the regression model equations in order to maximize the permeate flux and concentration of malvidin-3-O-glucoside, glucose and fructose in the clarified extract. The optimal operating conditions were found to be 1 bar, 29.01 °C and 5.64 L/min. Under these conditions, the permeate flux and concentration of malvidin-3-O-glucoside, glucose and fructose resulted in 65.78 L/m2h, 43.73 mg/L, 305.89 mg/L, and 274.85 mg/L, respectively.

Application of atomic force microscopy in the characterization of fruits and vegetables and associated substances toward improvement in quality, preservation, and processing: nanoscale structure and mechanics perspectives

Fruits and vegetables are essential horticultural crops for humans. The quality of fruits and vegetables is critical in determining their nutritional value and edibility, which are decisive to their commercial value. Besides, it is also important to understand the changes in key substances involved in the preservation and processing of fruits and vegetables. Atomic force microscopy (AFM), a powerful technique for investigating biological surfaces, has been widely used to characterize the quality of fruits and vegetables and the substances involved in their preservation and processing from the perspective of nanoscale structure and mechanics. This review summarizes the applications of AFM to investigate the texture, appearance, and nutrients of fruits and vegetables based on structural imaging and force measurements. Additionally, the review highlights the application of AFM in characterizing the morphological and mechanical properties of nanomaterials involved in preserving and processing fruits and vegetables, including films and coatings for preservation, bioactive compounds for processing purposes, nanofiltration membrane for concentration, and nanoencapsulation for delivery of bioactive compounds. Furthermore, the strengths and weaknesses of AFM for characterizing the quality of fruits and vegetables and the substances involved in their preservation and processing are examined, followed by a discussion on the prospects of AFM in this field.

Combining Ultrafiltration and Nanofiltration to Obtain a Concentrated Extract of Purified Polyphenols from Wet Olive Pomace

Despite the environmental concerns raised every year by the generation of high volumes of wet olive pomace, it contains valuable phenolic compounds that are essential for the valorization of this by-product. In this work, an integrated process to recover phenolic compounds from wet olive pomace is proposed. It consists of ultrasound-assisted solid-liquid extraction, followed by ultrafiltration and nanofiltration. Several commercial membranes were studied at different operational conditions. The ultrafiltration stage allowed the purification of biophenols, which were obtained in the permeate stream. Regarding organic matter, satisfactory rejection values were obtained with both commercial UH030 and UP005 membranes (Microdyn Nadir), but the latter provided more efficient purification and higher values of permeate flux, above 18 L·h^-1·m^-2 at 2.5 bar and 1.5 m·s^-1. Later, this permeate stream was concentrated by means of a nanofiltration process, obtaining polyphenol rejection values that surpassed 85% with the commercial NF270 membrane (DuPont), then achieving the concentration of the previously purified polyphenols.

Comprehensive analysis of phenolic compounds from natural products: Integrating sample preparation and analysis

The comprehensive analysis of phenolic compounds from natural products comprises critical steps, including quantitative extraction, extract preparation, and chromatographic procedure. Performing these steps off-line requires a long time to obtain results, besides being laborious and more error-prone. This work discusses the concept and presents the details of assembling and validating a new system to comprehensively analyze phenolic compounds in natural products. The system is based on a bidimensional separation through the combination of pressurized liquid extraction with in-line solid-phase extraction coupled online with HPLC-PDA. The system proved to be able to perform a bidimensional separation to characterize the sample and ensure quantitative extraction of all detected components using the most appropriate extraction solvent gradient depending on the raw sample analyzed. The 1st dimension separation is achieved by PLE-SPE with a solvent gradient and differential interactions of extracted compounds with the adsorbent. The 2nd dimension presents the HPLC-PDA separation. The extraction/separation process can be monitored in real-time, and kinetic extraction curves for individual compounds can also be obtained to ensure quantitative extraction. Thus, the 2D PLE-SPE × HPLC-PDA may provide fast and precise comprehensive analyses of a large plethora of phenolic compounds, finding relevant applications in the chemical, food, pharmaceutical, and agricultural fields.

