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- Kinetics of quality changes in cantaloupe melon as affected by MAP and temperature conditionsPublication . Amaro, A. L.; Pereira, M. J.; Pintado, M.Introduction: Fresh-cut fruit quality and shelf-life are limited by minimal processing operations and storage conditions. Modified atmosphere packaging and refrigerated storage are frequently used to reduce the respiration rate without negatively affecting the physiology of the fruit and to enhance shelf life. The effects of the production process upon the nutritional and phytochemical composition of cantaloupe melon was determined in order to validate the results obtained in real conditions and identify the critical points involved in the deterioration of the functional quality. The aim of this work is determine the kinetics of quality changes of fresh-cut cantaloupe melon as a function of oxygen partial pressure and storage temperature. Conclusions: The integration of all these results contributes to the understanding of the effects of storage conditions on overall quality of fresh-cut cantaloupe melon and provide useful information for developing processes aimed at the prediction and modulation of nutritional quality and shelf-life. The best conditions found for the preservation of overall quality of fresh-cut cantaloupe melon are initial package atmosphere of 5 % oxygen and storage temperature of 5 ºC.
- In vivo volatile organic compounds analysis in Pinus pinaster after infection with Bursaphelenxus xylophilusPublication . Silva, M. Nunes da; Ferreira, António C. Silva; Mota, Manuel; Vasconcelos, Marta W.
- Evaluation of quality changes during frozen storage of watercress (Nasturtium officinale R. Br.)Publication . Teixeira, I.; Gonçalves, E. M.; Abreu, M.; Brandão, T. R. S.; Silva, C. L.M.
- Combinatory approach for developing silk fibroin-based scaffolds with hierarchical porosity and enhanced performance for cartilage tissue engineering applicationsPublication . Ribeiro, Viviana; Yan, Le-Ping; Oliveira, Ana L.; Oliveira, Joaquim M.; Reis, Rui L.Introduction: The combination of several processing technologies can open the possibility for producing scaffolds with superior performance for tissue engineering (TE) applications. Hydrogels are structurally similar to the natural extracellular matrix microenvironment presenting high elasticity and resistance to compression forces. They have been extensively used in biomedical devices fabrication and for TE applications, including for cartilage defects repair[1]. Recently, it was found that proteins like silk fibroin (SF), presenting tyrosine groups can be used to prepare fast formed hydrogels with controlled gelation properties, via an enzyme-mediated cross-linking reaction using horseradish peroxidase (HRP) and hydrogen peroxide (H2O2)[2],[3]. Moreover, the high versatility, processability and tailored mechanical properties of SF, make this natural polymer attractive for the development of innovative scaffolding strategies for cartilage TE applications[4],[5]. Materials and Methods: The present work proposes a novel route for developing SF-based scaffolds derived from high-concentrated SF (16wt%) enzymatically cross-linked by a HRP/H2O2 complex. The combination of salt-leaching and freeze-drying methodologies was used to prepare macro/microporous SF scaffolds with an interconnected structure and specific features regarding biodegradation and mechanical properties (Fig. 1a). The scaffolds morphology and porosity were analyzed by SEM and micro-CT. The mechanical properties (Instron) and protein conformation (FTIR, XRD) were also assessed. In order to evaluate the scaffolds structural integrity, swelling ratio and degradation profile studies were performed for a period of 30 day. This work also aims to evaluate the in vitro chondrogenic differentiation response by culturing human adipose derived stem cells (hASCs) over 21 days in basal and chondrogenic conditions. Cell behaviour in the presence of the macro/microporous structures will be evaluated through different quantitative (Live/Dead, DNA, GAGs, RT PCR) and qualitative (SEM, histology, immunocytochemistry) assays. Results and Discussion: The macro/microporous SF scaffolds showed high porosity and interconnectivity with the trabecular structures evenly distributed (Fig. 1b,c). A dramatic decrease of compressive modulus was observed for samples in hydrated state. Chemical analysis revealed that SF scaffolds displayed the characteristic peaks for β-sheet conformation. Swelling ratio data demonstrated a large swelling capacity, maintaining their structural integrity for 30 days. As expected, when immersed in protease XIV the degradation rate of SF scaffolds increased. Based on the promising morphology and physicochemical properties of the developed SF scaffolds, in vitro chondrogenic differentiation studies with hASCs are envisioned in order to validate their performance for cartilage regeneration applications.
