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Hexadecyltrimethylammonium bromide complexed alginate-Ca 2+ microgels (C/AMGs) were developed as emulsifiers, which shown remarkably improved emulsifying performance than non-complexed alginate-Ca 2+ microgels (AMGs) in previous study. This work focus on the impact of deformability on the emulsifying performance of C/AMGs. By regulating alginate concentration (1.0-4.0 wt%), microgels with different deformability were prepared. Deformability was proved to have great influence on the emulsifying performance of C/AMGs, which was evaluated by Langmuir trough measurements, emulsion appearance, centrifugation stability, digestive behavior, and oxidative stability. Particle size and SEM images indicated microgels prepared with lower alginate concentration are more deformable. C/AMGs (2.0 wt%) exhibits the best emulsifying performance, which could be ascribed to the appreciated deformability and mechanical strength. Digestive behavior and oxidative stability of alginate-Ca 2+ microgel (2.0 wt%) stabilized emulsions were further investigated. Compared with alginate-Ca 2+ microgel (2.0 wt%) stabilized emulsions, C/AMGs (2.0 wt%) stabilized emulsions shown delayed lipid digestion and lower POV. Results of this work supporting that Mickering mechanism have potential in fabricating functional emulsions based on natural polysaccharides., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

Slow fermentable dietary fibers can be utilized by human gut microbiota in the distal region of the colon and thus exert a sufficient short-chain fatty acids (SCFAs) supplement in the distal region of the human colon. Alginate (Alg) based microgels are widely fabricated and used to control their digestion by digestive enzymes releasing active substances site-specifically. Herein, sodium alginate microgels with gradient calcium-ion (Ca 2+ ) cross-linking densities were developed, restricting their degradation by gut microbiota. Alg microgels were prepared using high-speed shearing after Alg was cross-linked with 10, 40, and 60 mmol/L Ca 2+ , respectively (named 10-Alg, 40-Alg, and 60-Alg). The fluorescence and atomic force microscopic results showed that the 40-Alg particle has the densest structure among the three cross-linked Alg. In vitro human fecal fermentation results revealed that the Ca 2+ cross-linking exerted more restricting effects than delaying effects on the fermentation of Alg, and the 40-Alg exhibited the slowest fermentation rate and the least fermentation extent, by characterizing the residual total carbohydrate content, residual monosaccharide content, pH, and total short-chain fatty acids. The 16S rRNA gene sequencing results indicated that cross-linking structures shaped a high specifical Bacteroides-type microbial community and that OTU205 (Bacteroides_xylanisolvens) highly correlated to the cross-linking density (R = 0.65, p = 0.047). In sum, Ca 2+ cross-linking generated a dense and compact structure of sodium alginate that facilitated a more restricted fermentation property and specificity-targeting microbial community structure in comparison to the original sodium alginate., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Ltd.)

Agarose microgels were prepared with bottom-up approach, and emulsifying properties of agarose microgels were investigated. Physical properties of microgels are varied with agarose concentration, and further affect the emulsifying performance of microgels. Enhanced surface hydrophobicity index and decreased particle size of microgels were recorded with the increasing of agarose concentration, which were conducive to emulsifying properties of microgels. Improved interfacial adsorption of microgels was evidenced by Dynamic surface tension and SEM. However, microscopic morphology of microgel at O/W interface indicated that increasing agarose concentration could weaken the deformability of microgels. The influence of external conditions (pH and NaCl) on the physical properties of microgels were investigated, and their effects on emulsion stability were evaluated. Compared with acidification, NaCl was appeared to be more destructive to emulsion stability. Results indicated acidification and NaCl could decrease surface hydrophobicity index of microgels, but there was differentiation in the variation of particle size. It was inferred that deformability of microgels could make contribution to the stability of emulsion. This study verified that microgelation was a feasible scheme to improve the interfacial properties of agarose, and the influence of agarose concentration, pH, and NaCl on the emulsifying performance of microgels was investigated., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Using non-amphiphilic polysaccharide to stabilize oil-in-water emulsions is still a challenge in food industry. Polysaccharide microgels showed emulsifying capacity, however, the stability of the formed emulsions is far from the requirements of the food industry. In this work, agarose microgel/Tween-20 suspensions were prepared and further employed in oil-in-water emulsion stabilization. Focuses were taken on the impact of Tween-20 on the emulsifying properties of agarose microgels. Results suggested that Tween-20 could complex with agarose microgels, and microamounts of Tween-20 (0.02 wt%) could apparently improve the emulsifying performance of microgels. Dynamic interfacial pressure and interfacial adsorption of microgels indicated that appropriate amount of Tween-20 (≤0.04 wt%) could benefit the interfacial adsorption of agarose microgels, while excessive Tween-20 (≥0.08 wt%) could compete with agarose microgels for adsorption sites on oil/water interface. Results of this work supporting that surfactant complexing could be a promising solution to prepare polysaccharides based Mickering emulsions. [ABSTRACT FROM AUTHOR]

