Valorisation of grape pomace: Fractionation of bioactive flavan-3-ols by membrane processing

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.

Novel Zero Headspace Solid-Liquid Extraction for the Recovery of Polyphenolic Fractions from Grape Pomace

Grape pomace (GP) is a good source of high-value compounds as up to 60% of grape polyphenols remain in it after wine-making. To overcome traditional membrane technologies’ d rawbacks, such as fouling, a novel Zero Head Space extraction (ZHE) procedure was developed. The reaction vessel comprised a filtration device with a nitrocellulose membrane. The separation was performed at 50 lb/in2 and 23 °C, with no headspace during the process. Water and methanol (both acidifie d) were evaluated as solvents during two extraction stages for the recovery and fractionation of polyphenols. Aqueous extract (AE) was mainly constituted by monomeric polyphenols while Methanol extract (ME) presented less soluble compounds, as well as a higher concentration of total anthocyanin content than AE. Additional methanolic (CE) and acetone (CAE) extractions of residual GP showed CE presented a similar profile to ME (at a lower concentration), indicating ZHE efficiency at extracting polyphenols in GP. CAE presented a non-resolved hump, characteristic of high proanthocyanidins’ polydispersity. ZHE rendered a monomeric fraction in ME (mean Degree of Polymerization, mDP of 1.38). Residual GP (cake) extractions demonstrated oligomeric polyphenol retention; mDP up to 3.05 when acetone was used. Fractionation of GP polyphenols was successfully established using a Zero Head space extractor.

Overview of Membrane Science and Technology in Portugal

Membrane research in Portugal is aligned with global concerns and expectations for sustainable social development, thus progressively focusing on the use of natural resources and renewable energy. This review begins by addressing the pioneer work on membrane science and technology in Portugal by the research groups of Instituto Superior Técnico—Universidade de Lisboa (IST), NOVA School of Science and Technology—Universidade Nova de Lisboa (FCT NOVA) and Faculdade de Engenharia—Universidade do Porto (FEUP) aiming to provide an historical perspective on the topic. Then, an overview of the trends and challenges in membrane processes and materials, mostly in the last five years, involving Portuguese researchers, is presented as a contribution to a more sustainable water–energy–material–food nexus.

Agri-Food Industry Waste as Resource of Chemicals: The Role of Membrane Technology in Their Sustainable Recycling

The agri-food sector generates substantial quantities of waste material on farm and during the processing of these commodities, creating serious social and environmental problems. However, these wastes can be resources of raw material for the production of valuable chemicals with applications in various industrial sectors (e.g., food ingredients, nutraceuticals, bioderived fine chemicals, biofuels etc.). The recovery, purification and biotransformation of agri-food waste phytochemicals from this microbial spoilage-prone, complex agri-food waste material, requires appropriate fast pre-treatment and integration of various processes. This review provides a brief summary and discussion of the unique advantages and the importance of membrane technology in sustainable recycling of phytochemicals from some of the main agri-food sectors. Membrane-based pressure -driven processes present several advantages for the recovery of labile compounds from dilute streams. For example, they are clean technologies that can operate at low temperature (20–60 °C), have low energy requirements, there is no need for additional chemicals, can be quite automated and electrifiable, and have low space requirements. Based on their permselective properties based on size-, shape-, and charge-exclusion mechanisms, membrane-based separation processes have unpaired efficiency in fractionating biological components while presenting their properties. Pressure-driven membrane processes, such as microfiltration (MF), ultrafiltration (UF) and nanofiltration (NF), as well as other advanced membrane-based processes such as membrane bioreactors (MBR), membrane emulsification (ME) and membrane distillation (MD), are presented. The integration of various membrane technologies from the initial recovery of these phytochemicals (MF, UF, NF) to the final formulation (by ME) of commercial products is described. A good example of an extensively studied agri-food stream is the olive processing industry, where many different alternatives have been suggested for the recovery of biophenols and final product fabrication. Membrane process integration will deliver in the near future mature technologies for the efficient treatment of these streams in larger scales, with direct impact on the environmental protection and society (production of compounds with positive health effects, new job creation, etc.). It is expected that integration of these technologies will have substantial impact on future bio-based societies over forthcoming decades and change the way that these chemicals are currently produced, moving from petrochemical-based linear product fabrication to a sustainable circular product design based in agri-food waste biomass.

