Short Glucan Chains Research Articles

Size-controlled interfacial crystallization of A-type resistant starch microparticles via acetone precipitation

Short-chain glucan (SCG) recrystallization has emerged as an effective approach for producing resistant starch microparticle (RSP), which hold promise in both food science and clinical nutrition. This study introduces a novel method utilizing Tween 80 (TW80) to mediate the interfacial recrystallization of SCG into A-type crystalline RSP (ARSP) through acetone precipitation. TW80 plays a crucial role by stabilizing water-in-oil microemulsion droplets within acetone-oil mixtures, facilitating the formation of uniform and spherical ARSP ranging in size from 0.2 μm to 2 μm. The surface characteristics of ARSP, including porosity and smoothness, are notably influenced by SCG concentration. As SCG concentration increases, the melting temperature of ARSP rises from 117 °C to 145 °C, accompanied by a decrease in average surface area from 12.07 to 8.35 m2/g, alongside an increase in crystallinity. Moreover, the in vitro digestion test revealed that the digestion rate of ARSP was decreased from 0.73 h−1 to 0.39 h−1 with increasing SCG concentration, while increasing the resistant starch (RS) content in ARSP from 48.6% to 70.5%. This enhancement offers a strategic approach for modulating the digestion rate of ARSP, presenting opportunities for tailored release profiles and improved stability in food science applications. These findings underscore the potential of ARSP as a functional ingredient with significant implications for nutritional and clinical settings.

The maltose-related starch degradation pathway promotes the formation of large and spherical transitory starch granules.

Previously, in Arabidopsis thaliana, we found atypical spherical starch granules in dpe2ss4 and dpe2phs1ss4. However, the mechanism of such abnormal morphogenesis is still obscure. By tracking starch granule length and thickness with leaf ageing, we reported that the starch granules in dpe2phs1ss4 gradually change to a spherical shape over time. In comparison, Col-0 and the parental line ss4 did not exhibit macroscopic morphological alteration. In this study, firstly, we specify that the additional lack of DPE2 resulted in the gradual alteration of starch granule morphology over time. Similar gradual morphological alterations were also found in dpe2, mex1, and sex4 but not in the other starch degradation-related mutants, such as sex1-8, pwd, and bam3. The gradual alteration of starch morphology can be eliminated by omitting the dark phase, suggesting that the particular impaired starch degradation in dpe2- and mex1-related mutants influences starch morphology. Secondly, we observed that spherical starch morphology generation was accompanied by prominent elevated short glucan chains of amylopectin and an increased amylose proportion. Thirdly, the interplay between soluble starch synthase 2 and branching enzymes was affected and resulted in the formation of spherical starch granules. The resulting spherical starch granules allow for elevated starch synthesis efficiency. Fourthly, the starch phosphate content at the granule surface correlated with the morphology alteration of the starch granules. Herewith, we propose a model that spherical starch granules, accumulated in mutants with a misbalance of the starch degradation pathway, are result of elevated starch synthesis to cope with overloaded carbohydrates.

Hierarchical mesoporous TiO2/starch-based microparticles used as an efficient and reusable adsorbent for removal of water-soluble dye

The widespread use of organic dyes in various industrial applications, driven by rapid industrialization, has become a significant environmental concern. Thus, highly efficient and reusable adsorbent for removal of pollutant dyes have gained increasing attention in water treatment. In this study, we present TiO2 nanoparticle-embedded mesoporous starch-based microparticle (TiO2@MSMP) with hierarchical rose-like structure were synthesis by using acetone precipitation of short-chain glucan (SCG) obtained from waxy maize starch. The resulting TiO2@MSMP exhibits an A-type crystalline polymorph and mean particle size of approximately 2 μm, displaying a type IV adsorption isotherm with a mean pore diameter of 19 nm and an average surface area of 12.34 m2/g. The adsorption ability of TiO2@MSMP towards methyl orange (MO) and crystal violet (CV) were 85.8 mg/g and 103.8 mg/g, respectively. The reusability of TiO2@MSMP was achieved by UV irradiation, which resulted in photodegradation of the adsorbed dye over 80 % while maintaining good absorption ability and structural stability during the recycling process. Given its cost-effectiveness, high adsorption capacity, and excellent reusability, TiO2@MSMP holds promise as an effective and environmentally friendly adsorbent with significant potential for removing dyes from aqueous solutions and purifying water.

