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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.
- Combined effect of pressure and temperature for yogurt productionPublication . Lopes, Rita P.; Mota, Maria J.; Sousa, Sérgio; Gomes, Ana M.; Delgadillo, Ivonne; Saraiva, Jorge A.Fermentation under non-conventional conditions has gained prominence in the last years, due to the possible process improvements. Fermentation under sub-lethal pressures is one of such cases, and may bring novel characteristics and features to fermentative processes and products. In this work, the effect of both pressure (10–100 MPa) and temperature (25–50 °C) on yogurt production fermentation kinetics was studied, as a case-study. Product formation and substrate consumption were evaluated over fermentation time and the profiles were highly dependent on the fermentation conditions used. For instance, the increase of pressure slowed down yogurt fermentation, but fermentative profiles similar to atmospheric pressure (0.1 MPa) were obtained at 10 MPa at almost all temperatures tested. Regarding temperature, higher fermentative rates were achieved at 43 °C for all pressures tested. Moreover, the inhibitory effect of pressure increased when temperature decreased, with complete inhibition of fermentation occurring at 50 MPa for 25–35 °C, contrasting to 43 °C where inhibition occurred only at 100 MPa. Therefore, an antagonistic effect seems to occur, since yogurt fermentation was slowed down by pressure increasing, on one hand, and by temperature decreasing, on the other hand. Additionally, some kinetic parameters were calculated and fermentation at 43 °C presented the best results for yogurt production, with lower fermentation times and higher lactic acid productivities. Interestingly, fermentation at 10 MPa/43 °C presented the optimal conditions, with improved yield and lactic acid production efficiency, when compared to fermentation at 0.1 MPa (efficiency of 75% at 10 MPa, against 40% at 0.1 MPa). As the authors are aware, this work gives the first insights about the simultaneous effect of pressure and temperature variation on a microbial fermentation process, which can be combined to modulate the metabolic activity of microorganisms during fermentation in order to improve the fermentative yields and productivities of the desired product.
- Physicochemical and microbial changes in yogurts produced under different pressure and temperature conditionsPublication . Lopes, Rita P.; Mota, Maria; Pinto, Carlos A.; Sousa, Sérgio; Silva, José A. Lopes da; Gomes, Ana M.; Delgadillo, Ivonne; Saraiva, Jorge A.Variations on fermentation conditions (temperature, pressure, etc.) can bring novel characteristics to fermentative processes and the respective final products. Regarding yogurt, both bacteria metabolism and physical properties of gel may be affected, resulting in different yogurts. Therefore, lactic acid fermentation was performed under different combinations of pressure (0.1, 10 and 30 MPa) and temperature (35, 43 and 50 °C), and microbiological and physical properties of the yogurts obtained were analyzed. Fermentation conditions affected the microbial growth, with Streptococcus thermophilus being more sensitive to the combination of high temperatures and pressures than Lactobacillus bulgaricus. Regarding physical properties, both syneresis and texture were influenced by fermentation conditions. Yogurts fermented at 10 MPa presented interesting features, with syneresis similar to control yogurts and a firm texture. Therefore, the fermentative conditions can be changed not only to regulate the fermentation kinetics, but also to produce a final product with different properties. Therefore, this approach opens the possibility of applying this type of strategy to a wide range of food fermentative processes, with potential to improve food quality and to create and develop food products with novel characteristics.
- 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.
- 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.
- Application of high pressure with homogenization, temperature, carbon dioxide, and cold plasma for the inactivation of bacterial spores: a reviewPublication . Lopes, Rita P.; Mota, Maria J.; Gomes, Ana M.; Delgadillo, Ivonne; Saraiva, Jorge A.Formation of highly resistant spores is a concern for the safety of low-acid foods as they are a perfect vehicle for food spoilage and/or human infection. For spore inactivation, the strategy usually applied in the food industry is the intensification of traditional preservation methods to sterilization levels, which is often accompanied by decreases of nutritional and sensory properties. In order to overcome these unwanted side effects in food products, novel and emerging sterilization technologies are being developed, such as pressure-assisted thermal sterilization, high-pressure carbon dioxide, high-pressure homogenization, and cold plasma. In this review, the application of these emergent technologies is discussed, in order to understand the effects on bacterial spores and their inactivation and thus ensure food safety of low-acid foods. In general, the application of these novel technologies for inactivating spores is showing promising results. However, it is important to note that each technique has specific features that can be more suitable for a particular type of product. Thus, the most appropriate sterilization method for each product (and target microorganisms) should be assessed and carefully selected.
- 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.
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