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Water desorption (closed symbols) and adsorption (open symbols) isotherms of seaweed Mastocarpus stellatus at different temperatures: 5 °C (♦), 25 °C (▲), 45 °C (■) and 65 °C (●). Lines correspond to Eq. (12), 5 °C (──), 25 °C (···), 45 °C (− · -) and 65 °C (─ ─)
Source publication
Water sorption isotherms from 5 up to 65 °C and air drying kinetics at 35, 45 and 55 °C of Mastocarpus stellatus seaweed were determined. Experimental sorption data were modelled using BET and Oswin models. A four-parameter model, based on Oswin model, was proposed to estimate equilibrium moisture content as function of water activity and temperatu...
Citations
... The results of the sorption isotherm indicate a characteristic behavior of biological origin products, such as polysaccharides extracted from seaweed, including carrageenan Oliveira et al. 2019), furcelaran (Eha et al. 2022), Mastocarpus stellatus (Arufe et al. 2018), dried persimmon leaves (Martínez-Las Heras et al. 2014), and carob powder (Červenka et al. 2019). Despite the parameter C having relatively high values, this behavior has been observed in other studies, such as in powders from the microalga Chlorella pyrenoidosa (Cheng et al. 2023) and yerba mate (Červenka et al. 2015). ...
Global consumption of nori, a widely consumed commercial edible algal film, is predominant in Asian countries. As the demand for Asian cuisine rises in Brazil, there is a growing need to explore alternatives to importation, such as producing edible films using seaweeds from the Brazilian coast—specifically Ulva lactuca and Kappaphycus alvarezii. In this study, seaweed film formulations varied in concentrations, from 80% U. lactuca and 20% K. alvarezii to an equal proportion of 50% of each alga, heating at 90°C for 3 and 5 minutes. Results showed that the filmogenic suspensions had a pseudoplastic behavior, with viscosity decreasing as K. alvarezii concentration increased. The resistance of heated gels increased with higher K. alvarezii concentrations and prolonged heating times. Surface uniformity improved with elevated K. alvarezii concentration and extended heating time. As K. alvarezii concentration increased, films exhibited less intense coloration, heightened transparency, and increased solubility. Films with higher K. alvarezii content demonstrated greater tensile strength, albeit without an increase in elongation capacity. Sorption isotherms exhibited a characteristic Type II pattern, and modeling using the GAB model suggested stronger bonds in treatments with extended heating times. Despite the need for enhanced flexibility, the results indicate potential applications in snacks or as alternatives to nori. Notably, these films were produced solely with seaweeds and water, aligning with Nori's minimalistic approach. Treatments with a concentration of 60% U. lactuca and 40% K. alvarezii proved to be the most promising. This study lays the groundwork for future research in developing edible films derived from seaweeds.
Graphical abstract
... Effective moisture diffusivities constitute basic elements for the dimensioning of an industrial dryer (Gupta et al. 2011). Some studies have been focused on seaweeds' drying but only a few on the process' modelling Vega-Gálvez et al. 2008;Moreira et al. 2016;Arufe et al. 2018;Le Loeuff et al. 2021). The impact of drying on seaweed composition is more widely studied in the literature. ...
... For example, for a brown species (Macrocystis pyrifera) Vega-Gálvez et al. (2008) determined the coefficient for temperature varying between 50 °C and 80 °C and obtained a value of 0.56 ± 0.04 × 10 -8 m 2 s −1 at 50 °C during convective tray drying at 2.1 ± 0.2 m s −1 . The drying of the red seaweed M. stellatus in a tray dryer with an air velocity of 2 m s −1 at 35, 45 and 55 °C resulted in a diffusion coefficient between 2.7 × 10 -8 to 4.6 × 10 -8 m 2 s −1 (Arufe et al. 2018). D app calculated for air impingement drying are significantly higher than the ones identified for oven drying. ...
Human populations in the Caribbean region, suffer recurrently for 12 years from brown tides followed by significant strandings of Sargassum spp. which cause environmental, economic and health issues. Given current interest in new renewable sources of chemicals, proteins, and polymers, this underexploited biomass represents a potential source to be explored in a biorefinery concept. Up the value chain in biorefinery process, seaweeds should be rapidly stabilised. Stabilisation by drying would permit to reduce the storage and transport costs and to obtain a product stable all year round. The aim of this work was to investigate oven drying and air impingement drying at two air velocities (7 and 21 m s⁻¹) on three species of Sargassum: S. fluitans III, S. natans I and S. natans VIII. The drying kinetics were studied. The apparent diffusivity coefficients were calculated thanks to the Fick’s diffusional model. Seven thin-layer equations were used to fit drying kinetics, namely Page, Modified Page, Diffusion approach, Verma, Two-term, Midilli-Kucuk and Henderson-Pabis modified. Freeze-drying, as a reference drying method, was applied on Sargassum in order to compare the effects of drying processes on several phytochemical components, which are neutral sugars, proteins, polyphenols, uronic acids and mineral matter. According to these results, air impingement drying was the better process to dry these three Sargassum species, but it also depended on the seaweed chain of valorisation after the stabilisation process.