Directed self-assembly of mesoporous starch-based microparticle: Characterization, antimicrobial activities, and digestibility

Porous starch has garnered increasing interest due to its distinctive properties and versatile applications. Here, we propose a sustainable and efficient method for producing highly uniform mesoporous starch-based microspheres (CSMP) with adjustable sizes through the directed self-assembly of short-chain glucan (SCG) using chitosan. Chitosan facilitates the layer-by-layer deposition of SCG nuclei in the circumferential direction, resulting in the formation of a porous structure on CSMP. By controlling the concentration of SCG, the particle size can be precisely tuned within the range of 400 nm–900 nm. The resulting CSMP exhibit enhanced properties compared to starch-based microspheres formed without chitosan, including a surface area of 20.54 m2/g, total pore volume of 0.13 cm³/g, average pore diameter of 25.5 nm, and water absorption capacity of 352.6%. Moreover, CSMP demonstrate remarkable antibacterial activity (over 93%) against Escherichia coli and Staphylococcus aureus, while containing a high level of resistant starch (over 60%), highlighting their potential for the development of functional foods.

Precision-controlled synthesis of monodisperse starch nanoparticles: Factors affecting the self-assembly kinetics

Enzymatic modification has emerged as a crucial technique for enhancing the physicochemical attributes of starch. In particular, the short-chain glucans (SCGs) obtained from the debranching of native starch has been utilized to produce functional micro- and nano-structures through their inherent self-assembly property. However, a significant challenge remains in controlling the self-assembly kinetics of SCGs, which often results in undesirable heterogeneous structures. This study explores the factors governing SCG self-assembly and their impact on the formation of monodisperse starch nanoparticles (SNPs). We discovered that incomplete removal of the debranching enzyme during SCG self-assembly leads to particle aggregation, with the degree of aggregation dependent on the concentration of remaining enzyme. Furthermore, the initial SCG concentration significantly influences SNP growth; high concentration results in gel-like structures, while lower concentration produces discrete and spherical nanoparticles. Complete dispersion of growth species, SCGs, before self-assembly through appropriate high-temperature heating was found to be critical for uniform nuclei formation, thereby resulting in the production of well-defined nanoparticles. Systematically manipulating these kinetic factors allowed us to fabricate monodisperse SNPs with an average size of 200 nm. This study advances our understanding of SCG self-assembly kinetics, providing valuable insights for the precision-controlled synthesis of starch-based nanoparticles.

Carbohydrate Profiling of Different Accessions of Three Underutilized Legumes: A Potential Source of Valuable Nutraceuticals and Pharmaceuticals

AbstractCarbohydrates are significant components of legumes, and their profiling can provide information about their nutritional value and potential health benefits. This study explores the proximate composition and carbohydrate profiles of accessions of three underutilized legumes, namely, Vigna radiata, Vigna mungo, and Macrotyloma uniflorum. The total starch and soluble sugar are determined. Starch granule morphology and diameter are determined using scanning electron microscopy and chain length distribution of amylopectin is analyzed using Capillary Electrophoresis. All accessions of the legumes vary both in their proximate composition and carbohydrate components. Accessions of M. uniflorum (PI‐658594‐01‐SD) have the highest carbohydrate component (7.6%) while V. radiata (TVR‐42) has the least (4.2%). Macrotyloma uniflorum accensions (PI‐658594‐01‐SD, and PI‐180437‐01‐SD) have the highest starch and sucrose contents, while V. mungo accensions (TVM‐13, and TVM‐11) have the lowest. The glucose and fructose contents are lower than sucrose in all the accessions of the legumes. Macrotyloma uniflorum accensions exhibit larger granules while accessions of Vigna species have the smallest granules. All species accessions exhibit similar amylopectin chain length distribution profiles although accessions of V. mungo slightly differ in their proportion of long and short glucan chains. The three species of underutilized legumes exhibit unique characteristics which make them suitable for consumption and may be exploited as a source of nutraceuticals and pharmaceuticals.

