50 research outputs found

    Influence of a heat-shock pre-treatment on wound-induced phenolic biosynthesis as an alternative strategy towards fresh-cut carrot processing

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    In fresh-cut vegetables, plant tissues are often challenged by (a)biotic stresses that act in combination, and the response to combinatorial stresses differs from that triggered by each individually. Phenolic induction by wounding is a known response contributing to increase products phenolic content. Heat application is a promising treatment in minimal processing, and its interference on the wound-induced response is produce-dependent. In carrot, two-combined stress effects were evaluated: peel removal vs. shredding, and heat application (100 C/45 s) vs. shredding, on changes in total phenolic content (TPC) during 10 days (5 C). By applying the first stress combination, a decrease in TPC was verified on day 0 ( 50%), ascribed to the high phenolic content of peels. Recovery of initial fresh carrot levels was achieved after 7 days owing to phenolic biosynthesis induced by shredding. For the second combination, changes in TPC, phenylalanine-ammonia-lyase (PAL), and peroxidase (POD) activity of untreated (Ctr) and heat-treated (HS) peeled shredded carrot samples were evaluated during 10 days. The heat-shock did not suppress phenolic biosynthesis promoted by PAL, although there was a two-day delay in TPC increments. Notwithstanding, phenolic accumulation after 10 days exceeded raw material TPC content. Also, the decrease in POD activity (30%) could influence quality degradation during storageinfo:eu-repo/semantics/publishedVersio

    Estudo do processo de absorção de plastificantes em polímeros de PVC

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    Mestrado em Engenharia QuímicaO presente trabalho teve como objetivo principal o estudo de absorção de plastificantes em polímeros de PVC produzidos através do processo de polimerização em suspensão (S-PVC). A CIRES, sendo a única empresa produtora de PVC em Portugal, dispõe de uma determinada gama de produtos que obriga a uma constante atualização do grau de conhecimento sobre o comportamento e desempenho desses mesmos produtos nas diversas aplicações finais no mercado. Este estudo tem como finalidade a comparação dos polímeros produzidos na CIRES com outros do mesmo tipo, designadamente com o mesmo valor K, mas com origens diferentes. Assim, foram utilizados quatro polímeros, sendo dois produzidos na CIRES (S1200 – K70 e S2000 – K80) e dois de origem diferente (S70-16 – K70 e S4080 – K80) existentes no mercado. Numa primeira fase do estudo caraterizaram-se os polímeros virgens, isto é na sua forma final após a reação de polimerização. Para a realização desta fase do trabalho realizaram-se quatro ensaios distintos: densidade aparente (DA), adsorção gasosa (BET), microscopia eletrónica de varrimento (SEM) e calorimetria diferencial de varrimento (DSC). A segunda parte do estudo consistiu na avaliação do processo de absorção utilizando três tipos de plastificantes (DINP, DIDP, TM8-10) e na determinação das condições favoráveis ao processo de absorção. Para a realização deste estudo efetuaram-se três ensaios: absorção de plastificante a frio (AP), determinação do tempo de mistura seca (DUT) e, de forma a complementar, foi adotado/desenvolvido um método para a determinação de absorção de plastificante em excesso (SI). Por fim, correlacionou-se o mais possível as características do PVC virgem com os resultados obtidos de absorção de plastificante. Este estudo demostrou que no caso dos polímeros com valor K de 70, o polímero S70-16 é um polímero que apresenta melhores propriedades de absorção de plastificante comparativamente ao produzido pela CIRES (S1200). Já para os polímeros com valor K de 80, o produto produzido pela CIRES (S2000) apresenta melhores propriedades na absorção. Também, de forma expectável tendo em conta as diferenças das propriedades físicas dos plastificantes, verificou-se que o TM8-10 (trimelitato) apresenta sempre maior tempo de mistura seca relativamente ao DINP e DIDP (ftalatos). Por fim, foi possível correlacionar as diferenças encontradas na velocidade de absorção de plastificante com a respetiva área superficial específica (BET) de cada um dos polímeros.The aim of this work was the study of the absorption of plasticizers in PVC polymers produced by suspension polymerization (S-PVC). In Portugal, CIRES is the only producer of poly(vinyl chloride) (PVC) that offers a specific range of suspension products which constantly demands an upgrade on the knowledge of their behavior and performance for final market applications. This study aims at comparing of the polymers produced in CIRES (S1200- K70 and S2000 – K80) within the same grade from different sources (S70-16 – K70 and S4080 – K80). In a first stage, the so called virgin polymers in its final form (obtained after the polymerization reaction), were characterized. The four parameters were determined: apparent density (DA), gas adsorption (BET), scanning electron microscope (SEM) and differential scanning calorimetry (DSC). The second part of this work was to evaluate three types of plasticizers (DINP, DIDP, TM8-10) in the absorption process and to determinate the favorable conditions of the absorption process. For the realization of this stage, three tests were done: Cold Plasticizer Sorption (AP), Dry-up-time (DUT) and also were adopted a method to determination of the excess plasticizer absorption (SI). This study demonstrated that among the K70 polymers, the S70-16 is a polymer that has better absorption proprieties when it is compared with produced by CIRES polymer (S1200). Relatively to the K80 range, the polymer produced by CIRES (S2000) has better absorption proprieties. Also, based on differences in the properties of plasticizers, it was found that the TM8-10 (trimellitate) always has high dry blend time relative to DINP and DIDP (phthalates). Finally, it was possible to correlate the differences in absorption rate of the plasticizer with the respective specific surface area (BET) of each of the polymers

