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- Impact of pulsed electric fields and high pressure processing pre-treatments on physicochemical, sensory, and microbiological quality of freeze-dried beetroot snacksPublication . Orvalho, T.; Dias, S.; Pino-Hernández, E.; Gonçalves, D.; Monteiro, V.; Alves, M.; Gomes, A.; Machado, D.; Soares, I.; Pinto, C.; Saraiva, J.Freeze-drying is widely recognized as one of the most effective dehydration methods for preserving the organoleptic properties and nutritional value of fruits and vegetables when compared to conventional drying techniques. However, the high energy consumption resulting from long processing times constrains its application at an industrial scale1. In this context, the development of assisted freeze-drying processes using emerging technologies has gained increasing attention. Nonthermal approaches such as Pulsed Electric Fields (PEF) and High-Pressure Processing (HPP) have demonstrated potential as a pretreatment to enhance drying efficiency, promote tissue permeabilization and induce structural modifications that facilitate mass transfer, while simultaneously preserving or even improving the quality and sensory attributes of the final products2,3. These structural modifications are essential for enhancing flavour incorporation, enabling the efficient infusion of solutes into the vegetable matrix. Consequently, these strategies are especially relevant in light of the growing demand for high-quality vegetable snacks within more sustainable food systems, contributing to the development of value- added dehydrated products1,2. The present study aimed to evaluate the effect of nonthermal emerging processing technologies, namely PEF and HPP, as pre-treatments in the development of a freeze-dried beetroot snack produced from low-caliber beetroot. The impact of these approaches on the physicochemical, sensory, and microbiological properties of the final product was assessed, while simultaneously targeting the valorisation of non-marketable vegetables for the development of new value-added food products, within a framework of sustainability and the promotion of circular economy principles. Low-caliber beetroot (Beta vulgaris) samples were sanitized and subjected to different pre-treatments using PEF (1.5 kV/cm; 5.4 kJ/kg) and HPP (450 MPa for 5 min) to enhance flavour incorporation by inducing cellular structural changes that modify membrane permeability and facilitate mass transfer. For the PEF pretreatment, beetroot samples were initially processed, then cut into cubes (10x10x10 mm) and mixed with salicornia and spices. For the HPP pretreatment, after sanitization, samples were cut into cubes (10x10x10 mm), mixed with salicornia and spices, vacuum-packaged, and subsequently subjected to HPP. Control samples were also prepared, consisting of cubed beetroot seasoned with salicornia and spices, without any pretreatment. Both pretreated and control samples were subsequently freeze-dried using an industrial freeze-dryer, with a total cycle time of 50 h and an initial temperature of −40 °C. Primary drying was carried out for 43 h, with temperatures ranging from −40 °C to 35 °C, under a vacuum between 1 mbar and 0.15 mbar. Secondary drying lasted 7 h, at temperatures between 37 °C and 40 °C, operating at an approximate vacuum of 0.025 mbar. Samples were then vacuum packed in polyamide/polyethylene bags to avoid rehydration. Sensory attributes (colour, aroma, flavour, texture, and overall acceptance) and purchase intention were evaluated. Analyses were performed in triplicate to evaluate physicochemical properties (texture and colour) and microbiological compliance within the scope of hygienic-sanitary control. At the sensory level, both PEF and HPP pretreatments showed a positive impact compared to the control samples. However, between both technologies studied, HPP proved to be slightly more promising, particularly in colour and flavour. Samples treated with HPP were preferred by consumers and showed the highest purchase intention. Regarding texture, significant differences were observed in the hardness parameter between control and those treated with PEF and HPP, indicating that the pretreatments influenced the mechanical resistance of the product. This result suggests increased crispness, in agreement with the sensory analysis findings. When it comes to instrumental colour, significant differences were observed in the lightness (L*), greenness/redness (a*), and blueness/yellowness (b*) parameters in HPP-treated samples compared to the others (PEF and control), corroborating the sensory analysis results, particularly in terms of consumer preference for colour. From a microbiological perspective, HPP treatment showed a significant effect in reducing microbial load when compared to the control and PEF pre-treated samples. Indeed, a 2-log reduction was observed in the total number of viable microorganisms at 30 °C, while Enterobacteriaceae counts were below the detection limit in HPP-treated samples, while no significant reduction in microbial load was observed for the PEF pre-treatment. These results highlight the potential of HPP, as a nonthermal technology, to enhance the microbiological safety of food products. The results highlight the potential of PEF and HPP technologies, when applied as pretreatments, in the development of dehydrated products, with particular emphasis on the improvement of sensory properties, where HPP stood out compared to PEF. In addition, HPP demonstrated high efficacy in reducing microbial load, reinforcing its relevance as a nonthermal technology for the development of freeze-dried products. Overall, these findings underline the contribution of these approaches to the valorisation of low-commercial-value raw materials through the production of value-added dehydrated foods.