Thermo-reversibility of short-chain glucan aggregates (SCGA) derived from various starches

Thermo-reversibility of short-chain glucan aggregates (SCGA) prepared from eight kinds of starches was investigated. All native SCGA showed the double helical melting transition between 70 and 105 °C. Upon immediate cooling after heating, the SCGA was recrystallized at 50 °C. The double helical melting temperature and enthalpy of all recrystallized SCGA were increased compared to native SCGA, indicating improved thermal stability of recrystallized SCGA. The morphology of recrystallized SCGA was similar to native SCGA with discrete particle shape and decreased the continuous phase cluster. Additionally, the crystallinity, thermal properties, and in-vitro digestibility of recrystallized SCGA were greatly affected by the heating temperature. Boiling (100 °C) showed higher relative crystallinity but lower double helical melting and resistant starch content compared to autoclaving (121 °C), suggesting that the remaining crystal seeds affected the re-assembly of short-chain glucans during the recrystallization. The physicochemical properties of SCGA would be controlled through its thermo-reversibility and heating temperature.

Modulation of the self-assembly kinetics and digestibility of type 3 resistant starch particles by co-crystallization with amino acid.

The effect of eight different l-amino acids (L-AA) on type-3 resistant starch particles (rSPs) derived from short chain glucan (SCG) was investigated. The L-AA were categorized based on their charge and polarity. The results reveal that positively charged L-AA, such as lysine and arginine, decreased the nucleation and growth rate of rSPs, while non-charged L-AA have negligible effects. Negatively charged L-AA, such as glutamic acid and aspartic acid, had a significant impact on the morphology and crystallinity of the rSPs, resulting in particle size of around 3μm and crystallinity of around 35%. This implies that charged L-AA influence the arrangement of SCG double helices in the particles. Furthermore, the complexation of SCG with charged L-AA reduced the level of RS in rSPs, indicating that L-AA could be useful in modulating the physical properties and digestibility of rSPs.

Metal ion-mediated modulation of morphology, physicochemical properties, and digestibility of type 3 resistant starch microparticle

Short-chain glucan (SCG) derived from debranched amylopectin has emerged as a promising candidate for the production of resistant starch particle (RSP) due to its controllable self-assembly features. Here, we investigated the effect of metal cations with different valencies and concentrations on the morphology, physicochemical properties, and digestibility of RSP formed by the self-assembly of SCG. The effect of cations on the formation of RSP followed the valency in the following order: Na+, Ka+, Mg2+, Ca2+, Fe3+, and Al3+, of which 10 mM trivalent cations increased the particle size of RSP over 2 μm and considerably decreased the crystallinity by 49.5 % ~ 50.9 %, which were significantly different from that of mono- and divalent ones. Importantly, RSP formed with divalent cations switched the surface charge from −18.6 mV to 12.9 mV, which significantly increased the RS level, indicating that metal cations would be useful for regulating physicochemical properties and digestibility of RSP.

Self-assembly kinetics of short-chain glucan aggregates (SCGA)

Self-assembly (formation and crystallization) kinetics of short-chain glucan aggregates (SCGAs) prepared at isothermal conditions (4, 20, 40, and 60℃) with or without nucleation (4℃, 1 h) were investigated. The fastest formation and crystallization rates of SCGA were observed when short-chain glucan was stored at 4℃ and 20℃, respectively. SCGA was not formed at 60℃. However, nucleation resulted in SCGA forming-ability at 60℃. Moreover, nucleation increased the yield in all temperature conditions. SCGA with nucleation decreased the crystal melting transition temperature range. All SCGAs had nanosized particles (<500 nm) with B-type crystal patterns regardless of temperature and nucleation. Consequently, self-assembly temperature and presence of nucleation step could change the physicochemical characteristics of SCGA, and manipulation of the nucleation step is expected to be an effective method to increase the yield of SCGA and produce SCGA at high temperature.

