Changes in structural, physicochemical, and digestive properties of normal and waxy wheat starch during repeated and continuous annealing

Insight into the multi-scale structure and retrogradation of corn starch by partial gelatinization synergizing with epicatechin/epigallocatechin gallate

Starch retrogradation is of great importance to the quality of starch-based food. This study investigated the effect of partial gelatinization (PG) synergizing with polyphenol (epicatechin, EC; epigallocatechin gallate, EGCG) on the multi-scale structure and short/long-term retrogradation of corn starch (CS). The PG synergizing with EC/EGCG substantially suppressed the short/long-term retrogradation properties of CS. These could be confirmed by the decreased storage modulus and viscosity, the relative crystallinity (1.54%, 3.56%), and the retrogradation degree (9.99%, 20.18%) of CS during storage for 1, 14 days after PG synergizing with EGCG and EC, respectively. This is because PG treatment promoted the hydrogen bond interaction between disordered starch molecules and EC/EGCG. These were proven by the larger aggregation, more and brighter fluorescents, and the reduced long/short-range order structures in CS after PG synergizing with EC/EGCG. This study is helpful for the development of foods with enhanced nutrition and low-retrogradation.

Green, tough, and heat-resistant: A GDL-induced strategy for starch-alginate hydrogels

Hydrogels fabricated by non-covalent interaction garnered significant attention for their eco-friendly and robust mechanical attributes, and are often used in food, medicine and other fields. Although starch-alginate hydrogels exhibit high adhesion and are environmentally sustainable, their applications are limited due to their low elasticity and hardness. Addressing this challenge, we introduce a solvent-induced strategy using glucolactone (GDL) to fabricate hydrogels with enhanced strength and thermal resilience. Utilizing corn starch with varying amylose contents, sodium alginate and calcium carbonate to prepare a double network structure. This GDL-induced hydrogel outperforms most previous starch-based hydrogels in mechanical robustness and thermal stability. Typical starch-alginate hydrogel had a homogeneous network structure and exhibited a high tensile stress of 407.57 KPa, and a high enthalpy value of 1857.67 J/g. This investigation furnishes a facile yet effective method for the synthesis of hydrogels with superior mechanical and thermal properties, thereby broadening the design landscape for starch-based hydrogels.

Effect of amylose partial extraction on citrate esterification of potato starch and its role in structure and physicochemical modification

This study examines the impact and influence of amylose on the starch esterification reaction through partial extraction of amylose. Citric acid was added for the esterification reaction, and then the esterified starches' multiscale structure, physicochemical, and functional properties were evaluated. As the extraction time of amylose increased, the amylose content in the starch decreased. Higher concentrations of citric acid will lead to samples with a higher degree of substitution, with DS rising from 0.203 % (0 h) to 0.231 % (3.5 h) at CA3 treatment. While removing amylose had minimal effects on the crystal structure of starch granules, it did decrease the ratio of A and B1 chains and the molecular weight of amylose. Acid hydrolysis exacerbated these changes upon the addition of citric acid. Furthermore, removing amylose followed by citrate esterification resulted in lower pasting viscosity, enthalpy of gelatinization (from 13.37 J to 2.83 J), and degree of short-range ordering. Also, digestion shows a decrease caused by the increasing content of slow-digesting starch. The presence of amylose in starch granules does affect the formation of starch esters, and removing it before esterification modification may improve production efficiency and reduce costs to some extent.

Investigation of the role of sodium chloride on wheat starch multi-structure, physicochemical and digestibility properties during X-ray irradiation

In this paper, different NaCl content was added to wheat starch and then subjected to X-ray irradiation to investigate the effect of salt on starch modification by irradiation. The results showed that the degradation of wheat starch intensified with the increase in irradiation dose. When irradiated at the same dose, wheat starch with sodium chloride produced shorter chains, lower molecular weight and amylose content, and higher crystallinity, solubility, and resistant starch than wheat starch without sodium chloride. The energy generated by X-rays dissociating sodium chloride caused damage to the glycoside bonds of the starch molecule. With a further increase in the mass fraction of NaCl, the hydrogen bonds of the starch molecules were broken, and the double helix structure was depolymerized, which exacerbated the extent of irradiation-modified wheat starch. At the same time, starch molecules will be rearranged to form a more stable structure.

