Browsing by Author "Oliveira, A."
Now showing 1 - 10 of 12
Results Per Page
Sort Options
- Auditing functional phytochemicals during fruit processingPublication . Oliveira, A.; Pintado, M.; Almeida, Domingos P. F.
- Bioactive compounds in ready-to-eat rocket leaves as affected by oxygen partial pressure and storage time: a kinetic modellingPublication . Pereira, M. J.; Amaro, A. L.; Oliveira, A.; Pintado, M.Storage techniques, such as low temperature and modified atmosphere packaging, are efficient in keeping visual quality of ready-to-eat (RTE) products such as processed leafy vegetables throughout the supply chain, but studies on appearance often neglect the effect of different storage conditions on their nutritional properties. The effects of initial O2 partial pressure (20, 10, 5 and 2.5 kPa O2) in packages and storage time (14 d) on RTE rocket leaves on the bioactive compounds, phenolics, ascorbic acid, and antioxidant activity were determined. Kinetic models were applied to allow the assessment and prediction of the influence of initial partial pressure on nutritional composition. The results show that lowering package initial O2 partial pressure from 20 kPa to 5–10 kPa reduced the respiration rate by 53 and 38%, respectively. However, antioxidant activity and ascorbic acid content showed most effects with an initial O2 of 5 kPa. The kinetic parameters are relevant to help predict phytochemical changes during storage under different package O2 partial pressures. To obtain an overall quality, the application of intermediate atmospheres would be beneficial.
- Comparison of spray drying, freeze drying and convective hot air drying for the production of a probiotic orange powderPublication . Barbosa, J.; Borges, S.; Amorim, M.; Pereira, M. J.; Oliveira, A.; Pintado, M. E.; Teixeira, P.Survival of two LAB in orange powders obtained by spray-(SD), freeze-(FD) and convective hot air drying (CD) was investigated during drying and subsequent storage. Colour and vitamin C content of the powders were also evaluated. There was no decrease in the cell number during SD and FD, but a reduction of ~2 log cycles was obtained in CD. During storage at 4 °C no significant differences (p > 0.05) in the survival of Lactobacillus plantarum 299v were observed for the orange powder obtained by the different techniques. However, during storage at room temperature, its survival was better in orange powders prepared by CD. For Pediococcus acidilactici HA-6111-2, reductions during storage were minimal for most of the conditions investigated. Considering the initial cell number obtained after each drying process, SD and FD allowed survival of an increased number of cells after storage period. The best colour retention was obtained by FD, with no maltodextrin, and the higher total vitamin C retention was achieved in SD and FD powders. By the high production costs and long drying times of FD, it can be concluded that SD could be a good method to produce a new functional non-dairy product, such as a probiotic orange juice powder
- Development and characterization of natural antioxidant-containing chitosan nanoparticlesPublication . Silva, S. Baptista da; Oliveira, A.; Ferreira, D.; Pintado, M.; Sarmento, B.The use of nanotechnology in medical sciences is an innovation that promises a new age of health. Among the different approaches explored so far, chitosan exhibits favourable and unique biological properties, such as biocompatibility, biodegradability, nonantigenic, non-toxicity and mucoadhesiveness. Natural extracts rich in antioxidant molecules have been incorporated in chitosan films, or macro/microparticles, becoming more effective as improving the antioxidant protection [da Silva 2010]. In the present study, chitosan nanoparticles with extracts of sage and savoury and rosmarinic acid were prepared and characterized in order to ensure their best size, efficient encapsulation and to test the retention of the active compounds and evaluate their controlled release performance. This work proposes for the first time in literature, a simultaneous HPLC method for the determination and quantification of phenolic and flavonoid compounds, namely quercetin and rosmarinic acid encapsulated into chitosan nanoparticles. The method can be used to determine the loading capacity and association efficiency as well as its in vitro release.
