Water sorption isotherms of different sodium alginates : thermodynamic evaluation and influence of mannuronate-guluronate copolymers

Water desorption isotherms of three alginates with different structural features were determined at 25, 37, and 50°C. The Halsey model was selected to fit the equilibrium water sorption data. Differential and integral enthalpy and entropy were estimated for tested alginates. Optimal storage conditions of tested alginates (moisture content from 0.15 to 0.20 kg water/kg dry solid and relative humidity from 35% to 50%) were determined from the maximum and minimum integral enthalpy and entropy values, respectively. A model was proposed to estimate the water sorption isotherms of al-ginates based on the alginate monomers (mannuronate, M, and guluronate, G) at low water activity (<0.4). M fraction was mainly responsible for the hygroscopicity of algi-nates. Alginates with similar G fraction showed different hygroscopic features by the presence of more homopolymeric G blocks that could form helical structures at low moisture content, decreasing the water affinityAuthors acknowledge the financial support of the Spanish Ministry of Science and Innovation (Project RTI2018-095919-B-C2) and the European Regional Development Fund (FEDER) and Xunta de Galicia (Consolidation Project ED431B 2019/01)S

Influence of Oxidation and Dialysis of Phlorotannins on Bioactivity and Composition of Ultrasound-Assisted Extracts from Ascophyllum nodosum

The isolation and chemical characterization of phlorotannins has gained special attention in recent years due to their specific health-promoting benefits. Flow-cell ultrasound-assisted extraction (90 W/cm2 of sonication power, 2 min of retention time and 20 g solvent/g algae of liquid–solid ratio) was carried out by using double-distilled water (WE) and acetone:water mixture (AWE) as extraction solvents. The AWE showed a higher total polyphenols content (TPC), carbohydrates (CHOs) and antioxidant activities than WE. However, when the WE was purified by using Amberlite XAD16 column, the purified WE (PWE) showed similar a TPC, decreased CHOs and increased antioxidant activity compared to WE. The oxidation of the PWE extract was evaluated under natural, forced and severe oxidation condition for 120 h. Only severe oxidation conditions were able to significantly reduce TPC and antioxidant activities. PWE was dialyzed (20, 10, 3.5 and 2 kDa). The main bioactive fraction of phlorotannins was obtained from 10 to 20 kDa. CHOs were distributed in fractions below 20 kDa. MALDI-TOF analysis was performed for PWE, PD20 and PD2 extracts to analyze the degree of polymerization of phlorotannins, which ranged from 4 to 17 phloroglucinol units/molecule. Fragmentation patterns allowed the proximate identification of several phlorotannins in Ascophyllum nodosum extractsThis work was supported by the Ministry of Science and Innovation of Spain and European Regional Development Fund (ERDF) of European Union by the research project (RTI2018–095919–B–C2R) and Xunta de Galicia, Spain (Consolidation Project ED431B 2019/01).S

Determination of thermal transitions of gluten-free chestnut flour doughs enriched with brown seaweed powders and antioxidant properties of baked cookies

A protocol for determining the characteristic temperatures of thermomechanical transitions on gluten-free flour doughs is proposed. This protocol is based on the mathematical analysis of experimental curve of storage modulus (G0 ) vs temperature obtained by means of Dynamic Mechanical Thermal Analysis (DMTA) technique. Doughs at constant consistency of chestnut flour with different levels (3, 6 and 9% flour basis, f.b.) of brown seaweed (Bifurcaria bifurcata, Fucus vesiculosus and Ascophyllum nodosum) powders addition, 2% f.b. of guar gum and 1.8% f.b. of salt with different water absorption were used to test the proposed protocol. The ranges of temperatures corresponding to starch gelatinization (59–97 C), amylopectin crystallites melting (82–101 C), reversible dissociation of lipid-amylose complexes (107–128 C) and amylose melting (133–171 C) showed a strong dependence with water absorption of samples. Doughs with the same water absorption submitted to starch gelatinization during mixing were also analysed to corroborate the protocol suitability. Total polyphenols content and radical scavenging activity of extracts from chestnut flour-seaweed powder blends and seaweed-enriched chestnut cookies baked at 180 C were determined. Extraction assisted with ultrasounds was carried out employing acetone-water (70:30 v/v) solution as solvent during 4 min with a liquid/solid ratio of 30 w/w. Seaweed powder addition had a positive effect on antioxidant properties of doughs before baking. However, the seaweed powder addition effect on baked products (cookies) is not clear due to antioxidant activity is overlapped by Maillard's products generated during bakingThis work was supported by the Ministry of Economy and competitiveness of Spain and European Regional Development Fund (ERDF) of European Union by the research project (CTQ 2013–43616/P)S

