Browsing by Author "Quintas, Mafalda A. C."
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- Antioxidant potential of two red seaweeds from the brazilian coastsPublication . Souza, Bartolomeu W. S.; Cerqueira, Miguel A.; Martins, Joana T.; Quintas, Mafalda A. C.; Ferreira, António C. S.; Teixeira, José A.; Vicente, António A.In this work, in vitro antioxidant activity of two Brazilian red seaweeds, Gracilaria birdiae and Gracilaria cornea, was characterized. The total phenolic content, the radical-scavenging activity and the antioxidant activity were determined in two solvent extracts of the algae. Liquid chromatography-mass spectrometry (LC-MS/MS) allowed identification of important antioxidant compounds. The ethanol extract of G. birdiae was found to have the highest value of total phenolic content: 1.13 mg of gallic acid equiv (GAE)/g of Extract. The radical-scavenging activity of G. birdiae and G. cornea extracts has been evaluated at different extract concentrations; the IC50 values of ethanolic extracts of G. cornea and G. birdiae were 0.77 and 0.76 mg mL(-1), respectively, while for methanolic extracts, the IC50 values of G. cornea and G. birdiae were 0.86 and 0.76 mg mL(-1), respectively. The antioxidant activities of these two seaweeds' extracts as assessed by the beta-carotene-linoleic acid assay were equally high, achieving values of beta-carotene oxidation inhibition of up to 40%. Finally, in the methanolic extracts, LC-MS/MS allowed identification in both algae of two important antioxidants: apigenin and gallic acid.
- Development of a safer formulation of egg yolk cream: physicochemical and sensorial characteristics assessmentPublication . Fundo, Joana F.; Quintas, Mafalda A. C.; Brandão, Teresa R. S.; Silva, Cristina L. M.Egg yolk cream is a sweet confectioned with egg yolk, sugar and water. The use of raw egg products is a potential safety hazard in its production. In this work, a safer formulation is developed by using an easier to manipulate raw material – pasteurized liquid egg. Because of previous heat treatment, pasteurized liquid egg presents different sensorial, nutritional and physical properties. These changes may alter the final product's characteristics. In this work, a study on adding pasteurized egg white (as bulking agent) to the pasteurized liquid yolk was carried out. Samples made with shell eggs and with pasteurized liquid eggs were compared in terms of physical and chemical parameters. Results allowed characterizing the properties of typical egg cream and of alternative formulations using pasteurized egg yolk and white. A new formula of egg cream was developed and its sensorial acceptance was tested against the typical formulation.
- Fresh-cut pear quality during storage: a NMR study of water transverse relaxation timePublication . Fundo, Joana; Carvalho, Alexandra; Feio, Gabriel; Silva, Cristina L.M.; Quintas, Mafalda A. C.Fresh-cut fruits have become an important food market segment due to increasing demand for fresh, healthy and convenient foods. However, processing fruits promotes a decrease in its stability with a faster physiological deterioration, biochemical changes and microbial degradation. Recently, food stability is strongly attributed to molecular dynamics and “water availability”. Understanding cooperatively changes in location and mobility of water is particularly important, considering that water dynamics profoundly influences physicochemical and microbiological quality of foods. The aim of this study was to use nuclear magnetic resonance spectroscopy (NMR) as a tool to evaluate storage fresh-cut fruit quality. Recently, NMR has evolved to become a powerful methodology to probe the molecular dynamics of food constituents, which in turns is a fundamental parameter to determine the dynamic properties of food components and contributes to food degradation reactions comprehension. In this work fresh-cut pear transverse relaxation time (T2) was measured for a period of 7 days of storage at 5 °C. The relationship between the obtained values, microstructure and quality parameters was investigated. In general, results show the existence of one class of water fluidity in the system, the one present in cells after processing. T2, a measure of this fluidity, is affected by the processing and storage time. Also, it is possible to find a relationships between T2 and the quality parameters: total colour difference (TCD), firmness and aw. T2 increases with aw, while it decreases with TCD and firmness. These results highlight the usefulness of NMR methodology application in food science
- Ideal skills for European food scientists and technologists: identifying the most desired knowledge, skills and competenciesPublication . Flynn, Katherine; Wahnström, Erik; Popa, Mona; Ruiz-Bejarano, Barbara; Quintas, Mafalda A. C.Training food scientists and technologists (FSTs) to have appropriate skills begins with identification of those skills most desired by employers. Between March 2010 and August 2011, 16 workshops in 16 countries had 315 local FST employers contribute ideas of skills desired in their FSTs. Attendees provided as many skills as possible and these descriptive data were quantifed and then analysed with multiple contingency tables and chi squared testing. Of the 3348 skill ideas provided, the most desired skill overall was Communicating, which was identified 13% of the time. Separate analysis of the 792 food sector skills indicated Product Development, at 28%, as the most desired. Geographical region, employment area and FST level of responsibility all significantly influenced the top 3 choices of overall skills and of food sector skills, indicating that most desired skills in the food industry are not uniform. These results should contribute to the improvement of FST training and thus benefit the European food industry. Industrial relevance: The data presented here suggest that improvements in FST training, particularly the acquisition of 'soft skills', will improve Europe's food workforce as these are the skills employers most desire. These data further suggest that geographical region significantly influences those skills most desired by industrial employers. Differences in desired skills at different levels of FST responsibility further suggest that continual FST training i.e., continual professional development, will contribute to improved FST performance. Overall, this study presents data which can improve FST performance and thus contribute to increased innovation and competitiveness of the food and drink industry.
