Search

Elevated atmospheric CO2 concentrations (e[CO2]) have a significant impact on plant physiology, grain yield and quality and the specific response of plants to e[CO2] is closely linked to cultivars. Here, five Chinese wheat (Triticum aestivum L.) cultivars were grown under ambient CO2 (a[CO2], 400 ppm) and e[CO2] (800 ppm). CO2 enrichment significantly increased net photosynthetic rate and water use efficiency but depressed stomatal conductance. e[CO2] increased the carbon (C) concentration but decreased the nitrogen (N) concentration in all five cultivars, whereas the effect of e[CO2] on grain yield was highly dependent on cultivar. Moreover, e[CO2] caused a significant reduction in grain minerals and protein, although the magnitude of reduction was different among these cultivars. The starch concentrations in the grains and flour viscosity were not significantly affected at e[CO2]. These findings improve our understanding of the interactive effect of CO2 conditions and cultivars on plant performances and provide a research basis to select suitable wheat cultivars to deal with food crisis in future climate.

Background: Cereals foods with a high content of dietary fibres or amylose have potential to lower postprandial glucose levels. Optimisation of cereal foods may delay development of or improve management of type 2 diabetes (T2D). Methods: We investigated the impact on postprandial glucose metabolism of bread made of hulless barley flour (50% or 75%) and wheat flour (50% or 25%) or an RNAi-based amylose-only barley flour (AmOn) (50%) and wheat flour (50%) in subjects with T2D. Design: Twenty adults with T2D were randomly allocated to one of four bread each corresponding to 50 g carbohydrate at four separate visits. We measured fasting and 4h postprandial responses of glucose, insulin, glucagon, triacylglycerol, free fatty acids, glucagon-like peptide-1 and gastric inhibitory polypeptide. Mixed model ANOVA was used to examine the differences. Results: Bread made from 50% AmOn lowered the postprandial glucose by 34%, 27%, 23% (P < 0.05) compared with 100% wheat, 50% or 75% hulless barley, respectively. Bread made from 75% hulless barley reduced the postprandial glucose by 11% (P < 0.05) compared to 100% wheat bread. Postprandial insulin responses were reduced for 50% AmOn by 24% and 35% (P < 0.05) compared with 100% wheat and 50% hulless barley, respectively. Postprandial insulin was reduced by 22% (P < 0.05) for 75% compared to 50% hulless barley bread. Conclusions: Bread made by replacing wheat flour with either 75% hulless barley or 50% AmOn flour lowered postprandial glucose responses compared to 100% wheat bread indicating a beneficial impact in management of T2D. This trial was registered at clinicaltrials.gov as NCT04646746.

Pasting and gelling behaviors of barley starches isolated from Cinnamon (waxy of 3.3% apparent amylose; WB), Golden Promise (normal of 26.2% amylose; NB), and amylose-only (high-amylose of 97.8% amylose; AO) varieties were examined over 95–140 °C cooking. Gelatinization temperatures of AO starch were significantly higher than those of WB and NB, thereby the former displaying negligible pasting viscosity at 95 °C heating. At 140 °C, AO starch was completely gelatinized and able to develop viscosity, particularly at the final pasting stage. Gel hardness of NB gradually decreased with higher cooking temperatures. After 140 °C cooking and storage, only AO starch formed a gel, exhibiting the largest hardness among the studied gels or pastes. Gelation mechanisms of the barley starches at 95—140 °C cooking were elucidated by visualizing their gel/paste microstructures under scanning electron microscopy. The insightful information on the physicochemical properties of the barley starches possessing 3.3–97.8% amylose will be meaningful for their industrial applications.

The molecular structure and the expression levels of starch biosynthesis-related genes of three types of high-amylose maize (HAM) genotypes and one normal maize (NM) genotype at 5-35 days after pollination (DAP) were studied. Size exclusion chromatography (SEC) analysis showed that the molecular size of amylopectin molecules in NM increased from 5 to 35 DAP and the amylose content in HAM genotypes increased from 15 to 35 DAP. Correlation analysis for both NM and HAMs combined showed that SBEIIb and ISAII were negatively correlated with the contents of amylose and long amylopectin chains (DP > 30) and positively correlated with the content of short amylopectin chains (DP ≤ 31) and the molecular size of amylopectin molecules. Correlation analysis for only the HAMs showed that amylose content was negatively correlated with SBEI and SSIIa. In both correlation analyses, SSIIa showed a negative correlation with the average chain lengths of amylose chains.