... Tables 5 and 6 show that all four sorption models evaluated fitted the data well, although the Oswin and Halsey models performed marginally poorer than the Caurie model. Previous seaweed desorption studies have not observed a significant performance variation between models tested (Arufe, Torres, Chenlo, & Moreira, 2018;Moreira, Chenlo, Sineiro, Sánchez, & Arufe, 2016). ...
The Northern Periphery and Arctic region faces unique economic and food security challenges that may be partly answered by commercial seaweed production. Alaria esculenta and Palmaria palmata are two seaweeds commonly found in the region and suitable for cultivation and processing for food and other commercial products. The drying kinetics for both species were obtained, and the Page and Weibull models best described the data. A drying air temperature increase from 40 to 70°C decreased drying time by 62.4% and 61.7% for A. esculenta and P. palmata, respectively. Desorption isotherms were obtained between 25 and 70°C and showed Brunauer Category III shapes, with water activity increasing with temperature for a fixed moisture content. Net heats of desorption were obtained, with drying to an equilibrium moisture content of 0.01 kgwater kgd.b.–1 requiring 18.1 and 3.94 kJ mol–1 K–1 for A. esculenta and P. palmata, respectively.
... 10 phenomenon has been previously described in different dehydrated marine algae such as Mastocarpus stellatus (red alga), 35 Fucus vesiculosus seaweed (brown alga), 36 Bifurcaria bifurcata (brown alga), 37 and Ulva spp. (green algae). ...
The green algal genus Ulva grows widely on all continents and is used for several applications such as functional foods, cosmeceuticals, nutraceuticals, and pharmaceuticals due to its nutritional characteristics. However, to increase its shelf-life and retain its bioactive components, it is necessary to apply some conservation technology, such as drying. The aim of this work is to describe the drying kinetic behavior of the green seaweed Ulva spp. by applying three dehydration methods: convective drying (CD), vacuum drying (VD), and solar drying (SD) by mathematical modeling and determining the retention of mineral content by atomic absorption spectroscopy and the antimicrobial potential against four strains such as Staphylococcus aureus, Escherichia coli, Saccharomyces cerevisiae, and Penicillium sp. by measurement of inhibition zones and α-glucosidase activity inhibition, as reported by IC50 determination. A freeze-dried sample was used as the control. The equilibrium moisture values calculated using the Guggenheim-Anderson-de Boer model were 0.0108, 0.0108, and 0.0290 g water/g d.m., for CD, VD and SD, respectively. The Midilli and Kucuk model showed robustness to fit all the experimental data of drying kinetic modeling. Ulva spp. is an important source of potassium with a ratio of Na/K < 0.29. Inhibition halos were observed in all samples against S. cerevisiae and Penicillium sp. with higher values than fluconazole action. An inhibitory effect on α-glucosidase activity was observed in all samples, mainly in the freeze-dried sample. Finally, dried Ulva spp. is a rich source of macro- and microminerals with antimicrobial activity and is a potential α-glucosidase inhibitor. Thus, it can be considered as a potential functional ingredient for food manufacturing.
... As expected, k parameter dropped from freeze to conventional drying and to MHG processing, involving a notably decrease in required processing time. The values for the conventional procedure are consistent with those previously reported for other similar carragenophyte seaweeds as Mastocarpus stellatus (Arufe et al., 2018). ...
Dehydration of the edible seaweed Chondrus crispus was performed by freeze-drying, conventional oven-drying and emerging microwave hydrodiffusion and gravity (MHG). In this work, the drying kinetics and modelling, estimating specific energy consumption and environmental impact of distinct processes were tested. Color and microstructural features of the dried macroalgae were also evaluated, as well as their nutritive characterization, chemical profile and bioactive potential (antioxidant and antimicrobial activities). Moreover, collected liquid phases from both the defrosted and MHG treated samples were also characterized. All methodologies provided solid phases with an adequate final moisture content. MHG significantly reduced the needed time, specific energy consumption and environmental impact, providing C. crispus with intermediate color and histological structure characteristics. Overall, this trend was also defined to tested chemical parameters and bioactivities. MHG provided aqueous extracts with potential bioactive compounds from this red alga, increasing the efficiency of this drying method.
... Similar results were observed for different brown algae [6, 9-11, 18, 19] and for a red alga [23]. As intuited on the drying kinetics, the influence of the air velocity at 40°C is particular. ...
The impact of air velocity and temperature on the drying curves of the invasive brown alga Sargassum muticum was studied. An air impingement dryer was used at five air velocities (7, 14, 21, 28 and 35 m s⁻¹) at 40 °C and at four air temperatures (40, 50, 60 and 70 °C) at 35 m s¹. Equilibrium moisture content was properly modeled by Oswin, Halsey and GAB models. Fick‧s diffusional model was applied to identify the apparent moisture diffusivity. The variation of the diffusivity versus the temperature and the velocity were determined. Three semi-empirical expressions, namely Page, Twoterm and Henderson-Pabis modified equations were selected to fit the drying kinetics. Two-term equation was the most appropriate to model the experimental data.
