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- Biosynthesis of antioxidant xanthan gum by Xanthomonas campestris using substrates added with moist olive pomacePublication . Crugeira, Pedro Jorge Louro; Almeida, Heloísa H.S.; Marcet, Ismael; Rendueles, Manuel; Pires, Marcella Golini; Rafael, Helder Martins; Rodrigues, Ana Isabel G.; Santamaria-Echart, Arantzazu; Rafael, Helder; Barreiro, M.F.; Pires, Marcella GoliniMoist olive pomace (MOP) is a high moisture content by-product of the olive oil industry. Managing this recalcitrant residue (transport, storage, and drying) is a priority demanding investment in finding alternative valorisation routes. In this context, the biosynthesis of xanthan gum (XG) incorporating MOP in the substrate (0.0 %, 5.0 %, 10.0 %, 15.0 %, 20.0 %, 25.0 %, 30.0 % and 50.0 %) to induce bacterial stress was attempted. XG biosynthesis yield was quantified, and the product was characterised by structural analysis (FTIR), thermal behaviour (TG), rheology and antioxidant capacity. Relative to the control (sample with no added MOP), a significant increase in XG biosynthesis was found for concentrations up to 30.0 % MOP. In particular, for XG produced with 15 % MOP, a 50.91 % (p < 0.0001) increase was achieved, together with 395.78 % for viscosity. In general, XG produced with MOP presence showed antioxidant activity, a value-added property, especially for applications in the food, pharmaceutical and cosmetic areas. The results indicated that the stress imposed by the MOP induced a microbial response leading to XG production increase, structural and viscosity modifications, and antioxidant properties incorporation. Overall, this work points out a new MOP application contributing to the sustainability of the olive oil productive chain from a biobased circular economy perspective.
- Ethosomes: an approach for bioactive plant extract preservation envisaging cosmetic applicationsPublication . Plasencia, Paula; Santamaria-Echart, Arantzazu; Heleno, S.A.; Colucci, Giovana; Garcia, Pablo; Barros, Lillian; Barreiro, FilomenaThe present work is focused on upgrading the commercial potential of berry crop by-products by encapsulating them into liposomes to preserve their bioactivity. The extracts have been obtained with an ethanol-water mixture using ultrasound-assisted extraction, and the most promising ones were encapsulated in ethosome system. To achieve this goal, ethosomes were prepared using the cold method. Ethosomal suspensions were characterized concerning particle size distribution by laser dispersion, differential scanning calorimetry, infrared Fourier-transform spectroscopy, encapsulation efficiency, and morphological analysis using optical, scanning electron, and transmission electron microscopy. These results indicate that ethosomes are an appropriate method to encapsulate hydroethanolic bioactive plant bioresidue extracts and a good option to preserve them for further use in industrial applications, such as cosmetics. Future work will include optimizing the process and proof of concept by developing a cosmetic application.
- Structural Characterization of Microcapsules from Common Bee Pollen for the Development of Delivery SystemsPublication . Ertosun, Seymanur; Aylanc, Volkan; Peixoto, Andreia F.; Santamaria-Echart, Arantzazu; Russo-Almeida, Paulo; Freire, Cristina; Vilas-Boas, MiguelExine, in the form of a natural microcapsule, refers to the outermost layer of the pollen grains and is composed of a complex mixture of sporopollenin, a highly resistant polymer, which makes it durable and able to withstand harsh conditions. Distinctive features of sporopollenin have attracted interest in the encapsulation of bioactive substances. Herein, we describe the pathway to producing sporopollenin microcapsules (SMCs) by exploiting bees and trapping common bee pollen pellets, offering a simple approach to acquiring substantial amounts of pollen grains for industrial application. Palynological results showed that separating bee pollen pellets by colour could lead to almost pure products ranging from 90 to 96%, depending on the pollen species. Subsequently, a single extraction technique removed around 82– 86% of the proteinaceous content, which could cause potential allergic reactions in humans. Detailed morphological analysis by scanning electron microscope (SEM), confocal laser scanning microscopy (CLSM), atomic force microscopy (AFM), and laser diffraction particle size (LDPS) analysis proved that the purified SMCs retained their 3D micro-structures, besides being hollow and uniform micron-scale size. Fourier-transform infrared spectroscopy (FTIR) findings point out that the sporopollenin biopolymer structure of the pollen grain comprises distinct aliphatic and aromatic domains, and the purification of the SMCs resulted in the loss of nitrogen-related peaks. The hydrophobic/hydrophilic properties of the SMCs, evaluated by contact angle measurements, showed variability between pollen, depending on the specificities of their chemical structure. Simultaneous thermal analysis (STA) confirmed SMCs thermal stability up to 451 °C. Altogether, we showed that green microcapsules with various morphological properties could be produced by simply processing Castanea spp., Cistus spp., Erica spp., Olea spp, and Rubus spp, all common bee pollen pellets available in large quantities in the northeast of Portugal, but also many other countries. These microcarriers promise applicability to various fields, from pharmaceuticals to the food industry.