Recovery of Anthocyanins and Monosaccharides from Grape Marc Extract by Nanofiltration Membranes

Wastewaters and by-products generated in the winemaking process are important and inexpensive sources of value-added compounds that can be potentially reused for the development of new products of commercial interest (i.e., functional foods). This research was undertaken in order to evaluate the potential of nanofiltration (NF) membranes in the recovery of anthocyanins and monosaccharides from a clarified Carménère grape marc obtained through a combination of ultrasound-assisted extraction and microfiltration. Three different flat-sheet nanofiltration (NF) membranes, covering the range of molecular weight cut-off (MWCO) from 150 to 800 Da, were evaluated for their productivity as well as for their rejection towards anthocyanins (malvidin-3-O-glucoside, malvidin 3-(acetyl)-glucoside, and malvidin 3-(coumaroyl)-glucoside) and sugars (glucose and fructose) in selected operating conditions. The selected membranes showed differences in their performance in terms of permeate flux and rejection of target compounds. The NFX membrane, with the lowest MWCO (150–300 Da), showed a lower flux decay in comparison to the other investigated membranes. All the membranes showed rejection higher than 99.42% for the quantified anthocyanins. Regarding sugars rejection, the NFX membrane showed the highest rejection for glucose and fructose (100 and 92.60%, respectively), whereas the NFW membrane (MWCO 300–500 Da) was the one with the lowest rejection for these compounds (80.57 and 71.62%, respectively). As a general trend, the tested membranes did not show a preferential rejection of anthocyanins over sugars. Therefore, all tested membranes were suitable for concentration purposes.

Application of a Natural Antioxidant from Grape Pomace Extract in the Development of Bioactive Jute Fibers for Food Packaging

There is an increasing demand for the use of new food packaging materials. In this study, natural jute fibers impregnated with a Petit Verdot Red Grape Pomace Extract (RGPE) was proposed as a new active food packaging material. Pressurized Liquid Extraction (PLE) and Enhanced Solvent Extraction (ESE) techniques were employed to obtain the bioactive RGPE. Afterward the supercritical solvent impregnation conditions to obtain RGPE-natural jute fibers were studied, by varying pressure, modifier percentage and dried RGPE mass. PLE technique offered the highest bioactive extract at 20 MPa, 55 °C, 1 h residence time using C₂H₅OH:H₂O (1:1 v/v), providing an EC50 of 3.35 ± 0.25 and antibacterial capacity against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa (MIC of 12.0, 1.5 and 4.0 mg/mL RGPE respectively). The natural jute fibers impregnated with 3 mL of that RGPE (90 mg/mL) at 50 MPa and 55 °C generated the most efficient packing material with regards to its food preservation potential.

Environmentally Friendly Methods for Flavonoid Extraction from Plant Material: Impact of Their Operating Conditions on Yield and Antioxidant Properties

The flavonoids are compounds synthesized by plants, and they have properties such as antioxidant, anticancer, anti-inflammatory, and antibacterial, among others. One of the most important bioactive properties of flavonoids is their antioxidant effect. Synthetic antioxidants have side toxic effects whilst natural antioxidants, such as flavonoids from natural sources, have relatively low toxicity. Therefore, it is important to incorporate flavonoids derived from natural sources in several products such as foods, cosmetics, and drugs. For this reason, there is currently a need to extract flavonoids from plant resources. In this review are described the most important parameters involved in the extraction of flavonoids by unconventional methods such as ultrasound, pressurized liquid extraction, mechanochemical, high hydrostatic pressure, supercritical fluid, negative pressure cavitation, intensification of vaporization by decompression to the vacuum, microwave, infrared, pulsed electric field, high-voltage electrical discharges, and enzyme-assisted extraction. There are no unified operation conditions to achieve high yields and purity. Notwithstanding, progress has been achieved in the development of more advanced and environmentally friendly methods of extraction. Although in literature are found important advances, a complete understanding of the extraction process in each of the unconventional techniques is needed to determine the thermodynamic and kinetic mechanisms that govern each of the techniques.