Rice starch, amylopectin, and amylose: molecular weight and solubility in dimethyl sulfoxide-based solvents

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.

Structural changes of thermally treated starch during digestion and the impact on postprandial glucose homeostasis

Intake of foods upon thermal treatment is typically associated with an elevated postprandial glycemic response, which is one of the risk factors for type 2 diabetes development and progression. In this study, rice starch was thermally treated using aqueous phase (boil), air phase (bake), and lipid phase (fry). Peak blood glucose levels in C57 mice increased by 16.94 %, 12.60 %, and 8.1 % after ingestion of thermally treated starch (20.23, 19.48, and 18.70 mmol/L), compared with raw starch (17.30 mmol/L). The insulin response to the intake of thermally treated starch increased (4.73 %-6.83 % higher than the control), whereas the concentration of GLP-1, a hormone used to promote insulin secretion, decreased (1.54 %-8.56 % lower than the control). Furthermore, thermally treated starch accelerated food absorption by enhancing gastrointestinal digestion, exacerbating postprandial glucose fluctuation at the next meal. Structural characterization showed thermal treatment reduced starch branching density and degree of structure order, which were not conducive to preventing the attack of enzymes. During digestion, they were highly hydrolyzed into low-molecular-weight fragments, and the proportion of ultrashort chains substantially increased. These findings provide a better understanding of the fine structure of starch that promotes hypoglycemia and initially explain how diets high in thermally treated starch impair glucose balance.

A high-strength, environmentally stable, and recyclable starch/PVA organohydrogel electrolyte for flexible all-solid-state supercapacitor

Hydrogel electrolytes have shown great promise in the field of flexible energy storage. However, the conventional hydrogel electrolytes have poor mechanical properties and are not recyclable. In addition, conventional hydrogel electrolytes cannot adapt to low and high temperature operating environments. In this study, starch/PVA/dimethyl sulfoxide/CaCl₂ (SPDC) organohydrogel was prepared by the freezing-thawing method. Dimethyl sulfoxide (DMSO) and CaCl₂ was introduced to enhance the mechanical properties and widen the working temperature range of the starch/PVA hydrogel. The SPDC organohydrogel had high strength, toughness and good recyclability. The SPDC organohydrogel and the recycled SPDC organohydrogel was used as the electrolyte to assemble the flexible supercapacitor with activated carbon as the electrode. The supercapacitor prepared by SPDC organohydrogel electrolyte exhibited high areal capacitance of 156.50 mF/cm² at a current density of 1 mA/cm² and high capacitance retention rate of 82.23 % after 8000 cycles of charging and discharging. The supercapacitor prepared by the recycled organohydrogel electrolyte exhibited a high capacitance retention rate of 97.58 %. In addition, the supercapacitor could withstand different angular bending shapes and had wide temperature adaptability from -20 °C to 80 °C. The work provided a new version for the development of "green" hydrogel electrolyte for all-solid-state supercapacitor.

The Mechanism Underlying the Amylose-Zein Complexation Process and the Stability of the Molecular Conformation of Amylose-Zein Complexes in Water Based on Molecular Dynamics Simulation

The aim of this study was to employ molecular dynamics simulations to elucidate the mechanism involved in amylose–zein complexation and the stability of the molecular conformation of amylose–zein complexes in water at the atomic and molecular levels. The average root mean square deviation and radius of gyration were lower for amylose–zein complexes (1.11 nm and 1 nm, respectively) than for amylose (2.13 nm and 1.2 nm, respectively), suggesting a significantly higher conformational stability for amylose–zein complexes than for amylose in water. The results of radial distribution function, solvent-accessible surface area, and intramolecular and intermolecular hydrogen bonds revealed that the amylose–zein interaction inhibited water permeation into the amylose cavity, leading to enhanced conformational stabilities of the V-type helical structure of amylose and the amylose–zein complexes. Furthermore, the amylose in amylose–zein complexes displayed the thermodynamically stable 4C1 conformation. These findings can provide theoretical guidance in terms of the application of protein on starch processing aiming to improve the physicochemical and functional properties of starch (such as swelling capacity, pasting properties, and digestibility) for developing novel low-digestibility starch–protein products.

