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- 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.
- The use of fourier-transform near and mid-infrared spectroscopy for sea salt quality characterizationPublication . Galvis-Sánchez, Andrea C.; Lopes, João Almeida; Delgadillo, Ivonne; Rangel, António O. S. S.
- Development of a Turbidimetric Sequential Injection System to Monitor the Codfish Desalting ProcessPublication . Santos, Inês C.; Mesquita, Raquel B. R.; Galvis-Sánchez, Andrea C.; Delgadillo, Ivonne; Rangel, António Osmaro S. S.Salt-cured codfish represents an ancient process of preservation but requires the rehydration of the codfish with the correspondent salt removal. This work describes the development of a sequential injection system for the online turbidimetric determination of chloride during a simulated desalting process. The samples are directly aspirated to the manifold with no need for previous offline treatments; this was possible due to the use on an inline dialysis process; a quantification range from 50.0 mg/L to 20.0 g/L was established using the same manifold configuration. For monitoring the entire process, involving several chloride determinations (ca. 10), less than 3 mL of the desalting water was needed. Furthermore, the overall reagent consumption was quite low: 0.211 mg of AgNO3, 30.6 mg of HNO3, and 31.1 μg of PVA per determination. The accuracy of the system was evaluated by comparison with a potentiometric reference method. The determination rate was 28 and 31 h−1 according to the chloride concentration range. Several simulated desalting processes, under different conditions, were effectively monitored with the developed method.
- Fourier transform near-infrared spectroscopy application for sea salt quality evaluationPublication . Galvis-Sanchez, Andrea C.; Lopes, João Almeida; Delgadillo, Ivonne; Rangel, António O.S.S.Near-infrared (NIR) spectroscopy in diffuse reflectance mode was explored with the objective of discriminating sea salts according to their quality type (traditional salt vs "flower of salt") and geographical origin (Atlantic vs Mediterranean). Sea salts were also analyzed in terms of Ca2+, Mg2+, K+, alkalinity, and sulfate concentrations to support spectroscopic results. High concentrations of Mg2+ and K+ characterized Atlantic samples, while a high Ca2+ content was observed in traditional sea salts. A partial least-squares discriminant analysis model considering the 8500-7500 cm(-1) region permitted the discrimination of salts by quality types. The regions 4650-4350 and 5900-5500 cm(-1) allowed salts classification according to their geographical origin. It was possible to classify correctly 85.3 and 94.8% of the analyzed samples according to the salt type and to the geographical origin, respectively. These results demonstrated that NIR spectroscopy is a suitable and very efficient tool for sea salt quality evaluation.
- Espectrometría de infrarrojo y análisis en flujo para la determinación de compuestos químicos en alimentosPublication . Galvis-Sánchez, Andrea C.; Tóth, Ildikó V.; Ganito, Susana; Delgadillo, Ivonne; Rangel, António O. S. S.
- Evaluation of some of the main inorganic ions in brine solutions used for sea salt production by flow injection analysis and fourier-mid infrared spectroscopyPublication . Galvis-Sánchez, Andrea C.; Santos, Inês C.; Mesquita, Raquel B. R.; Lopes, João A.; Delgadillo, Ivonne; Rangel, António O. S. S.
- Infrared spectroscopy and flow analysis for the determination of chemical constituents in food productsPublication . Galvis-Sánchez, Andrea C.; Tóth, Ildikó V.; Ganito, Susana; Delgadillo, Ivonne; Rangel, António O. S. S.
- Development of methods for monitoring cod desalting process based on flow injection analysis and fourier-mid infrared spectroscopyPublication . Galvis-Sánchez, Andrea C.; Tóth, Ildikó; Ganito, Susana; Delgadillo, Ivonne; Rangel, António O.S.S.
- Monitoring sodium chloride during cod fish desalting process by flow injection spectrometry and infrared spectroscopyPublication . Galvis-Sánchez, Andrea C.; Tóth, Ildikó V.; Portela, Ana; Delgadillo, Ivonne; Rangel, António O. S. S.In order to adapt to the market trends that are moving towards ready-to-use products cod !sh industry is including into their industrial operations as the desalting step. The desalting process is a high cost and time demanding operation. The optimization of the desalting process is of vital importance for the !sh industry in order to assure the homogeneity and predictable concentration of sodium chloride in the !nal hydrated cod !sh product. On the other hand, consumers are more aware about the necessity to bring sodium consumption down to healthy levels to prevent cardiovascular diseases. The application of rapid and simple analytical methodologies that permit the control of the process and ensure food quality is essential in the food industries. This work reports the optimization and application of two analytical methodologies with the objective of monitoring the variation of sodium chloride concentration during cod desalting process. A "ow injection analysis system was developed based on the reaction between chloride and silver nitrate, and the formed precipitate was assessed spectrophotometrically as a turbidity change. A Fourier-mid infrared spectroscopy attenuated total re"ection method was also applied. Different chemical and physical parameters of the "ow injection system were studied and the analytical characteristics of both systems were compared.
- Development of two methods for monitoring codfish desalting process based on flow injection analysis and Fourier-mid infrared spectroscopyPublication . Galvis-Sánchez, Andrea C.; Tóth, Ildikó V.; Ganito, Susana; Delgadillo, Ivonne; Rangel, António O. S. S.