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.

Cardioprotective effect of red wine and grape pomace

Several studies have related moderate consumption of red wine with prevention of cardiovascular diseases (CVD). According to epidemiological studies, those regions with high consumption of red wine and a Mediterranean diet show a low prevalence of CVD. Such an effect has been attributed to phenolic compounds present in red wines. On the other hand, by-products obtained during winemaking are also a significant source of phenolic compounds but have been otherwise overlooked. The cardioprotective effect of red wine and its byproducts is related to their ability to prevent platelet aggregation, modify the lipid profile, and promote vasorelaxation. Phenolic content and profile seem to play an important role in these beneficial effects. Inhibition of platelet aggregation is dose-dependent and more efficient against ADP. The antioxidant capacity of phenolic compounds from red wine and its by-products, is involved in preventing the generation of ROS and the modification of the lipid profile, to prevent LDL oxidation. Phenolic compounds can also, modulate the activity of specific enzymes to promote NO production and vasorelaxation. Specific phenolic compounds like resveratrol are related to promote NO, and quercetin to inhibit platelet aggregation. Nevertheless, concentration that causes those effects is far from that in red wines. Synergic and additive effects of a mix of phenolic compounds could explain the cardioprotective effects of red wine and its byproducts.

Tuning of Proanthocyanidin Extract's Composition through Quaternary Eutectic Solvents Extraction

Currently available proanthocyanidins extraction methods rely on dedicated crops and have low specificity and yield which limits their industrial application. Consequently, the development of novel methodologies and the use of sustainable sources is of great importance. Eutectic solvents have been proposed has good alternatives for conventional solvents due to their low price, easiness of preparation, biocompatibility and ability of being custom made to a specific application. Herein the effective extraction of proanthocyanidins from grape pomace and the possibility of tuning the extract's characteristics such as mean degree of polymerization and galloylation percentage is explored by means of varying the composition of a quaternary eutectic solvent composed by choline chloride, glycerol, ethanol and water. It was found that mean degree of polymerization values can vary from 6.0 to 7.37 and galloylation percentage can vary from 32.5% to 47.1% while maintaining extraction yield above 72.2 mg of proanthocyanidins per g of biomass. Furthermore, the increase of temperature up to 100 °C has showed a significant effect on the extraction yield being possible to increase it by 238% when compared to the conventional extraction method.

Green processing and biotechnological potential of grape pomace: Current trends and opportunities for sustainable biorefinery

Grape pomace is a high quality biodegradable residue of the winery industry. It is comprised of grape seed, skin and stalks, and is blessed with substantial quantities of phenols, flavonoids and anthocyanins with high antioxidant potential. Currently, there is huge emphasis on the isolation of bioactive molecules of grape pomace using green technologies such as microwave, ultrasound, supercritical fluids, high voltage discharge, enzymatic methods and other hybrid techniques. The major applications of these bioactives are contemplatedas nutraceuticals and extension in shelf-life of perishable foodstuffs. Alternatively, the crude form of grape pomace residues can be used for the production of energy, biofertilizers, biochar, biopolymers, composites, feed for ruminants and also, mushroom cultivation through microbial processing. This review discusses value-addition to grape pomace through biotechnological interventions and green processing, providing state-of-art knowledge on current scenario and opportunities for sustainability.

