Starch Molecules Research Articles

Insights into the relations between the molecular structures and physicochemical properties of normal and waxy wheat B‐starch after repeated and continuous annealing

SummaryThe effect of repeated annealing treatment (RANN) and continuous annealing treatment (CANN) on the structure, physicochemical properties and digestibility of wheat B‐starch were studied. Annealing degraded the starch molecules, disrupted amylopectin and amylose structures, and decreased the molecular weight and the long chain of amylopectin. Meanwhile, the double helix structure and the crystalline and amorphous region were broken, the starch and water molecules were rearranged after RANN and CANN. As a result, annealing increased the crystallinity, gelatinisation temperature, resistant starch and slowly digestible starch content, while decreased the solubility, swelling power and pasting viscosity. The different changes of structural and physicochemical properties for normal and waxy B‐starch upon annealing treatment were because of the different amylose contents and amylopectin chain mobility. The RANN exhibited greater advantages than CANN in the modification of the structural, physicochemical, and digestible properties of normal B‐starch; while CANN significantly affected properties of waxy B‐starch.

Causal relations among starch hierarchical structure and physicochemical characteristics after repeated freezing-thawing

In this study, hierarchical structural and characteristic changes of starches isolated from repeated freezing-thawing (FT) frozen dough were evaluated to understand the causal relations among intrinsic structures and physicochemical characteristics. The surface of FT-treated starch granules displayed pores and cracks, and more severe rupture was obtained as the increase of freezing-thawing cycles. Furthermore, the lamellar structure, crystalline and ordered molecular structure (i.e., short-range ordered molecular and helical structures) of starch were also destructed after FT. And these structural amorphization facilitated the interactions between water molecules and starch molecular chains, the leaching of starch molecules, the entanglements and interactions between amylose and amylopectin, eventually elevating the swelling power, solubility and characteristic viscosity of starch. Also, FT treatment led to an increase in storage modulus (G’) and a decrease in loss tangent (tan δ), which indicated the formation of strong gel network structure.

Retardant effect of different charge-carrying amino acids on the long-term retrogradation of normal corn starch gel

The effects of different charge-carrying amino acids (lysine, aspartic acid, and tyrosine) on the long-term retrogradation properties of normal corn starch (NCS) gel were studied by differential scanning calorimetry, X-ray diffractometry, low-field nuclear magnetic resonance, and dynamic rheological tests. The results suggested that these amino acids could inhibit the long-term retrogradation of NCS gels, among which the positively charge-carrying amino acid (lysine) showed the most significant inhibitory effect and the zero net charged amino acid (tyrosine) exhibited the worst inhibitory effect. These amino acids significantly decreased the retrogradation enthalpy, hardness, and R1047/1022 value of NCS gels, as well as inhibited the recrystallization of NCS. The results of retrogradation kinetics suggested that the recrystallization of NCS with amino acids followed the instantaneous nucleation and the crystallization rate constant k of recrystallization was reduced by these amino acids. The amino acids could interact with starch molecules to form hydrogen bonds and steric hindrance during the recrystallization process, which prevented the formation of double helix structures, as well as reduced the water diffusion and exudation from NCS. Therefore, the lysine could be used as a good retrogradation inhibitor for starch in food industry.

Anti-nutrient & bioactive profile, in vitro nutrient digestibility, techno-functionality, molecular and structural interactions of foxtail millet (Setaria italica L.) as influenced by biological processing techniques

The present investigation aimed at assessing the impact of biological processing techniques on bio-and techno-functional characteristics of foxtail millet (Setaria italica L.). Grains were exposed to soaking, germination, fermentation and combination of aforesaid treatments and significant variation (p < 0.05) in anti-nutritional factors, in vitro starch and protein digestibility, bioactive constituents and associated antioxidant potential was noted. Bioprocessed flours were characterized by altered functional properties due to hydrolytic action of activated enzymes. ATR-FTIR spectra and X-ray diffraction patterns revealed structural variation in macromolecular arrangement, synthesis of bioactive compounds in bioprocessed flours and slight reduction in the crystallinity of starch molecules. Bioprocessed flours exhibited degraded protein matrix; however, only fermentation and combination treatments caused hydrolysis of granular starch. Principal component analysis was employed to validate the differences in processing treatments and observations. The results are suggestive that bioprocessed flours could serve as potential ingredients with improved techno-and bio-functionality in valorized cereal products.

