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A critical survey of predictive mathematical models for migration from packaging
Poças, Maria F.; Oliveira, Jorge C; Oliveira, Fernanda A. R.; Hogg, TimothyThe migration of chemicals from food contact materials into foods is an important issue in food safety.The assessment of materials compliance with regulations includes migration monitoring for many monomers and additives. However,it is recognized that predictive mathematical modelling can be used in many cases, to avoid or to reduce the effort on migration experiments. This article reviews the approaches follow...
Influence of low oxygen and high carbon dioxide on shredded Galega kale quality...
Fonseca, Susana C.; Oliveira, Fernanda A. R.; Brecht, Jeffrey K.; Chau, Khe V.Respiration rate, sensory attributes, colour alterations, and water, chlorophyll and ascorbic acid contents were monitored during storage of shredded Galega kale (Brassica oleracea var. acephala DC.) at 20 ◦C to define an adequate range of O2 and CO2 partial pressures for product preservation. Different low O2 and high CO2 atmospheres were tested. First, tolerance to low O2 partial pressures (1, 2, 3 or 21 kPa ...
Modelling respiration rate of fresh fruits and vegetables for modified atmosphe...
Fonseca, Susana C.; Oliveira, Fernanda A.R.; Brecht, Jeffrey K.Respiration rate and gas exchange through the package material are the processes involved in creating a modified atmosphere inside a package that will extend shelf life of fresh fruits and vegetables. Thus, modelling respiration rate of the selected produce is crucial to the design of a successful modified atmosphere packaging (MAP) system. In this paper, general aspects of the respiration process are presented...
Modelling respiration rate of shredded Galega kale for development of modified ...
Fonseca, Susana C.; Oliveira, Fernanda A.R.; Frias, Jesus M.; Brecht, Jeffrey K.The design of modified atmosphere packaging (MAP) for fresh-cut produce requires an adequate model for prediction of respiration rate as a function of both temperature and gas composition. In this work, the O2 consumption and CO2 production rates of shredded Galega kale were studied. The storage temperatures used were 1, 5, 10, 15 and 20 C. The atmospheres tested were all combinations of 1, 5 and 10% v/v O2 pl...
Analysis of the heat transfer coefficient during potato frying
Costa, Rui M.; Oliveira, Fernanda A. R.; Delaneya, Olivia; Gekas, VassilisThe objective of this work was to study the dependence of the heat transfer coefficient (h) on the water loss rate of potato during frying. An indirect method was used where a metal piece with the same geometry of the potato pieces was placed on top of various potato samples at different frying times, and its temperature was recorded for 20–30 s. Another method consisted of direct recording of the temperature w...
Modelling ascorbic acid thermal degradation and browning in orange juice under ...
Manso, Maria C.; Oliveira, Fernanda A.R.; Oliveira, Jorge C.; Frías, Jesús M.The thermal degradation of ascorbic acid (AA) in orange juice was analysed over in a 20–45 °C temperature range. Dehydroascorbic acid (DA), pH and browning were also monitored. Small amounts of AA degradation could be described by first order kinetics, but when only low amounts of AA were retained sigmoidal kinetics were clearly appropriate. The Weibull model was used to describe this pattern (R2adj > 0.995). T...
Influence of the variability of processing factors on the F-value distribution ...
Varga, Szabolcs; Oliveira, Jorge C.; Oliveira, Fernanda A.R.The F-value distribution in a batch retort processing of in-pack conduction heating foods resulting from the variability of four processing factors (initial temperature, heating time, headspace and external heat transfer coe cient) was determined by mathematical modelling. Three hundred combinations were generated from normally distributed values for each factor, following the Monte Carlo approach. The retort t...
Modelling O2 and CO2 exchange for development of perforation mediated modifed a...
Fonseca, Susana C.; Oliveira, Fernanda A.R.; Lino, Isabel B.M.; Brecht, Jeffrey K.; Chau, Khe V.Perforation-mediated modi®ed atmosphere packaging relies on the use of macro perforations or tubes to control the O2 and CO2 exchange and create the desired atmosphere inside an otherwise gas-tight package. In this work, the O2 and CO2 exchange through a single tube was studied. Di erent temperatures (5±20°C) and tube dimensions (length from 9 to 17 mm and diameter from 6 to 30 mm) were tested. O2 and CO2 mass ...
Optimal experimental design for estimating the kinetic parameters of processes ...
Cunha, Luís M; Oliveira, Fernanda A. R.The optimum experimental design for systems following the ®rst-order Arrhenius model under linearly increasing temperature pro®les was studied by determining the sampling conditions that lead to a minimum con®dence region of the model parameters. It was found that experiments should be started at the lowest possible temperature and, for each initial temperature, there is an optimal heating rate. This heating ra...
Effect of milk fat and total solids concentration on the kinetics of moisture u...
Machado, M. Fátima; Oliveira, Fernanda A. R.; Cunha, Luís M.When immersed in milk, breakfast cereal easily take up moisture, lose their brittle texture and become soggy. Earlier comparative analysis of the moisture sorption by breakfast cereal immersed in water and milk indicated that milk solids might play an important role on the sorption kinetics. In this work, the moisture uptake by ready-to-eat corn breakfast cereal immersed in milk solutions, reconstituted from wh...
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