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- Flores comestíveis como fonte de compostos bioativos com atividade antioxidantePublication . Guiné, Raquel P. F.; Ferrão, Ana Cristina; Correia, Paula; Goncalves, J. C.; Gonçalves, Fernando JorgeExistem muitas espécies vegetais utilizadas na gastronomia, entre as quais as flores comestíveis (FC). Para que uma flor seja considerada comestível ela deve ser não tóxica, inócua e ter propriedades nutricionais. Historicamente, as FC têm sido usadas para fins culinários há séculos em várias partes do mundo, como Ásia, Grécia antiga, Roma e também na França medieval. Adicionalmente, constituem uma boa fonte de compostos bioativos, nomeadamente fitoquímicos, associados a várias propriedades farmacológicas, destacando a proteção contra doenças cardiovasculares e os efeitos ansiolíticos, anticancerígenos, antidiabéticos, anti-inflamatórios, antioxidantes, diuréticos, imunomoduladores e antimicrobianos. Recentemente, as FC têm despertado crescente interesse, devido às suas propriedades estéticas e organoléticas, bem como potenciais benefícios para a saúde, relacionados com a ocorrência de alguns compostos bioativos. Nesta medida, o objetivo do presente trabalho foi avaliar os teores de compostos fenólicos totais, antocianinas e flavonoides, bem como a atividade antioxidante num conjunto de FC. Para a análise foram obtidos extratos de onze espécies de FC que foram utilizados para a quantificação da composição fenólica e atividade antioxidante usando métodos espectrofotométricos. Dos resultados obtidos foi possível verificar que as rosas e cravos de coloração vermelha ou rosa se destacaram como contendo maiores teores de compostos fenólicos totais (18 a 27 mg EGA/g), e ainda maiores aportes de antocianinas (3 a 5 mg EC/g). Verificou-se ainda que eram também essas as FC com maior atividade antioxidante (12 a 16 mg ET/g). De destacar por fim o cravo vermelho como contendo maior quantidade de flavonoides (cerca de 18 mg EC/g). Em conclusão, verifica-se que as FC, para além das suas potencialidades gastronómicas, podem constituir um veículo para a ingestão de compostos com efeitos benéficos para a saúde, nomeadamente no que respeita ao combate aos radicais lives responsáveis pelo envelhecimento celular.
- Angular variation of fire rate of spreadPublication . André, Jorge C. S.; Goncalves, J. C.; Vaz, Gilberto C.; Viegas, Domingos X.Laboratory fire tests were performed in still air, for variable inclinations (10°, 15°) and fuel bed dimensions (1.28 × 2.50–3.0 × 4.6 m2), with homogeneous fuel beds of pine needles and pine wood excelsior. The fire ignition was made at a point, along a closed line with no fuel inside and along a straight edge of the fuel bed. The tests were recorded with an infrared camera and various techniques were developed to implement direct and indirect empirical methods of construction of the ‘orientation function’ of the fire in the given fuel bed and ambient conditions, showing how the rate of spread of a steady straight fire front depends on its orientation on the terrain. The direct method uses a set of straight fire fronts with various orientations whereas the indirect method uses essentially a point ignited fire front. Contrary to what is assumed in BehavePlus model, the orientation function is observed to depend significantly on the properties of the fuel bed. In all tests with closed fire fronts, the full steadiness required by the indirect method was not achieved (namely, at the head of the front), although, for slope angle of 10°, the corresponding errors induced on the orientation function were small.
- Angular variation of fire rate of spreadPublication . André, Jorge C. S.; Goncalves, J. C.; Vaz, Gilberto C.; Viegas, Domingos X.Laboratory fire tests were performed in still air, for variable inclinations (108, 158) and fuel bed dimensions (1.28 2.50–3.0 4.6m2), with homogeneous fuel beds of pine needles and pine wood excelsior. The fire ignition was made at a point, along a closed line with no fuel inside and along a straight edge of the fuel bed. The tests were recorded with an infrared camera and various techniques were developed to implement direct and indirect empirical methods of construction of the ‘orientation function’ of the fire in the given fuel bed and ambient conditions, showing how the rate of spread of a steady straight fire front depends on its orientation on the terrain. The direct method uses a set of straight fire fronts with various orientations whereas the indirect method uses essentially a point ignited fire front. Contrary to what is assumed in BehavePlus model, the orientation function is observed to depend significantly on the properties of the fuel bed. In all tests with closed fire fronts, the full steadiness required by the indirect method was not achieved (namely, at the head of the front), although, for slope angle of 108, the corresponding errors induced on the orientation function were small.