- Lignin from aldehyde-assisted fractionation can provide light-colored Pickering emulsions through colloidal particles formed using alkaline antisolventPublication . Colucci, Giovana; Ribeiro, Andreia; Figueirêdo, Monique Bernardes; Charmillot, Justine; Santamaria-Echart, Arantzazu; Rodrigues, Alírio; Barreiro, FilomenaColloidal lignin particles (CLPs) are gaining attention as eco-friendly stabilizers for Pickering emulsions. Still, conventional lignin sources, like kraft lignin, are often limited by their dark color and strong odor. This study explores, for the first time, the use of a light-colored lignin derived from an aldehyde-assisted fractionation with glyoxylic acid (GA-lignin) for producing CLPs and derived Pickering emulsions. CLPs were produced by anti- solvent precipitation with water (CLPs-W, pH 6) and alkaline buffer (CLPs-B, pH 8) as the antisolvents. The results revealed that the selected antisolvent significantly influenced the CLPs’ properties. CLPs-W were larger, uniform in size, and hydrophobic, whereas CLPs-B were smaller, agglomerated into clusters, and exhibited greater hydrophilicity. Despite both CLPs’ effectiveness in stabilizing oil-in-water emulsions, the stabilization mechanisms differed markedly; CLPs-W formed a robust membrane barrier at the oil-water interface, while CLPs- B facilitated oil droplet bridging. Overall, this work demonstrates that GA-lignin’s light color nature offers ad- vantages for Pickering emulsions design, surpassing a lignin typical limitation. This advancement highlights the versatility of GA-lignin-derived CLPs and supports the development of sustainable lignin-based products with significant commercial prospects
- Production of chitosan-based biodegradable active films using bio-waste enriched with polyphenol propolis extract envisaging food packaging applicationsPublication . Carli, Cristiane de; Aylanc, Volkan; Mouffok, Kheira; Santamaria-Echart, Arantzazu; Barreiro, M.F.; Tomás, Andreia; Pereira, Celeide; Rodrigues, Paula; Vilas-Boas, Miguel; Falcão, SoraiaDeveloping biodegradable active films has been a promising green approach to overcoming global concerns over the environmental pollution and human health caused by plastic utilization. This study aimed to develop active films based on chitosan (CS), produced from waste crayfish (Procambarus clarkii) shells enriched with bioactive extract (5–20%) of propolis (PS) and to characterize its properties, envisaging food packaging applications. The chromatographic profile of PS extract confirmed its richness, with 41 phenolic compounds. With increasing extract addition to the chitosan, the thickness of the films increased from 61.7 to 71.7 μm, causing a reduction in the light transmission rate, along with a greenish colour shift. The interactions between PS extract and CS was confirmed by infrared spectroscopy, at the same time that the microstructural integrity of the films was checked on the scanning electron microscopy micrographs. The findings also showed that addition of PS enhanced the films thermal stability and mechanical properties e.g., tensile modulus, yield strength, and stress at break. Besides, it improved the antioxidant and antimicrobial activities. Overall, CS-based composite films seem a promising green alternative to petroleum-based synthetic plastics allowing to extend the shelf life of food products due to their eco-friendly nature.