- Innovative food product development from underutilized crops and crop wild relatives for sustainable and healthy dietsPublication . Geraldo, Rafaela; Duarte, Rafael; Kaur, Harsimran; Machado, Joana; Pinto, Elisabete; Vasconcelos, Marta
- Bio-mechano-compatible electrospun scaffold as external support to prevent autograft dilatation in the ross procedurePublication . Reis, M. S.; Rosadas, M.; Ho, C. I.; Pazmino, C. A.; Costa, J. B.; Oliveira, A. L.; Ribeiro, V. P.Introduction: The Ross procedure is a surgical intervention that replaces a diseased aortic valve with the patient’s own pulmonary valve. Despite its advantages, associated with the adaptative growth and biocompatibility, the dilatation of the autograft due to high systemic pressure remains a concern. This study aims at producing a scaffold to prevent autograft dilatation combining mechanical resilience and controlled biodegradability with bioactive cues to improve biocompatibility, avoiding the low-porosity and stiffness of the current solutions. Materials and Methods: Tubular scaffolds of 2.5 mm inner diameter were electrospun using PCL (Mn ≈ 81.6 kg/mol), bovine elastin, and porcine aortic decellularized extracellular matrix (dECM) (19:0.5:0.5 w/v% ratio) (Fig. 1A). The results were compared to PCL and PCL:Elastin without dECM. Characterization included scanning electron microscopy (SEM) morphology, tensile testing, swelling, and accelerated hydrolytic degradation (0.2M NaOH). Cytocompatibility was assessed via conditioned medium and direct human dermal fibroblast (hDF) seeding on the tube lumen. Metabolic activity and DNA were quantified, while cellular morphology and attachment were visualized using SEM and 4',6-diamidino-2-phenylindole (DAPI) staining. Results: The incorporation of elastin and dECM into the scaffold provided consistent fibers (1 − 2 𝜇𝑚) leading to a reduction in the stiffness, as compared to pure PCL. Under physiological pressures, The tri-blend scaffold withstood failure, exhibiting supraphysiological burst pressures. Physicochemical analysis showed minimal swelling after 24h (3 ± 3%) and controlled weight loss, demonstrating superior structural stability compared to the faster degradation of PCL and PCL:elastin. In vitro, live/dead staining showed no harmful byproducts released by the tri-blend scaffolds, with hDFs maintaining a healthy phenotype, confirmed by cytocompatibility levels over 95% after 72h. Direct contact studies demonstrated successful scaffold colonization, with the tri-blend supporting robust hDF adhesion, viability, and proliferation over 14 days. Conclusion: PCL:Elastin:dECM electrospun scaffolds balanced mechanical reinforcement with biological functionality, avoiding the excessive rigidity of pure synthetic polymers. The blend promoted robust hDF adhesion and proliferation on the tube lumen. Since fibroblasts dominate the aortic adventitial layer, the interface for external supports, this bioactive scaffold offers a promising strategy for reinforcing pulmonary autografts in the Ross procedure.