Edible oleogels based on high molecular weight oleogelators and its prospects in food applications

Food industry is actively looking for alternative ingredients to replace saturated and trans fats in foods while preserving their original organoleptic attributes to ensure consumers' acceptance. A plausible approach is the replacement of solid fats with oleogels. Oleogels can be engineered to mimic properties that are commonly played by regular solid fats but using hydrophobic liquid vegetable oil with an optimum fatty acid profile and, they can also act as carriers for lipophilic bioactive substance. Low molecular weight oleogelators (LMOGs) are well studied and reviewed. In contrast, high molecular weight oleogelators (HMOGs) e.g., polysaccharides and proteins, are not fully researched yet. This review focusses on development of HMOG oleogels produced by means of emulsion templated, direct dispersion, foam templated and solvent exchange methods that can influence the stability, physicochemical properties and their potential application in food industry. Multi-component oleogels can solve the inefficiencies in a single component oleogel and, thus, combinations of HMOGs and HMOGs & LMOGs can produce oleogels with desired properties. These new oleogels can find application as fat substitutes in food products, providing better nutritional and sensory acceptance. A comprehensive overview of recent developments in the field of HMOG and multicomponent oleogels with HMOG is deeply reviewed.

Recent patents on water-soluble polysaccharides for advanced drug delivery, tissue engineering and regenerative medicine

Water-soluble polysaccharides have unique properties and have found wide application in the design of advanced drug-delivery systems and the biofabrication of tissue engineered scaffolds in regenerative medicine. This patent review provides a concise incursion into the mechanisms that define the key properties of water-soluble polysaccharides that have found embodiment within active patents recently granted (2020-2021). In addition, the relationship between their solubility and structural features such as molecular weight, ionic profile, degree of branching/crosslinking, side-chain flexibility and the presence/modification of functional groups that have been discusses. An assimilation of patents in which water-soluble polysaccharides are central to the design of therapeutic interventions applied to specialized treatments in oncology, infectious diseases and neuronal disorders is provided.

Synthesis of starch nanoparticles with controlled morphology and various adsorption rate for urea

Starch nanoparticles (SNPs) with different morphology and particle size can be prepared by modulating the reaction conditions over SNPs preparation. This study was to synthesize various SNPs by using ultrasound assisted nanoprecipitation method, and characterized by particle size analysis, SEM and XRD performing. SNPs were successfully produced via nanoprecipitation and the particle size were controlled in the range of 95 to 150 nm. Moreover, variously different morphologies were obtained when using corn, potato or Trichosanthes kirilowii pulp (TKP) starch to produce nanoparticles, including fiber, flake and film. Results shown film TKP SNPs demonstrated an improved urea adsorption rate to 135.60 mg/g with the highest q_m at 1.00 mg/mL. SNPs can be developed using ultrasound assisted nanoprecipitation method and the particle size together with surface morphology can be varied according to the source of starch and preparation method, while surface morphology is the key factor in altering adsorption performance.

KOH/thiourea aqueous solution: A potential solvent for studying the dissolution mechanism and chain conformation of corn starch

Non-derivatizing, high-efficiency and low-toxicity solvents are important for studying the dissolution behavior and potential applications of starch. In this study, we investigated the starch dissolution mechanism and molecular conformation in KOH/thiourea aqueous solutions and compared these with KOH/urea and KOH aqueous solutions. Solubility analysis revealed that the KOH/thiourea solution demonstrates a better ability to dissolve corn starch than KOH/urea and KOH solutions. Rheological behavior and dynamic and static light scattering indicated that starch is stable in KOH/thiourea solution and exists as a regular star structure. Fourier transform infrared spectroscopy, ¹³C NMR, and molecular dynamics simulations indicated that hydrated K⁺ and OH^- destroy the strong starch hydrogen bond interactions; thiourea hydrate self-assembles into a shell surrounding the starch-KOH complex through interaction with KOH, whereas there is no direct strong interaction between urea and KOH. Therefore, adding thiourea to a KOH solution can promote dissolution and prevent self-aggregation of the starch chain.

