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Kudzu is usually consumed at different growth years, yet the influences of growth years on its multi-scale structures and physicochemical features have not been fully disclosed. In this study, those influences occurred on kudzu starches (KS2, KS10, KS30 and KS50, isolated using precipitation method) were investigated. The granules size, crystallinity, short-range ordered structure, amylose content, intermediate and longer amylose chains reduced but the average thickness of crystalline lamella increased as the rise of growth years. KS2 had lower content of defective crystal structure and higher content of near-perfect crystal structure. Those signified that bulk density of molecules packing into starch substrate was higher for KS2, which was not beneficial for water molecules and enzymes entering into starch granules and thus elevated pasting temperature and reduced digestion rate. Besides, reduced proportions of defective ordered structures and enhanced lipid-amylose complex also reduced digestion rate. Both the peak and breakdown viscosity were in order of KS2 > KS10 > KS30 ≈ KS50. And KS2, KS10, and KS30 exhibited enhanced retrogradation tendency during cooling than KS50 as evidenced by the relative higher setback viscosity. Those results are favor for rational screen and usage of kudzu starch resources with different growth years for food applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

This work concerned the effects of amylose/amylopectin ratio on the structure and thermal stability of propionylated starches with high degree of substitution (DS). Four starches with different amylose content were used to obtain propionylated starches. Acylation partly disrupted granule morphology of native starches, and the imperfection and porous structures of starch granule were intensified along with the increased amylose content. It was noted that the crystalline structure of starch was destroyed and thus intense acylation occurred in both amorphous and crystalline regions. The acylated starch with high-amylose content displayed more ordered region compared to low-amylose starch. Acylation enhanced the thermal stability of starch, and this effect became more evident as the amylose content increased. Thus, the amylose/amylopectin ratio has been confirmed capable of affecting the structure and thermal behaviors of hydrophobic propionylated starch, which is of value for the design of starchy materials with tailored thermal stability., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Combined analytical techniques were used to explore the effects of alkali treatment on the multi-scale structure and digestion behavior of starches with different amylose/amylopectin ratios. Alkali treatment disrupted the amorphous matrix, and partial lamellae and crystallites, which weakened starch molecular packing and eventually enhanced the susceptibility of starch to alkali. Stronger alkali treatment (0.5% w/w) made this effect more prominent and even transformed the dual-phase digestion of starch into a triple-phase pattern. Compared with high-amylose starch, regular maize starch, which possesses some unique structure characteristics typically as pores and crystallite weak points, showed evident changes of hierarchical structure and in digestion rate. Thus, alkali treatment has been demonstrated as a simple method to modulate starch hierarchical structure and thus to realize the rational development of starch-based food products with desired digestibility., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Abstract Using combined techniques and two comparisons (maize and cassava starches), this work concerns the multi-scale structure and digestion rate of water chestnut tuber starch. Among the starches, the water chestnut starch showed altered hierarchical structural features and a relatively low digestion rate. The underlying mechanism on the reduced digestion rate of water chestnut starch was discussed from a hierarchical structural view. Specifically, compared with maize starch, the water chestnut starch contained no pores on the granule surface, with the thickened crystalline lamellae, the increased lamella ordering, and the elevated content of crystallites. Such structural features probably increased the bulk density of molecule assembly in starch and thus could hinder the diffusion of enzyme molecules in starch matrixes. Consequently, the absorption of enzyme to the starch glucan chains could be retarded, resulting in a reduced enzyme hydrolysis rate of starch chains. The relatively large amylose molecules of water chestnut starch also tended to reduce the starch digestion rate, associated with the enhanced molecule interactions such as that between starch chains. In addition, the further reduction in the digestion rate of cassava starch could be also ascribed to the variations in the multi-scale structural features. Graphical abstract Image 1014 Highlights • Water chestnut starch showed thickened lamellae relative to maize or cassava starch. • Water chestnut starch exhibited a relatively high crystallinity level. • Water chestnut starch had an intermediate amylose molecule size. • Water chestnut starch showed a larger amylose size than maize starch. • Water chestnut starch displayed a relatively low digestion rate. [ABSTRACT FROM AUTHOR]

