Preparation and properties of enzyme-modified cassava starch-zinc complexes

Insights into the effects of fucoidan and caffeic acid on pasting, thermal, rheological, freeze-thaw and structural properties of cassava starch

Fucoidan (FU) and caffeic acid (CA) can modify the physicochemical properties of starch and confer various health-beneficial functional characteristics to cassava starch (CS) products. This study utilized Rapid Visco Analyzer (RVA), Differential Scanning Calorimetry (DSC), rheometer, Fourier Transform Infrared Spectroscopy (FT-IR), X-ray Diffraction (XRD), and Scanning Electron Microscopy (SEM) to investigate the effects of FU andCA on the gelatinization, rheological properties, freeze-thaw stability, and structural characteristics of CS. Results from RVA showed that FU boosted the free expansion, shear resistance and gel thermal stability of CS while reducing their gel formation capacity and delaying short-term retrogradation. CA decreased the free expansion, shear resistance and gel formation ability of CS while delaying the short-term retrogradation of CS. The analysis of DSC showed that FU and CA could decrease the gelatinization enthalpy of CS. The rheological results revealed that each gel system was typical weak gel and pseudoplastic fluid. Both FU and CA weakened the relative motion of amylose molecules and reduced the energy required to disrupt the CS gel system. FU significantly enhanced the pseudoplasticity of CS gel (upward: 0.48 to 0.44; downward: 0.566 to 0.488, p < 0.05), whereas CA significantly decreased the thickening ability in the upward stage. FU and CA increased the hardness of CS gel (except 2.5 % CA). Furthermore, the addition of FU and CA was not conducive to the improvement of freeze-thaw stability of CS gel. FT-IR and XRD analyses exhibited that non-covalent bond mediated the effect of FU and CA on CS gel. SEM observations showed that FU and CA induced the formation of denser "honeycomb" pores in the CS gel. Both FU and CA were found to effectively retard the short-term retrogradation of CS, while enhancing the microstructural integrity of the gel network. These findings suggested that the incorporation of FU and CA could be utilized as a means to modulate the quality attributes of cassava starch-based products.

A glucose-rich heteropolysaccharide from Marsdenia tenacissima (Roxb.) Wight et Arn. and its zinc-modified complex enhance immunoregulation by regulating TLR4-Myd88-NF-κB pathway

A previously unreported immunological polysaccharide (MTP70-1) was obtained from Marsdenia tenacissima (Roxb.) Wight et Arn. MTP70-1 (2738 Da) is a heteropolysaccharide that mainly consists of (1 → 5)-linked-L-Araf, t-D-Glcp, (1 → 3,5)-linked-L-Araf, (1 → 4)-linked-D-Galp, (1 → 6)-linked-D-Glcp, and (1 → 3,6)-linked-D-Manp. In vitro cell assays revealed that MTP70-1 exhibits moderate immunomodulatory effects at the cellular level, and MTP70-1 was further modified with zinc to improve these effects. These modifications enhanced the immunomodulatory effects of MTP70-1, as phagocytosis was enhanced, the secretion of cytokines (TNF-α, IL-6, IL-1β, and IL-18) was increased, and the generation of chemokines (NO and ROS) in macrophages was enhanced. The intracellular mechanism by which MTP70-1 and MTP70-Zn activate macrophages was further revealed to be closely related to the TLR4-Myd88-NF-κB signaling pathway. In addition, a microscale thermophoresis binding (MST) assay confirmed that Zn modification can effectively enhance the binding affinity of MTP70-1 for TLR4. Ultimately, better immune-enhancing activity was attained with MTP70-Zn than MTP70-1. The immune-enhancing activity of MTP70-Zn was further demonstrated through zebrafish assays, which revealed that MTP70-Zn can effectively enhance the proliferation of macrophages and neutrophils.