Regulation nature of water-choline amino acid ionic liquid mixtures on the disaggregation behavior of starch

Fully green and renewable choline amino acid (choline glycine, [Cho][Gly]) ionic liquid (IL) was firstly explored and evaluated as a solvent for starch. By a thorough investigation of microstructure evolution of water-[Cho][Gly] (w:IL) mixtures, its regulation mechanism on disaggregation behaviors of starch was revealed and illuminated. Compared with pure water, existed hydrated free ions in w:IL-9:1 and w:IL-7:3 restrict starch-water interactions to disaggregate of starch, thus hampering gelatinization of starch. While the gelatinization temperatures decreased at w:IL-5:5 and w:IL-4:6 mixtures with a result of homogeneous starch solutions. The tight and water-separated ion pairs existed at w:IL-5:5 and w:IL-4:6 mixtures allow adequate ions to interact with starch to facilitate the disaggregation of starch. At w:IL-2:8 and w:IL-0:10 mixtures, an exothermic dissolution of starch was observed at high temperatures as a result of predominant starch-ion interactions. These results provide the possibility of using [Cho][Gly] solvent to meet various application requirements of starch.

A comparative investigation of gelatinized and regenerated starch composites reinforced by microfibrillated cellulose

This research demonstrated a novel and ecofriendly method for producing regenerated starch (RS)/microfibrillated cellulose (MFC) composite films with a nearly 1.4-fold improvement in tensile strength than traditional gelatinized starch (GS) films. Pure starch was dissolved in 14 wt% urea/4 wt% sodium hydroxide (NaOH) solution at 0 °C. Then, RS films and their biocomposite films containing MFC were prepared by dialyzing and solution-casting method. Results showed that the tensile strength and elongation at break of RS increased by 44.8% and 82.4%, compared with that of GS film, respectively. Owing to the adequate dispersion, lower viscosity-average molecular weight, higher amylose content, lower crystallinity and smaller crystal grain size, RS/MFC composite films exhibited significantly improved mechanical properties. The novel strategy used in this study will be helpful in preparing regenerated starch materials with excellent mechanical properties and biodegradability as alternatives to petrochemical plastics for the development of sustainable materials.

Characterization the structural property and degradation behavior of corn starch in KOH/thiourea aqueous solution

Finding an efficient and eco-friendly solution for starch dissolution has attracted considerable attentions in recent years. This study investigated the structural characteristics, and degradation behavior of corn starch in KOH/thiourea aqueous solution by the comparison with DMSO/LiBr and 1-allyl-3-methylimidazolium chloride (AMIMCl). Results showed that KOH/thiourea solution was an effective solvent for corn starch dissolution (30 min with 97.01% solubility). X-ray diffraction (XRD) and ¹³C CP-MAS NMR spectroscopy revealed that native crystallinity of the corn starch was altered by all tested solvents, especially DMSO/LiBr and AMIMCl. Conversely, this new solvent did not change the primary molecular structure, chain-length distribution, or thermal stability of starch, compared with the native starch. Furthermore, KOH/thiourea solution was more suitable for measuring the molecular weight of corn starch, with a weight-average molecular weight (M_w) of 7.18 × 10⁷ g/mol. Therefore, KOH/thiourea solution is a promising novel solvent for starch dissolution and structural exploration.