Composition and abundance of benthic microalgae from the Estuarine Complex of Paranaguá Bay (southern Brazil) with special emphasis on toxic species

This study addressed the occurrence and distribution of benthic microalgae, with emphasis on toxic species, on differentsubstrates (macroalgae, seagrass and sediments) along the outer, euhaline zone of the Estuarine Complex of ParanaguáBay, southern Brazil, from July 2015 to May 2016. Canonical analysis of principal coordinates (CAP) was used to identifythe potential environmental drivers of microphytobenthic assemblage structure. A total of 18 potentially toxic benthicmicroalgae species were reported, including 7 dinoflagellates, 9 cyanobacteria, one diatom and one euglenophyte.The abundance of all potentially toxic microalgae varied consistently along the investigated period. Dinoflagellatesdominated the microalgae assemblage in July and September 2015. Mean densities on macrophytes ranged from 33.6cells g-1 in May 2016 to 775.6 cells g-1 in September 2015, being positively correlated with dissolved nitrogen-nutrients,water transparency, salinity, and chlorophyll-a. Prorocentrum cf. lima was the most frequent and abundant dinoflagellate.Overall, the highest abundance of toxic species occurred in February 2016, when cyanobacterial mats dominated byLyngbya cf. aestuarii were observed throughout the estuary associated with periods of heavier rainfall and higher turbidity(shallower Secchi depth). At that time, a selected microphytobenthic extract exhibited acute toxicity on nauplii of thebrine shrimp Artemia salina in the laboratory

Impact of drying on the sodium alginate obtained after polyphenols ultrasound-assisted extraction from Ascophyllum nodosum seaweeds

Ultrasound-assisted extraction (UAE) of polyphenols from the brown seaweeds Ascophyllum nodosum leaves a solid phase where alginates can be extracted. This study characterizes alginates extracted after the UAE process, with and without an intermediate drying stage at different temperatures (50 and 90 °C) producing sequentially two bioactive compounds from a unique raw material. FT-IR and 1H NMR analyses showed the high purity of alginates with features in the range of commercial alginates. Drying at high temperature decreased average block length and viscosity average molecular weight (Mv) of alginate from 428 to 133 kg/mol. Steady-shear curves (shear-thinning behaviour) and viscoelasticity (liquid like character) features depended clearly on Mv. Solutions of alginates with high Mv were more viscous and the elastic character was more relevant. Cox-Merz rule was only accomplished within the semi-dilute regimes of alginate concentration. Tested process conditions allow the production of alginates with different propertiesS

Antioxidant and Antidiabetic Properties of Phlorotannins from Ascophyllum nodosum Seaweed Extracts

Seaweeds have gained considerable attention in recent years due to their potential health benefits and high contents of bioactive compounds. This review focuses on the exploration of seaweed’s health-promoting properties, with particular emphasis on phlorotannins, a class of bioactive compounds known for their antioxidant and antidiabetic properties. Various novel and ecofriendly extraction methods, including solid–liquid extraction, ultrasound-assisted extraction, and microwave-assisted extraction are examined for their effectiveness in isolating phlorotannins. The chemical structure and isolation of phlorotannins are discussed, along with methods for their characterization, such as spectrophotometry, nuclear magnetic resonance, Fourier transform infrared spectroscopy, and chromatography. Special attention is given to the antioxidant activity of phlorotannins. The inhibitory capacities of polyphenols, specifically phlorotannins from Ascophyllum nodosum against digestive enzymes, such as α-amylase and α-glucosidase, are explored. The results suggest that polyphenols from Ascophyllum nodosum seaweed hold significant potential as enzyme inhibitors, although the inhibitory activity may vary depending on the extraction conditions and the specific enzyme involved. In conclusion, seaweed exhibits great potential as a functional food ingredient for promoting health and preventing chronic diseases. Overall, this review aims to condense a comprehensive collection of high-yield, low-cost, and ecofriendly extraction methods for obtaining phlorotannins with remarkable antioxidant and antidiabetic capacities.This work was funded by the Ministry of Science and Innovation of Spain and European Regional Development Fund (ERDF) of European Union by the research project (RTI2018-095919-B-C2).S