Biopolymer electrolyte from banana powder-konjac glucomannan for zinc-ion batteries

Herein, the novel eco-friendly biopolymer electrolytes consisting of banana powder and konjac glucomannan host matrix doped with zinc acetate salt were successfully fabricated through simple casting technique. The biopolymer electrolyte exhibited satisfactory thermal stability and mechanical properties; tensile strength (13.82 MPa); elongation at break (60.52 %) and Young's modulus (93.2 MPa). The electrochemical studies were carried out in symmetrical cells Zn/Zn cells. Biopolymer electrolyte showed favorable ionic conductivity of 5.59 × 10-4 S/cm along with stable cycling performance. The potential stability was found to be 2.52 V. The as-prepared biopolymer electrolytes demonstrated the potential as green, simple yet effective biopolymer electrolytes for zinc-ion batteries.

Novel and safe debranched starch-zinc complexes with endoconcave structure as zinc supplements

Zinc deficiency is a serious risk to human health and growth, especially in children. The development of zinc supplements can effectively reduce this harm. Here, a series of debranched starch‑zinc complexes (DS-Zn) were prepared, whose zinc complexation was inversely proportional to the amylopectin content in the debranched starch (DS). The physicochemical properties of DS-Zn were characterized using the conductivity, XRD, iodine staining and thermogravimetry. Combined with XPS, solid-state 13C NMR and IR, it was elucidated that the structure of DS-Zn is endoconcave structure with 2-O and 3-O of DS on the inner side and 6-O of DS on the outer side, where zinc is located. The DS-Zn exhibits good biosafety including blood, cellular and mutagenicity. In vitro simulations of digestion and zinc-deficient cellular models showed that DS-Zn was more tolerant to the gastrointestinal environment and more effective in zinc supplementation (increased by 33 %) than inorganic zinc supplements. Utilizing the compressibility of starch, DS-Zn was prepared as a more palatable oral cartoon tablet for children. This study will provide important support to advance the development and application of novel starch-based zinc nutritional supplements.

Effect of solution on starch structure: New separation approach of amylopectin fraction from gelatinized native corn starch

The complete dissolution of starch without degradation are necessary prerequisites for starch fractionation to obtain amylose or amylopectin (AP). With the recent, continuous progress in finding efficient and eco-friendly starch-dissolving solutions, applying new solvents for starch fractionation is important. In this study, the effects of dimethyl sulfoxide (DMSO), NaOH, and CaCl2 solutions on starch structure and AP product parameters during starch fractionation were compared with respect to the starch deconstruction effect. This study proved that the CaCl2 solution could effectively dissolve corn starch (50 °C, solubility of 98.96 %), and promote the regeneration of starch into uniform and fine particles. Furthermore, the three solvents (DMSO, NaOH, and CaCl2) changed the crystal structure of corn starch, but they were all non-derivatizing solvents. The effect of the CaCl2 solution on the molecular structure of corn starch was the least significant of the three solvents. Finally, the extraction rate of AP from the CaCl2 solution reached 69.45 %. In conclusion, this study presents a novel and effective method for AP extraction.

Production and characterization of starch-lignin based materials: A review

In their pristine state, starch and lignin are abundant and inexpensive natural polymers frequently considered green alternatives to oil-based and synthetic polymers. Despite their availability and owing to their physicochemical properties; starch and lignin are not often utilized in their pristine forms for high-performance applications. Generally, chemical and physical modifications transform them into starch- and lignin-based materials with broadened properties and functionality. In the last decade, the combination of starch and lignin for producing reinforced materials has gained significant attention. The reinforcing of starch matrices with lignin has received primary focus because of the enhanced water sensitivity, UV protection, and mechanical and thermal resistance that lignin introduces to starch-based materials. This review paper aims to assess starch-lignin materials' production and characterization technologies, highlighting their physicochemical properties, outcomes, challenges, and opportunities. First, this paper describes the current status, sources, and chemical modifications of lignin and starch. Next, the discussion is oriented toward starch-lignin materials and their production approaches, such as blends, composites, plasticized/crosslinked films, and coupled polymers. Special attention is given to the characterization methods of starch-lignin materials, focusing on their advantages, disadvantages, and expected outcomes. Finally, the challenges, opportunities, and future perspectives in developing starch-lignin materials, such as adhesives, coatings, films, and controlled delivery systems, are discussed.

