A carregar...
Projeto de investigação
Strategic Project - LA 16 - 2011-2012
Financiador
Autores
Publicações
Evaluation of alternative preservation treatments (water heat treatment, ultrasounds, thermosonication and UV-C radiation) to improve safety and quality of whole tomato
Publication . Pinheiro, Joaquina; Alegria, Carla S.M.; Abreu, Marta M.M.N.; Gonçalves, Elsa M.; Silva, Cristina L.M.
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.
Application of optimal experimental design concept to improve the estimation of model parameters in microbial thermal inactivation kinetics
Publication . Gil, Maria M.; Miller, Fátima A.; Silva, Cristina L. M.; Brandão, Teresa R. S.
The estimation of model parameters with high precision is of major importance in mathematical predictions. If a mathematical model is properly chosen and if the primary objective is to improve parameter estimation, underlying statistical theories can be applied. Precision increases with the number of experimental points. However, and in many situations, maximum precision is attained when sampling consists of replicates of specific experimental points. Experimental conditions can be optimized using the D-optimal design concept based on minimization of the generalized variance of the parameter estimates. The objective of this work was to use this methodology for the design of experiments for microbial inactivation processes described by a Gompertz-based model under isothermal and non-isothermal conditions. The application of D-optimal design concept considerably improved parameters precision, when compared to the commonly used heuristic designs.
Unidades organizacionais
Descrição
Palavras-chave
Contribuidores
Financiadores
Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
6817 - DCRRNI ID
Número da atribuição
PEst-OE/EQB/LA0016/2011