    Quality changes during thermal processing of two mixed formulas of fruits and vegetables pulps

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    Research ArticleThe present work aimed to evaluate, through thermal degradation kinetics (80 °C to 98 °C in time intervals of 0.5 to 25 min), the effects of different thermal treatments on the biochemical, physicochemical, sensory and microbiological parameters of two mixed fruit and vegetable pulps, a yellow and a red one. The evaluated fruit and vegetable pulps resulted from the mixture of different fruits and vegetables proportions (pineapple, beetroot, strawberry and lemon juice) added to a 50% (p/p) pear-based pulp to maximize their bioactivity, physicochemical stability and sensorial acceptance. Evaluated quality parameters included the determination of peroxidase activity (POD), pH, soluble solids content (SSC), total phenolic content (TPC), CIELab colour, sensory evaluation (colour, taste and aroma) and total mesophilic aerobic counts (TAPC). Regarding heat treatments optimization for both pulps with lower pH, it was concluded that higher temperature treatments (90 to 98 °C) applied over a shorter time (less than 5 min) were more effective to inactivate POD, to reduce the initial microbial load (>2 log10 cycles) and to maximize sensorial attributes. In both mix pulps, total phenolic content (TPC) was not significantly influenced by the different applied time-temperature binomials. From the degradation kinetic models and as an example, it was possible to conclude that POD followed a 1st order kinetic, where the temperature effect was well fitted to the Arrhenius equation. The results allowed to obtain optimized time-temperature binomials for each pulp to simultaneously achieve POD enzyme inactivation, microbial reduction, and maximization of quality parameters relatively to fresh pulps, 90 °C/5 min and 98 °C/2.5 min, for the yellow pulp and red pulp, respectivelyinfo:eu-repo/semantics/publishedVersio

    Influence of postharvest ultrasounds treatments on tomato (Solanum lycopersicum, cv. Zinac) quality and microbial load during storage

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    Whole tomato fruits were treated at ultrasonic power levels from 10% to 100%, and at a constant frequency of 45 kHz, for different times (1-19 min). A central composite rotatable design (CCRD) was applied to optimise ultrasonic treatments for tomato quality (colour, texture and total phenolic content (TPC)) maintenance. According to response surface analysis, the optimal treatment parameters were 55%_10 min, 80%_15 min and 100%_19 min. At these conditions, and especially at higher power levels, a maximum retention of colour and texture, as well as an increase of TPC and microbial reduction were obtained in comparison with untreated fruits during 15 storage days at 10 degrees C. The ultrasounds treatment was found to be effective in delaying colour development and texture losses, preserving sensorial quality of whole tomato, with increase of TPC and microbial load reduction. Moreover, this postharvest treatment can be used as an alternative for extending fresh fruits shelf-life.info:eu-repo/semantics/publishedVersio