Comprehensive RNA-seq analysis revealed gene network associated with leaf morphogenesis in Vitis vinifera

ABSTRACT Leaf morphogenesis in Vitis vinifera is closely associated with the biosynthesis of various metabolites, starch, and growth-related molecules. In the present study, Illumina RNA deep sequencing-based on transcriptome analysis was deployed to understand leaf morphogenesis in Vitis vinifera. The KEGG pathway analysis revealed the transcripts involved in the biosynthesis of major metabolites leading to leaf growth. The highest number of DEGs were down-regulated at young leave-vs-mature leaves stages (3,501) followed by large leaves-vs-mature leaves (2,364); however, the minimum number of up-regulated transcripts were recorded at young leaves-vs-immature leaves (195). The gene regulation in the starch biosynthetic pathway, young leaves-vs-mature leaves showed the highest number of transcripts (24 up-regulated and 60 down-regulated). For ABC Transporters, 224 transcripts were expressed, among which the maximum number of transcripts (59) were recorded in large leaves-vs-mature leaves. Amino and nucleotide sugar metabolism showed 112 transcripts (22 up-regulated and 90 down-regulated), in which immature leaves-vs-mature leaves expressed 30 DEGs. In addition, Flavonoid pathway showed the highest number of transcripts i.e. 903 were expressed among the studied pathways. The findings of this study will also help to a better understanding of the underlying process during grape leaf morphogenesis and to unravel the mechanism.

Impact of superheated steam on the moisture transfer, structural characteristics and rheological properties of wheat starch

Superheated steam treatment (SST) can improve cereal-based foodstuff quality. Starch is the major component of cereal-based foodstuffs, playing a key role in food quality. For understanding the effect of SST on the moisture distribution, lamellar structure and molecular weight of wheat starch, the low-field nuclear magnetic resonance (LF-NMR), small angle X-ray scattering (SAXS) and size exclusion chromatography were employed. Compared with native starch, SST reduced the average thickness of crystalline layer and induced the depolymerization of starch molecules, which were attributed to the limited moisture transfer resulting in the partial gelatinization of starch granules. The structural variations had a synergistic effect on the rheological properties of starch samples. Upon SST, treated samples exhibited a weaker pseudoplasticity behavior and increased the deformability and mobility of gels systems. Furthermore, the lower tanδ values of treated starch samples were observed, indicating that the gels systems tended to the solid-like behaviors.

Preliminary Investigation of Amylase Producing-Bacteria from Soil in Gombe Metropolis

Amylases are enzymes that are able to hydrolyse starch or glycogen molecules into polymers of glucose units. They have great potential applications in various industrial processes like in pharmaceutical, fermentation and food industries. Research on starch degrading enzymes has resulted into increased applications of amylases in different industrial processes. These enzymes occupy a greater space in the current biotechnological processes such as detergent, starch degradation, pharmaceutical, foodstuff, textile, and paper manufacturing. In fact, amylases constitute nearly 25% of the total sale of global enzymes. Amylases have been screened and identified from various sources, both eukaryotic and prokaryotic organisms such as animals, plants, fungi and bacteria, respectively. To further isolate novel amylases with enhanced desirable properties for such diverse industrial application, more organisms need to be screened. In this study, a total of 27 bacterial isolates were isolated from soil samples in Gombe metropolis. The bacteria were screened for amylase production using plate screening method. Each isolate was streaked onto a 1% starch agar plate and incubated for 24h at 37 °C. The plates were covered with iodine solution and observed for positive amylase isolates based on the formation of clearing zones against the blue black background. The results confirmed eight (8) isolates of amylase-producing bacteria which include Bacillus subtilis, Escherichia coli, Streptococcus spp., Salmonella spp., Pseudomonas spp., Serratia spp., Proteus vulgaris, and Klebsiella spp. In conclusion, bacterial isolates capable of amylase production have been successfully screened and identified. This research may serve as a stepping stone to isolating functional amylase enzymes from these bacteria for promising industrial applications.

Analysis of the sol and gel structures of potato starch over a wide spatial scale.

We analyzed edible potato starch and observed the interaction between its granular structure and water molecules. We studied the changes caused by gelatinization during heating and stirring using microscopy, micro‐FT‐IR spectroscopy, and X‐ray scattering techniques. A wide range of spatial scales was revealed using these various techniques. The rate of gelatinization varied significantly and was dependent on the starch concentration. The process of adsorption of water on starch molecules was studied using the humidity‐controlled FT‐IR spectroscopy technique. Furthermore, by comparing the X‐ray scattering profiles of dry and wet granules, the 9‐nm repeat “cluster” structure was studied. A gradual collapse of the granules occurred during the processes of heating and stirring. A clustered smectic structure and a smectic‐like structure were observed in the opaque gel after gelatinization. Upon further heating, a transparent gel was obtained after the melting of the cluster.