High-amylose maize starch (HAMS) can provide dietary fiber to foods. In this study, we investigated the effects of three HAMSs (Gelose 50, Hylon VII, and NAFU50) on the functionality of casein (CA) and/or whey protein (WP) networks in acidified milk gels using normal maize starch (NMS) as a control thickener. When compared with NMS, HAMSs performed better in increasing the resistant starch content (RS), storage modulus, loss modulus, and complex viscosity of all the milk gels. The results are attributed to the retention of the starch granular integrity of HAMSs during the preparation of the milk gels, as observed by microscopy. HylonVII exhibited the highest RS and viscosity in all milk gel systems, especially in WP gels (71.8 % RS and3000 Pa.s at 1 Hz viscosity). Our data provide support for the potential of using HAMS to develop healthier yogurt products using functional thickeners from natural sources.

This paper evaluated the relationship between multi-scale structure and high-pressure gelation properties of nine types of starches with different amylose (AM) content and crystalline polymorphic structure by RVA 4800. Higher average chain lengths of long amylopectin (AP) chains (DP 36) and AM content, and lower relative content of short AP chains (DP ≤ 36) contributed to the higher peak temperature and peak time at 95-140 °C, and lower peak viscosity, through viscosity, and final viscosity at 95-110 °C. Rheological and texture parameters including storage modulus, loss modulus, hardness, and gumminess, had no significant correlation with starch structural parameters at 95-120 °C, but were instead controlled by AM molecular structure at 130-140 °C. AM content was mainly responsible for the rheological behaviors of starch gels at 130-140 °C, and short and intermediate AM chains were mainly associated with the texture of starch gels at the temperature ranges.

Starch with a high amylose (AM) content (high AM starch, HAS) has attracted increasing research attention due to its industrial application potential, such as functional foods and biodegradable packaging. In the past two decades, HAS structure, functionality, and applications have been the research hotspots. However, a review that comprehensively summarizes these areas is lacking, making it difficult for interested readers to keep track of past and recent advances. In this review, we highlight studies that benefited from rapidly developing techniques, and systematically review the structure, functionality, and applications of HAS. We particularly emphasize the relationships between HAS molecular structure and physicochemical properties.

The multi-scale structural dynamics of amylopectin-only barley starch (APBS), normal barley starch (NBS), and amylose-only barley starch (AMBS) digested with amylolytic enzymes for 120 min were investigated in this study. For all starches, 0–20 min was identified as a rapid digestion stage, followed by a 20–120 min slow digestion. For APBS and NBS, the content of short chains (DP ≤ 12) and the thickness of crystalline and amorphous nano-lamellae increased, whereas the crystallinity decreased, and pores were generated on the granular surface during the rapid digestion stage. At the following slow digestion stage, the branching degree and relative amount of double helices increased, the crystalline and lamellar structures were lost, and the hydrolyzed starch segments aggregated. For AMBS, the rapid digestion stage was characterized by an increased content of short chains (DP ≤ 8) and B-type crystals and decreased amounts of V-type crystals. Furthermore, the lamellar and granular structures were lost, and digestion residues aggregated during the first stage of AMBS, which were formed in the second digestion stage of APBS and NBS. The second slow digestion stage of AMBS was characterized by an increased branching degree and a decreased relative content of single helices. It is suggested that the aggregated digestion residues at the initial digestion stage are the main reason for the overall low digestibility of AMBS.

This review systematically documents the major different strategies of generating high-amylose (HAS) starch mutants aiming at providing high resistant starch, by engineering the starch biosynthesis metabolic pathways. We identify three main strategies based on a new representation of the starch structure: ‘the building block backbone model’: i) suppression of starch synthases for reduction of amylopectin (AP) side-chains; ii) suppression of starch branching enzymes (SBEs) for production of AM-like materials; and iii) suppression of debranching enzymes to restrain the transformation from over-branched pre-AP to more ordered AP. From a biosynthetic perspective, AM generated through the second strategy can be classified into two types: i) normal AM synthesized mainly by regular expression of granule-bound starch synthases, and ii) modified linear AP chains (AM-like material) synthesized by starch synthases due to the suppression of starch branching enzymes. The application of new breeding technologies, especially CRISPR, in the breeding of HAS crops is also reviewed.

BackgroundEnzymatic modification of foods is an important tool for enhancing starch functionality due to its safety, high efficiency, and specificity. Enzymatic modification of gelatinized starch systems is well reported in literature. However, to our knowledge, a review describing and comparing the effects of granular vs. gelatinized systems and enzyme-assisted modification of starch is both timely and lacking.Scope and approachWe summarize, discuss and point at future aspects of the consequences of using various techniques of enzymatic treatment of granular and gelatinized starch for modifying the structure and physicochemical properties, including the crystalline and granular structure, and functional properties. For gelatinized starch systems, we generally discuss catalytic mechanism, substrate specificity and product molecular structures for different types of starch-acting enzymes with emphasis on the resulting molecular structures. We critically discuss the problems of enzyme attack on granular starch in relation to two common strategies for starch granular pretreatment, namely, the preparation of porous starch and cold water-swelling of granular starch aimed at increasing the enzyme catalytic efficiency. Finally, we point out research directions to expand the applications of enzymatic treatments in starch modifications.Key findings and conclusionThe catalytic efficiency of starch-acting enzymes is higher on amorphous gelatinized starch than on semi-crystalline granular starch. To enhance the catalytic efficacy on granular starch, granules can be engineered to allow enzyme binding more efficiently onto granular surfaces. Additionally, we in-depth describe efforts to increase the specific surface area of the starch granular entities by I) generating pores and channels at the granular surface via treatment with hydrolases or by II) swelling granules via e.g., thermal pretreatment in the presence of ethanol. It is generally found that strategy I reduces the starch yield due to the hydrolytic effect, decreasing the pasting properties. Strategy II keeps a high yield of the starch product and generates granular starch with high pasting stability.