... Carrageenans are classified under hydrocolloids sourced from certain red seaweeds, the Rhodophyceae class algae that belong to the genera Hypnea, Eucheuma, Gigartina, Chondrus and Lridaea 9,10 . k-Carrageenan is specially procured from the extraction of the Kappaphycus alvarezii tropical seaweed, generally known as Eucheuma cottonii. ...
______________________________________________________________________________________________________ The purpose of present exploration was to modify kappa (k)-Carrageenan, by crosslinking, and assessed it as a tablet disintegrant to strengthen the solubility of the drug (aceclofenac) in tablet formulation. Modified k-Carrageenan was synthesized by reacting it with epichlorhydrin at heterogenous conditions. The swelling action of the product was investigated in order to optimize reaction circumstances for chemical cross-linking. Best modified k-Carrageenan procured by optimizing the reaction conditions and it was characterized for swelling index, particle size distribution, solubility, viscosity, gel strength and Fourier transform infrared spectroscopy (FTIR). Influence of modified k-Carrageenan on dissolution profile of therapeutic was also investigated along with other evaluation parameters. Modified k-Carrageenan exhibiting significant swelling index which is comparable to that of superdisintegrants. On comparative investigation as a tablet disintegrant by preparing anhydrous dicalcium phosphate tablet, modified k-Carrageenan showed disintegration time less than 20 seconds. Dissolution of aceclofenac (Class II) tablet formulaion utilizing modified k-Carrageenan was comparable with commercially available superdisintegrants. Faster dissolution of the accommodated drug was achieved with modified k-Carrageenan which was comparable with dissolution of the tablet formulation containing other superdisintegrants. The competent concentration of k-Carrageenan was found to be 5-15% as tablet disintegrant. Modified k-Carrageenan might be encouraging tablet disintegrant in fast dissolving formulations and can be worn in direct compression method.
... The adsorption and desorption isotherms of modified cassava flour at the three temperatures (27,40 and 50°C) were evaluated using the static gravimetric method previously used for agricultural-based products, e.g. carrot, pumpkin, and blueberry [18], tomato [19], bay laurel leaves [20], oak wood [21], Mastocarpus stellatus seaweed [22], bovine leather [23], apples [24], and green tea leaves [25]. In the present work, the experiments were conducted with six saturated salt solutions, i.e. ...
Modified cassava flour is produced by drying processes and usually, in Indonesia, stored for several months after production up to selling and utilization. During storage, flour can experience degradations in quality, particularly if ambient conditions are unfavorable. In the present study, the adsorption and desorption isotherms of modified cassava flour were determined over a range of water activities (aw) from 0.05 to 0.84 at three different temperatures (27, 40 and 50°C), which are commonly experienced in the tropical environment, using the static gravimetric method. The suitability of eight widely recommended mathematical models in the literature for food sorption isotherms were investigated. The modified cassava flour shows a type II (sigmoid) isotherm curve and the moisture sorption hysteresis loop was observed at all examined temperatures. The effect of the temperature on both adsorption and desorption isotherms for the complete range of water activity (aw) was observed. Adsorption and desorption data of modified cassava flour were best fitted by the Henderson, Peleg, and Chung-Pfost models at 27, 40 and 50°C, respectively. According to the adsorption results, the moisture content of modified cassava flour should not be higher than 9.34% (db) at room temperature (27°C) to ensure microbial stability during storage.
... Through Figure 2, it can be verified temperature influence over the sorption isotherms of paddy rice grain, since it requires an increment of water activity in order to attain the same equilibrium moisture content for increasing temperature. Recent studies reported the same behavior for different agricultural products Oliveira et al., 2017b;Zeymer et al., 2017;Arufe et al., 2018;Espinosa-Andrews & Rodríguez-Rodríguez, 2018). García-Pérez et al. (2008) argue that as temperature rises, there is an increase of the molecular disorder degree of water present at the adsorbent surface, leading to instability and facilitating the breakage of intermolecular connections between water molecules and sorption sites, thus allowing water vaporization and, consequently, decreasing equilibrium moisture content. ...
Knowledge on sorption isotherms is important for predicting drying and storage processes of a product. A sorption isotherm can be generated from two processes: desorption and adsorption. The lag between these two curves is called hysteresis. Static method was used to obtain the equilibrium moisture content of paddy rice grains, in different temperature (10, 20, 30, 40 and 50 ± 1°C) and relative humidity (between 11 and 76% ± 2%) conditions. Equilibrium moisture content data were correlated with eight mathematical models and. The Chung Pfost model had the best fit to the experimental data. Desorption and adsorption isotherms, represented by the Chung Pfost model, showed a sigmoidal shape, characteristic of type II curve. Equilibrium moisture content values obtained by desorption were higher than those obtained by adsorption, evidencing the hysteresis phenomenon.