Addition of wheat straw nanofibrils to improve the mechanical and barrier properties of cassava starch–based bionanocomposites

Cellulose nanofibrils (CNFs) were obtained from wheat straw, and different concentrations (0 %, 10 %, 20 %, 30 % and 50 %) of the CNFs were incorporated into cassava starch-based films. Thirty passages through a microfibrillator allowed us to obtain well-dispersed CNFs with reduced thickness (34.26 nm). The addition of CNFs promoted an average increase in tensile strength values on the order of 126.69 %. The treatments with higher CNF addition percentages (30 % and 50 %) presented higher Young's modulus values (566.68 and 585.72 MPa, respectively), which indicates an increase in stiffness. The elongation and puncture force decreased with the addition of CNFs, presenting average reductions of 83.72 % and 56.66 %, respectively. A significant decrease in water vapour permeability was observed for the treatments with higher percentages of CNFs added, with a drop from 2.15 × 10−6 in the control film to 1.39 × 10−6 g mm/KPa−1 day−1 m2 in the film with the maximum addition percentage. The contact angle values increased from 43.45° in the control film to 68.66° in the sample with the maximum CNF concentration. The lower hydrophilicity of the treatments with 30 % and 50 % CNF additions is evidenced by the lower values presented for the Cobb test (99.84 and 99.31 g m2), polar surface free energy (0.41 and 0.19 mN m-1) and polarity (0.01 and 0.007). In these treatments, there were stronger interactions between the CNF and starch molecules. Thus, the addition of 30–50 % wheat straw CNFs is recommended to strengthen the structure and improve the barrier properties of cassava starch-based films.

Understanding how starch constituent in frozen dough following freezing-thawing treatment affected quality of steamed bread

Understanding how starch constituent in frozen dough affected bread quality would be valuable for contributing to the frozen products with better quality. To elucidate the underlying mechanism, starch was fractionated from multiple freezing-thawing (F/T) treated dough and reconstituted with gluten. Results showed that F/T treatment destructed the molecular and supramolecular structures of starch, which were more severe as the F/T cycle increasing. These structural disorganizations made water molecules easier to permeate into the interior of starch granules and form hydrogen bonds with starch molecular chains, which elevated the peak, breakdown, setback and final viscosity of starch paste. In addition, F/T treatment resulted in decreased specific volume (from 1.54 to 0.90 × 103 m3/Kg) and increased hardness (from 42.98 to 52.31 N) for steamed bread. We propose the strengthened water absorption ability and accelerated intra- and inter-molecular rearrangement of starch molecules and weak stability of “starch-gluten matrices” would allow interpreting deteriorated bread quality.

Physical and Biodegradation Properties of Graphene Derivatives/Thermoplastic Starch Composites

Development of biodegradable materials for packaging is an issue of the utmost importance. These materials are an alternative to petroleum-based polymers, which contribute to environment pollution after disposal. In this work, graphene oxide (GO) and glucose-reduced graphene oxide (rGO-g) were incorporated to thermoplastic starch (TPS) by melt extrusion. The TPS/GO and TPS/rGO-g composites had their physical properties and biodegradability compared. X-ray diffraction (XRD) showed that the type of graphene used led to different dispersion levels of graphene sheets, and to changes in the crystalline structure of TPS. Tensile tests carried out for the compression-molded composites indicated that TPS/rGO-g composites presented better mechanical performance. The Young’s modulus (E) increased from E = (28.6 ± 2.7) MPa, for TPS, to E = (110.6 ± 9.5) MPa and to (144.2 ± 11.2) MPa for TPS with rGO-g incorporated at 1.0 and 2.0 mass% content, respectively. The acid groups from graphene derivatives promoted glycosidic bond breakage of starch molecules and improved biodegradation of the composites. GO is well-dispersed in the TPS matrix, which contributes to biodegradation. For TPS/rGO-g materials, biodegradation was influenced by rGO-g dispersion level.

Influence of Amylase Addition on Bread Quality and Bread Staling

In this study, the effect of two amylases (maltogenic amylase and maltotetraose-producing amylase) on the rheological properties of wheat flour as well as on the quality and staling of partially baked bread is investigated. The rheological measurements obtained from a Viscograph showed that both amylases reduced the peak viscosity, final viscosity, and setback viscosity of wheat flour, whereas maltotetraose-producing amylase significantly improved the specific volume of fresh bread. Furthermore, the addition of both types of amylases was able to reduce crumb firmness and amylopectin retrogradation, due to their ability to partially hydrolyze starch molecules and generate low molecular weight dextrin, which was confirmed by the analysis of the maltooligosaccharide composition of the breads. The results indicated that the effects of maltotetraose-producing amylase were more pronounced than those of maltogenic amylase in terms of slowing bread staling.

