Starch Molecules Research Articles

Impact of ultrasonication on functional and structural properties of Indian wheat (Triticum aestivum L.) cultivar starches

In the present study, functional and structural properties of wheat starches treated with ultrasonication for 15 and 30 min (US-15 and US-30, respectively) were studied. Functional properties such as swelling power, amylose content and oil absorption capacity increased significantly (P ≤ 0.05) upon ultrasonication. A-type crystalline nature of wheat starches remained unaffected with ultrasound treatment, whereas relative crystallinity increased after US-15 and US-30, but the percentage increase was less in case of US-30 (30.82–34.06%) as compared to US-15 (33.70–37.36%). FTIR spectral patterns showed that no new bond was formed or broken by ultrasonication in starch molecule, whereas the absorbance ratios 1022/995 cm−1 decreased significantly (P ≤ 0.05) and ranged between 0.976 and 1.056 and 1.003–1.055, for US-15 and US-30, respectively. Scraps and deformities made on granule surfaces by ultrasonic waves were clearly observed in SEM images, which were more prominent in case of large sized starch granules. Particle size analysis revealed that the percent volume of A-type granules increased with both US-15 (68.85–79.72%) and US-30 (70.96–79.89%), whereas that of B-type granules decreased after US-30 treatment.

Cover Image, Volume 44, Issue 8

The cover image is based on the Original Article Mechanism of bridging and interfering effects of tea polyphenols on starch molecules by Wei-Cai Zeng et al., https://doi.org/10.1111/jfpp.14576.

Biofilm material based triboelectric nanogenerator with high output performance in 95% humidity environment

Moisture in environment can severely decrease the output of the solid-solid triboelectric nanogenerators (TENGs) which usually hinders their further practical applications. To solve this problem, in this paper we fabricated a new type of biofilm materials based TENG, which can work stably in high humidity environment with high output performance by forming hydrogen bond with water molecules. In high humidity environment the hydroxyl-rich biomaterials, such as starch molecules, and water molecules could form hydrogen bonds spontaneously to fix water molecules on the surface, which allows water molecules to participate in triboelectric charging as a more electropositive material to obtain a higher output of TENG. Different from the traditional polymer materials based TENGs, the output of the starch films based TENG increases with the increase of the environmental humidity. The output current and voltage could increase from 6.2 μA to 110 V to 16.6 μA and 330 V with the ambient humidity increasing from 15% to 95%, respectively, which is about 12 times larger than that of the traditional nylon-11 based TENG in the humidity of 95%. It is an important supplement of TENG family and highly expand application scopes for energy harvesting and self-powered sensors in high humidity environment, especially in cloudy, foggy days or under water and sweat conditions.

Comparing the multi-scale structure, physicochemical properties and digestibility of wheat A- and B-starch with repeated versus continuous heat-moisture treatment

The effects of continuous heat-moisture treatment (CHM) and repeated heat-moisture treatment (RHM) on multi-scale structure, physicochemical and digestibility properties of wheat A- and B-starch were investigated and compared. Both A- and B-starch granules maintained integrity after repeated and continuous modification. Changes in starch molecules induced the diversification of crystal structure and physicochemical properties. Crystal type of CHM and RHM starches maintained the original A-type while the crystallinity decreased after treatmnt. For wheat A-starch, the RS and RDS contents of RHM starches were obviously lower than native ones while the SDS content increased. Meanwhile, the RDS and SDS contents of treated B-starch were significantly higher than native ones but the RS content was lower. At the same conditions, B-starches exhibited a lower relative crystallinity, lower viscosity parameters, lower To, Tc, Tp and ΔH values than A-starches. In general, the repeated heat-moisture treated samples obtained superior characteristics than continuous treated ones, and the results of A- and B-starch varied greatly.

Effect of the stirring speed in the in vitro activity of α-amylase

Amylases are one of the main enzymes used in industry for hydrolyzing starch molecules into simple sugar constituents, can be sourced from plants, animals and microorganisms. Starch converting α-amylase has applications in different industrial sectors, and an ongoing research topic is to improve processing conditions leading to enhanced enzymatic activity and lower processing costs. Surprisingly, there are basically no studies regarding the impact of stirring speed on α-amylase activity. In this work, the effect of stirring speed (0, 50, 250, 500, 1000 and 1500 rpm) on the hydrolysis of gelatinized corn starch dispersions (5 g starch dry basis/100 L) by pancreatic α-amylase (0.125 and 0.250 μg/mL) was studied. The analysis of the hydrolysis kinetics curves showed that relatively small stirring speeds had positive effect on the hydrolysis rate. This effect was likely caused by improvements in the mass transfer coefficient by virtue of increased flow velocities. However, the enzyme activity exhibited a negative trend for high stirring speeds. FTIR analysis of α-amylase subjected to stirring indicated that changes in the Amide I secondary structure might be behind the decreased hydrolysis at high stirring speeds. This short communication provides insights for enhancing the bio-conversion of starch by α-amylase via stirring speed mediation.