A zinc-modified Anemarrhena asphodeloides polysaccharide complex enhances immune activity via the NF-κB and MAPK signaling pathways

Anemarrhena asphodeloides polysaccharide (AAP70-1) was reported to have immunomodulatory effects in our previous report. To further improve the immunomodulatory effects of AAP70-1, an A. asphodeloides polysaccharide-zinc complex (AAP-Zn) was synthesized using a ZnCl2 modification method, and the potential mechanisms by which AAP-Zn activates macrophages were investigated. The results showed that the structural features of AAP-Zn were similar to those of AAP70-1 with a Zn content of 0.2 %, confirming that Zn mainly interacted with AAP70-1 by forming ZnO coordination bonds and Zn…OH bonds. In addition, the administration of AAP70-1 and AAP-Zn effectively improved the immunomodulatory effects by enhancing phagocytosis and upregulating the mRNA expression of cytokines (TNF-α, IL-6, IL-1β, and IL-18), as well as increasing the production levels of nitric oxide (NO) and reactive oxygen species (ROS) in zebrafish embryos. The intracellular mechanism by which AAP-Zn activates macrophages was found to involve activation of the NF-κB and MAPK signaling pathways. Our findings suggested that AAP-Zn may be a potential immunopotentiator in the field of biomedicine or functional foods.

Combining pulsed electric field and cross-linking to enhance the structural and physicochemical properties of corn porous starch

In this study, corn porous starch (CPS) was firstly prepared using enzymatic hydrolysis, followed by pore formation enhancement using the treatment of a pulsed electric field (PEF). Subsequently, the PEF treated porous starch (CPS-PEF) was cross-linked with sodium trimetaphosphate (STMP) to investigate its structural and functional properties. The results showed PEF treatment increased the oil absorption of CPS by 26.92% and improved its specific surface area, total pore volume value, solubility and swelling power. After cross-linking of the CPS-PEF, C-O-P covalent bonds were formed between CPS-PEF molecules, resulting in a further increase in oil absorption and specific surface area properties. Moreover, the covalent bonds enhanced the intermolecular forces, resulting in increased thermal stability of the cross-linked porous starch (ScPS). The double modification resulted in significantly improved adsorption properties and better thermal stability of the ScPS, indicating that the double modification is an effective method for the preparation of porous starches.

Synthesis, characterization, DFT studies, and adsorption properties of sulfonated starch synthesized in deep eutectic solvent

In this study, sulfonated starch (SS) was successfully synthesized using sulfamic acid as a sulfonating agent in a deep eutectic solvent (DES). Four-factor and three-level orthogonal experiments were conducted to determine the optimal preparation conditions, which were found to be a molar ratio of starch to urea of 1:20, a reaction temperature of 90 °C, a reaction time of 5 h, and a stirring speed of 200 rpm. The sulfonation reaction mechanism was extensively studied using various techniques, including Fourier transform infrared spectroscopy, elemental analysis, X-ray diffraction, molecular weight, particle distribution, X-ray photoelectron spectroscopy, scanning electron microscopy, and DFT calculations. The results showed that the sulfonation reaction slightly damaged starch granules, occurred on the surface of starch granules, and on the O6 atoms of the glucose unit. SS exhibited a wide pH range of application (5-10), a fast adsorption rate (400 s to reach adsorption equilibrium), and a high adsorption capacity (118.3 mg/g) under optimal conditions. The adsorption process of SS for methylene blue followed the pseudo-first-order kinetic model and was consistent with the Langmuir model, which was endothermic and spontaneous. The adsorption process was attributed to hydrogen bonding and electrostatic interactions.