Octenyl succinate anhydride (OSA) modified high amylose maize starch (HAMS) showed limited emulsion stability due to the OSA groups were located on the surface of starch granules. However, amylose is enriched in the internal region of HAMS and provides the reaction site for OSA groups. In this study, five types of starches with different amylose content were prepared using optimized reaction conditions. Our data showed that amylose content (AC) was the most important parameter controlling the degree of substitution (DS), in comparison with temperature, pH, starch concentration and time. DS reached a maximum (2.1%) at AC of 58%. Importantly, OSA groups were mainly located in the internal regions of HAMS under the optimized reaction conditions. This was supported by (1) the decrease of the crystallinity, (2) the weaker fluorescence intensity of the starch fluorophore probe 8-amino-1,3,6-pyrenetrisulfonic acid (APTS) in the internal regions of HAMS, and (3) unchanged signals from Fourier transform infrared spectroscopy which characterized the granular surface structure ordering. This new OSA reaction pattern permits HAMS to be used in stabilizing Pickering emulsions This is the first report that OSA groups located in the internal regions of HAMS granules.

Sweet potato was planted at three soil and air temperatures (21, 25 and 28 °C) with the same humidity and light time/intensity. Root tuber starches were isolated, and their multi-scale structures were investigated to reveal the effects of growth temperature on starch properties. Growth temperature did not change the morphology and amylose content of starch, but markedly increased the size of starch from volume-weighted mean diameter 12.2 μm to 17.0 μm. Starch grown at high growth temperature exhibited less A branch-chains and lower branching degree of amylopectin and more B2 and B3+ branch-chains of amylopectin than at low growth temperature. With increasing growth temperature, starch changed from C

Starch from 15 different rice genotypes with amylose content (AC) ranging 1.5%–30.6% were investigated for relationships between structures and properties. For parameters related to the granular level, the most important relationships were found for AC, average chain lengths (ACL) of the amylopectin (AP) fb1 chains having a length of DP 13-24, crystallinity, and the thickness of the crystalline (dc) and the amorphous lamellae (da) of the starch granule. AC and dc were negatively correlated with the peak gelatinization temperature (Tp), thermal enthalpy (ΔH), and peak viscosity (PV), but positively correlated with swelling power. ACLfb1 and da, as compared to AC and dc, had the opposite effects on these parameters, demonstrating important roles of specific molecular and lamellar structures on the starch granular stability. For the gelatinized systems, increasing ACLfb1 decreased retrogradation, while AC increased retrogradation by increasing the resistant starch (RS) content, storage modulus (G′), and setback (SB).

Supplemental irrigation (SI) is an important strategy to improve the water-use efficiency (WUE) of crops without compromising the yield. However, such strategy can influence the starch and grain quality. Hence, the effects of SI on winter wheat starch structure and functionality were studied on ridge-furrow (RF) and flat tillage (FT) treated fields. Flat irrigation was set as control. RF + SI significantly increased the grain yield throughout the study period (2016–2018). SI decreased the amylose content and the content of amylopectin chains with DP 13–24 but increased the proportions of amylopectin chains with DP 6–12 and 25–36. The starch granule relative crystallinity decreased, and more B-type granules were produced by SI treatment. SI significantly increased the resistant starch content in both raw and cooked starch systems. Flat tillage enhanced the effect of SI on granule specific surface area (SSA) and viscosity, which increased starch paste viscosity, while SI + RF showed the opposite effects. Our study demonstrates important combined effects of SI and tillage on wheat starch quality.

In this study, we report important relationships between kernel starch and kernel dehydration rate for eight maize inbred lines with different dehydration characteristics. High-throughput RNA sequencing data of starch biosynthesis-related genes showed that kernel moisture content and dehydration rate were both associated with differential expression of most starch biosynthetic genes. Especially, kernel moisture content was positively correlated with the increased expression of SBEI and SBEIIb, thereby potentially inducing biosynthesis of amylose with low molecular weight and amylopectin with low content of amylopectin chains with degree of polymerization (DP) 6-12 in inbred lines with fast kernel dehydration rate. We found a negative correlation between short amylopectin chains (DP 6-12) and the starch retrogradation rate. Hence, a low amount of amylopectin chains with DP 6-12 in the inbred lines with fast kernel dehydration rate was a plausible reason for their high short- and long-term retrogradation.