- Textile-based silk scaffolds for bone tissue engineering applicationsPublication . Ribeiro, Viviana; Morais, Alain; Correlo, Vitor M.; Marques, Alexandra P.; Ribeiro, Ana; Silva, Carla; Durães, Nuno; Bonifácio, Graça; Sousa, Rui; Oliveira, Joaquim M.; Reis, Rui L.; Oliveira, Ana L.INTRODUCTION: Scaffolds developed for bone tissue engineering (TE) need to facilitate and promote cell adhesion, proliferation and neo-tissue formation. They must possess specific properties to allow the new tissue to integrate with the material, without inducing any inflammatory response. The intra-architectural scaffold geometry, porosity, scaffold material and surface area play important roles in this process . Several polymeric systems (natural and/or synthetic) and processing methods and have been proposed to develop the “ideal” scaffold for bone TE. However, so far the proposed strategies do not fulfil all the requirements for effective bone regeneration. Textile-based technologies constitute an innovative alternative for the production of 3D structures for bone TE applications, offering a superior control over scaffolds’ design, manufacturing and reproducibility. Silk fibroin (SF) derived from silkworm Bombyx mori has already proved to be a good biomaterial for bone TE applications. SF-based structures offer impressive mechanical properties, biodegradability, biocompatibility and stability, which meets the basic requirements for the design of structures for bone regeneration applications. EXPERIMENTAL METHODS: In this work we describe for the first time the processing of natural silk yarns into 3D scaffolds, combining standard knitting fabrics spaced by a monofilament of polyethylene terephthalate (PET). A comparative study is established using a stable polymeric system made entirely of PET. The obtained knitted spacer constructs were described in terms of morphology and mechanical properties. An in vitro biological assay was performed to evaluate the potential of the developed structures to support human Adipose- derived Stem Cells (hASCs) adhesion, proliferation and osteogenic differentiation. Cells were cultured over 28 days in standard basal and osteogenic conditions and evaluated through different quantitative (DNA, ALP, Calcium, RT-PCR) and qualitative (SEM, Alizarin Red, immunocytochemistry) assays. The in vivo biocompatibility of the textile materials was assessed by subcutaneous implantation in mice model. After 2 and 4weeks of implantation the explants were collected and the obtained slides were stained with hematoxylin and eosin (H&E). RESULTS AND DISCUSSION: The cross-sections of the developed spacer textile constructs reveal a significant increase of the scaffolds three-dimensionality induced by the PET monofilament (Figure 1a). The hASCs seeded onto the spacer textile scaffolds were able to attach, spread, proliferate and differentiate, both in osteogenic and basal conditions (Figure 1b). Great evidences of ECM mineralization were observed, also penetrating and colonizing the PET monofilament (Figure 1a). The preliminary in vivo results revealed that the implanted scaffolds allowed tissue ingrowth, without inducing any acute inflammatory reaction (Figure 1c). CONCLUSION: In this study, innovative 3D biotextile scaffolds able to support cell adhesion, proliferation and osteogenesis were successfully developed. Furthermore, these scaffolds allowed the new tissue formation and integration within the material, when subcutaneously implanted in mice. Thus, the proposed textile-based scaffolds can be promising candidates for bone TE applications such as the craniomaxilofacial complex.
- Chitosan as natural food preservative for sauces: a proof of conceptPublication . Costa, E. M.; Silva, S.; Silva, N.; Couto, J. A.; Gomes, A. M.; Pintado, M. M.Introduction: Nowadays, consumers demand more natural, nutritionally balanced, less caloric, and minimally processed foods leading to the emergence of sauces with low fat content and without chemical preservatives. This market pressure has led to the modification of a well-established and microbiologically stable matrix, triggering the search for new antimicrobial compounds of natural origin, compounds whose inhibitory efficacy must be studied [1]. Chitosan has attracted attention as a potential food preservative of natural origin due to its antimicrobial activity against a wide range of foodborne pathogens and contaminants. However, the antimicrobial capacity of chitosan, despite being extensively reported, is primarily based upon in vitro trials, where the compound, unimpeded, acts upon microorganisms. Currently, inclusion of chitosan in a food matrices is in its early steps with works reporting the application of chitosan in bread, egg, fruits, vegetables, juices, meat, milk and others, with various degrees of success [2]. In food sauces examples of chitosan application are few and scarce, as most works report on the usage of chitosan as an emulsifier or a emulsifier stabilizer and only Roller and Covill [3] described the successful usage of a chemically altered chitosan as a food preservative. As such, in this work we sought to ascertain the potential of chitosan as a viable, natural, alternative to traditional food preservatives used in food sauces, namely ketchup, mayonnaise and mustard, through assessment of the effect of chitosan containing sauces on the inhibition of lactic acid bacteria isolated therefrom and sensorial analysis of the developed prototypes.
- Enantiomeric fraction evaluation of pharmaceuticals in an aerobic granular sludge sequencing batch reactorPublication . Amorim, Catarina L.; Moreira, Irina S.; Ribeiro, Ana Rita; Santos, Lúcia H. M. L. M.; Delerue-Matos, Cristina; Tiritan, Maria Elizabeth; Castro, Paula M. L.