Relationships among molecular, physicochemical and digestibility characteristics of Andean tuber starches

This study aimed to determine and correlate the physicochemical, thermal, pasting, digestibility and molecular characteristics of native starches, such as mashua (Tropaeolum tuberosum R. and P.), oca (Oxalis tuberosa Mol.), and olluco (Ullucus tuberosus C.), which were extracted via successive washing and sedimentation. The morphology of native starches was determined by scanning electron microscopy, granule size distribution, thermal properties, pasting properties, X-ray diffraction (XRD), amylopectin chain-length distribution and amylose and amylopectin molecular weights. Mashua starch was smaller in size than oca and olluco starches. Moreover, the granules of mashua starch were round in shape, whereas those of oca and olluco starches were ellipsoidal in shape. The B XRD spectra showed similar profiles for the three Andean tuber starches. Mashua and olluco starches exhibited the lowest gelatinization temperatures and enthalpy values, and olluco amylopectin exhibited a longer chain length than mashua and oca starches. The resistant starch of gelatinized and ungelatinized samples exhibited a positive and strong correlation with the molecular properties of amylose and amylopectin, gelatinization enthalpy and molecular order.

Physicochemical studies of nanocrystals of starches from two rice (Oryza sativa L.) types and their characteristics using various modern instrument techniques

BACKGROUND

Starch nanocrystals have received considerable attention, due to their biodegradability, nontoxicity and renewable and abundant sources. The objective of this research is to compare the morphology, physicochemical characteristics and rheological properties of native (NSNC) and waxy rice starch nanocrystals (WSNC).

RESULTS

Both NSNC and WSNC exhibited a platelet-like shape, and they tended to show square-like platelet morphology with increasing initial amylopectin content. Compared to native starches, three weight loss stages of NSNC and WSNC in thermogravimetric analysis curves were observed, while the thermal depolymerization of NSNC started earlier than that of WSNC. The relative crystallinity of NSNC and WSNC was 38.6% and 48.3%, respectively, which were markedly higher than that of native starches. Fourier transform infrared spectra revealed that NSNC presented the highest ratio of 1045/1014 cm^-1 bands among the tested samples, which was probably due to the re-association of retrograded amylose to double-helices structure in NSNC. Moreover, the introduction of sulfur atoms on the surface of NSNC and WSNC was confirmed from the results of X-ray photoelectron spectroscopy. At 5% (w/v) and 10% (w/v) concentration levels, all SNC suspensions exhibited a shear-thinning behavior as the shear rate increased from 0.1 to 100 s^-1 .

CONCLUSIONS

Starch nanocrystals obtained from native and waxy rice starch can be potentially used as reinforcement in biodegradable nanocomposites for packaging, fat replacers, thickening agents and emulsion stabilizers. © 2020 Society of Chemical Industry.

Starch and Glycogen Analyses: Methods and Techniques

For complex carbohydrates, such as glycogen and starch, various analytical methods and techniques exist allowing the detailed characterization of these storage carbohydrates. In this article, we give a brief overview of the most frequently used methods, techniques, and results. Furthermore, we give insights in the isolation, purification, and fragmentation of both starch and glycogen. An overview of the different structural levels of the glucans is given and the corresponding analytical techniques are discussed. Moreover, future perspectives of the analytical needs and the challenges of the currently developing scientific questions are included.

Starch/microcrystalline cellulose hybrid gels as gastric-floating drug delivery systems

We report hybrid gels based on a high-amylose starch and microcrystalline cellulose with demonstrated properties for gastric-floating drug delivery purposes. The starch/cellulose gels were prepared by ionic liquid dissolution and regeneration, resulting in a continuous surface and a porous interior and a type-II crystalline structure of cellulose. These polysaccharide gels displayed satisfactory elasticity (0.88), recovery (0.26-0.36) and equilibrium swelling (1013-1369%). The hybrid gels were loaded with ranitidine hydrochloride as a model drug and subsequently, low-density starch/cellulose tablets were fabricated by vacuum-freeze-drying. In vitro tests in a simulated gastric fluid indicate that the 3:7 (wt./wt.) starch/cellulose system could maintain the buoyancy for up to 24 h with a release of 45.87% for the first 1 h and a sustained release for up to 10 h. Therefore, our results have demonstrated the excellent gastric-floating ability and sustainable drug release behavior of the starch/cellulose hybrid gels.