Zinc nutrition and dietary zinc supplements

As the second most abundant trace element in the human body, zinc nutrition is constantly a hot topic. More than one-third population is suffering zinc deficiency, which results in various types of diseases or nutritional deficiencies. Traditional ways of zinc supplementation seem with low absorption rates and significant side effects. Zinc supplements with dietary components are easily accessible and improve zinc utilization rate significantly. Also, mechanisms of maintaining zinc homeostasis are of broad interest. The present review focuses on zinc nutrition in human health in inductive methods. Mainly elaborate on different diseases relating to zinc disorder, highlighting the impact on the immune system and the recent COVID-19. Then raise food-derived zinc-binding compounds, including protein, peptide, polysaccharide, and polyphenol, and also analyze their possibilities to serve as zinc complementary. Finally, illustrate the way to maintain zinc homeostasis and the corresponding mechanisms. The review provides data information for maintaining zinc homeostasis with the food-derived matrix.

3D printed hydroxyapatite - Zn2+ functionalized starch composite bone grafts for orthopedic and dental applications

Hydroxyapatite (HA) - polymer composite based 3D printed bone grafts require extensive mechanical and biological property optimization for specific clinical needs. This fuels the need to develop innovative methods of optimization. Using an in-house extrusion-based 3D printer, we show the feasibility of fabricating hydroxyapatite- Zn2+ functionalized starch composites as artificial bone graft substitutes. The experimental procedure for this purpose is fortified with a univariate multi-objective optimization strategy to predict the best composition. The compressive strength of the grafts improves up to ~ 4 folds by parametric optimization and Zn2+ functionalization, without any post-processing. These grafts maintain mechanical integrity and strength during 6 weeks of dissolution study in simulated body fluid (SBF), while the non -functionalized starch-HA grafts fully degrade within a week. The Zn2+ functionalization results in up to ~ 79% antibacterial efficacy against S. aureus. Osteoblast cell viability increases ~ 1.6 folds on these graft surfaces on day 11. Our innovative methods of optimization are expected to reduce the experiment time, cost, and chance of human error in 3D printing. This study redefines the importance of understanding composition and process dependence for making a functionalized 3D printed bone graft for repairing low load-bearing defects such as craniomaxillofacial bone.

Preparation and Characterization of Auricularia cornea Ehrenb Polysaccharide-Zn Complex and Its Hypoglycemic Activity through Regulating Insulin Resistance in HepG2 Cells

With Auricularia cornea Ehrenb polysaccharide (ACEP) as raw material, the purpose of the study was to prepare Auricularia cornea Ehrenb polysaccharide-zinc (ACEP-Zn) complex. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), nuclear magnetic resonance (NMR), and other means are used to analyze the physical-chemical properties and structure of ACEP and ACEP-Zn, to investigate the inhibition of α-glycosidase and α-amylase enzymes, and to explore its effects on the glucose metabolism of insulin-resistant HepG2 cells. Nuclear magnetic resonance (NMR) results show that a group of COO-, -CH3, and -OH in the sugar chain binds to Zn2+. Compared with the original polysaccharides, the surface morphology of ACEP-Zn changed obviously, and the molecular weight (Mn) of ACEP-Zn decreased, but the molecular agglomeration of ACEP-Zn increased. Moreover, the inhibitory effect of ACEP-Zn on α-glucosidase and α-amylase was stronger than that of the original polysaccharide. The results indicated that the structure of Auricularia cornea Ehrenb polysaccharide was changed obviously after the zinc complex, and its hypoglycemic activity was enhanced in vitro. In the cell experiment, the glucose consumption of IR-HepG2 cells was significantly increased at a concentration of 50–200 μg/mL ( $P<0.05$ ). The activity of SOD and NOS significantly increased ( $P<0.01$ ), and the activity of intracellular PK increased ( $P<0.05$ ). Therefore, it was speculated that the hypoglycemic effect of Auricularia cornea Ehrenb polysaccharide combined with zinc was related to the alleviation of liver cell damage caused by oxidative stress and the improvement of glucose metabolism of IR-HepG2 cells. The study provides a theoretical basis for the application of the polysaccharide-zinc complex in the hypoglycemic functional food field.