In this research, sodium alginate (ALG) microgels were prepared with different ALG concentrations, and physicochemical and emulsifying profiles of these hydrophilic microgels were comparatively analyzed. Results showed that these microgels possessed different size, hardness, and surface charge. All these microgels could stabilize an oil-in-water emulsion through the Mickering mechanisms, and smaller microgels had better emulsifying capacity. The surface hydrophobicity and interfacial tension of the microgels had no exact effects on their emulsifying behaviors. Compared with the harder microgels (prepared with high ALG concentration, e. g. 4 mg/mL), the emulsifying capacities of the softer ones (prepared with low ALG concentration, e.g. 1 mg/mL) were more sensitive to the high salt concentration (200 mM NaCl) but stable under acidic environment (pH 2.0). Our research would afford a new strategy for the manufacture and application of the novel polysaccharide-based emulsifiers. [ABSTRACT FROM AUTHOR]

Although polysaccharide microgels exhibit potential as clean-label emulsifiers, the stability of emulsions in commercial application is still a challenge. The current work points out that specific complexation between polysaccharide molecules and polysaccharide microgels can benefit the interfacial adsorption of polysaccharide microgels and emulsion stability. The complexation of κ-carrageenan microgels (KCMs) and locust bean gum (LBG) was investigated for the first time, which was evaluated by visual appearance, rheological behavior, thermal stability, and microscopic morphology. Results indicate the low concentration of LBG promotes the clustering of KCMs, whereas high concentration of LBG can envelop and segregate KCMs. Subsequent blending with LBG could enhance the interfacial adsorption of KCMs, and multi-layers are observed when LBG concentration exceeds 0.3 wt%. LBG can obviously decrease the emulsion droplets size and improve the storage stability of emulsions, KCMs + LBG (0.2–0.5 wt%) stabilized emulsions could keep stable after three consecutive freeze-thaw cycles. Based on the specific complexation between KCMs and LBG, the layer-by-layer emulsification could be achieved. This strategy can inspire other polysaccharide microgel emulsifiers, which could be a feasible solution for improving the stability of polysaccharides microgels stabilized emulsions. [Display omitted] • Locust bean gum (LBG) could complex with κ-carrageenan Microgels (KCMs). • Complexation pattern of LBG and KCMs at aqueous phase was identified. • Interfacial complexation of LBG and KCMs improves emulsion stability. • Interfacial complexation endows emulsions with improved freeze-thaw stability. [ABSTRACT FROM AUTHOR]

In the current study, complexes (CAMs) of alginate microgels (AMs) and hexadecyltrimethylammonium bromide (CTAB) were prepared, and further used to stabilize O/W emulsions. Physical properties and emulsifying capacity of CAMs with different CTAB concentration were investigated, which indicated emulsifying capacity of AMs could be extensively improved by CTAB. Improved stability against centrifugation (3000 rpm), pH value (2.0–8.0), and NaCl concentration (0–200 mM) was also reported in CAMs stabilized emulsions. Interfacial adsorption and morphology observation suggested that the interfacial activities of CAMs were benefited from CTAB complexing, and an interfacial layer could be observed on the surface of the CAMs stabilized oil droplets. In this work, even a slight amount of surfactant (0.4 mM, or 0.01456 wt% CTAB) could make remarkable improvement on the emulsifying performance of alginate microgels. However, excessive CTAB would result in over aggregation of AMs, which was not conducive to the emulsifying performance of CAMs. This study proposed that the surfactant complexing was a feasible strategy to improve the emulsifying performance of polysaccharide microgels. [Display omitted] • Emulsions based on Ca2+-alginate microgels (AMs) were manufactured. • Slight CTAB was complexed with AMs (CAMs) to improve its emulsifying properties. • Excessive CTAB leads to deteriorated emulsifying properties of CAMs. • CAMs stabilized emulsions exhibit remarkable stability. [ABSTRACT FROM AUTHOR]