- Encapsulation of rosmarinic acid into chitosan nanoparticlesPublication . Silva, S. B.; Amorim, M.; Oliveira, A.; Ramos, O.; Pintado, M.; Ferreira, D.; Sarmento, B.Introduction: The use of nanotechnology in medical sciences is a innovation that promises a new age of health. Among the different approaches explored so far, chitosan exhibits favourable and unique biological properties, such as biocompatibility, biodegradability, non-antigenic, non-toxicity and mucoadhesiveness . On the other hand, natural extracts have been incorporated in chitosan films, or macro/microparticles, becoming more effective as antimicrobial or improving the antioxidant protection. The combination of antioxidants and nanoparticles is seen as the key to success in the topical administration of therapeutic antioxidants . Phenolic compound like rosmarinic acid are potent natural antioxidant with a multitude of biological activities like anti-inflammatory, antimutagen, antibacterial and antiviral as well as high potential radical scavenging activity.
- Endodontia de dente permanente imaturo em paciente adulto – caso clínicoPublication . Martins, I.; Oliveira, A.; Gomes, D.; Paulo, M.; Cardoso, M.; Noites, R.
- Fractura do terço médio radicular: controlo de caso clínicoPublication . Oliveira, A.; Vilaça, L.; Silva, O.; Martins, M.
- Functional silk sericin-calcium loaded hydrogels: advancing towards human skin equivalentsPublication . Veiga, A.; Foster, O.; Kaplan, D.; Oliveira, A.; Ribeiro, V.Silk sericin (SS), is a protein traditionally discarded during industrial silk processing, contaminating waste waters, with negative economic and ecological impact to the environment. In recent years there has been a growing interest in the recovery and utilization of SS due to its interesting biological properties. SS-based biomaterial platforms, such as hydrogels, are capable of cell incorporation and maintenance over time, acting as a nutritive natural-based environment for cell proliferation1. This opens new avenues to develop more reliable and reproducible in vitro models for a better understanding of human skin conditions while minimizing animal studies. Our team has previously developed an enzymatic crosslinked SS hydrogel using horseradish peroxidase (HRP), to be applied in situ for wound healing. This hydrogel promoted cell viability and complete skin regeneration after 21 days when applied in a diabetic wound model2. These promising results have motivated the use of this formulation as a platform for cell encapsulation, in an approach to develop a natural-based human skin equivalent (HSE). The incorporation of nanoparticles (NPs) within hydrogels is reported to further enhance the biological behavior of encapsulated cells3. In this context, calcium plays an important role in maintaining skin homeostasis and modulating cell proliferation and differentiation4. In a recent study, we explored hydroxyapatite (HAp) and HAp/SS NPs as materials to enhance the adhesion and proliferation of human dermal fibroblasts (HDFs), validating the use of this particulate system to support cell growth. The NPs were produced using a continuous manufacturing process in a new modular oscillatory flow plate reactor (MOFPR). The reaction system enables the production of tailored and homogeneous NPs. In the present work, HDFs and HaCaT were incorporated within a SS/HRP hydrogel to construct a HSE. The system was further optimized with the addition of NPs to the system: a screening was conducted using different HAp and HAp/SS NP concentrations. Our results show that the HAp/SS particles at a low concentration, were associated with the best biological performance (0.05 mg/mL). The co-culture SS system was assembled with a stable silk-fibroin (SF) porous scaffold embedded with human adipose tissue with the addition of neural cells (hiNSCs), as reported by Vidal et al.5 to develop a full-thickness HSE (Figure 1). The sustained viability of the cells in the model over 21 days suggests the formation of a stable and reproducible model representing well some of the characteristics and functionality of native skin (Figure 2).
- Gangrena de Fournier: experiência de 12 anosPublication . Miranda, L.; Carvalho, Â.; Vaz, M.; Oliveira, A.; Alves, P.
- Perineal necrotizing fasciitis, a challengePublication . Miranda, L.; Carvalho, A.; Marques, C.; Martins, D.; Oliveira, A.Necrotizing perineal fasciitis is a complex situation, with high morbidity and mortality, mainly because most patients seek medical services late, at an advanced stage of theinfectiousprocess1. There are several studies that recommend the use of Negative Pressure Therapy in the treatment of lesions of this nature, with benefit in the patient's wellbeing and in reducing healing time.