Highlights • Yam bean starch had relatively flawed lamellae and crystallites. • Yam bean starch had smaller molecule sizes than did potato starch. • Yam bean starch had fewer amylose and amylopectin long chains. • Yam bean starch was less resistant to hydrothermal effects and enzyme digestion. • Yam bean starch showed higher paste stabilities during heating and cooling. Abstract This work discloses the multi-scale structure and pasting/digestion behaviors of yam bean tuber starches (YB-GD and YB-SC). Compared to potato starch, YB starches exhibited varied pasting/digestion features that were understood from a multi-scale structural view. Especially, YB starches showed relatively polydisperse lamellae, less perfect crystallites, and fewer amylose molecules. These features should reduce the bulk density of starch chain packing, and could facilitate the water or enzyme diffusion in starch matrixes. Consistently, not only was starch's resistance to hydrothermal effects weakened (shown by reduced pasting temperature), but also the enzyme absorption to starch chains and the subsequent hydrolysis events were accelerated. Furthermore, YB starch molecules had more short chains, which played roles in reducing the paste viscosity along with the reduced granule size and in enhancing the paste stabilities during heating and cooling. Also, those molecular features tended to speed up the enzyme diffusion and digestion events. [ABSTRACT FROM AUTHOR]

This work explores the influence of starch amylose/amylopectin ratio on the gel-related features of gelatin/starch system using small and large amplitude oscillation shear methods. The higher self-aggregation and self-entanglement ability of amylose reduced the miscibility of gelatin and starch, and increases zero-shear viscosity (ŋ 0) and reduces sol-gel transition temperature (T gel) by enhancing the difficulty of molecule movement and thus the difficulty of gel formation. The gelatin/amylopectin-rich system has higher gel hardness and wider linear viscoelastic region, which are related to the higher integrity and uniformity of network structure. The gelatin/amylose-rich system shows enhanced ability to resist deformation against external shear forces (suggested by higher storage and complex modulus) under small amplitude oscillatory shear (SAOS), which is ascribed to the larger rigidity and entanglement degree of amylose. At strain amplitude up to 50% (middle amplitude oscillatory shear, MAOS), gelatin/amylose-rich system exhibits reduced structure recovery ability (reflected by larger semi-minor axis of ellipse, and lower strain amplitude for inflexion of elastic stress) under MAOS, but enhances restructuring capacity at strains of 500% and 1000% (large amplitude oscillatory shear, LAOS) (indicated by occurrence of secondary loop) than gelatin/amylopectin-rich system. Those seemingly contradictory phenomena are correlated with the preference of hydrogen bond forming ability among amylose rather than with gelatin. This weakens interactions between amylose and gelatin and thus inhibits recovery of bulk structure under MAOS, but is favor for the formation of amylose aggregations, which is helpful for the local structure restructuring and thus enhances structure restructuring capacity under LAOS. The results help us comprehensively understand the gel-related properties of gelatin/starch system and are valuable for rational design of gelatin/starch systems with improved gel-related features. [Display omitted] • Higher amylose content reduces compatibility of gelatin and starch. • Higher amylose content decreases gel hardness of gelatin/starch composite. • Amylose-rich system exhibits higher G ′ in SAOS than amylopectin-rich one. • Amylopectin-rich system has higher structural resilience in MAOS than amylose-rich one. • Amylose-rich system has stronger restructuring in LAOS than amylopectin-rich one. [ABSTRACT FROM AUTHOR]

From a microstructural view, the focus of this work was on the water absorption rate of starch-based superabsorbent polymers (starch-SAPs) prepared under high starch concentration (0.27:1 w/w starch:water). The effects of starch amylose/amylopectin ratio were disclosed. The increase in amylopectin reduced the amount ( C PAM ) of polyacrylamide (PAM) in starch-SAPs but increased the ratio of starch carbons grafted with PAM, which eventually decreased the average length ( L PAM ) of PAM chains. The shorter PAM chains could reduce starch-SAP chain flexibility, thus inducing larger mass fractal gels in swollen starch-SAPs. In general, the increases in C PAM and L PAM were preferable for a higher water absorbent capacity ( WAC ), whereas the denser fractal gels reduced WAC . Interestingly, all starch-SAPs had a dual-phase absorption process with the first stage showing a higher rate than the second phase ( k 1 > k 2 ). The shorter PAM chains caused increases in k 1 and k 2 . [ABSTRACT FROM AUTHOR]

Starch/agar systems are highly potential for versatile applications such as packaging and biomedical materials. Here, how combined factors affect the features of a starch/agar binary system were explored. An increase of starch amylose/amylopectin ratio from 0/100 to 50/50 increased the sol-gel transition temperature and gel hardness of the aqueous starch/agar mixture. An increased agar content (mainly from 30% to 70%) allowed increases in both the tensile strength (reaching 50–60 MPa) and elongation at break of the starch/agar binary films. This phenomenon should be related to the strengthened crystalline structure and the weakened hydrogen bonding between starch chains (reflected by infrared spectroscopy). Furthermore, a higher relative humidity (from 30% to 70%) allowed enhanced chain interactions and probably nanoscale molecular order but weakened the crystalline structure, leading to reduced tensile strength and increased elongation at break. This work could facilitate the design of starch/agar binary systems with improved sol-gel and mechanical performance. [ABSTRACT FROM AUTHOR]