High methoxyl pectin enhances the expansion characteristics of the cornstarch relative to the low methoxyl pectin

The addition of dietary fiber pectin in extruded foods is beneficial for human health. However, pectins with different methyl ester levels may have different effects on the quality of extrudates. Hence, in this study, low and high methoxyl pectin were extruded with corn starch to investigate their impact on the expansion characteristics of corn starch. Pasting and thermal properties of the blends and structural characteristics and physical properties of extrudates were evaluated. Pectin interacted with starch molecules and restricted water adsorption into amorphous regions of corn starch, which influenced the gelatinization. Low methoxyl pectin increased the viscosity of the blends from 718.0 ± 8.7 to 773.0 ± 9.5 mPa·s, but high methoxyl pectin showed the opposite effect (from 718.0 ± 8.7 to 664.3 ± 4.7 mPa s). The extrudates of high methoxyl pectin and corn starch blends showed better quality than that of low methoxyl pectin and corn starch blends, especially on the expansion ratio (3.76 ± 0.01 for 15% HMP addition and 2.85 ± 0.04 for 15% LMP addition). The results of this work demonstrated that high methoxyl pectin addition, even at high levels, had little effect on the quality of corn starch extrudates compared to the one without pectin addition.

Functional characteristics, dry heating and irradiation treatment of starch – A short review

Physical modification of starches using dry heating, gamma and electron beam irradiation are considered greener and more cost effective than using crosslinking chemicals for starch modification. Chemical modification of starches generates lot of downstream waste. Alternatively, dry heating of starches can also be utilized to influence hydrolysis as well as crosslinking of chains and requires no catalyst. Gamma and electron beam irradiation although used largely for preservation of foods can introduce carboxyl groups into starch molecules as well as degrade starch chains. Gamma and electron beam irradiation can hydrolyze as well ascross link starches which can have various applications in food and process industries. Irradiation and dry heating are promising techniques and can be used in conjunction with other modifications type for making specialty and resistant starches. To the best of our knowledge dry heating of starches has not been reviewed. Need was also felt to critically review irradiation techniques since there are many ongoing debates on its implications.

Investigating the structure and self-assembly behavior of starch-g-VAc in starch-based adhesive by combining NMR analysis and multi-scale simulation

This work investigated the structure and self-assembly behavior of grafted starch (GS) prepared by grafting vinyl acetate (VAc) on the starch molecule. Our preliminary structure characterization, NMR, and quantum mechanical simulation demonstrated the C2 of the glucose unit as the main grafting site. The grafting frequency and chain length (starch, VAc) were calculated based on the result of gel permeation chromatography. Molecular dynamics simulation showed that, when compared with native starch, GS had less hydrogen bonding interaction, lower orderness, and higher extensibility, which were supported by the experimental results. In dissipative particle dynamics simulation, GS was shown to self-assemble into a core-shell structure (latex) and form a bridge structure with cross-linking interaction. The overall results indicate that chain entanglement and hydrogen bonding interaction of starch play a significant role in adhesive curing. This research provides a novel insight into the grafting and molecular interaction mechanism in the GS adhesive system.

Fabrication of starch blend films with different matrices and their mechanical properties

The objective of the study was to determine the effects of molecular sizes of amylose (AM) and starch granules on the mechanical properties of thermoplastic starch (TPS) blend films. Leached amylose solution from cassava (CS_ AM) and mung bean (MB_AM), and two forms of amylopectin (AP) (granular; g and non-granular; ng) of waxy cassava (WxCS) starch were used. Four types of film matrices were fabricated and all TPS blend films contained same amount of AM and glycerol. Results displayed that molecular weight profiles of starch films and presence of granule remnants significantly controlled the film matrix formation, types of crystal formation, and percent of relative crystallinity (%RC) (p < 0.05). Tensile property of TPS films was controlled by %RC and presence of granule remnants. Percent elongation at break (%Eb) of TPS films increased when the films had a large range of molecular weight distribution (from 5.5 × 107 g/mol to 0.4 × 105 g/mol) and contained a high weight fraction (~58%) of starch molecules with Mw~0.4 × 105 g/mol.