Differences and Mechanism of Waxy Corn Starch and Normal Corn Starch in the Preparation of Recrystallized Resistant Starch (RS3)

This study prepared resistant starch (RS) from waxy corn starch and normal corn starch and analyzed the effects of its molecular and microstructural characteristics on RS content. The RS content of waxy corn resistant starch (RS-WCS) was highest at 57.8%, whereas that of normal corn resistant starch (RS-NCS) was 41.46%. The short-chain amylose contents of RS-WCS and RS-NCS were 47.08% and 37.24%, respectively, proportional to their RS content. Additionally, RS content positively correlated with crystallinity, short-range order degree, and degree of polymerization (DP), exceeding 25. Electron microscopic images, before and after enzymolysis, revealed that RS-WCS was hydrolyzed from the surface to the center by pancreatic α-amylase, while RS-NCS underwent simultaneous hydrolysis at the surface and center. These results indicate that the higher RS content in RS-WCS, compared to RS-NCS, is attributable to the synergistic effects of molecular structure and microstructure.

Sequential effects of autoclaved heat treatment and electron beam irradiation on acorn starch: Multiscale structural differences and related mechanisms

In this study, the differences in the modification effects and related mechanisms of different times (20 and 40 min) of autoclaved heat (AH) treatment and different doses (2 and 4 kGy) of electron beam irradiation (EBI) in different sequences of effects on acorn starch were investigated. The results showed that both AH and EBI reduced the amylose content (22.70 to 19.59%) and enthalpy (10.28 to 1.84%) of starch but increased the resistant starch content (53.69 to 64.11%). AH treatment made the crystalline regions of the residual starch granules denser, which was resistant to the action of amylase enzymes. EBI degraded the long chain of starch, which increased the solubility. Notably, EBI pretreatment improves the reactive sites by inducing depolymerization and disorder in starch internal structure, thus increasing the modification extent of AH-modified starch, forming starch with lower viscosity, better hydration, and digestibility resistance, therefore being used as an ingredient for functional foods.

Effect of dielectric barrier discharge (DBD) plasma treatment on physicochemical and 3D printing properties of wheat starch

In recent years, the focus has shifted towards carbohydrate-based hydrogels and their eco-friendly preparation methods. This study involved an investigation into the treatment of wheat starch using dielectric barrier discharge (DBD) plasma technology over varying time gradients (0, 2, 5, 10, 15, and 20 min). The objective was to systematically examine the impact of different treatment durations on the physicochemical properties of wheat starch and the suitability of its gels for 3D printing. Morphology of wheat starch remained intact after DBD treatment. However, it led to a reduction in the amylose content, molecular weight, and crystallinity. This subsequently resulted in a decrease in the pasting temperature and viscosity. Moreover, the gels of the DBD-treated starch exhibited superior 3D printing performance. After a 2-min DBD treatment, the 3D printed samples of the wheat starch gel showed no significant improvements, as broken bars were evident on the surface of the 3D printed graphic, whereas DBD-20 showed better printing accuracy and surface structure, compared to the original starch without slumping. These results suggested that DBD technology holds potential for developing new starch-based gels with impressive 3D printing properties.