    Propuesta de mejora basada en la NTP-ISO 9001:2009 para una empresa comercializadora de material y equipos médicos

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    Universidad Nacional Agraria La Molina. Facultad de Economía y Planificación. Departamento Académico de Gestión EmpresarialEl presente Trabajo Académico es una investigación no experimental desarrollada en la empresa IMPORT MEDIC S.A.C. (nombre irreal), la cual es una empresa que se dedica a la comercialización de material y equipos médicos a nivel nacional desde hace 36 años. Este trabajo tuvo como objetivo principal determinar la situación inicial de la empresa en lo referente a la calidad y a partir de ello diseñar una propuesta de implementación del Sistema de Gestión de la Calidad basado en la NTP ISO 9001:2009 para el proceso de comercialización de material y equipos médicos. El desarrollo del método no experimental se llevó a cabo mediante el uso de diferentes herramientas de recopilación de datos como son las entrevistas a los gerentes y responsables de área, revisión de la documentación, las cuales fueron cotejadas a través de observaciones a las operaciones e instalaciones de la empresa. Para evaluación del contexto organizacional se utilizaron las herramientas de gestión Cinco Fuerzas Competitivas de Porter, Matriz BCG, Matriz FODA, Matriz EFE y EFI y la Cadena de Valor. Para el diagnóstico del Sistema de Gestión de la Calidad se utilizaron las herramientas Encuesta de Costos de la Calidad (IMECCA) y la Lista de Verificación en base a la NTP ISO 9001:2009. En cuanto a la Determinación de los Aspectos Deficitarios de la empresa, se utilizaron las herramientas de Tormenta de Ideas, Matriz de Selección de Problemas y Diagrama Causa Efecto (ISHIKAWA), de las cuales se determinaron las causas y efectos del problema principal. Como respuesta a todo lo mencionado anteriormente se elaboró la propuesta de mejora para la gestión y la propuesta de mejora para el Sistema de Gestión de la Calidad. La implementación del Sistema de Gestión de la Calidad propuesto para IMPORT MEDIC S.A.C., basado en los requisitos de la en la NTP ISO 9001:2009, tiene un horizonte de tiempo de 7 meses y un costo de inversión 11,700 dólares estadounidenses. Adicionalmente, se realizó una estimación económica en las etapas posteriores a la planificación del Sistema de Gestión de la Calidad propuesto. Actualmente la empresa posee una rentabilidad de 11.4 por ciento y se estima que con la implementación del Sistema de Gestión de la Calidad se incrementará en un 13.1 por ciento en un horizonte de 5 años con una inversión de 11, 700 dólares estadounidenses.The following academic project is a non experimental research taking place at the company IMPORT MEDIC S.A.C (fictional name), company dedicated to the commercialization of medical supplies and equipment nation wide for 36 years. The main objective of this survey was to determinate the company’s initial situation concerning to quality and from this point, design a proposal to implement the Quality Management System based on the NTP ISO 9001:2009 for the process of commercialization of medical supplies and equipment. The development of the non experimental method took place by using different data collection tools such as area managers and director’s interviews and document review, which were compared and collate by observing the company installments and operations. To evaluate the organizational context the following management tools were used: Porter’s Five Competitive Forces, BCG matrix, SWOT matrix, EFE and IFE Matrix and Value Chain. For the Quality Management System diagnosis we used Quality Cost Survey tools and Verification List based in NTP ISO 9001:2009. For the Determination of Deficent Aspects of the company, the tools Brainstorm, Cause & Effect (ISHIKAWA) diagram, Problem Selection Matrix were used, and those determinate the cause effects from the principal problem. As a response to everything mentioned before we elaborated a proposal for improvement for management and improvement proposal for Quality Management System. The Quality Management System implementation proposed for IMPORT MEDIC S.A.C, based on the NTP ISO 9001:2009 requirements, has a time lapse for 7 months and an investment cost of $ 11,700. In addition, an economic estimate was made in the post planning stages of the proposed Quality Management System. Currentlym the company has a 11.4% profit and with the implementation of the Quality Management System will increase by 13.1 percent over a 5 year horizon with an investment of 11,700 US dollars.Tesi