Understanding the molecular weight distribution, in vitro digestibility and rheological properties of the deep-fried wheat starch.

The effects of frying temperature on the properties of wheat starch were investigated, including the microstructure, weight-average molar mass (Mw), crystalline properties, functional groups, in vitro digestibility, static rheological properties, swelling power and solubility. SEM micrographs showed that the disc-shaped starch granules ruptured after being fried, and formed a continuous and dense gel structure. With the increasing frying temperature, the starch molecules underwent violent degradation, and the Mw decreased from 3.04×107g/mol to 0.80×107g/mol. The XRD and FTIR data indicated the formation of starch-lipid complexes during the frying process. In vitro digestion analysis revealed that the digestion rate of starch decreased, while the content of resistant starch (RS) increased after being fried. Besides, the shear stability of fried starch increased, whereas its swelling power and solubility decreased. These significant variations in physicochemical properties of starch could provide scientific basis for further improving the quality of instant noodles.

Purification and Characterization of Natural Solid-Substrate Degrading and Alcohol Producing Hyperthermostable Alkaline Amylase from Bacillus cereus (sm-sr14).

Amylases enzymes hydrolyze starch molecules to produce diverse products including dextrins, and progressively smaller polymers. These include glucose units linked through α-1- 1, α-1-4, α-1-6, glycosidic bonds. This enzyme carrying an (α /β) 8 or TIM barrel structure is also produced containing the catalytic site residues. These groups of enzymes possess four conserved regions in their primary sequence. In the Carbohydrate-Degrading Enzyme (CAZy) database, α-amylases are classified into different Glycoside Hydrolase Families (GHF) based on their amino acid sequence. The present objective was to study one such enzyme based on its molecular characterization after purification in our laboratory. Its main property of solid-natural starch degradation was extensively investigated for its pharmaceutical/ industrial applications. Amylase producing bacteria Bacillus cereus sm-sr14 (Accession no. KM251578.1) was purified to homogeneity on a Seralose 6B-150 gel-matrix and gave a single peak during HPLC. MALDITOF mass-spectrometry with bioinformatics studies revealed its significant similarity to α/β hydrolase family. The enzyme showed an efficient application; favourable Km, Vmax and Kcat during the catalysis of different natural solid starch materials. Analysis for hydrolytic product showed that this enzyme can be classified as the exo-amylase asit produced a significant amount of glucose. Besides the purified enzyme, the present organism Bacillus cereus sm-sr14 could degrade natural solid starch materials like potato and rice up to the application level in the pharmaceutical/ industrial field for alcohol production.

Combination of parallel and sequential digestion kinetics reveals the nature of digestive characteristics of short-term retrograded rice starches

Cooked rice is commonly consumed after a short period of cooling, which results in the short-term starch retrogradation. Starch fine molecular structures that are important for its in vitro digestibility after short-term retrogradation were thus investigated in this study. A modified first-order kinetics model was developed in order to consider both the sequential and simultaneous digestion phases in the system. Correlation analysis between the resulted digestion parameters with starch fine molecular structures, i.e. chain-length distribution and molecular size distribution, showed that the number of digestion phases was determined by the amount of amylose short to medium chains and starch molecular size; relatively lower amount of these chains and larger starch molecules could result in two digestible fractions (fast versus slow) that possess a combination of sequential and parallel digestion pattern. Among the starches with two digestible fractions, a relatively larger amylose molecules, higher amount of amylose short to medium chains, shorter amylose medium chains, as well as longer amylopectin medium chains would result in a slower digestion rate for both the fast- and slow-digestible starch fraction. The initiation time of the digestion of slow-digestible starch fraction was positively correlated with the amount of amylose short to medium chains, while negatively correlated with the amylose molecular size. These results could enable rice breeders to develop rice varieties with slower starch digestibility by introducing desirable starch fine molecular structures.

Flow rate effect on partially modified potato starch microspheres formation process

Abstract Natural biopolymers are the most likely choice for biomedical applications, and starches can be considered the best materials for such applications. This comes from the fact of their natural origin and their high biodegradable behavior. Native starches have weak hydrogen bonding and a leaching behavior – making it a candidate for drug delivery application. Still, to make starch useful as a drug delivery carrier, this hydrogen bonding must be strengthened. In this work, native sweet potato starch was used, and the hydrogen bonding between starch molecules was enhanced by introducing glycerol as a hydrogen bonding source and sodium alginate (SA) as a thickener. This blend was tested by means of FTIR and DSC, and based on the test results, improved hydrogen bonding had taken place. Furthermore, potato starch microspheres were successfully produced at different flow rates. In the work, a microfluidic capillary device was harnessed to form microsphere generating total flow rates ranging between (0.00031 and 0.00054) cm3/sec. Herein, a starch/sodium alginate/glycerol mixture was used as a dispersed phase and PVA+tween 80 was used as continuous phase. At high flow rates (0.00062-0.00054) cm3/sec, the microspheres took an oval shape. At flow rates (0.00034-0.00048) cm3/sec, the microspheres took a spherical shape. At very low flow rate (0.00031) cm3/sec, the microspheres shell was weak and caused core oozing. In this work, starch microspheres were successfully formed with diameter ranging from (151-263) µm.