Advancements in enhancing resistant starch type 3 (RS3) content in starchy food and its impact on gut microbiota: A review

Resistant starch type 3 (RS3), often found in cooked starchy food, has various health benefits due to its indigestible properties and physiological functions such as promoting the abundance of gut beneficial microbial flora and inhibiting the growth of intestinal pathogenic bacteria. However, it is challenging to develop starchy food with high RS3 content. This review aims to provide a detailed overview of current advancements to enhance RS3 content in starchy food and its effects of RS3 on gut microbiota. These approaches include breeding high-amylose cereals through gene editing techniques, processing, enzyme treatments, storage, formation of RS3 nanoparticles, and the incorporation of bioactive compounds. The mechanisms, specific conditions, advantages, and disadvantages associated with each approach and the potential effects of RS3 prepared by different methods on gut microbiota are summarized. In conclusion, this review contains important information that aims to provide guidelines for developing an efficient RS3 preparation process and promote the consumption of RS3-enriched starchy foods to improve overall health outcomes.

Effects of microwave radiation on the physicochemical properties, structure, and digestibility of the synthesized different crystal forms of malic acid starch ester

The effects of microwave combined with L-malic acid treatment on the degree of substitution (DS), structure, physicochemical properties, and digestibility of sweet potato starch (A-type), potato starch (B-type), and pea starch (C-type) were evaluated. The order of DS obtained was: DSM-POS > DSM-SPS > DSM-PES. Fourier transform-infrared spectroscopy (FT-IR) showed that the obtained modified starch produced a new absorption band at 1735 cm-1. Scanning electron microscopy (SEM) and polarized light microscopy indicated that different types of native starches exhibited different granular morphologies and appeared to have different degrees of damage, but still had polarized crosses after modification. Sweet potato starch had the smallest particle size, while potato starch had the largest. X-ray diffractometry (XRD) showed that the modified starches still retained the same crystal structure as the native starches, but the relative crystallinity decreased. The apparent viscosity and swelling power of modified starches dropped, but their water/oil holding capacity, amylose content, and resistant starch content all increased. The results demonstrate that the degree of influence on the structure, physicochemical properties, and digestibility of different starches varies under the same modification conditions.

Improving the Storage Stability of Soy Protein Isolate through Annealing

This study investigated the effect of annealing treatment on the stability of soy protein isolate (SPI) during storage. Different SPI samples with varying denaturation levels were subjected to varying annealing temperatures and durations before being stored at 37 °C for 12 weeks to assess their stability. Our findings revealed that annealing at 65 °C for 30 min significantly mitigated protein deterioration, improving the stability of highly denatured proteins during storage. Surface hydrophobicity and endogenous fluorescence analyses indicated that this annealing condition induced protein structure unfolding, an initial increase in SPI hydrophobicity, and a blue shift in the maximum absorption wavelength (λmax). The slowest increase in hydrophobicity occurred during storage, along with a red shift in the maximum absorption wavelength by the 12th week. These results suggest that annealing treatment holds promise for mitigating the issue of reduced SPI stability during storage.

Insight into the improvement in pasting and gel properties of waxy corn starch by critical melting treatments

To improve the pasting and gel properties of waxy corn starch (WCS), the native starch was modified by critical melting (CM) at the onset temperature (TO), peak temperature (TP), and conclusion temperature (TC) (labeled CMO, CMP, and CMC respectively). CM treatments significantly enhanced the thermal stability of the WCS, as indicated by the increase in the peak gelatinization temperature, pasting temperature, and peak time. In addition, after CMP treatment, the storage modulus, hardness, gumminess, springiness, and chewiness of starch gels significantly increased by 43.29 %, 31.14 %, 23.36 %, 8.26 %, and 61.43 %, respectively, and the syneresis rate significantly decreased by 19.69 % (p < 0.05). These results indicated that CMP treatments significantly improved the gelling ability and freeze-thaw stability of the WCS. These results are ascribed to the partial disruption and enhanced rearrangement of the starch crystalline structure. CMP treatment induced the crystalline structure of starch to be partially disrupted and a hard structure was formed on the surface of starch granules. The hard structure in CMP-treated starch supplied more attachment points for crystalline structure rearrangement during gelatinization. Therefore, the above results indicated that CMP treatments can be used to modify starch to improve the pasting and gel properties of starch-based food products.