    Evolução do perfil sensorial de textura de pera Rocha durante o período de armazenamento

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    IX Simpósio Ibérico de Maturação e Pós Colheita. Sessão Pós colheita de maçã e peraA textura é uma das principais características de qualidade da pera ‘Rocha’. Esta característica multidimensional tem uma complexidade mecânica e sensorial que não pode ser reduzida à simples avaliação da dureza. Este estudo teve por objetivo descrever o perfil sensorial da textura de pera ‘Rocha’ e as suas alterações durante o amadurecimento e ao longo do período de armazenamento. Frutos de pera ‘Rocha’ foram armazenados em quatro regimes distintos e analisados após 3, 5 e 7 meses de armazenamento a -0,5 ºC, em dois momentos após a retirada das câmaras. Foi efetuada a análise do perfil de textura sensorialmente com um painel treinado de 11 provadores de acordo com a norma ISO 11036:1994. O perfil de textura da pera ‘Rocha’ após 3 meses de armazenamento apresenta elevada dureza, fracturabilidade, coesividade, gomosidade e mastigabilidade, uma suculência intermédia, e reduzida adesividade e elasticidade. Com o amadurecimento da pera diminuiu a dureza, a fracturabilidade, a coesividade, a gomosidade e a mastigabilidade e aumentou a suculência e a adesividade. As variações do perfil sensorial de textura durante o amadurecimento pós-armazenamento foram equivalentes em frutos armazenados no ar ou em atmosfera controlada com 3 kPa de O2, mas distintos em peras tratadas com 1-metilciclopropeno (1-MCP). Frutos tratados apresentaram, nos diferentes períodos de armazenamento, valores de dureza, fracturabilidade, gomosidade e mastigabilidade superiores, enquanto a adesividade e coesividade foram inferiores aos dos frutos não-tratados. No período pós-armazenamento, frutos tratados com 1-MCP apresentaram dureza e fracturabilidade superior mas a mastigabilidade foi o atributo mais afetado pelo tratamento. Em períodos de armazenamento mais prolongados esta distinção é ainda mais notória pelos elevados níveis de mastigabilidade registados nos frutos tratadosinfo:eu-repo/semantics/publishedVersio

    Estudo exploratório do aproveitamento de águas pluviais numa escola do campus do IPS

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    Trabalho apresentado em 1ª Conferência Campus Sustentável - CCS2019, 2019, Porto, PortugalN/

    Protocolo de angioplastia pulmonar de balão num centro de referência nacional em hipertensão pulmonar