As biodegradable and eco-friendly bio-resources, polysaccharides from a wide range of sources show steadily increasing interest. The increasing fossil-based production of materials are heavily associated with environmental and climate concerns, these biopolymers are addressing such concerns in important areas such as food and biomedical applications. Among polysaccharides, high amylose starch (HAS) has made major progress to marketable products due to its unique properties and enhanced nutritional values in food applications. While high amylose-maize, wheat, barley and potato are commercially available, HAS variants of other crops have been developed recently and is expected to be commercially available in the near future. This review edifies various forms and processing techniques used to produce HAS-based polymers and composites addressing their favorable properties as compared to normal starch. Low toxic and high compatibility natural plasticizers are of great concern in the processing of HAS. Further emphasis, is also given to some essential film properties such as mechanical and barrier properties for HAS-based materials. The functionality of HAS-based functionality can be improved by using different fillers as well as by modulating the inherent structures of HAS. We also identify specific opportunities for HAS-based food and biomedical fabrications aiming to produce cheaper, better, and more eco-friendly materials. We acknowledge that a multidisciplinary approach is required to achieve further improvement of HAS-based products providing entirely new types of sustainable materials.

Starch can provide food (such as cake) with a good texture. However, starch also causes the postprandial glycaemic response, which leads to Type-2 diabetes and cardiovascular diseases. In this study, we developed high-amylose starch as a new ingredient. The molecular structure of high-amylose maize starch (HAMS) was also studied to explore the effects of HAMS on the physicochemical, digestion and texture properties of high-amylose maize flour cakes (HAMFCs). The results showed the small molecular size, low amounts of short amylopectin chains, and high amounts of long amylopectin chains and amylose chains of HAMS are helpful to understand the texture (the increase in hardness, cohesiveness, chewiness and resilience and the decrease in springiness) and digestion (the increase in SDS and RS and the decrease in RDS) properties, and the formation of V-type crystalline structure in HAMFCs. Special molecule structure of HAMS and V-type crystalline are the main reason for the improvement of RS in HAMFCs. Sensory evaluation showed that HAMFCs would be accepted by customers and 20% HAMF addition is the best scheme. In sum, the molecular structure of HAMS helps understand the quality of HAMFCs; and HAMFCs could be developed as novel food with a higher RS and acceptable sensory attributes.

A method for efficient functional modification of starch granules by thermal ethanol pre-treatment and subsequent maltogenic α-amylase (MA) and branching enzyme (BE) post-treatments is described. Ethanol pre-treatment significantly increased the swelling power of starch granules thereby increasing the MA and BE susceptibility. Ethanol pre-treated granules became shrunk and twisted after incubating in buffer. Sequential MA post-treatments remarkably increased the α-1,6 to α-1,4 ratio and the content of amylopectin short chains (DP 1–10), contributing to the low retrogradation rate. BE post-treatments significantly decreased the product yield, increased the relative crystallinity of starch granules, suggesting BE had intramolecular transglucosylation activity which altered the branch position and reduced the molecular size by forming cyclic structures. Moreover, BE post-treatments showed an α-1,6 to α-1,4 transglucosylation activity by decreasing the α-1,6 to α-1,4 ratio, especially during simultaneous MA and BE catalysis. However, in the simultaneous MA and BE post-catalysis, MA dosage was predominant by noticeably hydrolyzing amylopectin and amylose molecules and increasing the α-1,6 to α-1,4 ratio, thereby leading to the lowest digestibility and retrogradation.

Dynamic changes of rice starch granules selected for different amylose contents were analyzed in excess water while heated in-situ in a small-angle X-ray scattering (SAXS) instrument. Normal rice starch (NS) and rice starch with high amylopectin (HAP) and high amylose (HAM) were used as models. A 1D linear correlation function and a combination power-law and Gaussian function were used to extract the starch lamellar structure parameters and the fractal dimension, ordering and distribution of starch lamellae from SAXS data. For the resulting starch paste/gels, a model of two-correlation length was fitted to afford the correlation length (ξ) for the paste/gel system. The results showed that HAM exhibited higher long period (LP) and thickness of the crystalline layers (dc) values than HAP and NS. However, HAP showed the highest ordering lamellar structure. HAP granules were more thermostable than the amylose containing starches. For the gelatinized starches, HAM showed the highest correlation length values but these notably decreased with increasing temperature indicating strong chain segment interaction. This research reveals essential structural changes in lamellae of rice starch granules and rice starch gel structure, which provides potentially useful in the working of starch-based foods and materials.