Physicochemical properties of ultrasound-pretreated pea starch and its inclusion complexes with lauric acid

Ultrasound is a promising green technology for modifying starch. The influence of ultrasound pretreatment (UPT) at diverse temperatures on the morphology and molecular structure of pea starch and its ability to form inclusion complexes with lipids were investigated. After UPT at each temperature, the starch granules retained an unchanged crystalline structure but exhibited notable changes in short-range molecular order and molecular structure. In comparison with the samples treated at 0 and 20 °C, pea starch subjected to UPT at 40 °C had a significantly (P ≤ 0.05) higher complexing index with lauric acid (LA) and the starch-LA inclusion complex exhibited a higher enthalpy change, relative crystallinity, and resistant starch content. These differences were attributed to the higher temperature causing changes in the disruption points of starch chains and an enlargement in the molecular weight of linear chains. These results may promote the utilization of ultrasound for effective starch modification.

Altering structure and enzymatic resistance of high-amylose maize starch by irradiative depolymerization and annealing with palmitic acid as V-type inclusion compound

This study explored a new physical modification approach to regulate enzymatic resistance of high-amylose starch for potentially better nutritional outcomes. High-amylose maize starch (HAMS) was subjected to chain depolymerization by electron beam irradiation (EBI), followed by inducing ordered structure through annealing in palmitic acid solution (APAS). APAS treatment significantly promotes the formation of ordered structure. Starch after the combinative modification showed up to 5.2 % increase in total crystallinity and up to 1.2 % increase in V-type fraction. The EBI-APAS modification led to increased gelatinization temperature (from 66.1 to 87.6 °C) and reduced final digested percentage under in vitro stimulated digestion conditions. The moderate extent of depolymerization resulted in higher enzymatic resistance, indicating that the extent of depolymerization is crucial in EBI-APAS modification. Pearson analysis showed a significant correlation between gelatinization onset temperature and digestion kinetic parameter (k1, rate constant of fast-phase digestion). Overall, the result suggests that ordered structures of degraded molecules induced by the combinative modification contribute to the enzymatic resistance of starch. This study sheds lights on future applications of EBI-APAS approach to regulate multi-scale structures and nutritional values of high-amylose starch.

A review of starch swelling behavior: Its mechanism, determination methods, influencing factors, and influence on food quality

Swelling behavior involves the process of starch granules absorbing enough water to swell and increase the viscosity of starch suspension under hydrothermal conditions, making it one of the important aspects in starch research. The changes that starch granules undergo during the swelling process are important factors in predicting their functional properties in food processing. However, the factors that affect starch swelling and how swelling, in turn, affects the texture and digestion characteristics of starch-based foods have not been systematically summarized. Compared to its long chains, the short chains of amylose easily interact with amylopectin chains to inhibit starch swelling. Generally, reducing the swelling of starch could increase the strength of the gel while limiting the accessibility of digestive enzymes to starch chains, resulting in a reduction in starch digestibility. This article aims to conduct a comprehensive review of the mechanism of starch swelling, its influencing factors, and the relationship between swelling and the pasting, gelling, and digestion characteristics of starch. The role of starch swelling in the edible quality and nutritional characteristics of starch-based foods is also discussed, and future research directions for starch swelling are proposed.

Effect of electron beam irradiation on granular cold-water swelling chestnut starch: Improvement of cold-water solubility, multiscale structure, and rheological properties

In this study, granular cold-water swelling (GCWS) starch was prepared from chestnut starch by ethanol-alkali method, after which it was further modified by electron beam irradiation (EBI) technique to investigate the effect of EBI on GCWS chestnut starch. It was shown that the alcohol-alkali treatment disrupted the starch double helix structure and the starch crystalline form had been changed from "C" to "V" type. On this basis, EBI continued to act on the disrupted starch chains and further cleaved the long chains into short chains, which significantly improved the solubility of starch to 90.08 % in cold water at a 24 kGy irradiation dose. Therefore, this study can broaden the application scope of starch and provide new ideas for GCWS starch applications in food and water-soluble pharmaceutical industries.