Influence of sodium alginate on the gelatinization, rheological, and retrogradation properties of rice starch

Adding hydrocolloids into native starch is a secure and effective method of physical modification. In this study, the effect of sodium alginate (AG) on the gelatinization, rheological, and retrogradation properties of rice starch (RS) was investigated by measuring the pasting parameters, melting enthalpy (ΔH), rheological characteristic parameters, intensity ratio of 1047 cm−1 to 1022 cm−1 (R1047/1022), and relative crystallinity (RC) of RS–AG blends. Rapid visco analysis shows that AG could significantly change the gelatinization parameters of RS. Differential scanning calorimetry results show that the ΔH values of RS initially decreased in the low AG concentration range (0.10%–0.30%), but increased in the high AG concentration range (0.30%–0.50%). Dynamic rheological analysis reveals that the modulus (G′, G′′) and the loss tangent (tan δ) increased with the rise of the AG concentration from 0.10% to 0.50%. Fourier transform infrared spectroscopy and X-ray diffraction patterns collectively prove that the crystallinity of RS decreased with the addition of AG during the retrogradation periods. The interactions between AG and starch molecules in RS–AG blends were hypothesized to correlate with the aforementioned results.

Antagonistic effects of amylopectin and amylose molecules on the starch inter- and intramolecular interactions during retrogradation

Starch retrogradation property is critical for developing functional foods with desirable nutritional and textural attributes, while its nature currently remains elusive. The current study investigated the relations between starch chain-length distributions (CLDs) and interaction patterns (i.e. intermolecular versus intramolecular interactions) of starch molecules during the retrogradation process. CLDs for different waxy potato and sago starch mixtures were characterized by size-exclusion chromatography, and molecular interactions were characterized by differential scanning calorimetry and small amplitude oscillatory shear rheological test. Results for the first time showed that amylose molecules were involved in the formation of short-range intermolecular interactions with amylopectin molecules. Most intermolecularly heterogenous double helices were formed at the 1 : 1 mixing ratio of waxy potato to sago starch. Although the addition of waxy potato starch to sago starch increased the overall amount of short-range double helices, the amount of short-range intermolecular double helices was decreased. It suggests that there was an antagonistic effect between the formation of short-range inter- and intramolecular double helices. These results help a better understanding of the interaction patterns of amylose and amylopectin molecules during the retrogradation process.

Cellulose‐Reinforced Starch Biocomposite: Optimization of the Effects of Filler and Various Plasticizers using Design–Expert Method

AbstractIn this study, the effect of cellulose as a reinforcement agent and different ratio of glycerol/sorbitol as plasticizers to improve properties in starch biocomposite are optimized with Design–Expert method for the first time. Thermoplastic starch granule is produced with plasticized and cellulose‐reinforced starch by a twin extruder. After conditioning, the starch granule, is molded into sheet using a hot press with thick plates. Dynamic mechanical thermal analysis show that cellulose increases the glass transition temperature to 120 °C. Optimum point of the starch composite obtained by Design–Expert software 7.1.5, is run with 5 wt% cellulose, 17.5 wt% glycerol and 17.5wt% sorbitol that has water vapor permeability value equally of 7.81E‐10g s−1 m−1 Pa−1, tensile strength of 0.85 MPa, Young´s modulus equally of 377.65 MPa, and elongation at break of 7.08%. Field emission scanning electron microscopy of the optimized biocomposite shows uniform distribution of cellulose in the matrix. Hydroxyl stretching vibrations at 3286 cm−1 is a result of new hydrogen bonding between cellulose and starch molecules and peaks at 3366 and 1702 cm−1 are attributed to glycerol and sorbitol, respectively in the Fourier transform infrared spectra.

Digestibility and structure changes of rice starch following co-fermentation of yeast and Lactobacillus strains

Rice is sometimes fermented with microorganisms to develop health-promoting foods, but the contribution of a short-term fermentation (a necessary step for fermented rice cake-preparation) to properties of rice starch is not resolved yet. The effects of microorganism fermentation with different amount of starter cultures on multi-scale structures and digestibility of rice starch were investigated. The amount of starter cultures significantly affected structures and digestibility of fermented starch. The fermentation with a lower amount of starter cultures induced starch degradation (corrosion of starch granules, reduction of lamellar orders and compactness, decrease in crystallinity, double helix, short ranger-ordered structures, and molar mass) and a slightly reassembly, which increased the content of slowly digestible starch (SDS). While, the fermentation produced more starch fractions with Mw between 0.60 × 107 g/mol and 1.50 × 107 g/mol as the amount of starter cultures increased, and these starch molecules tended to reassemble and form more ordered multi-scale structures including double helical and short range-ordered structures, starch lamellar orders and compactness, which elevated SDS content. The SDS content of fermented starchy foods could be improved via controlling starch reassembly and multi-scale ordered structures through modulating the amount of starter cultures during fermentation.