- Lipid composition optimization in spray congealing technique and testing with curcumin-loaded microparticlesPublication . Sorita, Guilherme Dallarmi; Santamaria-Echart, Arantzazu; Gozzo, Ângela Maria; Gonçalves, Odinei Hess; Leimann, Fernanda Vitória; Bona, Evandro; Manrique, Yaidelin A.; Fernandes, Isabel P.; Ferreira, Isabel C.F.R.; Barreiro, M.F.Spray-congealing, a technique based on the fast solidification of sprayed molten lipids, is considered a novel strategy to encapsulate natural products. Among others, it is a safe, low cost, fast and reproducible technique, with rising interest for several applications (e.g. food applications). One of the key parameters for the application of this technique is the lipid solidification temperature, which can be modulated by optimizing the lipid composition. In this work, three lipid components (beeswax, carnauba wax, and medium-chain triglycerides (Miglyol 812)) were selected, and the mixture composition modelled using a simplex-centroid experimental design. Three different lipid compositions were chosen to validate the proposed model, then tested in the preparation of curcumin-loaded microparticles (1.5%, w/w). The produced microparticles were analysed in terms of colour, morphology, particle size, encapsulation efficiency and load, physicochemical, crystalline, and thermal properties. Results evidenced that microparticle's properties, including encapsulation efficiency, vary according to the used lipid mixture, supporting their tailoring role. This fact brings advantages in the design of microencapsulation systems based on spray congealing processes, broadening their applicability. Moreover, lipid composition optimisation was proved to be an important tool to precede the development of spray-congealing applications.
- Bioinks functionalized with natural extracts for 3D printingPublication . Larraza, Izaskun; Santamaria-Echart, Arantzazu; Fernandes, Isabel Rodrigues; Barreiro, M.F.; Arbelaiz, Aitor; Eceiza, ArantaxaIn the search of materials valid for direct ink writing (DIW) 3D printing and with special interest for the biomedical and pharmaceutical applications, the development of bioactive inks for DIW is of great interest. For that purpose, in this work bioactive waterborne polyurethane–urea inks were prepared by addition of natural extracts (logwood, chestnut, and alder buckthorn) and cellulose nanofibers (CNF). The rheological behavior of the inks proved to be strongly dependent on the extract type and content, and the addition route used. Inks prepared by ex-situ incorporation of the extracts showed a strong gel-like behavior, as did inks prepared with chestnut and alder buckthorn extracts, which, in turn, hindered a continuous flow during the printing process, resulting in 3D printed parts with poor shape fidelity. On the other hand, inks prepared insitu and with logwood extract showed more facility to flow and higher homogeneity, which translated in better printability and better shape fidelity, further enhanced for CNF containing inks. 3D printed composites showed reinforced mechanical behavior, as well as in materials with enhanced antibacterial behavior. Overall, the possibility to successfully prepare bioactive inks valid for 3D printing was proven.
- Development of waterborne polyurethane-ureas added with plant extracts: Study of different incorporation routes and their influence on particle size, thermal, mechanical and antibacterial propertiesPublication . Santamaria-Echart, Arantzazu; Fernandes, Isabel P.; Barreiro, M.F.; Retegi, Aloña; Eceiza, Arantaxa; Corcuera, Maria AngelesPolyurethane-ureas are a versatile family of polymers which can be employed in a wide range of applications. Among them, waterborne polyurethane-urea (WBPUU) dispersions are gaining relevance in the field of environmentally-friendly products since their productive process adopts green synthesis routes, avoiding the use of organic solvents. Furthermore, their waterborne character can be exploited to incorporate several water compatible ingredients able to confer functional properties to the final materials. Among them, plant extracts, which are known to have relevant bioactivities, can be viewed as interesting candidates. Therefore, in this work, two extracts known to present antimicrobial activity (Melissa officinalis L. and Salvia officinalis L.) were obtained by the infusion method and incorporated into the WBPUU (1, 3 and 5 wt%) following different incorporation routes comprising its adding during different phases of the productive process (post-, in-situ and pre- methods). Thereafter films were prepared by solvent-casting and characterized from the viewpoint of physicochemical, thermal, mechanical, thermomechanical and antibacterial properties and morphologically. The studied incorporation routes resulted in different intercalation mechanisms that varied from extract positioned among the polyurethane-urea nanoparticles (post-method) to extract partially embedded inside them (in-situ and pre-methods), which produced stiffening or flexibilizing effects in the produced films, enhancing in general the antimicrobial characteristics of films after 4 days of incubation comparing with base WBPUU, especially when the extract is embedded.