Due to the semi-crystalline structure of native starch granules, enzymatic modification of these solid, raw, entities by branching enzyme (BE) is limited. Here, we describe a method to efficiently modify starch by BE after maltogenic α-amylases pre-treatment. This pre-treatment produced pores at the starch granule surface, which decreased the granular yield, but increased the branching degree in starch molecules. BE post-treatments recovered the yield, increased the content of long amylose chains, and the starch crystallinity. WAXS analysis showed that BE transformed the unresolved doublet peak at 2θ 17° and 18° to a strong peak at 2θ 17°, i.e. transformed the granules from the A-type to a mixed A-, B-type allomorph. Syneresis of starch gels increased with increasing BE concentrations and increased the content of slowly digested starch in retrograded starch preparations. Rheology data demonstrated that low and medium BE concentrations produced starch gels with higher G′ and G″ after storage for 1day, whereas high BE concentrations reduced both G′ and G’’. Our data demonstrate the potential of clean, enzyme-based protocols using sequential addition of starch active enzymes for post-harvest modification of raw starch granules to obtain clean and functional starch.

International audience; Pure granular amylose (AM) and pure granular amylopectin (waxy) starch (AP) granules have the high nutritional value in food industry. Effects of microwave treatment (400 W/g DW, 1–8 min) on the structure and properties of transgenic AM granules and AP granules were investigated in direct comparison. Microwave treatment, especially during the first 3 min, decreased the molecular weight of molecules in both the AM and the AP samples. The crystallinity of AM starch initially increased from 15.6% to 20.6%, which was associated with the formation of new Vh-type crystals. After that, crystallinity decreased alongside to 11.3% with the complete disruption of B-type crystals. In contrast, the crystallinity of AP starch initially decreased from 18.9% to 10.8% followed by an increase to 20.0%. Upon prolonged treatment of AM granules, the resistant starch and water solubility was significantly increased. Our data demonstrate notable different microwave-dependent reorganization patterns for pure granular AM and AP molecules as native granular systems, which is helpful to the improvement of functionality of these two starches

Subgroups of starch granules from five maize phenotypes including waxy-, normal-, popcorn-, sweet corn- and high-amylose maize were sorted by flow cytometry (FC) utilizing the side scatter channel (SSC) and forward scatter channel (FSC). SSC and FSC mainly reflecting internal object complexity, and object size, respectively. Subgroups with higher FSC signal always showed higher SSC signal, indicating larger granules exhibited higher internal structural complexity. Wide-angle and small-angle X-ray scattering analysis showed that the subgroups showing high SSC signal intensity also had high lamellar scattering intensity, and low crystallinity. Vibrational transitions of bonds analyzed by Fourier Transform Infrared Spectroscopy (FT-IR) showed that the subgroups of maize starches, except sweet corn starch, with high SSC signal had high intensities at 1045 and 1022 cm−1. Hence, our data demonstrate that the structural complexity detected by the SSC signal is mainly associated with lamellar and crystalline features of starch granules.

Particle-size distribution, granular structure, and composition significantly affect the physicochemical properties, rheological properties, and nutritional function of starch. Flow cytometry and flow sorting are widely considered convenient and efficient ways of classifying and separating natural biological particles or other substances into subpopulations, respectively, based on the differential response of each component to stimulation by a light beam; the results allow for the correlation analysis of parameters. In this study, different types of starches isolated from waxy maize, sweet maize, high-amylose maize, pop maize, and normal maize were initially classified into various subgroups by flow cytometer and then collected through flow sorting to observe their morphology and particle-size distribution. The results showed that a 0.25% Gelzan solution served as an optimal reagent for keeping individual starch particles homogeneously dispersed in suspension for a relatively long time. The bivariate flow cytometric population distributions indicated that the starches of normal maize, sweet maize, and pop maize were divided into two subgroups, whereas high-amylose maize starch had only one subgroup. Waxy maize starch, conversely, showed three subpopulations. The subgroups sorted by flow cytometer were determined and verified in terms of morphology and granule size by scanning electron microscopy and laser particle distribution analyzer. Results showed that flow cytometry can be regarded as a novel method for classifying and sorting starch granules. © 2017 International Society for Advancement of Cytometry

Microwave processing is a suitable technology for starch-based food processing. This work investigated the changes of structures and properties of high-amylose maize starch (HAMS) during short-time microwave irradiation (1–4 min). After 1 min of treatment, short amylopectin chains (DP 6–36) and intermediate amylose chains (DP 150–2000) of HAMS were partially broken down. Compared with native HAMS, treated HAMS (1 min) had the higher relative crystallinity, the intensity of the 9 nm lamellar peak, and fluorescence intensity under CLSM. Moreover, 1-min microwaving caused the lower viscosity and higher resistant starch content of HAMS. In the 2–4 min of treatment, the crystallinity, intensity of the lamellar peak and fluorescence intensity of HAMS granules decreased significantly, but no breakdown of starch molecule chains was observed, suggesting the realignment of the crystalline region during the process. Correspondingly, the viscosity increased and resistant starch content decreased. Our study provides a deeper understanding of the mechanistic effects of short-time microwave irradiation on high-amylose starch, which is of value for the processing of HAMS to produce novel functionality and nutritional values.