- Utilization of a novel biofertilizer for iron deficiency chlorosis prevention in common bean and soybean plantsPublication . Silva, Emmanuella V. N.; Roriz, Mariana; Sarmento, Bruno; Stamford, Newton P.; Pintado, Manuela E.; Oliveira, Wagner S.; Vasconcelos, Marta W.
- The impact of iron deficiency on the tetrapyrrole and antioxidative systems in soybean plants (Glycine max L.)Publication . Santos, Carla S.; Roriz, Mariana; Carvalho, Susana M. P.; Rangel, António O. S. S.; Vasconcelos, Marta W.Introduction: Iron deficiency chlorosis (IDC) is a serious physiological disorder (OU agronomical problem), prevalent on calcareous soil, contributing to decreased crop growth and yield. Its main visible symptom is leaf yellowing due to decreased chlorophyll concentrations. Understanding the mechanisms underlying iron uptake, trafficking and homeostasis is essential in order to prevent IDC and enhance plant productivity. The tetrapyrrole cycle is involved in the biosynthesis of chlorophyll and heme, and it starts with the formation of 5- aminolevulinic acid (ALA). As iron is necessary for hemoproteins (heme containing proteins, such as Fe reductases, catalases and peroxidases) and chlorophyll synthesis, its absence leads to decreased photosynthetic capacity and damaged antioxidative defence. In this study photosynthetic pigments, Fe accumulation, root reductase activity, ALA and hemin (the oxidized version of heme) concentration and antioxidant enzymes activity were evaluated to better understand the impact of Fe deficiency on the tetrapyrrole cyle. Material and Methods: An efficient (EF - PI437929 / VIR 316) G. max accession for Fe deficiency (Vasconcelos and Grusak, 2014) was selected from the USDA (United States Department of Agriculture) germplasm collection via GRIN (Germplasm Resources Information Network) (http:
- Could pre-treatments with sub-lethal stresses enhance the ability of lactic acid bacteria to survive after spray-drying in orange juice?Publication . Barbosa, Joana; Borges, Sandra; Teixeira, PaulaIntroduction: The demand for new functional non-dairy based products makes the production of an orange juice powder with pre- and probiotic characteristics, an encouraging challenge. Spray drying is a simple and inexpensive way to produce a dried orange juice incorporating probiotics (Barbosa et al., 2015). However, drying processes, and subsequent storage, greatly affect the viability of the dried probiotic cultures due to the exposure to various stresses such as high temperatures and rapid dehydration (Tripathi and Giri, 2014). Solutions are required since probiotic microorganisms should be present in foods in numbers of about 106-107 cfu/g or cfu/mL until the time of consumption and must remain viable during passage through the gastro-intestinal tract (GIT) of the consumer (FAO/WHO, 2002; Sanz, 2007). The aim of this work was to investigate if the pre-exposure to sub-lethal conditions of temperature, acidic pH and hydrogen peroxide could influence the viability of Pediococcus acidilactici HA-6111-2 and Lactobacillus plantarum 299v during spray drying in orange juice and subsequent storage under different conditions. Also the survival of both lactic acid bacteria (LAB) through simulated GIT was determined at the end of storage. Conclusions: For all the sub-lethal conditions investigated, there were no significant (p>0.05) reductions in cell viability during the drying process (data not shown). Prior exposure of L. plantarum 299v to any of the sub-lethal stresses applied, increased their survival during 180 days of storage at room temperature (graph A); this effect was not observed (p>0.05) for cells stored at 4 ºC (graph B). At this temperature, cell inactivation was very low, as previously demonstrated by other researchers (Teixeira et al., 1995). For storage at room temperature, initially, reductions in viable cell numbers were greater for cells exposed to lactic acid (about -2 log units), but from 90 days until the end of the storage, the reduction in viable cells not exposed to sub-lethal stress was greater (more than 3 log units). Temperature conferred the highest protection, followed by treatment with HCl, H2O2, and finally by lactic acid. The exposure to any of the sub-lethal treatments prior to spray drying, did not result in the enhancement of survival of P. acidilactici HA-6111-2 during storage (graphs C and D). On the contrary, survival during storage was negatively influenced by previous exposure to all the sub-lethal conditions investigated. After simulation of GIT conditions for the spray dried cells at the end of storage at 4 ºC, L. plantarum 299v and P. acidilactici HA-6111-2 were present in numbers of ca. 107 cfu/mL, despite the exposure to sub-lethal stresses did not have improved their viability. As a conclusion of this study, the influence on the viability of two LAB after the exposure to different sub-lethal stress conditions prior spray drying and subsequent storage in orange juice was species/strain dependent. Considering that to have a beneficial effect on health, a probiotic must be present in minimum quantities of 107 cfu/mL in the product and remain viable during passage through the GIT, both L. plantarum 299v and P. adicilactici HA-6111-2 seem to be good candidates for use in the production of a new functional orange juice powder.