Facile preparation of highly uniform type 3 resistant starch nanoparticles

Resistant starch (RS) has emerged as a promising functional food ingredient. To improve the textural and sensory characteristics of RS, there need to be an effective approach to produce RS with well-defined size and shape. Here, we present a facile approach for the synthesis of highly uniform resistant starch nanoparticles (RSNP) based on recrystallization of short-chain glucan (SCG) originated from debranched starch. We found that the ratio of SCG to partially debranched amylopectin was a key parameter in regulating the morphology, size, and crystallinity of the nanoparticles, which enable us to prepare highly uniform RSNP with an average diameter of around 150 nm, while showing a good colloidal stability over a broad range of pH (2–10). Moreover, the in-vitro digestibility and RS content of RSNP was not affected over the ten successive cycles of assembly and disassembly, which would provide useful insights for the development of RS-based functional food ingredients.

Fabrication of starch/zein-based microcapsules for encapsulation and delivery of fucoxanthin

As a drug carrier, starch-based microparticle (SMP) has attracted widespread attention. However, because SMP is commonly formed in aqueous media, it is facing the challenge of encapsulation of hydrophobic bioactive. Here, we present an effective method for encapsulating fucoxanthin (Fx), a model hydrophobic bioactive, within SMP formed by self-assembly of short-chain glucans (SCG), using zein nanoparticles as intermediate vectors. SMP exhibited higher encapsulation efficiency to chitosan-coated Fx-zein nanoparticles (∼91%) at a given concentration of 50 μg/mL compared to soybean polysaccharide-coated ones. Fx in SMP was found to be more stable against UV radiation-induced degradation and FeCl3-catalyzed oxidative stresses than free Fx. Furthermore, SMP conferred controlled release of Fx in the duodenum (6%), jejunum (13%), ileum (32%), and colon (42%), implying that this approach could be useful in designing an effective drug carrier for delivering several hydrophobic bioactives to different parts of the intestine.

The amino acid on the top of the active groove allosterically modulates product specificity of the 1,4-α-glucan branching enzyme

The 1,4-α-glucan branching enzymes (GBEs, EC 2.4.1.18) catalyse the formation of α-1,6 branching points in starch, presenting several potential applications in modifying starch. Previous study proved that W285 is considered to act as a “switch” to stop extension of substrates in the structure of GBE from Cyanothece sp. (cceBE). In the structure of GBE from Rhodothermus obamensis STB05 (RoGBE), the amino acid 160 site is structurally similar to the W285 in cceBE. In order to explore the role of this site in RoGBE, several engineered mutants individually substituted with Arg, Phe and Ala at G160 were studied in our research. The results show that substitution with Arg and Phe increased branching activity significantly, and the ratio of short glucan chains among all oligosaccharides increased. Finally, we proposed that the G160 is a ‘door model’ to elucidate introduced mutagenesis that triggers and controls the length of binding glucan chains of starch.

Effects of stirring during gelatinization and shaking during hydrolysis on the characteristics of short-chain glucan aggregates (SCGA)

Effects of stirring during gelatinization and shaking during hydrolysis on physicochemical properties of short-chain glucan aggregates (SCGA) were investigated. Both stirring and shaking improved SCGA yield, and also affected the formation and crystallization kinetics of SCGA. Without stirring and shaking, slow SCGA forming rate, large size (∼1.32 μm), high relative crystallinity (RC), high endothermic onset temperature, and high melting enthalpy (ΔH) were observed. Stirring and shaking yielded the fastest SCGA formation and crystallization rates as well as the smallest SCGA size (∼0.57 μm). Small SCGA had a low RC and low heat stability, possibly due to the presence of imperfections and low double helix content. Formation yield was negatively correlated with size, ΔH, RC, and the resistant starch content of SCGA. The highest correlations were observed between ΔH and RC. This study proves that the SCGA characteristics can easily be controlled by stirring during gelatinization and shaking during enzymatic hydrolysis.