The relationship between molecular structure and crystalline and lamellar structures of fifteen types of rice starches was studied. GPC and HPAEC were used for the molecular chain analysis and WAXS, SAXS, and CP/MAS 13C NMR were employed for aggregation structural analysis. The amylopectin content and the average lengths of fb1-chains (the degree of polymerization (DP) 13-24) were positively correlated with the amount of double helices (r2 = 0.92 and 0.57, respectively). In contrast, amylose content was positively correlated with the amounts of amorphous materials in starch (r2 = 0.77). The amount of double helices, which constitute a major part of the crystalline matrix, was positively correlated with the lamellar ordering (r2 = 0.81), and negatively correlated with the thickness of crystalline lamellae (r2 = 0.90) and lamellar repeat distance (r2 = 0.84). Conversely, the amount of the amorphous matrix was correlated with these parameters in the opposite way (r2 = 0.50, 0.75, and 0.75, respectively).

High amylose maize flour (HAMF), normal maize flour (NMF), extruded normal maize flour (ENMF) and extruded high amylose maize flour (EHAMF) were employed to analyze the effects of the extrusion process on their physicochemical properties and in vitro digestion. The disruption degree of NMF and HAMF under extrusion followed the degree of gelatinization order. HAMF and EHAMF had higher onset temperature, peak temperature and conclusion temperature but lower melting enthalpies in comparison with NMF and ENMF. Extrusion treatment decreased viscosity and transformed A-type and B-type starch in NMF and HAMF into B + V-type. The solubility of all samples and swelling power of NMF and HAMF showed an increase, while swelling power of extruded maize flour decreased with increasing temperature. HAMF and EHAMF had a higher content of resistant starch but a lower content of slowly digestible starch and rapidly digestible starch than NMF and ENMF.

We describe a method for permitting efficient modification by transglucosidase (TGA), from glycoside hydrolase family 31 (GH31), sequentially after the pre-treatment by maltogenic α-amylases (MA) from GH13. TGA treatment without MA pre-treatment had negligible effects on native starch, while TGA treatment with MA pre-treatment resulted in porous granules and increased permeability to enzymes. MA→TGA treatments lead to decreased molecular size of amylopectin molecules, increased α-1,6 branching, and increased amounts of amylopectin chains with the degree of polymerization (DP)

Structures and functionality of two groups of high-amylose maize hybrids starches (HAMHSs) with the same maternal parent but different paternal parent were investigated. H1 and H2 (Group 1) and H3 and H4 (Group 2) had the same maternal parents within the groups, respectively. Paternal parent affected the molecular size of amylopectin components of HAMHS as deduced by gel-permeation chromatography (GPC) analysis of native samples. GPC analysis of debranched samples and further amylose fitting analysis showed the paternal parent effect on the average chain lengths of amylose and long amylopectin (DP > 36). WAXS and SAXS data showed paternal parent only affected the thickness of crystalline lamellae and the amorphous lamellae, but had no effect on polymorph type, crystallinity, lamellar ordering, and long periodic distance of HAMHS. In addition, water solubility and contents of rapidly digestible starch, slowly digestible starch, and resistant starch were all affected by the paternal parent. In summary, we report some significant differences of HAMHS with the same maternal parent but different paternal parent.

Two high amylose (HAM) inbred lines with apparent amylose contents of 55 % and 62 %, respectively, were selected to explore the relationship between molecular structure and gene expression of starch-synthase involved enzymes. GPC analysis of debranched starches showed that the HAM starches (HAMSs) had shorter amylose chains and longer amylopectin chains than normal maize starch (NMS). FACE analysis showed that these HAMSs had a higher content of amylopectin chains of DP > 21. Quantitative Real-Time PCR analysis showed that the HAM lines had specifically low expression of the starch branching enzyme IIb (SBEIIb), and the starch synthase IIIa (SSIIIa) homologue, and high expression of the isoamylase 2 (ISA2), potentially suppressing the generation of amylopectin molecules through deficient branching and excessive debranching process, thereby increasing the relative amylose content. A high expression of GBSS1 was potentially associated with increased short amylose chain lengths in HAMSs.

