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- Microstructural, physicochemical and sensorial effects of pears (cv. Rocha) stored under controlled atmosphere conditionsPublication . Galvis-Sánchez, Andrea C.; Teixeira, Claudia; Fonseca, Susana C.; Malcata, F. Xavier
- 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.
- Automatic standard addition method for potentiometric fluoride determination at low levels in food productsPublication . Galvis-Sánchez, Andrea; Santos, João Rodrigo; 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.
- A total analytical system featuring a novel solid–liquid extraction chamber for solid sample flow analysisPublication . Galvis-Sánchez, Andrea C.; Santos, João Rodrigo; Rangel, António O. S. S.In this work, a total flow analysis system based on a novel solid–liquid extraction chamber is presented. This strategy enables all the main experimental procedures for the analysis of a solid sample to be performed automatically: enrichment of the liquid extract, sample treatment, filtration of the liquid extract from the solid sample, directing the extract towards detection, and finally cleansing of the chamber for the following solid sample to be analyzed. The chamber designed to be incorporated in the flow manifold presents two main features: it accommodates stirring bars for enhancing the extraction process, and it presents replaceable solid sample containers (a spare part of the solid–liquid extraction chamber) to easily replace the solid sample and therefore enhance sample analysis throughput. The chamber performance was assessed using two different solid samples, an ion exchanger resin and vegetable samples, focussing on proton and nitrate on extraction, respectively. The main figures of merit achieved were relative standard deviation (RSD) and relative error values below 7 % for all determinations. The determination rate for vegetable samples was ca. 12 samples h−1. The proposed strategy may be exploited to perform automatically the analysis of solid samples as it embodies a simple automatic strategy of a very important but time consuming and laborious analytical operation.
- Effects of controlled atmosphere (ca) storage on pectinmethylesterase (PME) activiy on texture of "Rocha" pearPublication . Galvis-Sanchez, A. C.; Morais, Alcina M. M. B.
- Effect of different levels of CO2 on the antioxidant content and the polyphenol oxidase activity of ‘Rocha’ pears during cold storagePublication . Galvis-Sánchez, Andrea C.; Fonseca, Susana C.; Gil-Izquierdo, Ángel; Gil, María I.; Malcata, F. XavierAbstract: Pears (Pyrus communis L. cv. ‘Rocha’) were exposed to air or controlled atmosphere (CA) containing various concentrations of CO2: 0, 0.5 and 5 kPa, all with 2 kPa O2. After 4months of storage at 2 ◦C, the fruits were transferred to air at room temperature, and assessed in terms of soluble solids, titratable acidity, pH, incidence of brown heart and flesh browning, phenolic content, vitamin C content and polyphenol oxidase activity. By 4months of storage, soluble solids and pH increased, and acidity decreased relative to harvest, but no differences were detected between pears stored under air or any of the CA tested. Higher contents of hydroxycinnamic derivatives and flavan-3-ols in the peel than in the flesh were recorded. However, the content of arbutin was higher in the flesh than in the peel, whereas flavonols were only detected in the peel. In general, hydroxycinnamic derivatives and flavonols were stable throughout storage, but flavan-3-ols decreased in concentration under air or CA. Arbutin was the only phenolic compound that increased in concentration as time elapsed. No clear relation was found between the storage conditions tested and the phenolic concentration in pears. Regarding ascorbic acid (AA) and dehydroascorbic acid (DHA), their concentrations were higher in the peel than in the flesh. Furthermore, AA and DHA were strongly affected by storage: the former decreased, whereas the latter increased in content. A decrease in PPO activity was apparent after harvest and during storage, particularly under higher levels of CO2. The combination 2 kPa O2 + 5kPa CO2 increased the incidence of internal disorders (viz. brown heart and flesh browning) after storage.
- Sea saltPublication . Galvis-Sánchez, Andrea C.; Lopes, João Almeida; Delgadillo, Ivone; Rangel, António O. S. S.The geographical indication (GI) status links a product with the territory and with the biodiversity involved. Besides, the specific knowledge and cultural practices of a human group that permit transforming a resource into a useful good is protected under a GI designation. Traditional sea salt is a hand-harvested product originating exclusively from salt marshes from specific geographical regions. Once salt is harvested, no washing, artificial drying or addition of anti-caking agents are allowed; then, other salts associated with sodium chloride are also maintained. Two quality types of salt can be commercially considered: ‘flower of salt’ and salt, which have distinctive physico-chemical characteristics. The application of analytical methodologies such as atomic spectroscopy, molecular spectroscopy, separation techniques and flow injection systems coupled with chemometric tools can provide significant evidence of sea salt uniqueness, give precise and concise information and promote fair competition in the market, bringing benefits for the producers and consumers.