Morphological and spectroscopic analysis of snow and glacier algae and their parasitic fungi on different glaciers of Svalbard

The results show the morphological analyses and spectroscopic studies of snow and glacier algae and their parasitic fungi in Svalbard (High Arctic). Fixed algal cells of two species, Sanguina nivaloides and Ancylonema nordenskioeldii, were imaged using light microscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM). Fluorescence microscopy using Calcofluor white stain supported the observations of parasitic fungi on the algal cells. Images in brightfield microscopy showed chytrid-like fungi penetrating the cells of both algal species. Parasites were found to colonize the cells of A. nordenskioeldii and hypnozygotes of S. nivaloides, while no fungi infected the cyst stages of S. nivaloides. The autofluorescence analysis revealed the ability of S. nivaloides to glow when excited with different wavelengths, while A. nordenskioeldii did not fluoresce. The hypnozygotes of S. nivaloides emitted brighter fluorescence than the cysts, and the most intense luminosity was observed in the UV range. The Fourier-transform infrared spectroscopy (FTIR) and energy-dispersive X-ray spectroscopy (EDS) spectroscopic analysis showed differences in the chemical composition between samples collected from three different sites. Samples dominated by cyst cells were characterized by the presence of an abundant polysaccharide envelope.

Bifunctional Fe3O4 nanoparticles as magnet and inducer in bioextruded fabrication of starch-based composite with hierarchical pore architecture

Starch (St) was used as green and renewable matrix (> 80%, db) for the preparation of Zn-St-MOCP/nFe₃O₄ composite via bioextrusion. Bifunction of Fe₃O₄ NPs as magnet and pore-inducer was confirmed and could be more homogeneously embedded in the St-based framework with hierarchical porous structure via SEM-EDS mapping. For the nFe₃O₄-induced microstructure of Zn-St-MOCP/nFe₃O₄ composite, submicronic pores and nanopores were observed with Fe₃O₄ NPs onto the inner surface of micron channels. According to the XPS, XRD, FTIR, TGA analyses, it is probably due to the coordination between Fe^3+/2+ and Zn²⁺/hydroxy groups and the recombination of St chains in crystalline/amorphous zones interfered by Fe₃O₄ NPs. Saturation magnetization value was measured with an excellent separation behavior. Seven kinetic equations were conducted for the fitting of dye adsorption data. Overall, the nFe₃O₄-assisted bioextrusion strategy is developed for the continuous fabrication of bio-based materials with rapid magnetic separation and hierarchical-pore architecture promising in practical adsorption.

Micronutrients encapsulation by starch as an enhanced efficiency fertilizer

Developing different paths to achieve sustainable agriculture is no longer an option; it is a necessity. EEF materials are alternatives to improve the efficacy of the agrochemicals in the soil and plant, reducing wasting and environmental contamination. The present work aims to develop EEF materials based on starch and micronutrients, considering few works address EEFs materials with micronutrients. Monoelementary dispersions of gelatinized starch with micronutrients (Fe, Cu, Mn) were spray-dried and thermally, structurally, and morphologically characterized. We evaluated water-medium nutrient release, release kinetics, and the swelling degree. Different micronutrients affect morphology, size distribution, swelling degree, release, kinetics, and interaction between polymer-nutrient. Bigger particle sizes achieved a higher swelling degree, which led to decreased micronutrient release in the water. The Peppas-Sahlin model mainly ruled the release kinetics (fitted to all the materials). This result confirmed our hypothesis that a swelling starch delays the release.