The molecular and lamellar structures and in vitro digestibility of high amylose maize starch granules were investigated. Size-exclusion chromatography (SEC) analysis of hydrodynamic radius (Rh) and relative contents (RC) of different amylose and amylopectin pools revealed that increased amylose content resulted in the decrease of RC of short amylopectin chains (AP1, DP 36). Fluorophore-assisted carbohydrate electrophoresis (FACE) analysis showed the average chain lengths of defined structures of fa, fb1, and fb3, and the content of fb3 were increased with the amylose content and at AC content of 43%, the chain lengths decreased with the amylose content. The relative contents of fa and fb1and the degree of branching had the converse trends. Hence, HA-2, having an AC content of 43%, was the tipping point for these structural changes. Small angle X-ray scattering (SAXS) and its normalized 1D correlation function and SAXS scattering curve parametric fitting showed that the crystalline lamellar thickness was negatively correlated with proportion of short amylose chains (AM1, 100

The structures and properties of normal popcorn starch (PCS) and porous PCS were studied. In comparison with normal dent corn starch (DCS), PCS had more amylopectin chains with degree of polymerization (DP) 12–24, fewer amylopectin chains with DP > 36, and shorter amylose chains. PCS had a lower crystallinity, a more disordered lamellar structure, thicker lamellae, larger granules, a more porous granular surface, lower viscosity, and a lower gelatinization temperature than DCS. After α-amylase hydrolysis at sub-gelatinization temperatures, both PCS and DCS had more porous granular surfaces, shorter amylose and outer amylopectin chains, and higher relative crystallinities. However, as compared to DCS, PCS had a lower overall yield, larger pores, a higher percentage of hydrolyzed amylose and long amylopectin chains, smaller granules, and greater water- and oil-absorption capacities. These differences were attributed to the indentations on the granular surface of PCS as well as to its fragile structure. These results increased our understanding of the structures and properties of PCS, and provided a framework for PCS preparation. In addition, our results suggested that PCS has a high potential for porous starch applications.

In this study, the molecular and aggregation structures of nine types of pure amylopectin (waxy) starches from sorghum (WSS), wheat (WWS) and millet (WMS) were combinedly studied by Gel-Permeation Chromatography (GPC), Fluorophore-Assisted Carbohydrate Electrophoresis (FACE), Wide Angle X-ray Scattering (WAXS), and Small Angle X-ray Scattering (SAXS). The chain lengths (CL) and contents of amylopectin chain fractions were mainly related to the genotype. Pearson correlation analysis suggests that short amylopectin chains 1 (S1 chains, DP 6–18) were the main contributors to crystalline lamella; longer S1 chains resulted in decreased thickness (dc) of the crystalline lamellae. However, also the lengths of the short amylopectin chains 2 (S2, DP 19–30) related to dc showing a positive correlation. Therefore, WWS samples, with the highest average CL of the S2 chains and lowest CL of S1 chains, displayed the thickest crystalline lamellae and longest long period distance i.e. the sum of the crystalline and amorphous lamellar thickness, dac. Among the different starches, WMS exhibited the thinnest crystalline lamellae and shortest dac, and consequently had the second-highest CL of S1 chains and lowest CL of S2 chains of the samples. The dc and dac of WSS were intermediate and related to its medium length of S1 chains and S2 chains. Our study provides information of structural parameters of different types of amylopectin starches and specifically provides evidence of the importance of S2 chains on the lamellar structure. Importantly, our data demonstrate that the total CLD of amylopectin can reflect internal CL of importance for starch granule lamellar features.

There is a huge interest to develop low‐sugar baked products for reducing risks of some diseases, such as adiposis, diabetes, and high blood pressure. A low‐sugar cookie was prepared with butter, xylitol, and high‐amylose maize flour (HAMF) through response surface methodology. ANOVA of models for sensory profiles, texture, and digestibility showed the models for sensory attributes, hardness, and resistant starch were significant (p

Because of its biodegradable trait, starch has been widely used as the raw material for packaging. Effects of different thermal treatment methods (high temperature-high pressure heating (HH), microwave heating (MH) and alkali heating (AH) with and without glycerol on physical properties of high amylose maize starch films (HASFs) were investigated in this study. HASFs under HH had highest elongation at break (E%), and lowest tensile strength (TS), modulus of elasticity (EM) and opacity (OC). HASFs under MH had highest TS, water holding capacity (WHC) and OC, and lowest thickness (TN), E%, solubility in water (SW) and solubility in oil (SO), while HASFs under AH had highest TN, EM, SW and SO, and lowest WHC. Compared with water, plasticized HASFs with glycerol had higher TN，E%, WHC, SW and OC, and lower TS, EM and SO. XRD results revealed the V-type polymorph and the difference in intensity of diffraction peaks of HASFs under three methods. This study would be helpful to design and prepare HASFs.