Effects of Continuous and Cycled Annealing on the Physicochemical Properties and Digestibility of Water Caltrop Starch

The effects of treatment time of continuous annealing (ANN) and cycle numbers of cycled ANN on the structural, physicochemical, and digestive properties of water caltrop starch were studied under 70% moisture at 65 °C. It was found that continuous and cycled ANN have no significant effects on the morphology of starch granules. However, the relative crystallinity and content of resistant starch increased pronouncedly, possibly due to crystalline perfection, which also led to the rise in gelatinization temperature and the narrowed gelatinization temperature range of starch. The treatment time in continuous ANN generally showed a pronounced effect on the rheological properties of water caltrop starch. During pasting, the breakdown viscosity and setback viscosity of all treatment decreased, implying that ANN modified starch was less susceptible to the condition in heating and continuous shearing, and less likely to cause short-term retrogradation. In contrast, peak viscosity decreased with increasing treatment time of continuous ANN, indicating crystalline perfection restricted the swelling of starch granules and viscosity development during pasting process, which was consistent with the results of steady and dynamic rheological evaluation. All ANN-modified samples showed pseudoplastic behavior with weak gel viscoelastic characteristic. Under a total annealing time of 96 h, the pasting and rheological properties of water caltrop starch were essentially less affected by annealing cycle numbers. However, multistage ANN showed stronger resistance to enzyme hydrolysis.

Spotlight on the Multiscale Structural and Physicochemical Properties of Red Adzuki Bean Starch through Partial Amylose Removal Combined with Hydrochloric Acid

To explore the effect of amylose within starch granules on the efficiency of starch hydrolysis by acid, we chose the warm water extraction method to treat red adzuki bean starch to obtain different degrees of amylose removal granule models and to prepare samples in combination with acid hydrolysis. The amylose content was reduced after acid hydrolysis, reducing the peak viscosity (2599-1049 cP), while the solubility was significantly increased. In contrast, the short-chain content of the deamylose-acid hydrolysis samples was reduced considerably, exacerbating the trend towards reduced starch orderliness and increased solubility. This work reveals the granular structure of starch from the point of view of deamylose and contributes to a thorough understanding of the mechanisms of acid hydrolysis. It might add to knowledge in starch science research and industrial applications for the acid processing of starch-based foods, particularly with regard to the most important factors controlling the structure and function of starch.

Starch modification through its combination with other molecules: Gums, mucilages, polyphenols and salts

Apart from its non-toxicity, biocompatibility and biodegradability, starch has demonstrated eminent functional characteristics, e.g., forming well-defined gels/films, stabilizing emulsions/foams, and thickening/texturizing foods, which make it a promising hydrocolloid for various food purposes. Nonetheless, because of the ever-increasing range of its applications, modification of starch via chemical and physical methods for expanding its capabilities is unavoidable. The probable detrimental impacts of chemical modification on human health have encouraged scientists to develop potent physical approaches for starch modification. In this category, in recent years, starch combination with other molecules (i.e., gums, mucilages, salts, polyphenols) has been an interesting platform for developing modified starches with unique attributes where the characteristics of the fabricated starch could be finely tuned via adjusting the reaction parameters, type of molecules reacting with starch and the concentration of the reactants. The modification of starch characteristics upon its complexation with gums, mucilages, salts, and polyphenols as common ingredients in food formulations is comprehensively overviewed in this study. Besides their potent impact on physicochemical, and techno-functional attributes, starch modification via complexation could also remarkably customize the digestibility of starch and provide new products with less digestibility.