- Parametric study on the performance of an air curtain based on CFD simulations - New proposal for automatic operationPublication . Goncalves, J. C.; Costa, J.J.; Lopes, A.M.G.This paper presents a parametric study on the performance of an air curtain installed over an access door of a refrigerated room. The aim of this work is to quantify, in an integrated way, the influence of the following geometrical and dynamic parameters: door height; temperature difference between rooms, nozzle thickness; initial orientation angle; jet discharge velocity. A numerical model was used to simulate the turbulent non-isothermal 3D airflow generated in the transient period after the door is opened, with the air curtain device turned on or off. Turbulence effects were taken into account with the k-SST model. Results show that the optimum discharge velocity of the air curtain increases with the door height, as well as with the temperature difference between both sides of the air curtain. It was also possible to find an optimum jet nozzle width corresponding to maximum sealing efficiency and lower jet airflow rate. A proposal is made for an empirical correlation to predict the optimum jet discharge velocity as function of the variables used in the parametric study. Additionally, to ensure that the air curtain operates near the optimum conditions, the appropriate air curtain settings are discussed and a new strategy is suggested.
- Computational Fluid Dynamics Modeling of Ammonia Concentration in a Commercial Broiler BuildingPublication . Goncalves, J. C.; Lopes, António M. G.; Pereira, José L.S.In the present study, a numerical model was developed to predict the flow pattern inside a broiler building. The model intends to predict the velocities fields inside the domain and am-monia (NH3) emitted or released by litter from poultry housing. The numerical model developed in Computational Fluid Dynamics (CFD) commercial code, intends to represent a commercial broiler building, and intends to simulate the 3D and heat transfer, in steady state flow. The evaporative cooling pads were also included in the model. The validation of the model was based in experimental measurements obtained in previous studies. The simulations were fo-cused on Summer, Winter and also Mid-Season situation. The numerical results of NH3 concen-tration were compared with the experimental measurements, and a quite good agreement was verified. The numerical results allowed the characterization of: the inside flow pattern devel-oped for the summer and winter situation; the inside NH3 distribution, and the velocity field distribution inside the broiler building. It was found that NH3 concentration increases along the tunnel, especially in low flow rate imposed from the exhaust fan. Also, it was verified that the low velocities inside domain are no sufficient to remove the gaseous pollutants.
- Determination of drying kinetics, speci fi c energy consumption, shrinkage, and colour properties of pomegranate arils submitted to microwave and convective dryingPublication . Kaveh, M.; Golpour, I.; Goncalves, J. C.; Ghafouri, S.; Guiné, RaquelIn this study, the drying kinetics, e ff ective moisture di ff usivity (D e ff ) , speci fi c energy consumption ( SEC ) , colour, and shrinkage (S b ) of pomegranate arils were compared when dried by convective ( CV ) drying and microwave ( MW ) drying. The experiments were per - formed at air temperature of 50, 60, and 70°C and air velocity of 1 m/s for CV drying and 270, 450, and 630 W for MW drying. The results showed that increasing air temperature and MW power increased the D e ff. The cal - culations demonstrated that the maximum D e ff for pome - granate arils was obtained for MW drying ( 630 W ) . Maximum SEC for pomegranate arils in the CV dryer was 145.12 kWh/kg, whereas in the MW dryer was 35.42 kWh/kg. In MW dryer, the lowest values of colour change and shrinkage were 6.77 and 50.5%, respec - tively. Comprehensive comparison of the di ff erent drying methods ( MW and CV ) revealed that MW drying had best drying performance for pomegranate arils, considering the drying time, e ff ective moisture di ff usion, SEC, colour, and shrinkage
- A Study on the Sealing Efficiency of Air Curtains: 2D and 3D ApproachesPublication . Goncalves, J. C.; Costa, J.; Figueiredo, R.; Lopes, A.In industrial refrigerated spaces, such as retail stores, where sometimes doors must be open for long periods, the infiltration loads can represent more than half of the total refrigeration load. The use of air curtains can significantly reduce the air infiltration through doorways and, at the same time, it allows the free access by persons and equipment [1]. Besides the experimental research, computational fluid dynamics (CFD) has been commonly used, either adopting a two dimensional (2D) approach [1] or, more recently, through a three-dimensional (3D) perspective [2,3]. This work presents a numerical and experimental study on the performance of air curtain devices in the aerodynamic sealing of access doors of refrigerated spaces. For this propose, a 3D numerical model was developed aiming at the simulation of the turbulent non-isothermal airflow generated by the air curtain since the moment the door is opened. The calculation domain represents a laboratory scale model consisting of two similar adjacent rooms connected by a doorway over which the air curtain device is installed. One of these rooms represents a refrigerated chamber and the other, the outdoor environment. The numerical study was carried out using a commercial CFD code (ANSYS-CFX) and the turbulence effects were approached by k-_SST turbulent model. In the experimental study, the tracer gas technique was used to estimate the air exchange rate through the doorway in the initial period of the transient process and consequently assess the sealing effect obtained with the air curtain device operating at different jet velocities. The numerical results show that the air curtain simulated is appropriate to protect the doorway in its whole width, and a good agreement is verified with the experimental measurements. Results of a simplified 2D approach are also shown and compared with the 3D simulation
- Consumer attitudes and perceptions towards chilled ready-to-eat foods: a multi-national studyPublication . Smigic, Nada; Ozilgen, Sibel; Gómez-López, Vicente M.; Osés, Sandra María; Miloradovic, Zorana; Aleksic, Biljana; Miocinovic, Jelena; Smole Možina, Sonja; Kunčič, Ajda; Guiné, Raquel; Goncalves, J. C.; Trafialek, Joanna; Czarniecka-Skubina, Ewa; Goel, Gunjan; Blazic, Marijana; Herljevic, Dora; Nikolić, Aleksandra; Mujčinović, Alen; Djekic, IlijaUnderstanding consumers’ behavior and their handling of high-risk foods at home is essential for reducing the number of foodborne illnesses. This study shows the results of a cross-national analysis of consumers’ perception from nine countries, and the identification of customers’ clusters and its characteristics in order to understand customers’ behavior, and to build safe chilled ready-to-eat (RTE) foods prevention strategies. The cluster analysis resulted in two clusters: (1) “Precautious consumers” characterized by the orientation towards pre-packed RTE foods, with consumers mainly coming from Bosnia and Herzegovina, India, Poland, Portugal, Spain, and Turkey. Their attitudes and self-reported practices may be categorized as less risky in terms of food-borne illnesses connected with the consumption of RTE foods; (2) “Unconcerned consumers” preferred cutting and slicing RTE foods freshly at the point of purchase, usually sold at the delicatessen department in a supermarket or at open markets. Those consumers mostly came from Croatia, Serbia and Slovenia and their attitudes and self-reported practices were riskier. These results allow a better understating of what characterizes consumers of RTE foods in different countries.
