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Composite adsorbent comprised of curdlan (CURD) and sodium carboxymethylcellulose (CMC) were fabricated through a single-step heating process, targeting the removal of methylene blue (MB) from wastewater. The CURD/CMC composite adsorbents had a honeycomb porous structure. The integration of CMC not only increased the storage modulus of the CURD/CMC composite hydrogels but also affected the thermal stability and swelling behavior of the composite adsorbents in different pH solutions. Specifically, the addition of 1.2 % CMC increased the peak temperature (184.73 °C) of CURD/CMC composite adsorbent melting by 5.99 °C compared to CURD adsorbent. The addition of CMC improved the swelling ratio of the composite adsorbent at pH 3,7, and 12 with swelling ratio up to 918.07 %. The synergistic interaction between CURD and CMC led to an enhanced adsorption capacity of the aerogel for MB, achieving a maximum adsorption capability of 385.85 mg/g. Adsorption isotherm assessments further demonstrated that the Langmuir isotherm model well fitted the adsorption data of the composite adsorbent on MB. Collectively, these findings underscore the potential of the developed biodegradable adsorbents as promising adsorbents for efficiently eliminating organic dyes from water.

RESUMEN

Swelling behavior involves the process of starch granules absorbing enough water to swell and increase the viscosity of starch suspension under hydrothermal conditions, making it one of the important aspects in starch research. The changes that starch granules undergo during the swelling process are important factors in predicting their functional properties in food processing. However, the factors that affect starch swelling and how swelling, in turn, affects the texture and digestion characteristics of starch-based foods have not been systematically summarized. Compared to its long chains, the short chains of amylose easily interact with amylopectin chains to inhibit starch swelling. Generally, reducing the swelling of starch could increase the strength of the gel while limiting the accessibility of digestive enzymes to starch chains, resulting in a reduction in starch digestibility. This article aims to conduct a comprehensive review of the mechanism of starch swelling, its influencing factors, and the relationship between swelling and the pasting, gelling, and digestion characteristics of starch. The role of starch swelling in the edible quality and nutritional characteristics of starch-based foods is also discussed, and future research directions for starch swelling are proposed.

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In this study, the network strength of starch hydrogels was improved by adjusting the pH value (3-11.5) and adding iron ions (Fe3+), and the mechanical properties and swelling properties of the hydrogels were improved. The complex modulus of the starch hydrogel with a pH value of 11.5 and containing Fe3+ was above 3400 Pa. SEM showed that the hydrogel structure became more compact with the increase of pH value. In addition, the hardness of the hydrogel increased from 50.29 g at pH 3.0 to 215.1 g at pH 11.5, while the addition of 0.5 mol/L Fe3+ at pH 11.5 promoted a further hardness increase to 301.8 g. Moreover, the swelling rate of the hydrogel decreased from 670.2 % at pH 7.0 to 464.4 % at pH 11.5, and the addition of 0.5 mol/L Fe3+ further decreased the swelling rate to 191.8 %. Overall, the results indicate that the mechanical properties of starch hydrogels can be improved by making simple adjustments to the pH and the iron ion concentrations.

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Although synthetic polymer hydrogels have excellent mechanical properties, they are not easily degraded, are toxic, and easily cause environmental pollution. Therefore, starch-based hydrogels have attracted great interest due to their biodegradability, biocompatibility, and non-toxicity. First of all, this review describes in detail the preparation of starch-based hydrogels by physical retrogradation method and chemical crosslinking methods, as well as the intrinsic and extrinsic factors that affect the performance of the hydrogels. Moreover, the commonly used methods to characterize starch-based hydrogels and the properties of responsive (thermo-, pH-, and enzyme-responsive) starch-based hydrogels have also attracted wide attention from researchers. In addition, the applications of starch-based hydrogels in starch noodles, treatment of sewage from the food industry, and food bioactive ingredient carriers are discussed. Furthermore, prospects and future directions of starch-based hydrogels are discussed. We believe that this review provides a valuable reference for the efficient preparation and application of starch-based hydrogels.

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This study aimed to enhance the content of slowly digestible starch (SDS) and resistant starch (RS) by designing a type of novel shell-controllable calcium alginate/curdlan/corn starch@calcium alginate (CA/CL/CS@CA) core-shell structured macrocapsule. These macrocapsules were obtained by coating calcium alginate/curdlan/corn starch beads with different concentrations of sodium alginate. The results of the swelling power indicated that as the concentration of sodium alginate in the shell increased from 0% to 0.5%, the swelling degree of the macrocapsules at 95 °C decreased from 5.64 ± 0.09 g/g to 4.30 ± 0.12 g/g. The in vitro digestion experiments indicated that the content of SDS and RS of the macrocapsules at a sodium alginate concentration of 0.5% reached 42.21 ± 1.04% and 28.82 ± 1.05%, respectively. These results suggest that the CA/CL/CS@CA core-shell structured macrocapsules have the potential to be used as functional foods for cardiovascular disease, diabetes, and obesity patients.