- Literature Review on Single and Twin-Screw Extruders Design for Polymerization Using CFD SimulationPublication . Delvar, Elham; Oliveira, Inês; Brito, Margarida S. C. A.; Silva, Cláudia G.; Santamaria-Echart, Arantzazu; Barreiro, M.F.; Santos, Ricardo J.This work presents a comprehensive review of the evolution in modeling reactive extrusion (REx), tracing developments from early analytical models to advanced computational fluid dynamics (CFD) simulations. Additionally, it highlights the key challenges and future directions in this field. Analytical models to describe the velocity profiles were proposed in the 1950s, involving certain geometrical simplifications. However, numerical models of melt polymeric flow in extruders have proven to be crucial for optimizing screw design and predicting process characteristics. The state-of-the-art CFD models for single and twin-screw extruders design address the impact of geometry (type of mixing elements and geometrical simplifications of CFD geometries), pressure and temperature gradients, and quantification of mixing. Despite the extensive work conducted, modeling reactive extrusion using CFD remains challenging due to the intricate interplay of mixing, heat transfer, chemical reactions, and non-Newtonian fluid behavior under high shear and temperature gradients. These challenges are further intensified by the presence of multiphase flows and the complexity of extruder geometries. Future advancements should enhance simulation accuracy, incorporate multiphase flow models, and utilize real-time sensor data for adaptive modeling approaches.
- Spirulina (Arthrospira platensis) protein-rich extract as a natural emulsifier for oil-in-water emulsions: optimization through a sequential experimental design strategyPublication . Silva, Samara Cristina; Almeida, Thayná Domingues; Colucci, Giovana; Santamaria-Echart, Arantzazu; Manrique, Yaidelin A.; Dias, Madalena M.; Barros, Lillian; Fernandes, Ângela; Colla, Eliane; Barreiro, M.F.Spirulina (Arthrospira platensis) proteins have been proven to present emulsifying properties. In this work, a Spirulina protein-rich extract obtained by ultrasound extraction (SpE) was tested to stabilize oil-in-water (O/W) emulsions. For this purpose, a sequential experimental design strategy (Fractional Factorial Design (FFD) 24–1 followed by a Central Composite Rotatable Design (CCRD) 22)) was applied. The effect of four variables, SpE concentration, O/W weight ratio, pH and storage time, on emulsions’ zeta potential and number-mean droplet diameter was considered for the FFD 24–1, indicating SpE concentration and storage time as the relevant variables for the CCRD 22. According to zeta potential and number-mean droplet diameter evaluation, for the studied SpE concentration range (2–5 wt%), quite stable emulsions were obtained along the tested 30-days period. Even so, for 5%, visual inspection revealed extract segregation after 20-days. The optimal solution comprised 4 wt% of SpE, for an O/W weight ratio of 30/70 and a pH of 7.0 (number-mean droplet diameter of 55.66 nm and zeta potential of -43.83 mV). Overall, SpE has proven to be an excellent emulsifier, offering the potential to substitute animal-based proteins and synthetic emulsifiers. In addition, no signs of contamination by microorganisms were observed, suggesting that the SpE may also act as an antimicrobial agent.