Structural, rheological, pasting, and digestive properties of wheat A-starch: Effect of outshell removal combined with annealing

Wheat A- starch was subjected to single and combined CaCl₂ and annealing (ANN) treatments. The influence of the treatment on wheat A- starch's structural, rheological, pasting, and digestive characteristics were studied. The results indicated that the application of CaCl₂ treatment caused the removal of the outer layer of wheat A-starch, disrupted the integrity of the growth ring structure, and lowered the molecular weight of amylopectin and relative crystallinity. Meanwhile, the application of outshell removal combined with ANN treatment led to significant damage to the starch granules, resulting in a marked reduction in relative crystallinity, as well as the molecular weight of amylopectin and amylose. However, no changes were found in the non-Newtonian pseudoplastic behavior of starch after single or combined treatments. Furthermore, the combination of outshell removal and annealing treatment resulted in a decreased peak viscosity as well as trough viscosity of starch. Moreover, long-time ANN treatment had the potential to improve the resistant starch (RS) content of deshell starch.

The alterations in granule, shell, blocklets, and molecular structure of pea starch induced by ultrasound

Understanding the alterations to starch multi-scale structure induced by ultrasound treatment can help in determining the effective application of ultrasound in functional-starch preparation. This study aimed to comprehensively characterize and understand the morphological, shell, lamellae, and molecular structures of pea starch granules treated by ultrasound under different temperatures. Scanning electron microscopy and X-ray diffraction analyses showed that UT (ultrasound treatment) did not change C-type of crystalline, but caused a pitted surface and endowed a looser structure and higher enzyme susceptibility as the temperature increased above 35 °C for pea starch granules. Fourier transform infrared spectroscopy and small-angle X-ray scattering analyses revealed that UT reduced the short-range ordering and increased the thickness of semi-crystalline and amorphous lamellae by inducing starch chain depolymerization, which was manifested by molecule weight and chain length distribution analysis. The sample ultrasound-treated at 45 °C had the higher proportion of B2 chains compared with the other ultrasound-treated samples because the higher ultrasonic temperature altered the disruption sites of starch chains.

Starch-based controlled release fertilizers: A review

Starch, as a widely available renewable resource, has the potential to be used in the production of controlled-release fertilizers (CRFs) that support sustainable agriculture. These CRFs can be formed by incorporating nutrients through coating or absorption, or by chemically modifying the starch to enhance its ability to carry and interact with nutrients. This review examines the various methods of creating starch-based CRFs, including coating, chemical modification, and grafting with other polymers. In addition, the mechanisms of controlled release in starch-based CRFs are discussed. Overall, the potential benefits of using starch-based CRFs in terms of resource efficiency and environmental protection are highlighted.

Unlocking the Potential of High-Amylose Starch for Gut Health: Not All Function the Same

High-amylose starch has unique functional properties and nutritional values in food applications. This type of starch is generally resistant to enzymatic digestion in the gastrointestinal tract, and contains an increased fraction of resistant starch (RS), which is a type of dietary fiber. The digestion and fermentation of high-amylose starch in the gut are of current research interest, as the processes are related to its nutritional functionality. This review summarizes recent in vitro and in vivo studies on the digestion and fermentation of high-amylose starches from different botanical sources and those that have been obtained by modifications. The RS content and fermentation properties are compared among high-amylose starches. This review aims to provide a current understanding of the relationship between high-amylose starch structures and fermentation-related nutritional properties. The results of these studies suggest that both modifications and food processing of high-amylose starch result in distinct fermentation products and nutritional properties. The review provides insight into the potential future applications of diverse high-amylose starches as bioactive compounds to modulate colonic fermentation.

Exploiting the Native Microorganisms from Different Food Matrices to Formulate Starter Cultures for Sourdough Bread Production

The use of sourdough for bread production involves fermentation, which is dominated by lactic acid bacteria (LAB) and yeast. Sourdough can be inoculated with a starter culture or through a food matrix containing microorganisms to initiate sourdough fermentation. Sourdough is used as leavening agent for bread making, and metabolites produced by LAB and yeast confer a specific aroma and flavor profile to bread, thus improving its sensory attributes. However, few publications report the effect of microorganisms from different food products and by-products on sourdough fermentation. This review focuses on using different starter cultures from various food sources, from wheat flour to starter cultures. Additionally, included are the types of sourdough, the sourdough fermentation process, and the biochemical transformations that take place during the sourdough fermentation process.