Starch is the main storage carbohydrate in plants and an important natural resource for food, feed and industrial raw materials. However, the details regarding the pathway for starch biosynthesis and the diversity of biosynthetic enzymes involved in this process are poorly understood. This study uses a comprehensive phylogenetic analysis of 74 sequenced plant genomes to revisit the evolutionary history of the genes encoding ADP-glucose pyrophosphorylase (AGPase), starch synthase (SS), starch branching enzyme (SBE) and starch de-branching enzyme (DBE). Additionally, the protein structures and expression patterns of these four core genes in starch biosynthesis were studied to determine their functional differences. The results showed that AGPase, SS, SBE and DBE have undergone complicated evolutionary processes in plants and that gene/genome duplications are responsible for the observed differences in isoform numbers. A structure analysis of these proteins suggested that the deletion/mutation of amino acids in some active sites resulted in not only structural variation but also sub-functionalization or neo-functionalization. Expression profiling indicated that AGPase-, SS-, SBE- and DBE-encoding genes exhibit spatio-temporally divergent expression patterns related to the composition of functional complexes in starch biosynthesis. This study provides a comprehensive atlas of the starch biosynthetic pathway, and these data should support future studies aimed at increasing understanding of starch biosynthesis and the functional evolutionary divergence of AGPase, SS, SBE, and DBE in plants.

Particle-size distribution, granular structure, and composition significantly affect the physicochemical properties, rheological properties, and nutritional function of starch. Flow cytometry and flow sorting are widely considered convenient and efficient ways of classifying and separating natural biological particles or other substances into subpopulations, respectively, based on the differential response of each component to stimulation by a light beam; the results allow for the correlation analysis of parameters. In this study, different types of starches isolated from waxy maize, sweet maize, high-amylose maize, pop maize, and normal maize were initially classified into various subgroups by flow cytometer and then collected through flow sorting to observe their morphology and particle-size distribution. The results showed that a 0.25% Gelzan solution served as an optimal reagent for keeping individual starch particles homogeneously dispersed in suspension for a relatively long time. The bivariate flow cytometric population distributions indicated that the starches of normal maize, sweet maize, and pop maize were divided into two subgroups, whereas high-amylose maize starch had only one subgroup. Waxy maize starch, conversely, showed three subpopulations. The subgroups sorted by flow cytometer were determined and verified in terms of morphology and granule size by scanning electron microscopy and laser particle distribution analyzer. Results showed that flow cytometry can be regarded as a novel method for classifying and sorting starch granules. © 2017 International Society for Advancement of Cytometry.

High amylose starch is a potential material to produce biodegradable films with the better physical properties than normal starch. In this research, Taguchi's design and analysis of variance were used to compare the effects of gelatinization methods, starch concentrations, and plasticizers on physical properties of high amylose starch films. The results showed that the gelatinization method was the most significant factor for transparency, and the highest transparency was obtained through high temperature-high pressure treatment. The starch concentration impacted farthest on thickness, tensile strength, elongation at break, and solubility in oil. The highest thickness and tensile strength were obtained from 10% starch concentration, the highest elongation at break were created by 5% concentration, and the lowest solubility in oil was produced by 2% concentration. Solubility in water was affected by plasticizers most, especially in xylitol. The information in this study is helpful to choose optimal parameters for preparing high amylose starch films with desired physical properties. Practical applications Due to the biodegradable and environmentally-friendly traits, high-amylose starch film is a promising alternative to plastic film. Most studies were focused on the changing of one of the independent parameters at a time while maintaining the others at fixed levels. However, studying the interactive effects of these parameters is beneficial to the development of high-amylose starch films at a whole insight. For this purpose, the effects of different preparation parameters under different levels on physical properties of high-amylose starch film were studies under Taguchi design in this study. Results showed the different effects of gelatinization methods, starch concentrations, and plasticizers on different properties such as mechanical properties, solubility in water and oil, and transparency of high-amylose starch films. The information provided by this study will play a guiding role for the production of high-amylose starch films in different applications with optimal parameters.

To investigate the applicability of high-amylose corn grits (HACG) to the process for extruded products, a single screw extruder was used to produce extrudates under feed rate of 220 g/min, barrel temperature of 120°C, and screw rotational speed of 150 rpm. The nutritional, physical and sensory properties were investigated in the HACG extrudate and normal corn grits (NCG) extrudate acting as control. The results indicated that the HACG extrudate had higher (P≤ 0.05) protein (7.07%), fiber (5.41%), lipid (1.48%), ash (0.76%), resistant starch (2.89%), zein (4.65%), calcium (22.34 mg/kg), magnesium (718.63 mg/kg), iron (19.47 mg/kg), zinc (22.73 mg/kg) contents and 16 of 17 types of amino acids compared to the NCG extrudate. In regards to physical properties, the bulk density (BD), radial expansion index (REI) and water solubility index (WSI) values of the HACG extrudate, which were 57.94 mg/ml, 45.47 and 43.25, respectively, were significantly lower (P≤ 0.05) than those of the NCG extrudate. However, the HACG extrudate had a higher special length (SL), indicating a higher axial expansion, water absorption index (WAI), frangibility and cohesiveness (7.34 cm/g, 3.69, 68.79 and 0.32, respectively), and a more sponge-like structure. A sensory analysis indicated that the HACG extrudate had higher values for frangibility, cohesiveness, chewiness and overall taste with a lower coarseness and adhesiveness (to teeth).