Polysaccharide–dextrin thickened fluids for individuals with dysphagia:Recent advances in flow behaviors and swallowing assessment methods

The global aging population has brought about a pressing health concern: dysphagia. To effectively address this issue, we must develop specialized diets, such as thickened fluids made with polysaccharide–dextrin (e.g., water, milk, juices, and soups), which are crucial for managing swallowing-related problems like aspiration and choking for people with dysphagia. Understanding the flow behaviors of these thickened fluids is paramount, and it enables us to establish methods for evaluating their suitability for individuals with dysphagia. This review focuses on the shear and extensional flow properties (e.g., viscosity, yield stress, and viscoelasticity) and tribology (e.g., coefficient of friction) of polysaccharide–dextrin-based thickened fluids and highlights how dextrin inclusion influences fluid flow behaviors considering molecular interactions and chain dynamics. The flow behaviors can be integrated into the development of diverse evaluation methods that assess aspects such as flow velocity, risk of aspiration, and remaining fluid volume. In this context, the key in-vivo (e.g., clinical examination and animal model), in-vitro (e.g., the Cambridge Throat), and in-silico (e.g., Hamiltonian moving particles semi-implicit) evaluation methods are summarized. In addition, we explore the potential for establishing realistic assessment methods to evaluate the swallowing performance of thickened fluids, offering promising prospects for the future

Biofunctional chitosan–biopolymer composites for biomedical applications

In light of escalating biomedical demands across diverse diseases, there arises a pressing need for the development of sophisticated biocompatible materials exhibiting augmented biological functionality. Chitosan, a cationic polyelectrolyte copolymer of natural origin, distinguishes itself through its extraordinary biological properties, positioning it as a promising starting material to develop versatile biomedical materials. Tremendous attention has been directed towards the creation of high-performance biocomposites, achieved through the strategic manipulation of chitosan’s structure or its derivative, along with the amalgamation of other biopolymers. This comprehensive review intricately explores recent advancements in chitosan-based biofunctional materials, delving into formulations involving various biopolymers including polysaccharides and proteins. It places specific emphasis on the progress in chitosan chemistry and materials development, encompassing particles, hydrogels, aerogels, membranes, films, and sponges. Also, this review critically evaluates the development and functional properties of biofunctional chitosan–biopolymer composite materials, spotlighting interactions, both dynamic covalent and noncovalent, and their pivotal roles in materials formation. These interactions may either be inherent or realized through chemical modification such as “Click” chemistry, polymer grafts, mussel-inspired chemistry, and selective oxidation. Furthermore, the text illustrates the current and potential biomedical applications of these biofunctional composite materials, spanning from wound dressing to tissue engineering (skin, bone, cartilage, and nerve), the controlled release and targeted delivery of drugs/bioactive compounds, biosensing, and 3D printing. Additionally, it addresses critical challenges within the field, posits potential solutions, and provides a forward-looking perspective on the future directions of functional biomaterials and design strategies

Towards superior biopolymer gels by enabling interpenetrating network structures:A review on types, applications, and gelation strategies

Gels derived from single networks of natural polymers (biopolymers) typically exhibit limited physical properties and thus have seen constrained applications in areas like food and medicine. In contrast, gels founded on a synergy of multiple biopolymers, specifically polysaccharides and proteins, with intricate interpenetrating polymer network (IPN) structures, represent a promising avenue for the creation of novel gel materials with significantly enhanced properties and combined advantages. This review begins with the scrutiny of newly devised IPN gels formed through a medley of polysaccharides and/or proteins, alongside an introduction of their practical applications in the realm of food, medicine, and environmentally friendly solutions. Finally, based on the fact that the IPN gelation process and mechanism are driven by different inducing factors entwined with a diverse amalgamation of polysaccharides and proteins, our survey underscores the potency of physical, chemical, and enzymatic triggers in orchestrating the construction of crosslinked networks within these biomacromolecules. In these mixed systems, each specific inducer aligns with distinct polysaccharides and proteins, culminating in the generation of semi-IPN or fully-IPN gels through the intricate interpenetration between single networks and polymer chains or between two networks, respectively. The resultant IPN gels stand as paragons of excellence, characterized by their homogeneity, dense network structures, superior textural properties (e.g., hardness, elasticity, adhesion, cohesion, and chewability), outstanding water-holding capacity, and heightened thermal stability, along with guaranteed biosafety (e.g., nontoxicity and biocompatibility) and biodegradability. Therefore, a judicious selection of polymer combinations allows for the development of IPN gels with customized functional properties, adept at meeting precise application requirements.</p