- Empirical correlation to estimate the optimum jet velocity of an air curtainPublication . Goncalves, J. C.; Costa, José; Figueiredo, A. Rui; Lopes, AntónioThis paper presents the results of a parametric study to quantify the influence of some thermal and geometrical parameters (door height) on the performance of an Air Curtain Device (ACD). The experimental facility consists of two similar adjacent rooms connected by a door over which the ACD device was installed. The tracer gas technique was used to calculate the sealing effect achieved with the air curtain at different jet velocities. Using a commercial CFD software, a numerical study was also performed to simulate the heat and mass transfer phenomena, as well as the aerodynamic sealing efficiency. A good agreement was observed between experimental and numerical results, showing that the optimum discharge velocity of the ACD air jet increases almost linearly with the door height, as well as with the temperature difference between both sides of the air curtain. It was possible to establish an empirical correlation that predicts reasonably well the optimum discharge jet velocity of a vertical air curtain device, depending on the temperature difference and the doorway height. An electronic device can be included in the ACD enabling the automatic adjustment of the air curtain jet velocity based this correlation, in order to continuously operate close to maximum sealing efficiency.
- Consumers’ purchasing habits and food poisoning risk - A portuguese surveyPublication . Goncalves, J. C.; Guiné, Raquel P. F.; Djekic, I.; Smigic, NIn the Western countries, despite tight food safety legislation, food poisoning episodes are still quite frequent. According to the European legislation, it is mandatory for all European member states the annual reporting of information on food-borne outbreaks. In Portugal, the National Institute of Health (INSA) notifies each year the European Food Safety Authority (EFSA) about the data of the foodborne outbreaks occurred in Portugal, namely information about the pathogenic microorganism responsible, the food products involved and the places where the contamination or consumption have occurred. The aim of this research was to evaluate the Portuguese consumer knowledge about food products commonly responsible for poisoning outbreaks, and witch pathogenic microorganisms are most associated to those food poisoning episodes. In 2017, the Department of Food and Nutrition (DAN) of INSA, carried out laboratory research on 18 outbreaks of food-borne infections that occurred in Portugal which caused 323 cases of illness and involved 145 hospitalizations, with no deaths being reported. Also, we were collecting information through a questionnaire, which was disclosed in the google forms online platform. Ethical issues were respected in the design and application of the questionnaire, and validated by the CERNAS Research Centre. The questionnaire was approved by the Ethics Committee at the Polytechnic Institute of Viseu, in June 2021 with reference 52/ SUB/2021. The data was collected between June of 2021 and January of 2022, involving 350 adult participants that voluntarily answered the questionnaire. Data analysis was made using Excel. In the EFSA report of 2017, a total of 5,079 foodborne outbreaks were reported. In these events, Salmonella spp. was the commonest detected agent, causing one out of seven outbreaks. Also, Salmonella spp. in eggs and in meat and meat products were identified as the highest risk agent/food pairs. Concerning the place where the food was prepared or consumed, 75% were in public places (institutions, residential, canteens, school bars, schools, colleges, kindergartens, day-care centers, restaurants, hospitals, and nursing homes) and 25% at home, i.e. all the patients involved belonged to the same household. The major foodborne pathogens, associated food vehicles, include: Escherichia coli, Listeria monocytogenes, Salmonella typhimurium, and Staphylococcus aureus. Listeria monocytogenes is able to grow at temperatures approaching 0 0 C, and is responsible for outbreaks of listeriosis often associated to the consumption of ready to eat meat, dairy and fishery products. The results show that consumers are quite well informed about food contamination by pathogenic microorganism. They consider products like eggs, meat, and dairy products, as having the greatest risk to the health of consumers and identify the salmonella as the microorganism most associated to those contamination.