Preparation and characterization of self-assembled short-chain glucan aggregates (SCGAs) derived from various starches

Short chain glucan aggregates (SCGAs) forming ability of starches from different botanical sources and physicochemical characteristics of the produced SCGAs from various starches were investigated. SCGAs were obtained by enzymatic hydrolysis and centrifugation followed by self-assembly of their hydrolysates in supernatant. Size of SCGAs was 0.68–1.30 μm and its shape was spherical with high agglomeration. Yield showed negative correlation with amylose content (R2 = 0.9024) indicating that starches with low amylose content or high amylopectin content produced more SCGAs. Chain length distribution of SCGAs prepared from various starches were similar possibly due to the removal of large and insoluble portions using centrifugation after enzymatic hydrolysis. Main constituent of SCGAs was a B1 chain (13 = DP ≤ 24). All SCGAs showed B-type crystal pattern with relative crystallinity of 14.5–19.4%. DSC endothermic transition of SCGAs occurred at higher temperature than native starch indicating the improved thermal stability. Colloidal dispersion stability of SCGAs was increased with increasing absolute value of zeta potential and decreasing particle size. Consequently, SCGAs can be obtained from all kinds of starches regardless of amylose content and type of crystallinity, and have distinctive physicochemical properties. This study provides helpful information on the preparation of SCGA from various starches and their characteristics resulting that SCGAs can be customized with appropriate properties using different starches.

Preparation of starch-based drug delivery system through the self-assembly of short chain glucans and control of its release property

Here, we report a starch-based carrier system for the delivery of insoluble bioactive compound via oral route. We utilized the intrinsic characteristics of debranched amylopectins that self-assemble into a spherical microparticle in aqueous environment to encapsulate guest molecules. Upon complexation with β-cyclodextrin, the model bioactive compound, curcumin (CUR), was effectively incorporated into the starch microparticles (SMPs) to form CUR-CD@SMPs during the self-assembly reaction. The stability of encapsulated curcumin against environmental stresses, such as photodegradation and chemical oxidation, was greatly enhanced upon encapsulation. The size of CUR-CD@SMPs could be precisely controlled from 0.3 μm to 2 μm by modulating the rate of debranching reaction. A change of release profiles from concave-downward to sigmoidal form was observed upon increasing the size of CUR-CD@SMPs, suggesting that the release site could be controlled by modulating the crystallinity or size of the carrier microparticles.

Biochemical analysis of a new sugary-type rice mutant, Hemisugary1, carrying a novel allele of the sugary-1 gene.

A novel allele of the sugary-1 rice mutant was isolated. The single amino acid change led to isoamylase activity reduction and accumulation of high-molecular-weight phytoglycogen in seeds. A new sugary rice variety with an improved seed appearance has been isolated and designated Hemisugary1. This mutant, which was derived from Japonica-type cultivar Tsugaruroman treated with sodium azide, has about half the isoamylase activity of seeds in the original Tsugaruroman. The mutant also accumulates significant phytoglycogen, albeit approximately 40% of the total phytoglycogen in the existing sugary cultivar Ayunohikari which is defective in its most isoamylase activity. The site of mutation was identified using a re-sequence of the whole genome and a cleaved amplified polymorphic sequence (CAPS) marker. The hemisugary phenotypes of the F2 progeny were entirely consistent with the results of genotyping using the CAPS marker. Segregation analysis of the F2 population showed that the hemisugary phenotype was controlled by a single recessive gene, which was produced by a G → A single nucleotide polymorphism in the sugary-1 gene, resulting in a missense mutation from glycine to aspartic acid at amino acid position 333. Zymogram showed that this amino acid replacement resulted in a decrease in isoamylase activity with a concomitant reduction in the formation of isoamylase complexes. Phytoglycogen molecules from Hemisugary1 seeds were 3.5 times larger and contained more short glucan chains than did Ayunohikari seeds. Our data provide new insights into the relationship between isoamylase structure and phytoglycogen formation.