Insights into the hierarchical structure and digestion rate of alkali-modulated starches with different amylose contents

Combined analytical techniques were used to explore the effects of alkali treatment on the multi-scale structure and digestion behavior of starches with different amylose/amylopectin ratios. Alkali treatment disrupted the amorphous matrix, and partial lamellae and crystallites, which weakened starch molecular packing and eventually enhanced the susceptibility of starch to alkali. Stronger alkali treatment (0.5% w/w) made this effect more prominent and even transformed the dual-phase digestion of starch into a triple-phase pattern. Compared with high-amylose starch, regular maize starch, which possesses some unique structure characteristics typically as pores and crystallite weak points, showed evident changes of hierarchical structure and in digestion rate. Thus, alkali treatment has been demonstrated as a simple method to modulate starch hierarchical structure and thus to realize the rational development of starch-based food products with desired digestibility

Plasticized starch/agar composite films : processing, morphology, structure, mechanical properties and surface hydrophilicity

Natural biopolymers, which are renewable, widely available, biodegradable, and biocompatible, have attracted huge interest in the development of biocomposite materials. Herein, formulation–property relationships for starch/agar composite films were investigated. First, rapid visco analysis was used to confirm the conditions needed for their gelation and to prepare filmogenic solutions. All the original crystalline and/or lamellar structures of starch and agar were destroyed, and films with cohesive and compact structures were formed, as shown by SEM, XRD, and SAXS. All the plasticized films were predominantly amorphous, and the polymorphs of the composite films were closer to that of the agar-only film. FTIR results suggest that the incorporation of agar restricted starch chain interaction and rearrangement. The addition of agar to starch increased both tensile strength and elongation at break, but the improvements were insignificant after the agar content was over 50 wt.%. Contact angle results indicate that compared with the other samples, the 4:6 (wt./wt.) starch/agar film was less hydrophilic. Thus, this work shows that agar dominates the structure and properties of starch/agar composites, and the best properties can be obtained with a certain starch/agar ratio. Such composite polysaccharide films with tailored mechanical properties and surface hydrophilicity could be useful in biodegradable packaging and biomedical applications (wound dressing and tissue scaffolding)

Starch-based food matrices containing protein : recent understanding of morphology, structure, and properties

Starches and proteins are two major types of biopolymer components, especially in many flour (starch)-based foods consumed worldwide, which provide energy and nutrition needed by the human body. In many such starch-based matrices (the main structural component of such foods), proteins and their interactions with starches greatly influence the matrix structure and properties. Studying the different roles played by proteins (endogenous and exogenous) in various starch-based food systems can provide a frame of reference for the design and production of improved starch-based food products with tailored properties and desirable nutritional functions. Scope and approach Significant efforts have recently been made to tailor the morphology, structure, and properties of many starch-based food systems, and thus to design various starch-based food products with satisfactory attributes. This review surveys the latest literature on starch-based matrices containing proteins. Discussed are the influences of proteins and their interactions with starches on the morphologies and structures (e.g. short- and long-range orders) of starch-based matrices, as well as on their pasting, thermal, rheological, textural, sensory, and digestive properties. Also, current understandings of structure–property links are presented, along with their implications on the production of various starchy foods (e.g. pastas, breads, cakes, and biscuits), including gluten-free versions. Key findings and conclusions Proteins in many starchy food matrices can encapsulate the starch phase (or be adsorbed on its surfaces) on a micron scale, and thereby interact with starch chains via both non-covalent (e.g. hydrogen bonding, hydrophobic, and electrostatic) and covalent bonds (e.g. via Maillard reactions). These facts and protein features (e.g. hydration and gelation abilities) can play major roles in inhibiting starch retrogradation (the reassembly of cooked starch chains into ordered structures) and in regulating various other properties of such starch-based matrices, including viscosity, transition temperatures, moduli, hardness, sensory, digestibility, and shelf-life. Despite the fact that the current literature presents considerable information on the structure–property relationships of many different starch-based matrices and their applications in the processing of various starchy foods (e.g. pastas, noodles, and biscuits), it is still highly necessary to define more comprehensive correlations among starch–protein interactions, starch-protein matrix structures, and the resulting properties of such food products

