Carlos Pascoal Neto’s research while affiliated with University of Aveiro and other places

In this study the viability of the integrated exploitation of E. globulus leaf essential oil and triterpenic acids was evaluated through the development of a novel extraction process that can be implemented sequentially in a biorefinery context. Thus, essential oil (EO) collected by hydrodistillation was used for the first time as a bio-based solvent to recover triterpenic acids (TTAs) from the residue resulting from the EO recovery (from the hydrodistilled leaves). Ursolic, oleanolic, betulonic and betulinic acids were successfully extracted with EO with, for comparison purposes, its major component, 1,8-cineole (CO), showing TTAs extraction yields of 2.8 and 2.7% dw, respectively. Both EO and CO were particularly efficient in extracting ursolic (18.3 and 17.9 g kg⁻¹ dw) and oleanolic (6.0 and 5.7 g kg⁻¹ dw, respectively) acids, the major components of crude extracts. In addition, cytotoxicity evaluation showed that EO and CO crude extracts are non-toxic to macrophage cell lines at concentrations less than or equal to 0.04 and 0.08 mg mL⁻¹, respectively. Crude extracts dissolved in the EO and CO also showed higher anti-inflammatory activity than a synthetic mixture representative of the TTAs detected, demonstrating the synergistic effect between EO or CO and the extracted components. In summary, the EO is a potential bio-based solvent, which could be applied in biorefinery processes, replacing organic solvents such as n-hexane in the recovery of TTAs, without environmental side effects, and even with potential applications of the crude extracts themselves in the nutraceutical and pharmaceutical fields.

Green composites made of bioplastics reinforced with natural fibers have gained considerable attention over recent years. However, the use of natural fibers in composites usually compromise some key properties, such as the impact strength and the processability of the final materials. In the present study, two distinct additives, namely an epoxidized linseed oil (ELO) and a sugar-based surfactant, viz. GlucoPure® Sense (GPS), were tested in composite formulations of poly(lactic acid) (PLA) or poly(hydroxybutyrate) (PHB) reinforced with micronized pulp fibers. Both additives showed a plasticizing effect, which led to a decrease in the Young’s and flexural moduli and strengths. At the same time, the elongation and flexural strain at break were considerably improved on some formulations. The melt flow rate was also remarkably improved with the incorporation of the additives. In the PHB-based composites, an increment of 230% was observed upon incorporation of 7.5 wt.% ELO and, in composites based on PLA, an increase of around 155% was achieved with the introduction of 2.5 wt.% GPS. ELO also increased the impact strength to a maximum of 29 kJ m⁻², in formulations with PLA. For most composites, a faster degradation rate was observed on the formulations with the additives, reaching, in the case of PHB composites with GPS, a noteworthy weight loss over 75% under burial testing in compost medium at room temperature.

Green composites, composed of bio-based matrices and natural fibers, are a sustainable alternative for composites based on conventional thermoplastics and glass fibers. In this work, micronized bleached Eucalyptus kraft pulp (BEKP) fibers were used as reinforcement in biopolymeric matrices, namely poly(lactic acid) (PLA) and poly(hydroxybutyrate) (PHB). The influence of the load and aspect ratio of the mechanically treated microfibers on the morphology, water uptake, melt flowability, and mechanical and thermal properties of the green composites were investigated. Increasing fiber loads raised the tensile and flexural moduli as well as the tensile strength of the composites, while decreasing their elongation at the break and melt flow rate. The reduced aspect ratio of the micronized fibers (in the range from 11.0 to 28.9) improved their embedment in the matrices, particularly for PHB, leading to superior mechanical performance and lower water uptake when compared with the composites with non-micronized pulp fibers. The overall results show that micronization is a simple and sustainable alternative for conventional chemical treatments in the manufacturing of entirely bio-based composites.

The results of a survey of 28 over-The-counter tablet preparations of isoflavones extracted from soy and 2 with black cohosh that are available in Portuguese pharmacies are presented. All were remedies for hot flushes and post-menopause related problems. Their isoflavone content was analysed by HPLC/DAD and LC/MS-MS. The results show that the isoflavonoids in soy extracts sold by the pharmaceutical companies in Portugal are mainly daidzin, glycitin and genistin.