Performance of Starch Gels on In Vitro Enzymatic Hydrolysis Assessed by Rheological Methodologies

Starch hydrolysis is attracting much attention due to its relationship to digestion and glucose release. The objective is to propose rapid and continuous analytical methods that allow measuring gels hydrolysis following apparent viscosity (μ). Three different starches (corn, wheat, and rice) are tested recording starch gelatinization followed by gels digestions (digestograms) using a rapid-visco analyzer (RVA) or a rheometer. Results are compared with those obtained by measuring glucose release along hydrolysis. A modified first-order kinetic model in the RVA (R2 > 0.99) and rheometer (R2 > 0.99) describes the gels digestograms. Wheat gel shows a higher hydrolysis rate (k), which indicates faster digestion followed by rice and corn gels. The proposed models allow rapid analysis of starch digestograms, allowing to discriminate among hydrolysis rate of different starches. These less time-consuming methods can be an option to continuously analyze starch gelatinization followed by enzymatic digestion.Generalitat Valenciana (Prometeo 2017/189) and Xunta de Galicia (Consolidation Project ED431B 2019/01).S

Régimen de precipitaciones y evaporación para riego en el multipropósito Chone, Ecuador

Around 2250 ha will be developed from the agricultural point of view in Chone, province of Manabí, Ecuador, in the second stage of one of the emblematic and strategic projects of Ecuador, known as Multipurpose Chone. For this purpose, climatic and soil parameters, water availability, crops, etc. are required. This paper makes a contribution in the climatic branch. The monthly distributions of precipitation and evaporation are determined for the subsequent calculation of the crops irrigation regime. A statistical analysis of precipitation and evaporation data from 1990 to 2012 is accomplished, and as a main result is obtained that 2005 is the one meeting the 75 % of surpass probability for rainfall and 25 % for evaporation.. Index Terms— frequency distribution, normal distribution, cumulative frequency, Multipurpose Chon

Effect of air drying temperature on phytochemical properties of brown seaweed Bifurcaria bifurcata

[EN] The purpose of this study was to determine the effects of convective air-drying at different temperatures (35, 50, 60 and 75°C) on the color of Bifurcaria bifurcata (BB) seaweed powders obtained after milling, the antioxidant activity and polyphenolic and carbohydrate content of the aqueous extracts obtained by ultrasound-assisted extraction. BB seaweed powders exhibited significant color differences between powders obtained from BB dried at 35ºC (yellowish-green) and 50–75 °C (brown). High air drying temperature (above 60ºC) significantly reduced the total polyphenolic, carbohydrate content and scavenging activity of aqueous extracts of BB.The authors acknowledge the financial support of the Ministry of Economy and Competitiveness of Spain and European Regional Development Fund (ERDF) of European Union by the research project (CTQ 2013-43616/P).Arufe, S.; Sineiro, J.; Chenlo, F.; Moreira, R. (2018). Effect of air drying temperature on phytochemical properties of brown seaweed Bifurcaria bifurcata. En IDS 2018. 21st International Drying Symposium Proceedings. Editorial Universitat Politècnica de València. 865-872. https://doi.org/10.4995/IDS2018.2018.7496OCS86587

SOBRE LOS POLINOMIOS DE HERMITE Y SU CONVERGENCIA EN SERIE

In this paper we make a study of the results on the properties of the Hermite polynomials. These polynomials form a family of orthogonal polynomials with respect to the Gaussian measure and it is a closed system. We present the basic properties until we introduce the convergence of Fourier-Hermite series. We also present a definition for Hermite polynomials with a certain parameter, as an extension of these polynomials in the classical form, motivating to study complex Hermite poly- nomials and their properties.En este trabajo hacemos un estudio de los resultados sobre las propiedades de los polinomios de Hermite. Estos polinomios forman una familia de polinomios ortogonales respecto a la medida gaussiana y es un sistema cerrado. Presentamos las propiedades básicas hasta introducir la convergencia de series Fourier-Hermite. También presentamos una definición para polinomios de Hermite con cierto parámetro, como una extención de estos polinomios en la forma clásica, motivando a estudiar a los polinomios de Hermite complejo y sus propiedades