Highly branched α-limit dextrins attenuate the glycemic response and stimulate the secretion of satiety hormone peptide YY

Starch molecules are hydrolyzed to linear malto-oligosaccharides and branched α-limit dextrins (α-LDx) by salivary and pancreatic α-amylases in the gastrointestinal tract. In this study, we investigated the physiological responses to chromatographically purified branched α-LDx, which are slowly hydrolyzed owing to their high α-1,6 linkage ratios. Our results demonstrate that the digestion of branched α-LDx by mammalian α-glucosidases is slower than that of malto-oligosaccharides in vitro. In vivo experiments using mice showed that the glucose spike at the initial stage of α-LDx hydrolysis was significantly (p < 0.05) attenuated owing to an extended glycemic response. Branched α-LDx stimulated the secretion of peptide YY, which controls the satiety level and rate of gastric emptying by regulating the hypothalamus activity. In conclusion, the slow digestibility of branched α-LDx decelerated glucogenesis in vitro and in vivo; this phenomenon may result in beneficial physiological effects for regulate type 2 diabetes, obesity, and related chronic diseases by controlling post-prandial glucose homeostasis.

Inhibition of Starch Digestion by Dallic Acid and Alkyl Gallates

Abstract Objectives Retardation of starch digestion is an effective way of optimizing glycemic response. Certain bioactive food components inhibit starch digestion by binding with starch digestive enzymes or starch molecules in the digestive tract. Inclusion complexation between starch and guest compounds is a specific non-covalent binding mode and may contribute to a lower digestibility of starch. The aim of this study was to examine the inhibitory effects of alkyl gallates on in vitro starch digestion and the mechanism of inhibition. Methods Raw and cooked high amylose maize starch (HAMS) and potato starch (PS) were tested for in vitro enzymatic digestion. Gallic acid (GA) and alkyl gallates, including butyl (BG), octyl (OG), dodecyl (DG), hexadecyl (HG), and octadecyl (SG) gallates, were either added during digestion or processed to form inclusion complexes with starch prior to digestion. Starch digestibility profiles, represented by rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) contents, were determined. Results GA and alkyl gallates significantly increased (P &amp;lt; 0.05) RS content in raw starches. Cooked starches had significantly lower RS contents than raw starches. GA and BG increased RS content in cooked HAMS, while all compounds except for SG increased RS content in cooked PS. DG and HG caused a significant increase in SDS contents in cooked HAMS but not in raw starches and cooked PS. Significant increases in SDS and RS contents were seen in HAMS inclusion complexes with DG and HG, compared with uncomplexed starch. Conclusions The bioactive food components tested could all inhibit starch digestion either by inhibiting the enzymes or by forming starch inclusion complex. As alkyl chain length increased, their inhibition on enzymatic activity decreased, but their ability to bind starch increased. While cooking makes starch more digestible, adding certain bioactive food components could compensate for RS loss, suggesting a practical way of modulating glycemic response. Funding Sources USDA National Institute for Food and Agriculture.

Penetration control of surface sizing starch using cationic PAM and its effect on the bending stiffness of paper

Surface sizing is employed to increase the wetting resistance against liquids and to improve strength and surface properties of paper. Starch solution is the most widely used for surface sizing, and its effect is highly dependent upon how deep the starch solution penetrates into the paper structure. Better tensile strength can be obtained when starch penetrates deep into the thickness direction of paper. However, holdout of starch solution is beneficial for improving the stiffness and air or liquid resistance. This study was focused on the use of cationic polyacrylamide (PAM) as a surface sizing additive to control the penetration of starch solutions into paper, thus improving bending stiffness of paper. The effects of the ionic property, viscosity, and charge density of PAM on starch penetration and bending stiffness of surface sized papers were investigated. The penetration of starch solution was investigated with confocal laser scanning microscopy. The enthalpy changes accompanying the mixing of cationic PAMs with oxidized starch was determined using an isothermal titration calorimeter to see the molecular level interaction between PAM and starch in mixing. The addition of cationic PAM to oxidized starch solution made starch molecules stay on the paper surface rather than penetrating into the paper structure.