The composition of the lipophilic and phenolic fractions of the wood of Eucalyptus grandis cultivated in Portugal, Brazil and South Africa, was studied. The lipophilic fraction of the studied E. grandis wood is mainly composed of sterols, fatty acids and phenolic compounds. Three triterpenic acids were detected for the first time in the wood extracts from Brazil. E. grandis wood from Portugal presents the largest lipophilic content (1.67 g kg⁻¹ of dry wood), followed by South Africa (1.56 g kg⁻¹ of dry wood) and Brazil (1.05 g kg⁻¹ of dry wood). 51 Phenolic compounds were identified in E. grandis wood MeOH:H2O extracts, from which 11 are reported for the first time as E. grandis constituents and 4 phenolic compounds are firstly reported as Eucalyptus genus components. E. grandis wood from Brazil shows the highest phenolic content (∼2.36 g kg⁻¹ of dry wood), followed by South Africa (∼1.90 g kg⁻¹ of dry wood) and Portugal (∼1.30 g kg⁻¹ of dry wood), demonstrating the influence of the geographic origin over E. grandis wood extractives composition and abundance, as well as on the antioxidant activities of the phenolic fractions. The detailed knowledge of these E. grandis extracts can contribute on the one hand to prevent their impact in the bleaching process, and, on the other demonstrates the potential of this species as a source of bioactive phytochemicals for nutraceutical applications.

The main purpose of this study was to investigate the potential of suberin (a naturally occurring aromatic–aliphatic polyester ubiquitous to the vegetable realm) as a renewable source of chemicals and, in particular, to assess their physical properties. A comparison between cork and birch suberin fragments obtained by conventional depolymerisation processes (hydrolysis or methanolysis) is provided, focusing essentially on their thermal and crystallinity properties. It was found that suberin fragments obtained by the hydrolysis depolymerisation of birch had a high degree of crystallinity, as indicated by their thermal analysis and corroborated by the corresponding XRD diffractions, as opposed to hydrolysis-depolymerised cork suberin counterparts, which were essentially amorphous.

In this work the preparation of viscoelastic bio-based polyurethane foams (PUFs) using polyols obtained via acid liquefaction of coffee grounds wastes has been optimized. In a first stage, the effect of different ratios of isocyanate content to hydroxyl number (0.6, 0.7 and 0.8) and of three distinct percentages of catalyst (3%, 5% and 7%) on the extent of the polymerization reaction was studied by infrared spectroscopy. Next, different percentages of surfactant (14%, 16% and 18%) and blowing agent (12%, 14% and 16%) were used to assess their effect on the density, thermal conductivity and mechanical properties of the foams, including their recovery time. The mechanical properties of the ensuing foams proved to be very interesting due to their viscoelastic behavior. PUFs were also characterized by scanning electron microscopy (SEM) revealing a typical cellular structure and by thermogravimetric analysis (TGA) which proved that these materials are thermally stable up to 190 °C. These results suggest other potential applications for these materials beyond heat insulation in areas where damping properties can be an added value.

A series of bacterial cellulose (BC)/polycaprolactone (PCL) nanocomposite films were successfully prepared by supplementation of the BC culture medium with variable amounts of PCL powder followed by hot-pressing of the BC/PCL mixtures obtained after incubation. PCL powder was fully incorporated into the BC network during its production and did not change the BC network morphology. The obtained films showed a homogenous distribution of PCL throughout the BC network, as well as good thermal stability (up to 200°C) and improved mechanical properties, when compared to pristine PCL. In addition, the intrinsic biodegradability and biocompatibility of the nanocellulose fibers and PCL opens the possibility of using this novel nanocomposite in the biomedical field and food packaging. The BC biosynthetic approach combined with the hot-pressing proved successful for the sustainable development of nanocomposites combining hydrophobic thermoplastic matrices and hydrophilic nanocellulose fibers, without the use of harmful organic solvents commonly used to dissolve this type of polymeric matrices. Copyright © 2015 Elsevier Ltd. All rights reserved.