Comparison of functional properties of porous starches produced with different enzyme combinations

To obtain porous starch granules with higher absorption capacities, three types of enzyme combinations were adopted to modify wheat and maize starches: (1) sequential α-amylase (AA) → glucoamylase (GA); (2) sequential branching enzyme (BE) → GA; and (3) sequential AA→BE→GA. The results indicated that AA→BE→GA treatment had a most optimal influence on porous starches. Compared to AA→GA and BE→GA, the mesopores in wheat starch granules treated with AA→BE→GA decreased by 52.82 and 48.70%, respectively. Conversely, the macropores increased by 216.68 and 138.18%, respectively. While for maize starch, the percentages of mesopores and macropores hardly changed after three enzyme combinations. Comparing the three enzyme treatments showed that pore volume (0.005 and 0.007 cm³/g) and pore size (36.35 and 26.54 nm) were largest in the AA→BE→GA treated wheat and maize starches, respectively. Compared to the AA→GA and BE→GA, the adsorption capacities for oil, dye and heavy metal ions, wheat starch treated with AA→BE→GA increased by 46.61 and 242.33%, and 44.52 and 134.41%, and 28.83 and 271.72%, respectively. Correspondingly, that of maize starch increased by 29.71 and 133.29%, and 42.92 and 79.93%, and 28.16 and 161.43%, respectively. These results may provide a new and valuable enzyme combination for optimising porous starch granules with higher absorption capacities.

Convenient environmentally friendly on-site quantitative analysis of nitrite and nitrate in seawater based on polymeric test kits and smartphone application

Nowadays, nitrate (NO₃^-) and nitrite (NO₂^-) in aquatic ecosystems have increased due to various anthropogenic activities leading to deterioration of the ecosystem and can accelerate eutrophication. A Griess reagent-doped hydrogel test kit and a zinc powder-doped starch film were thus developed for on-site quantitative analysis of nitrate and nitrite. A clear colorless hydrogel tablet (diameter 1.5 cm 2 mm thickness) turned pink-violet after reacting with a standard solution of nitrite while the gray zinc-doped starch film (8.36 μm thickness) fabricated on the inner lid of small plastic tube was used for the in-tube reduction of nitrate to be nitrite. The use of this film followed by nitrite testing using the hydrogel tablet was used as a nitrate test. Both the materials developed were used in conjunction with digital image colorimetry (DIC) using smartphone application for on-site quantitative analysis of nitrite and nitrate. Good linearity (R² > 0.99) ranges of 0.05 to 5 mg L^-1 for nitrite and 1 to 50 mg L^-1 for nitrate were obtained and detection limits of 50 μg L^-1 for nitrite and 0.32 mg L^-1 for nitrate were achieved. Good accuracy was obtained in terms of a relative error in a range of 0.75 to 2.68% with inter-day precision in a range of 0.20 to 0.50%RSD (n = 3). Quantitative analysis of nitrate and nitrite in 10 seawater samples taken in Phuket was in good agreement with the standard method (95% confidence level). Since the method developed employs test kits synthesized using biodegradable polymers and DIC using a smartphone application, it will allow the rapid on-site quantitative detection of nitrate and nitrite in a more convenient and environmentally friendly system.

Insights into the microstructure and interconnectivity of porosity in porous starch by hyperpolarized 129Xe NMR

For the first time, hyperpolarized (HP) ¹²⁹Xe NMR measurements are utilized to explore porous structures of porous starch (PS) successfully. Some micropores resided inside the mesopore walls of PS were detected by variable temperature (VT) HP ¹²⁹Xe NMR, and the pore sizes of micropores were also estimated using the empirical relationship. Furthermore, the interconnectivity of pores was investigated in detail by two-dimensional (2D) exchange spectroscopy (EXSY). The exchange process of xenon from microporosity within pore walls to the free gas space was occurred at the mixing time of ≥12 ms at 173 K, which indicated the well interconnectivity between micropores and mesopores. This study not only exhibits a new approach for investigation of pores and hollows of PS, but also provides a better understanding of porous structures for rational design in adsorbing functional compounds.