The Influence of Temperature Changes on the Rice Starch Structure and Digestive Characteristics: One and Two-Step Annealing

This study investigated the effects of annealing on the structural and physicochemical properties of rice starch below the onset temperature (To) by 5 °C and 15 °C. The results revealed that annealing improved the gelatinization temperature of rice starch, decreased the swelling power, solubility, and paste viscosity of rice starch, and had no significant effects on the morphological structure and crystal configuration of rice starch. In one-step annealing, the annealing temperature of 60 °C is more conducive to the rearrangement of starch molecules, so its crystallinity, short-range ordered structure, and gelatinization temperature are higher than at 50 °C; however, its RDS, SDS, and RS contents will be increased. During the two-step annealing treatment, the temperature change is not conducive to the molecular chain rearrangement and to the formation of perfect crystalline structure, which increases the sensitivity of enzymes to starch, so the RDS content of starch increases significantly, while the RS content decreases.

Physical modification of maize starch by gelatinizations and cold storage

The effects of gelatinization at three selected temperatures (DSC characteristic peaks temperature: TO, TP, and TC) and subsequent cold storage (CS) treatment on structural characteristics, pasting, and rheological properties of maize starch (MS) were investigated. The pasting, rheological properties of MS was changed with the increase of gelatinization temperature from TO to TC, but were not further significantly changed if the gelatinization temperature was higher than TC. Pasting and thermal properties analysis suggested that gelatinization at TC (TC treatment) significantly increased the gelatinization and pasting temperature of MS. Moreover, TC treatment decreased breakdown viscosity by 8.49 times and setback viscosity by 2.53 times. Dynamic rheological measurements revealed that the TC treatment caused the lower G' and G" of MS, and decreased the thickening coefficient by 55.17 %. These results indicated that TC treatment could enhance the thermal stability properties of MS, inhibiting the shear and short-term retrogradation, the shear-thinning behavior of MS. Interestingly, the CS treatment further inhibited the shear and short-term retrogradation and the shear-thinning behavior of MS. The leaked starch molecules aggregate to form a harder structure after gelatinization and starch molecules were further aggregated after CS treatment, these all were hypothesized to be responsible for these results.

Heat-moisture modified blue wheat starch: Physicochemical properties modulated by its multi-scale structure

Blue wheat starch was modified by heat-moisture treatment (HMT) with varying moisture contents (MCs). Changes in physicochemical properties were evaluated on the basis of its multi-scale structure. Following HMTs with MC below 30 %, the starch remained brighter and presented total phenolics content up to 0.20 mg/g. As treating MC increased, structural disruptions became more pronounced, which were characterized by crystallinity loss, lamellae's loosening, hydrogen bonding breakage, and debranching. Furthermore, HMTs decreased the proportion of external A chains of amylopectin. Concomitantly, modified starches showed progressively increased transition temperatures but decreased enthalpy values. Despite the swelling power decrease, HMTs with MC of 15 % showed markedly higher peak viscosity than control, as a result of the more compact semi-crystalline lamellae and homogenous electron distribution. Besides, all HMT-starches showed lowered breakdown and setback. This novel modified starch would be promising ingredients for modulating the viscoelasticity of healthy anti-staling staple foods.

Changes in structures and digestibility of amylose-oleic acid complexes following microwave heat-moisture treatment

Amylose-oleic acid complexes (AOA) were exposed to microwave heat-moisture treatment (M-HMT) with different moisture content (MC), and the variations in structures and digestibility were investigated. M-HMT caused the dissociation of helical structures and destruction of short-range molecular order of AOA. Meanwhile, the molecules of amylose and oleic acid rearranged and more amylose-oleic acid complexes were formed during M-HMT, the complexing index of AOA was increased from 25.41 % to 41.20 % when treating at 35 % MC. Moreover, the relative content of single helix increased with increasing MC, resulting in higher V-type relative crystallinity. With ≥30 % MC, the treated complexes showed greater thermostability than that of original AOA. The treatment increased the enzymatic digestibility of AOA, and sample treated with 35 % MC had the highest resistant starch content of 82.33 %, which was 17.96 % higher than that of native AOA. The improved enzyme resistance should be correlated to increased molecular interplay and formation of amylose-oleic acid complexes.