Multiscale structural disorganization of indica rice starch under microwave treatment with high water contents

While the cooking of rice into porridge or similar foods is widely practiced, how microwave treatment, a rapid heating technology, changes the structure of rice starch with excess water remains largely unexplored. This work describes the multiscale structural changes of indica rice starch (IRS) with high water contents (70, 80, and 90 wt %, wet basis) subjected to microwave treatment for 1–3 min. Microwave treatment destructed crystalline lamellae, changed the crystalline type from A to B+V, and decreased crystallinity and double-helix content. While these changes depend on both water content and treatment time, the former had a stronger effect due to combined effects of water and heat for starch gelatinization. Interestingly, a highly porous material can be obtained simply upon microwave treatment of IRS for 3 min at a water content of 90 wt %. Thus, this work presents a simple method for creating such material promising for encapsulation and delivery applications

A Novel and Accurate Method for Moisture Adsorption Isotherm Determination of Sultana Raisins

A novel method (dynamic water transfer–based water activity analyzer (DWT) method) based on Fick’s law of diffusion for the accurate measurement of moisture sorption isotherm (MSI) has been developed and was compared with saturated salt solutions (SSS) method and dynamic vapor sorption (DVS) method. MSIs at 25 °C of sultana raisins obtained by the three methods were analyzed and compared, and four adsorption models (BET, Halsey, GAB, and Peleg) were used to fit the results. The MSI curves obtained by the three methods all showed the similar type III isotherm characteristic, but equilibrium moisture content at the same relative humidity (RH) showed some differences, and the repeatability and accuracy were different. Generally, results obtained by the SSS method may have relatively low accuracy due to the relatively high measurement error; results obtained by the DVS method may lack representativeness due to the small sample size; results obtained by the DWT method may have high representativeness and accuracy at the same time. The fitting results of adsorption models indicated that MSI results obtained by the DWT method had the highest fitting degree with the Peleg model. This study may contribute to deepened understandings on MSI measurement of semi-dried foods

Influence of crosslinker amount on the microstructure and properties of starch-based superabsorbent polymers by one-step preparation at high starch concentration

This work concerns how crosslinker amount (N, N′-methylene-bisacrylamide) affects the microstructural, absorbent and rheological features of one-step prepared starch-based superabsorbent polymers at a high starch concentration (0.27:1 w/w starch-water). The increased crosslinker amount evidently altered the microstructure and the absorbent and rheological features. Then, the variations in starch-based superabsorbent polymer properties were discussed from a microstructure viewpoint. Particularly, the higher crosslinker quantity rose the crosslinking density and the ratio (GR) of grafted anhydroglucose unit on starch backbone (from 27% to 52%), but short the average polyacrylamide (PAM) chain length (LPAM). These structural features suppressed the chain stretch within starch-based superabsorbent polymer fractal gels (confirmed by smaller Rg value) and promoted the formation of smaller chain networks, thus weakening the water absorption to the starch-based superabsorbent polymer chain networks. Also, the increased GR and reduced LPAM, with lowered chain extension and elevated crosslinking density, probably decreased the flexibility and mobility of chain segments in starch-based superabsorbent polymer gel matrixes. This caused the enhanced robustness and storage modulus of the gels with reduced chain energy dissipation ability

Understanding the multi-scale structure and digestion rate of water chestnut starch

Using combined techniques and two comparisons (maize and cassava starches), this work concerns the multi-scale structure and digestion rate of water chestnut tuber starch. Among the starches, the water chestnut starch showed altered hierarchical structural features and a relatively low digestion rate. The underlying mechanism on the reduced digestion rate of water chestnut starch was discussed from a hierarchical structural view. Specifically, compared with maize starch, the water chestnut starch contained no pores on the granule surface, with the thickened crystalline lamellae, the increased lamella ordering, and the elevated content of crystallites. Such structural features probably increased the bulk density of molecule assembly in starch and thus could hinder the diffusion of enzyme molecules in starch matrixes. Consequently, the absorption of enzyme to the starch glucan chains could be retarded, resulting in a reduced enzyme hydrolysis rate of starch chains. The relatively large amylose molecules of water chestnut starch also tended to reduce the starch digestion rate, associated with the enhanced molecule interactions such as that between starch chains. In addition, the further reduction in the digestion rate of cassava starch could be also ascribed to the variations in the multi-scale structural features