Enhanced and Selective Adsorption of Zn(II), Pb(II), Cd(II), and Hg(II) Ions by a Dumbbell- and Flower-Shaped Potato Starch Phosphate Polymer: A Combined Experimental and DFT Calculation Study

Microwave-ultrasound-assisted facile synthesis of a dumbbell- and flower-shaped potato starch phosphate (PSP) polymer, hereafter PSP, was carried out by cross-linking the hydroxyl groups of native potato starch (NPS) using phosphoryl chloride as a cross-linking agent. Structural and morphological analysis manifested the successful formation of the dumbbell- and flower-shaped PSP biosorbent with enhanced specific surface area and thermal stability. Viscoelastic behavior of NPS and PSP suggested increased rigidity in PSP, which helped the material to store more deformation energy in an elastic manner. The synthesized PSP biosorbent material was successfully tested for efficient and quick uptake of Zn(II), Pb(II), Cd(II), and Hg(II) ions from aqueous medium under competitive and noncompetitive batch conditions with q m values of 130.54, 106.25, 91.84, and 51.38 mg g-1, respectively. The adsorption selectivity was in consonance with Pearson's hard and soft acids and bases (HSAB) theory in addition to their order of hydrated radius. Adsorption of Zn(II), Pb(II), Cd(II), and Hg(II) followed a second-order kinetics and the adsorption data fitted well with the Langmuir isotherm model. Quantum computations using density functional theory (DFT) further supported the experimental adsorption selectivity, Zn(II) > Pb(II) > Cd(II) > Hg(II), in terms of metal-oxygen binding energy measurements. What was more intriguing about PSP was its reusability over multiple adsorption cycles by treating the metal(II)-complexed PSP with 0.1 M HCl without any appreciable loss of its adsorption capacity.

Magnetic (Zn-St)10Fe0n (n = 1, 2, 3, 4) Framework of Macro-Mesoporous Biomaterial Prepared via Green Enzymatic Reactive Extrusion for Dye Pollutants Removal

Biobased materials have the potential to be developed into green multifunctional products to replace their chemosynthetic counterparts, which have environmental and economic concerns. However, designing magnetic and porous biomaterials without pore spaces being occupied by exogenous magnets via traditional encapsulation, load, and/or deposition methods remains challenging. This paper describes a novel, facile, top-down strategy of fabricating zerovalent iron particles (Fe⁰ Ps) embedded into a three-dimensional (3D) zinc-modified starch (Zn-St) framework using the enzymatic reactive extrusion (eREX) method. Raw St underwent Zn-atom fortification, in situ Fe-atom deposition, and micromixing extrusion to produce (Zn-St)₁₀Fe⁰_n (n = 1, 2, 3, 4) extrudates (Es) in a continuous and large-scale mode. A hierarchical porous structure was formed during eREX processing, with mesopores (∼2-4 nm) and macropores (∼50-300 nm and ∼5-100 μm) generated regularly. The (Zn-St)₁₀Fe⁰_n Es were excellent at dye adsorption and magnetic separation, with high levels of St (>70%) as a biodegradable resource. For instance, (Zn-St)₁₀Fe⁰₂ Es (St > 83%) removed 61.03 mg/g of methylene blue (∼19 times higher than that of raw St) at 298 K and pH 4.0 via simultaneous physisorption and degradation and were successfully separated due to their saturation magnetization (M_s) value of 25.41 emu/g. The dye adsorption rate and M_s of the (Zn-St)₁₀Fe⁰_n Es can be increased by manipulating the amount of Fe⁰ Ps. Thus, the novel 3D (Zn-St)₁₀Fe⁰_n Es are promising biomaterials for water purification applications, as well as other food, biological, and environmental fields.