- Beans and greens: development and expert evaluation of an innovative fava bean recipe book to promote sustainable dietsPublication . Osorio, Jazmín; Gros, Capucine; Pinto, Elisabete; Vasconcelos, Marta W.Promoting sustainable dietary patterns requires strategies beyond product development, including educational and dissemination tools. Fava beans are nutritionally valuable but underused, partly due to perceptions of limited culinary versatility. This study aimed to develop a recipe book with innovative fava bean-based preparations to enhance the ingredient’s appeal, versatility, and applicability.
- A novel biological dermal matrix for skin reconstructionPublication . Rosadas, Marta; Pereira, Ana Beatriz; Reis, Mariana; Gomes, Patrícia; Sousa, Alda; Oliveira, Ana L.; Ribeiro, Viviana P.Skin and soft tissue defects resulting from trauma, burns, or surgical resection remain a major clinical challenge. Biological dermal substrates have become an important component of modern reconstructive surgery by providing temporary structural support and promoting tissue regeneration, neovascularization and wound healing. Despite their clinical success, there remains a need for accessible biological alternatives with comparable clinical performance. In this study, we developed a novel biological dermal substrate derived from rabbit skin, a sustainable agri-food by-product, with preserved tissue integrity and extracellular matrix (ECM) organization. The processed purified dermal substrate retained the collagen-elastin network and structural features that closely resemble human dermis, providing a biologically instructive microenvironment for skin regeneration. Its performance was benchmarked against two commercially available skin substitutes, Matriderm® (MedSkin) and NovoSorb® (PolyNovo). Matrix preservation was evaluated, as well as residual DNA, endotoxin levels, degradation profile, wound fluid absorption, water vapor transmission rate (WVTR), and their ability to support the formation of a dermo-epidermal skin substrate using human dermal fibroblasts and keratinocytes. The developed dermal matrix preserved its native ultrastructure and high collagen content, with endotoxin levels below the FDA acceptance limit. The biological matrices exhibited a comparable performance with a balanced fluid management, high wound exudate absorption and controlled water vapor exchange, whereas the synthetic NovoSorb® presented lower permeability. A similar trend was also observed on cell performance as the dermo-epidermal models established on the biological substrates showed significantly enhanced metabolic activity over the 30 days of culture. In conclusion, the developed dermal substrate combines the preservation of the native dermal ultrastructure with an excellent in vitro performance, matching the clinically established reference Matriderm® while outperforming the synthetic NovoSorb®. mportantly, preserving the native dermal architecture helps maintain the matrix's mechanical integrity and long-term structural stability. It also retains a high collagen content and biologically active elastin, creating an instructive microenvironment that supports tissue integration and skin regeneration.
- A novel biological dermal matrix for skin reconstructionPublication . Rosadas, Marta; Pereira, Ana Beatriz; Reis, Mariana; Gomes, Patrícia; Sousa, Alda; Oliveira, Ana L.; Ribeiro, Viviana P.Skin and soft tissue defects from trauma, burns, or surgical resection remain a major clinical challenge. Biological dermal substrates support reconstructive surgery by providing a scaffold for neovascularization and wound healing, but accessible alternatives with comparable performance are still needed. We developed a novel dermal substrate from rabbit skin, a sustainable agri-food by-product, preserving a collagen-elastin network and ECM organization similar to human dermis. Its performance was benchmarked against two commercial substitutes, Matriderm® (MedSkin) and NovoSorb® (PolyNovo).