Coupling Ultrafiltration-Based Processes to Concentrate Phenolic Compounds from Aqueous Goji Berry Extracts

In this work, a membrane-based process for the purification and concentration of antioxidant compounds from aqueous Goji (Lycium barbarum L.) berry extracts was investigated. The aqueous extract was previously clarified with hollow fiber ultrafiltration (UF) membranes in order to remove suspended solids and β-carotene and to produce a clarified extract enriched in phenolic compounds. Then, three UF flat sheet polyamide membranes with a molecular weight cut-off (MWCO) in the range 1000–3500 Da were tested to purify and concentrate phenolic compounds from the clarified extract. The effect of MWCO and transmembrane pressure (TMP) on the performance of selected membranes in terms of productivity and selectivity towards total dissolved solids (TDS), total phenolic compounds (TPC), total carbohydrates (TC) and total antioxidant activity (TAA) was evaluated. Experimental results indicated that the 2500 Da membrane exhibited a lower fouling index, higher cleaning efficiency, lower rejection towards carbohydrates (lower than 30%) and higher rejection towards phenolic compounds (higher than 50%) in comparison to the other investigated membranes. The inclusion of a diafiltration process in the treatment of the clarified extract with this membrane in a spiral-wound configuration improved the concentration of sugar compounds in the permeate stream and increased the purification of phenolic compounds in the retentate fraction.

Parametric and phenomenological studies about ultrasound-enhanced biosorption of phenolics from fruit pomace extract by waste yeast

In this work, sonication (20-kHz) was conducted to assist the biosorption of phenolics from blueberry pomace extracts by brewery waste yeast biomass. The adsorption capacity of yeast increased markedly under ultrasonic fields. After sonication at 394.2 W/L and 40 °C for 120 min, the adsorption capacity was increased by 62.7% compared with that under reciprocating shaking. An artificial neural network was used to model and visualize the effects of different parameters on yeast biosorption capacity. Both biosorption time and acoustic energy density had positive influences on yeast biosorption capacity, whereas no clear influence of temperature on biosorption process was observed. Regarding the mechanism of ultrasound-enhanced biosorption process, the amino and carboxyl groups in yeast were considered to be associated with the yeast biosorption property. Meanwhile, ultrasound promoted the decline of the structure order of yeast cells induced by phenolic uptake. The interactions between yeast cells and phenolics were also affected by the structures of phenolics. Moreover, the mass transfer process was simulated by a surface diffusional model considering the ultrasound-induced yeast cell disruption. The modeling results showed that the external mass transfer coefficient in liquid phase and the surface diffusion coefficient under sonication at 394.2 W/L and 40 °C were 128.5% and 74.3% higher than that under reciprocating shaking, respectively.

Valorization of olive pomace by a green integrated approach applying sustainable extraction and membrane-assisted concentration

Olive pomace is a semi-solid paste resulting from the two-phase olive oil production, being the most significant waste generated by this agro-industry. Olive pomace is reported as an environmental hazard due to its high content in phenolic compounds (phytotoxic). Nevertheless, these compounds, when recovered, can have impactful actions in different human physiological conditions, namely, skin protection, dysfunction treatment or diseases prevention. Therefore, their recovery from olive pomace is crucial for environmental and economical sustainability, without forgetting the functional challenge. In a previous work, lipid and aqueous fractions of olive pomace were studied regarding its major bioactive compounds. The present research aims to describe an environmentally friendly integrated approach to extract and concentrate (by a pressure-driven membrane processing) the phytotoxic compounds of olive pomace. Three types of polymeric composite membranes (NF90, NF270 and BW30) were tested. The composition of the resulting streams (permeates and concentrates) were compared and the process efficiency assessed based on: (1) antioxidant activity and total phenolic and flavonoid contents; (2) inorganic elemental composition (by Inductively Coupled Plasma Atomic Emission Spectroscopy); (3) pH, conductivity and total organic carbon; and (4) permeate flux, membranes' apparent target solutes rejection and fouling index. The BW30 membrane presented the lowest fouling index and was the most effective for extracts concentration, with no phenolic compounds in the permeates, preventing completely the loss of such compounds.