Synthesis, physicochemical and emulsifying properties of C-3 octenyl succinic anhydride-modified corn starch

A new method of synthesis of C-3 octenyl succinic anhydride-modified corn starch (C-3-OS starch) assisted by thexyldimethyl chlorosilane (TDMS-Cl) was developed for directional modification of starches. The protective effect of TDMS-Cl on carbon 2,6 hydroxyl groups was confirmed by nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) analysis. The FTIR and 1H NMR results demonstrated the successful introduction of OSA into starch molecules. Compared with OSA modified starch (OSCS), C-3-OS starch showed higher gelatinization temperatures with a rough surface, irregular shapes, and different size. Moreover, the volume average particle diameters and negative zeta potential of emulsions prepared with C-3-OS-starch were 371.17 nm and −18.7 mV, respectively, which were lower than those of OSCS stabilized emulsion. It has therefore been shown that C-3-OS-starch is more suitable for stabilization of emulsions.

The impact of endogenous proteins on hydration, pasting, thermal and rheology attributes of foxtail millet

The cooking and eating quality of grain can be negatively affected by endogenous proteins. To further understand their effects, endogenous proteins were removed and the consequent changes in physicochemical properties of foxtail millet during the hydro-thermal processing were investigated. Protein-removal increased water absorption, swelling power, peak viscosity, breakdown value, gelatinization enthalpy, storage modulus (G′), and loss modulus (G″). In contrast, it decreased in water mobility, pasting temperature, and gelatinization temperature. Scanning electron microscopy revealed tighter and thicker connections among the laminate structures of foxtail millet paste in the absence of proteins. Thus, endogenous proteins limited the hydration, gelatinization, and viscoelasticity of starch granules in foxtail millet. Also, deproteinization caused higher FV and SB values, a greater porous network structure, and a faster final increase in G′ and G″ of the paste during cooling. In general, these proteins restricted the binding of water molecules to starch granules, reduced the hydration and gelatinization of granules, and further promoted the retrogradation of starch molecules in foxtail millet.

Properties and Structure of Modified Taro Starch: Comparison of Ultrasound and Malic Acid Treatments

AbstractThe properties and structure of native taro starch and three modified starches (ultrasonically modified starch, malic acid modified starch, and ultrasound‐malic acid modified starch) are compared and analyzed in this work. Experimental results demonstrate that ultrasound and malic acid change the properties and structure of taro starch. Compared with the native starch, the combination of ultrasound and malic acid (UM) leads to the decrease of the viscosity values and ΔH, as well as the improvement of swelling power, water holding capacity, and oil absorption rate. In addition, scanning electron microscopy (SEM) microgram shows that UM results in the damage and degradation of starch granules. Laser diffraction analysis indicates that native starch and modified starches all exhibit bimodal distribution, and ultrasound leads to the decrease of starch particle size, while malic acid results in the increase. The FT‐IR spectra suggest that UM changes the peak intensity and width of starch molecules and produces a new characteristic peak at 1741 cm−1. In conclusion, UM is effective for modifying starch, and it can promote the taro starch process.

Functional nanoparticle reinforced starch-based adhesive emulsion: Toward robust stability and high bonding performance

Sustainable bio-based adhesive is a promising substitute for petroleum-based adhesives to alleviate serious environmental and health problems. In this work, a nanoengineered starch-based adhesive was fabricated by grafting vinyl acetate (VAc) onto starch molecule and subsequently incorporating the functional nanoparticle [TiO2-coupling-poly(butyl acrylate, BA), TKB] to overcome the drawbacks present in conventional nanocomposite adhesive. Results showed that the presence of BA altered the surface property of TKB, leading to improved dispersion. In the adhesive with 4% (mass ratio to starch) TKB, TKB aggregates played the role as a sliding bridge, which significantly promoted the storage stability and shear strength in both dry and wet states. Additionally, the latex film with 4% TKB exhibited high compatibility and water resistance due to the promoted hydrophobicity. This study provides a fundamental insight into the improvement of functional nanoparticles on the performance of starch-based adhesive, suggesting a novel strategy for designing high-performance bio-adhesive.