A single base change at exon of Wx-A1 caused gene inactivation and starch properties modified in a wheat EMS mutant line

BACKGROUND

Wheat is an essential source of starch. The GBSS or waxy genes are responsible for synthesizing amylose in cereals. The present study identified a novel Wx-A1 null mutant line from an ethyl methanesulfonate (EMS)-mutagenized population of common wheat cv. SM126 using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and agarose gel analyses.

RESULTS

The alignment of the Wx-A1 gene sequences from the mutant and parental SM126 lines showed only one single nucleotide polymorphism causing the appearance of a premature stop codon and Wx-A1 inactivation. The lack of Wx-A1 protein resulted in decreased amylose, total starch and resistant starch. The starch morphology assessment revealed that starch from mutant seeds was more wrinkled, increasing its susceptibility to digestion. Regarding the starch thermodynamic properties, the gelatinization temperature was remarkably reduced in the mutant compared to parental line SM126. The digestibility of native, gelatinized, and retrograded starches was analyzed for mutant M4-627 and the parental SM126 line. In the M4-627 line, rapidly digestible starch contents were increased, whereas resistant starch was decreased in the three types of starch.

CONCLUSION

Waxy protein is essential for starch synthesis. The thermodynamic characteristics were decreased in the Wx-A1 mutant line. The digestibility properties of starch were also affected. Therefore, the partial waxy mutant M3-627 might play a significant role in food improvement. Furthermore, it might also be used to produce high-quality noodles. © 2021 Society of Chemical Industry.

Preparing potato starch nanocrystals assisted by dielectric barrier discharge plasma and its multiscale structure, physicochemical and rheological properties

Non-thermal plasma has increasingly been used for surface modification of various materials as a novel green technology. In this study, we prepared potato starch nanocrystals (SNCs) assisted by dielectric barrier discharge plasma technology and investigated its multiscale structure, physicochemical properties and rheology. Plasma treatment did not change the morphology and crystalline pattern of SNCs but reduced the crystallinity. The amylose content, swelling power, gelatinization temperature, and apparent viscosity of SNCs decreased after the plasma process by depolymerizing the amylopectin branch chains and degrading SNCs molecules. Besides, plasma increased the rapidly digestible starch and resistant starch content. Changes in rheological properties of plasma treated SNCs suggested that the plasma process increased the flowing capacity. The effective structural and functional changes of plasma treated SNCs confirm that plasma technology has great potential for modification of SNCs.

Interaction of B-type starch with gluten skeleton improves wheat dough mixing properties by stabilizing gluten micro-structure

Some recent studies have revealed individual and the combined interactions of gluten and starch affecting dough mixing properties. However, the combined influence of high-molecular-weight glutenin subunits (HMW-GS) and starch on dough mixing and rheological properties requires elucidation. Thus four recombinant inbred lines, SS 1, SS 2, ZZ 1 and ZZ 2, were selected based on their HMW-GSs compositions. Compared to ZZ 1 and ZZ 2, both SS 1 and SS 2 carried superior HMW-GS alleles, and exhibited extended dough development and stability time, indicating their significant dough mixing characteristics. The gluten skeleton of the wheat lines SS 2 and ZZ 2 with higher B-type starch proportions exhibited fewer breakages along with the rise of dough temperature during mixing. Higher content of B-type starch strengthens interaction between starch and gluten skeleton at the dough heating stage, suggesting a specific range of B-type starch proportion can improve dough mixing characteristics.