Banana starch and molecular shear fragmentation dramatically increase structurally driven slowly digestible starch in fully gelatinized bread crumb

The role of native (NB) and extruded (EB) banana starch, and a 1:1 native:extruded banana starch composite (MB), in slowing down the starch digestibility of bread crumb and crust was investigated. During extrusion, the molecular weight of banana starch was reduced from 2.75 × 10⁸ to 4.48 × 10⁶ g/mol (HPSEC-MALS-RI). Results showed a slowly digestible starch (SDS) increase from 1.09% (control) to 4.2, 6.6, and 7.76% in NB, MB and EB crumbs (fully gelatinized), respectively. DSC data attributed this occurrence to the formation of supramolecular structures upon storage involving amylopectin branches (especially those from fragmented amylopectin in EB). The hedonic sensory test showed no differences in overall liking between MB, EB and control, validating feasibility of including banana in the formulation. For the first time, this study shows a molecular size reduction as a strategy to manufacture selected starches that result in highly gelatinized baked products rich in structurally driven SDS.

Molecular structure of starch isolated from jackfruit and its relationship with physicochemical properties

The molecular structure of starches isolated from five jackfruits (M2, M3, M4, M8 and X1) and its relationship with physicochemical properties were investigated. Although they had uniform amylose (AM) content, the five jackfruit starches displayed different physicochemical properties, including their pasting, thermal, crystal and texture properties. Furthermore, differences in the molecular structure (i.e., average weight-average molar mass (Mw) of amylose and amylopectin (AP) as well as the same AP fine structure) were also found in the five jackfruit starches. The results indicated that jackfruit starch with a larger Mw of amylose and proportions of DP 25–36, DP ≥ 37 and chain length had a lower peak viscosity, breakdown, final viscosity, setback and adhesiveness, but a higher pasting and gelatinization temperature, gelatinization temperature range, gelatinization enthalpy and relative crystallinity. Xiangyinsuo 1 hao (X1) starch, which originated from Xinglong in Hainan province, China, had special physicochemical properties, which were ascribed to its lower amylopectin Mw, smaller particle size, and perfect amylopectin structure. The results showed that the most important intrinsic factors that could determine the physicochemical properties of starch were its molecular structure, including the Mw of amylose and AP as well as a fine AP structure.

Re-evaluation of oxidised starch (E 1404), monostarch phosphate (E 1410), distarch phosphate (E 1412), phosphated distarch phosphate (E 1413), acetylated distarch phosphate (E 1414), acetylated starch (E 1420), acetylated distarch adipate (E 1422), hydroxypropyl starch (E 1440), hydroxypropyl distarch phosphate (E 1442), starch sodium octenyl succinate (E 1450), acetylated oxidised starch (E 1451) and starch aluminium octenyl succinate (E 1452) as food additives

Following a request from the European Commission, the EFSA Panel on Food Additives and Nutrient sources added to Food (ANS) was asked to deliver a scientific opinion on the re-evaluation of 12 modified starches (E 1404, E 1410, E 1412, E 1413, E 1414, E 1420, E 1422, E 1440, E 1442, E 1450, E 1451 and E 1452) authorised as food additives in the EU in accordance with Regulation (EC) No 1333/2008 and previously evaluated by JECFA and the SCF. Both committees allocated an acceptable daily intake (ADI) 'not specified'. In humans, modified starches are not absorbed intact but significantly hydrolysed by intestinal enzymes and then fermented by the intestinal microbiota. Using the read-across approach, the Panel considered that adequate data on short- and long-term toxicity and carcinogenicity, and reproductive toxicity are available. Based on in silico analyses, modified starches are considered not to be of genotoxic concern. No treatment-related effects relevant for human risk assessment were observed in rats fed very high levels of modified starches (up to 31,000 mg/kg body weight (bw) per day). Modified starches (e.g. E 1450) were well tolerated in humans up to a single dose of 25,000 mg/person. Following the conceptual framework for the risk assessment of certain food additives, the Panel concluded that there is no safety concern for the use of modified starches as food additives at the reported uses and use levels for the general population and that there is no need for a numerical ADI. The combined exposure to E 1404-E 1451 at the 95th percentile of the refined (brand-loyal) exposure assessment scenario for the general population was up to 3,053 mg/kg bw per day. Exposure to E 1452 for food supplement consumers only at the 95th percentile was up to 22.1 mg/kg bw per day.