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    © 2021 Sociedade Portuguesa de Cardiologia. Published by Elsevier España, S.L.U. This is an open access article under the CC-BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).Introduction: Balloon pulmonary angioplasty (BPA) has emerged as a promising therapeutic option for patients with chronic thromboembolic pulmonary hypertension (CTEPH) who are not eligible for pulmonary thromboendarterectomy (PEA) or who have recurrent or persistent pulmonary hypertension after surgery. There is no standardized technique for BPA and, its complexity and high risk of severe complications, requires skills and appropriate training and should be reserved for expert CTEPH centers, as a complementary intervention to medical and surgical therapy. Objective: The purpose of this document is to describe the BPA protocol used at a high-volume center nationwide, validated by its results. Methods: The present protocol includes technical details, definition of outcomes and complications, as well as patient full diagnostic work-up and treatment algorithm, before and after BPA. Results: The technical, hemodynamic, and clinical results of the application of this protocol will be subject of a later publication where they will be described in detail. In conclusion, we present a percutaneous intervention protocol in the treatment of pulmonary hypertension in the context of chronic pulmonary thromboembolism, validated by its clinical, hemodynamic, and technical results.Introdução: A angioplastia da artéria pulmonar com balão (APB) é uma opção terapêutica promissora para doentes com hipertensão pulmonar tromboembólica crónica (HPTEC), não elegíveis para tromboendarterectomia pulmonar ou que apresentam hipertensão pulmonar recorrente ou persistente após cirurgia. Não existe uma técnica padronizada para APB, a sua complexidade e seu elevado risco de complicações severas requerem competências e um treino apropriado e deve ser reservada para centros especializados em HPTEC e como uma intervenção complementar à terapêutica médica e cirúrgica. Objetivo: Divulgar um protocolo de APB usado num centro com elevado volume a nível nacional, validado pelos seus resultados. Métodos: O presente protocolo inclui detalhes técnicos, definição atual de resultados e complicações, bem como o algoritmo de avaliação diagnóstica e tratamento do doente antes e depois da APB. Resultados: Os resultados técnicos, hemodinâmicos e clínicos da aplicação deste protocolo serão alvo de uma publicação posterior, na qual serão descritos em detalhe. Conclusão: Apresentamos um protocolo de intervenção percutânea no tratamento de hipertensão pulmonar em contexto de tromboembolismo pulmonar crónico, validado pelos seus resultados clínicos, hemodinâmicos e técnicosinfo:eu-repo/semantics/publishedVersio

    Fresh-cut carrot (cv. Nantes) quality as affected by abiotic stress (heat shock and UV-C irradiation) pre-treatments

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    Available at Sciverse ScienceDirectAbiotic stresses such as heat shock and UV-C irradiation can be used to induce synthesis of bioactive compounds and to prevent decay in fresh-cut fruits and vegetables. This study aimed to evaluate the effects of heat shock and UV-C radiation stress treatments, applied in whole carrots, on the overall quality of fresh-cut carrot cv. Nantes during storage (5 C). Heat shock (HS, 100 C/45 s) and UV-C (0.78 0.36 kJ/m2) treated samples had higher phenolic content and exhibited reduced POD activities during storage when compared to control (Ctr) samples (200 mg/L free chlorine/1 min). All samples showed reduced carotenoid content considering raw material. Nonetheless, UV samples registered a three-fold increase in carotenoid content in subsequent storage. Fresh-cut carrot colour showed a continuous increase in whiteness index (WI) values during storage regardless of treatment without impairing visual quality. Respiratory metabolism was affected by both abiotic stress treatments since reduced O2/CO2 rates were found, more significant in HS samples. The decontamination effect was more expressive in HS samples, where a 2.5 Log10 cfu/g reduction in initial microbial load and reduced microbial growth were achieve

    Evaluation of alternative preservation treatments (water heat treatment, ultrasounds, thermosonication and UV-C radiation) to improve safety and quality of whole tomato

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    Previously optimised postharvest treatments were compared to conventional chlorinated water treatment in terms of their effects on the overall quality of tomato (‘Zinac’) during storage at 10 °C. The treatments in question were water heat treatment (WHT = 40 °C, 30 min), ultrasounds (US = 45 kHz, 80 %, 30 min), thermosonication (TS =40 °C, 30 min, 45 kHz, 80 %) and ultraviolet irradiation (UV-C: 0.97 kJ m−2). The quality factors evaluated were colour, texture, sensorial analysis, mass loss, antioxidant capacity, total phenolic content, peroxidase and pectin methylesterase enzymatic activities, and microbial load reduction. The results demonstrate that all treatments tested preserve tomato quality to some extent during storage at 10 °C. WHT, TS and UV-C proved to be more efficient on minimising colour and texture changes with the additional advantage of microbial load reduction, leading to a shelf life extension when compared to control trials. However, at the end of storage, with exception of WHT samples, the antioxidant activity and phenolic content of treated samples was lower than for control samples. Moreover, sensorial results were well correlated with instrumental colour experimental data. This study presents alternative postharvest technologies that improve tomato (Zinac) quality during shelf life period and minimise the negative impact of conventional chlorinated water on human safety, health and environment.info:eu-repo/semantics/publishedVersio
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