- Molecular dynamics and structure in physical properties and stability of food systemsPublication . Fundo, Joana F.; Quintas, Mafalda A. C.; Silva, Cristina L. M.Physical properties and stability are critical for delivering safe and healthy food to the consumers and thus is a theme that attracts food scientists for a long time. Recently, literature suggests that stability can be fully grasped only if food molecular dynamics and structure are taken into consideration, i.e. an appropriate understanding of the behaviour of food products requires knowledge of its composition, structure and molecular dynamics, through the three-dimensional arrangement of the various structural elements and their interactions. Food systems behaviour is strongly dependent on the water molecular dynamics. Understanding changes in location and mobility of water represents a significant step in food stability knowledge, since water "availability" profoundly influences the chemical, physical and microbiological quality of foods. Nuclear magnetic resonance has been presented as a powerful technique to investigate water dynamics and physical structures of foods through analysis of nuclear magnetisation relaxation times, because it provides information on molecular dynamics of different components in dense complex systems. The application of this technique may be very useful in predicting food systems physicochemical changes, namely texture, viscosity or water migration. This paper aims at reviewing some of the main aspects related to food physical properties and stability, and the role of water in these properties. More specifically, this paper intends to contribute to a deeper understanding of the relationship of molecular constituents-structure-function of food systems, contributing to the development of foods with improved functionality.
- Molecular mobility and the thermomechanical properties of chitosan filmsPublication . Fundo, Joana F.; Quintas, Mafalda A. C.; Silva, Cristina L. M.
- Profile of currently employed European food scientists and technologists: education, experience and skillsPublication . Flynn, Katherine; Ruiz-Bejarano, Barbara; Wahnström, Erik; Echim, Camelia; Quintas, Mafalda A. C.The food and drink (F & D) sector in Europe ranks low in innovation and the European F & D industry has been losing importance in the global market. The food professionals, i.e., food scientists and technologists (FSTs), may not be meeting the varied demands of the sector. Here, education, experience and skills of current FSTs were identified and compared geographic regions and employment areas. Between 2009 and 2012, 287 questionnaires representing over 4000 FSTs were collected from employers in 16 countries. Analyses showed that more than 80% of FSTs have a university degree; but only in Industry in the Central European region are most degrees in food science/technology. More than half of FSTs, and almost 60% in the South, have less than 10 years' experience. The most common FST job title is Quality Manager, but with several variations based on region and employment area. Among skills, the most common is Communicating; found in over 90% of FSTs in all regions and employment areas. Food Safety is the most common of the food sector-specific skills, present in more than 75% of FSTs, yet there are differences in food sector skills based on employment area. Overall, these data suggest similarities among currently employed food professionals throughout Europe; they are young and highly educated, but also differences, especially in their food sector-specific skills. An understanding of the current FST should contribute to the improvement of FST training and thus benefit the European food sector.
- Storage stability of an egg yolk cream formulation: texture and microbiological assessmentPublication . Fundo, Joana F.; Quintas, Mafalda A. C.; Brandão, Teresa R. S.; Silva, Cristina L.M.BACKGROUND: Egg yolk cream is confectioned with egg yolk, sugar and water. Pasteurized liquid eggs may be used in order to increase product safety, although these samples may differ from the classic ones produced with raw eggs. The objective was to evaluate and compare the stability (physicochemical characteristics, such as texture assessment, pH and water activity, and microbiological assessment) of a classic formulation and an alternative one produced with pasteurized eggs, during storage at 6, 26, 30 and 37◦C. RESULTS: From a microbiological point of view (mesophile and psychrotrophic activity), no differences were observed in either formulations.At 6 and 26 ◦C, rheological behaviour of both formulations remained approximately constant. At 30 and 37 ◦C, differences were only detected after 20 days of storage. Texture was better retained in samples prepared with pasteurized eggs, while the classic samples showed an increase in complex viscosity. CONCLUSION: Cream storage did not require refrigeration. In terms of texture and microbial load, results obtained at 6 and 26 ◦C were identical. The formulations only differed in texture when stored at 30 and 37 ◦C and for long periods. These conclusions may allow reduction of costs related to refrigerated distribution/storage of either classic or alternative formulations.
- The effect of polymer/plasticiser ratio in film forming solutions on the properties of chitosan filmsPublication . Fundo, Joana; Galvis-Sanchez, Andrea C.; Delgadillo, Ivonne; Silva, Cristina L. M.; Quintas, Mafalda A. C.In this work physical-chemical properties of chitosan/ glycerol film forming solutions (FFS) and the resulting films were analysed. Solutions were prepared using different concentrations of plasticising agent (glycerol) and chitosan. Films were produced by solvent casting and equilibrated in a controlled atmosphere. FFS water activity and rheological behaviour were determined. Films water content, solubility, water vapour and oxygen permeabilities, thickness, and mechanical and thermal properties were determined. Fourier transform infrared (FTIR) spectroscopy was also used to study the chitosan/glycerol interactions. Results demonstrate that FFS chitosan concentration influenced solutions consistency coefficient and this was related with differences in films water retention and structure. Plasticiser addition led to an increase in films moisture content, solubility and water vapour permeability, water affinity and structural changes. Films thermo-mechanical properties are significantly affected by both chitosan and glycerol addition. FTIR experiments confirm these results.