Superparamagnetic Iron Oxide Nanoparticles-Complexed Cationic Amylose for In Vivo Magnetic Resonance Imaging Tracking of Transplanted Stem Cells in Stroke

Cell-based therapy with mesenchymal stem cells (MSCs) is a promising strategy for acute ischemic stroke. In vivo tracking of therapeutic stem cells with magnetic resonance imaging (MRI) is imperative for better understanding cellular survival and migrational dynamics over time. In this study, we develop a novel biocompatible nanocomplex (ASP-SPIONs) based on cationic amylose, by introducing spermine and the image label, ultrasmall superparamagnetic iron oxide nanoparticles (SPIONs), to label MSCs. The capacity, efficiency, and cytotoxicity of the nanocomplex in transferring SPIONs into green fluorescence protein-modified MSCs were tested; and the performance of in vivo MRI tracking of the transplanted cells in acute ischemic stroke was determined. The results demonstrated that the new class of SPIONs-complexed nanoparticles based on biodegradable amylose can serve as a highly effective and safe carrier to transfer magnetic label into stem cells. A reliable tracking of transplanted stem cells in stroke was achieved by MRI up to 6 weeks, with the desirable therapeutic benefit of stem cells on stroke retained. With the advantages of a relatively low SPIONs concentration and a short labeling period, the biocompatible complex of cationic amylose with SPIONs is highly translatable for clinical application. It holds great promise in efficient, rapid, and safe labeling of stem cells for subsequent cellular MRI tracking in regenerative medicine.

Scalable preparation, characterization, and application of alkali-treated starch as a new organic base catalyst

Preparation, characterization, and application of alkali starch (AS) given by dry co-grinding of starch and alkali is described in this work. Grinding using a mortar (agate) and pestle or, more conveniently, a ball mill has been found to be satisfactory for the preparation of the AS. The AS products were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) and x-ray fluorescence (XRF) analyses. The base capacities of ASs were 4.25-4.45 mmol/g, respectively. AS is a low cost and easy to handle base catalyst that showed promising catalytic performance in the synthesis of a dihydroquinazoline-based antibacterial drug that involves tandem hydration or decarboxylative amidation, imination, and Aza-Michael reactions.

Isolation, characterization and the potential use of starch from jackfruit seed wastes as a coagulant aid for treatment of turbid water

Fruit wastes constituting up to half of total fruit weight represent a large pool of untapped resources for isolation of starch with diverse applications. In this work, the possibility of isolating starch from tropical fruit wastes and its extended application as a natural coagulant was elucidated. Amongst the 12 various parts of fruit wastes selected, only jackfruit seeds contained more than 50% of total starch content. Using alkaline extraction procedures, starch has been successfully isolated from local jackfruit seeds with a yield of approximately 18%. Bell-shaped starch granules were observed under SEM with a granule size ranging from 1.1 to 41.6 μm. Detailed starch characteristics were performed to provide a comparison between the isolated seed starch and also conventional starches. Among them, chemical properties such as the content of starch, amylose, amylopectin and the corresponding molecular weights are some of the key characteristics which governed their performance as natural coagulants. The potential use of isolated seed starch as an aid was then demonstrated in both suspensions of kaolin (model synthetic system) and Chlorella sp. microalga (real-time application) with plausible outcomes. At optimized starch dosage of 60 mg/L, the overall turbidity removal in kaolin was enhanced by at least 25% at a fixed alum dosage of 2.1 mg/L. Positive turbidity and COD removals were also observed in the treatment of Chlorella suspensions. Starches which served as bridging agents aided in the linkage of neighbouring microflocs and subsequently, forming macroflocs through a secondary coagulation mechanism: adsorption and bridging.