Colorimetric Determination of the Activity of Starch-Debranching Enzyme via Modified Tollens' Reaction.

Nelson–Somogyi and 3,5-dinitrosalicylic acid (DNS) assays are the classical analytical methods for the determination of activity of starch-debranching enzymes, however, they have a narrow detection range and do not adapt to the quantitative measurement of linear polysaccharides. Herein, we developed a simple and accurate colorimetric assay for determining the activity of starch-debranching pullulanase through the modified Tollens’ reaction in combination with UV irradiation. Silver nanoparticles (AgNPs) were formed by reducing aldehyde groups in short-chain glucans (SCGs) generated by debranching of waxy maize starch using pullulanase through the modified Tollens’ reaction. In addition to providing a reducing moiety to the Tollens’ reaction, the debranching product, SCGs, also enhanced the colloidal stability of synthesized AgNPs, of which the amplitude of its surface plasmon resonance (SPR) absorbance peak was proportional to the concentration of SCGs ranging from 0.01–10 mg/mL. The detection limit of this system was 0.01 mg/mL, which was found to be 100 times higher than that of the conventional DNS assay. The purification of SCGs by recrystallization and gelatinization improved the selectivity of this colorimetric assay for debranching products, which provides a simple and accurate means of monitoring the debranching process and characterizing the activity of starch-debranching enzymes.

Structural Characterization and Digestibility of Curcumin Loaded Octenyl Succinic Nanoparticles.

Curcumin displays anti-cancer, anti-inflammatory and anti-obesity properties but its water insolubility limits the wholesome utility. In this study, curcumin has been encapsulated in an amphiphilic biopolymer to enhance its water solubility. This was accomplished through self-assembly of octenyl succinic anhydride–short glucan chains (OSA–SGC) and curcumin. The nanoparticles were prepared with the degree of substitution (DS) of 0.112, 0.286 and 0.342 of OSA. Thus prepared nanoparticles were in the range of 150–200 nm and display high encapsulation efficiency and high loading capacity of curcumin. The Fourier-transform infrared (FTIR) and X-ray diffraction analyses confirmed the curcumin loading in the OSA–SGC nanoparticles. The complexes possessed a V-type starch structure. The thermo gravimetric analysis (TGA) revealed the thermal stability of encapsulated curcumin. The OSA–SGC nanoparticles greatly improved the curcumin release and dissolution, and in-turn promoted the sustained release.

Synthesis of monodisperse starch microparticles through molecular rearrangement of short-chain glucans from natural waxy maize starch

Here, we report a sustainable approach for the synthesis of starch-based microparticles with well-defined shape and size through molecular self-assembly of short-chain glucan (SCG) obtained enzymatically from waxy maize starch. We employed chitosan as a steric stabilizer to modulate the nucleation process, which significantly reduced undesirable aggregations during the nucleation and growth phases, resulting in the production of highly monodisperse microparticles. The size of chitosan-assisted starch microparticles (CS-SMPs) was effectively controlled by the concentration of debranching enzyme as well as by debranching time, of which the factors influencing the final size were investigated. By modulating the rate and time of debranching reaction in combination with the steric stabilizing effect of chitosan, we were able to prepare highly monodisperse CS-SMPs from 200 nm to 5 μm with a production yield of over 70% from natural starch. Furthermore, the potential of CS-SMPs as a carrier system for oral delivery of bioactive compounds were demonstrated using model guest molecules.