Cellulose-starch Hybrid Films Plasticized by Aqueous ZnCl₂ Solution

Starch and cellulose are two typical natural polymers from plants that have similar chemical structures. The blending of these two biopolymers for materials development is an interesting topic, although how their molecular interactions could influence the conformation and properties of the resultant materials has not been studied extensively. Herein, the rheological properties of cellulose/starch/ZnCl₂ solutions were studied, and the structures and properties of cellulose-starch hybrid films were characterized. The rheological study shows that compared with starch (containing mostly amylose), cellulose contributed more to the solution's viscosity and has a stronger shear-thinning behavior. A comparison between the experimental and calculated zero-shear-rate viscosities indicates that compact complexes (interfacial interactions) formed between cellulose and starch with ≤50 wt % cellulose content, whereas a loose structure (phase separation) existed with ≥70 wt % cellulose content. For starch-rich hybrid films prepared by compression molding, less than 7 wt % of cellulose was found to improve the mechanical properties despite the reduced crystallinity of the starch; for cellulose-rich hybrid films, a higher content of starch reduced the material properties, although the chemical interactions were not apparently influenced. It is concluded that the mechanical properties of biopolymer films were mainly affected by the structural conformation, as indicated by the rheological results.

Starch-metal complexes and metal compounds

Recently, metal derivatives of starch evoked considerable interest. Such metal derivatives can take a form of starch compounds bearing metal atoms and metal carrying moieties either covalently bound or complexed. Starch metal complexes may have a character of either Werner, inclusion, sorption or capillary complexes. In this publication, preparation, structure, properties and numerous current and potential applications of those compounds as well as benefits resulting from the application and formation of the complexes are presented. © 2017 Society of Chemical Industry.

Performance of Granular Starch with Controlled Pore Size during Hydrolysis with Digestive Enzymes

Studies on porous starch have been directed to explore different industrial applications as bio-adsorbents of a variety of compounds. However, the analysis of starch digestibility is essential for food application. The objective of this study was to determine the impact of porous structure on in vitro starch digestibility. Porous starches were obtained using a range of concentrations of amyloglucosidase (AMG), α-amylase (AM), cyclodextrin-glycosyltransferase (CGTase) or branching enzyme (BE). Porous starches exhibited major content of digestible starch (DS) that increased with the intensity of the enzymatic treatment, and very low amount of resistant starch (RS). Porous starches behaved differently during in vitro hydrolysis depending on their enzymatic treatment. AMG was the unique treatment that increased the digestive amylolysis and estimated glycemic index, whereas AM, CGTase and BE reduced them. A significant relationship was found between the pore size and the severity of the amylolysis, suggesting that a specific pore size is required for the accessibility of the digestive amylase. Therefore, pore size in the starch surface was a limiting factor for digestion of starch granules.

Preparation and characterization of debranched-starch/phosphatidylcholine inclusion complexes

In this study, debranched-starch/phosphatidylcholine inclusion complexes were prepared. The effect of reaction parameters such as reaction temperature, reaction time, and addition amount of phosphatidylcholine on the phosphatidylcholine payload and inclusion rate was investigated. The phosphatidylcholine payload and inclusion rate prepared under the optimal conditions were 106 mg/g and 84.8%, respectively. The formation of debranched-starch/phosphatidylcholine inclusion complexes was confirmed by the results of XRD and FT-IR. Furthermore, the molecular, cluster, and fractal structures of the complexes were investigated using (13)C CP/MAS NMR and SAXS. The results indicated that the inclusion complexes were formed by hydrophobic interactions between alkyl chain of phosphatidylcholine and debranched-starch helix cavity. The complexes possessed a mass fractal structure, and a semicrystalline structure with a Bragg distance of 19.04 nm formed. After complexation, the stability of phosphatidylcholine was significantly improved, and phosphatidylcholine of the complexes can be gradually released with pancreatin treatment. This study revealed that debranched-starch can be used as an effective carrier of phosphatidylcholine for the purpose of improving its stability.