Mechanism of bridging and interfering effects of tea polyphenols on starch molecules

Mechanism of bridging and interfering effects of tea polyphenols on starch molecules

Preparation of thermally stable and digestive enzyme resistant flour directly from Japonica broken rice by combination of steam infusion, enzymatic debranching and heat moisture treatment

Through a series of gelatinization, enzymatic debranching and heat moisture treatment, unmilled japonica broken rice was applied to prepare thermally stable and digestive enzyme resistant flour. The optimal conditions of gelatinization temperature, enzyme/substrate ratio, and debranching duration were determined by the three-factor three-level response surface methodology (RSM). Raw flour and products processed in each step were collected to test and compare the hydration ability, reheated solubility, pasting property, starch classification (RDS, SDS, RS) and in vitro digestibility. The results of RSM showed that E/S ratio was the main factor influencing the RS formation, while influence aroused by hydrolysis time and gelatinization temperature were minor. Gelatinization broke down the intermolecular bonds of starch molecules, allowed the hydrogen bonding sites to engage more water, and improved the availability of digestion. However, debranching provided an opportunity for the alignment of short-chain and long-chain amylose molecules. Therefore, RS increased to 42%, and digestibility decreased accordingly. HMT could further enhance the molecular rearrangement, while the RS was increased to as high as 55% and the final product met the low GI criteria.

Enzymatic digestion of amylose and high amylose maize starch inclusion complexes with alkyl gallates

The interactions between starch and phenolic compounds have a great impact on the physicochemical and nutritional properties of starch-containing foods. One particular form of the interaction is starch-guest inclusion complexation, which is a specific non-covalent interaction formed between starch and guest molecules. This study investigates complexation ability and enzymatic digestibility profiles of amylose and high amylose maize starch (HAMS) inclusion complexes with gallic acid (GA) and alkyl gallates of various chain lengths, including butyl (BG), octyl (OG), dodecyl (DG), hexadecyl (HG), and octadecyl (SG) gallates. The formation of inclusion complex was examined by complementary techniques including differential scanning calorimetry (DSC), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. The digestibility profiles, represented as rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) contents, were obtained through simulated in vitro enzymatic digestion assays. The results showed that while GA, BG, and OG were not capable of forming inclusion complex with either amylose or HAMS, gallates with longer alkyl chains were able to form more stable inclusion complexes. Precipitated amylose and HAMS samples without inclusion complex formation contained the lowest RDS and highest SDS + RS, probably due to starch retrogradation. Amylose and HAMS inclusion complexes with long alkyl chain, particularly HG and SG, also possessed the lowest RDS and highest SDS + RS, but higher SDS proportions than the non-complexed starch samples. It was suggested that the inclusion complexes, especially amylose-HG and SG, and HAMS-DG, HG, and SG, might have contributed to the increase in SDS content. The water insusceptibility and high thermal stability of these inclusion complexes helped retard the starch digestion. The resistant yet steady digestion behavior of the starch-gallate inclusion complexes has significant implications in modulating glycemic response, as well as enabling a slow and sustained release of bioactive guest compounds into the gastrointestinal tract.

Intensification and monitoring by Raman spectroscopy of parboiling process

Although parboiling is dependent on a hydration step, knowledge of the paddy rice characteristics during this stage is lacking. This study aimed to identify changes in the morphological structure of starch during hydration, as well as the elementary chemical composition of the grain. In addition, water absorption kinetics was adjusted and simulated by mathematical models. Concentration gradient, temperature, and physical properties of paddy rice influenced mass transfer during hydration. Certain hydrothermal conditions promoted an irreversible disorganization in molecules of starch (crystalline structure to amorphous), which characterized its gelatinization and the parboiling of paddy rice. The hydrothermal conditions altered the intensity of excitation of the chemical groups identified, what suggests the Raman technique as a potential method of monitoring moisture. The application of this information reduces costs of industrial processes. Furthermore, mathematical modeling can also be used as a process control tool, reducing the need for experimental tests. Practical applications This study allowed the characterization of moisture transfer in the hydration stage of paddy rice parboiling process. From the collected data, it was possible to affirm that parboiling of paddy rice takes place during hydration when the right conditions are use. Then, there would be no need for later steps, reducing costs for the industries and providing the process intensification. In addition, the Raman technique is suggested as a possible alternative method for moisture monitoring and mathematical modeling as a tool for process optimization, since it is able to predict and simulate water gain in the hydration step, eliminating the need for experimental tests.