- BioUpCycle: circular innovation for the bioeconomy through the upcycling of agro-residuesPublication . Vilas-Boas, Ana Martins; Sousa, Ana Sofia; Magalhães, Daniela; Coelho, Marta; Cunha, Marta Fernandez; Pintado, Manuela
- Valorization of xylo-oligosaccharides from brewer’s spent grain: antioxidant, antimicrobial and glycemic modulation potentialPublication . Anthero, Ana Gabriela da Silva; Castilho, Pamela Alves; Silva, Sara; Costa, Eduardo; Rodrigues, Antonio Augusto; de Sá-Nakanishi, Anacharis Babeto; Pintado, Manuela; Goldbeck, RosanaBrewer’s spent grain (BSG), the main by-product of the brewing industry, is an abundant lignocellulosic material with potential for the production of value-added functional ingredients. The recovery of xylo-oligosaccharides (XOS) from BSG represents a sustainable strategy for by-product valorization, as these compounds are associated with prebiotic and health-promoting properties. In this context, the study aimed to produce, purify, characterize, and evaluate the functional properties of XOS obtained from BSG, including antioxidant, antimicrobial, and glycemic modulation potential. XOS were produced through alkaline extraction followed by enzymatic hydrolysis of the hemicellulosic fraction. After production, the XOS fraction was purified and concentrated, and the oligosaccharide profile was characterized by ion-exchange chromatography. Phenolic compounds content and antioxidant activity were evaluated before and after simulated gastrointestinal digestion using Folin–Ciocalteu and ABTS assays, respectively. Antimicrobial activity was determined by the minimum inhibitory concentration (MIC) method against foodborne pathogens, including Gram-positive (Staphylococcus aureus, Bacillus cereus, and Listeria monocytogenes) and Gram-negative (Salmonella enterica and Escherichia coli) strains. The potential for glycemic modulation was evaluated in vivo using an oral starch tolerance test with purified XOS at 3 g/L. As a result, the XOS profile consisted mainly of low-degree-of-polymerization oligomers, with a predominance of xylobiose (X2), followed by X3–X6 fractions, indicating efficient enzymatic hydrolysis of xylan and the formation of soluble short-chain oligosaccharides with potential functional applications. Digested XOS exhibited enhanced antioxidant responses compared with non-digested samples, suggesting increased availability of bioactive compounds after gastrointestinal processing. Purified XOS showed antimicrobial activity against all tested microorganisms, with a MIC of 2 g/L. In the in vivo assay, XOS supplementation reduced postprandial glucose peaks compared with the starch control group. Overall, purified BSG-derived XOS demonstrated multifunctional properties, combining antioxidant capacity, antimicrobial activity, and potential for glycemic modulation. The predominance of short-chain XOS and their biological effects highlights the potential of brewer’s spent grain as a sustainable source of functional ingredients for innovative food applications.
- Characterization of microbial colonization of three mural painting’s churches (N. Portugal): preliminary study of microbial growth, biocides activity evaluation and future intervention proposalPublication . Marco, A.; Vieira, E.; Pintado, M.; Moreira, P. R.
- Extracellular ligninolytic enzyme activities in yeast isolates from wastewater treatment plantsPublication . Silva, A. R.; Moreira, P. R.; Pintado, M.Many microorganisms have been found to be capable of degrading dyes; these include bacteria, filamentous fungi, yeasts, actinomycetes and algae. When compared to bacteria and filamentous fungi, yeasts present advantages; they grow rapidly and have the ability to resist unfavourable conditions. However, degradation of synthetic dyes by yeasts has not been extensively reported, namely its relation with extracellular ligninolytic enzymes. Forty six yeast strains isolated from two wastewater treatment stations along with other 81 cheese isolates were compared on their ability to decolorize five textile dyes in solid media. After a screening methodology that included liquid culture decoulorisation ability evaluation, yeasts isolates, LIII S 36 and L III ST 7 presented the best performance in the decolourisation for the five dyes tested: Remazol Black B-A, Remazol Yellow RR, Levafix Blue CA, Remazol Brilliant Blue R and Levafix® Red CA). As an attempt to understand the mechanism of decolourisation of the strains, L III ST 7 and L III S 36, spectral scanning and enzymatic activity assays were performed. It was possible observe that, depending on the dye, decolourisation might be achieved through mechanisms of either adsorption or true degradation. The presence of extracellular ligninolytic manganese peroxidase activity was detected in strains L III ST 7 and L III S 36 with an average of 2.30 and 2.06 IU. l-1, respectively; this enzymatic activity rarely demonstrated in yeasts might be related to the mechanism of true degradation as already proven for several filamentous fungi.