Cold-chain cooked rice is an instant food consumed worldwide. Through inspecting rice structural alterations during digestion, this work discloses how microwave reheating tailors the starch digestibility of cooked rice following cold storage. The cold storage allowed approximately 2% of B-type (not V -type) starch crystallites, more nanoscale and short-range orders, and smaller pores in the rice matrix. These changes retarded the hydrolysis of structural domains (e.g., amorphous regions and short-range orders) during digestion, which increased the content of slowly digestible starch to about 38.16%. Then, microwave reheating partially disrupted the B-type crystallites and nanoscale orders, but unaffected the contents of V -type crystallites and short-range orders. Even with such structural disruptions, the resistant starch content was apparently increased to approximately 30.06%, as the structural domains became less susceptible to the digestion. Additionally, for the rice samples, the percentage of V -type crystallites could be largely increased from ca. 3% to 13%–14% during digestion. • Refrigeration enriched molecular orders at different scales and slowly digestible starch. • Refrigeration retarded the hydrolysis of non-crystalline domains during digestion. • Microwave reheating disrupted molecular orders but increased resistant starch. • Microwave reheating enhanced the resistance of non-crystalline domains to digestion. • The content of V -type starch crystallites was gradually increased during digestion. [ABSTRACT FROM AUTHOR]

This work concerns the multi-scale structures and digestion behaviors of indica rice starches with apparent amylose contents (AAC s) of ca. 14%–24%. A higher AAC not always allowed a lower digestion rate (k), different from previous findings that starches containing more amylose normally show slowed digestion. Here, the proportion of stable molecular orders (melting temperature above ca. 73 °C) and AAC synergistically governed starch digestion rate. With a similar AAC , a higher amount of stable orders (R h/l , ratio of enthalpy of stable orders to that of the rest) led to a lower k. Also, with a similar R h/l , a larger AAC caused a lower k. Consistently, JPZ starch had almost the highest AAC and R h/l , showing the lowest k. Regarding this, amylose and stable orders played roles in increasing the bulk density of starch structure matrices, and eventually slow the diffusion, absorption and catalysis events of digestion enzymes within the matrices. • Starches contained varied amounts of stable molecular orders melted above 73 °C. • Stable orders and amylose content synergistically affect starch digestion rate. • With similar amylose content, more stable orders reduced starch digestion rate. • With similar stable orders, more amylose reduced starch digestion rate. [ABSTRACT FROM AUTHOR]

• Microwave cooking-storage induced more orders than did conventional cooking-storage. • Microwave cooking-storage induced more amorphous-crystalline structures. • Microwave cooking-storage increased the content of slowly digestible starch. • Microwave cooking-storage lowered the digestion rate of starch. • The evolutions in starch digestion features were enhanced by the increased amylose. By inspecting starch hierarchical structural evolutions, this work explores how microwave cooking with storage tailors the slowly digestible features of indica (IRS) and waxy (WRS) rice starches. Particularly, relative to conventional cooking-storage, the microwave treatment especially at high powers (8 and 10 W/g) increased the molecular orders (crystallites) and periodic amorphous-crystalline structures. Such changes facilitated the formation of domains with intermediately-densely packed starch chains, being modestly accessible to the diffusion, absorption and catalysis of enzymes and dominantly showing slowly digestible features. Consistently, the microwave processed starches showed a higher SDS (slowly digestible starch) level and a lower digestion rate. This microwave-enhanced SDS generation became more prominent for IRS, and the treated IRS at 10 W/g showed the highest SDS content (ca. 54%). This is related to the enhanced reassembly of glucan chains into ordered/semicrystalline structures and the formation of slowly digestible domains as induced by the increase of amylose molecules. [ABSTRACT FROM AUTHOR]

Abstract: Biodegradable superabsorbent polymers (SAPs) were prepared by grafting acrylamide onto starches then crosslinking with N,N′-methylene-bisacrylamide. This work focused on the effects of the amylose/amylopectin ratio of starches from the same source (corn) on the grafting reactions and performance of the resultant starch-based SAPs. To characterise each SAP, the acrylamide groups grafted onto the starch were detected by FTIR; grafting ratio and grafting efficiency were evaluated by a gravimetric method; and graft position and the length of the grafted segment were investigated by NMR. The relationships between the microstructures of the starches, and the graft reactions and performance of the SAPs were studied based on the amylose content in the starches. It was found that under the same reaction conditions, the grafting ratio and efficiency increased with increasing amylose content, which corresponds with water absorption ratio. NMR results indicated that the acrylamide group mainly grafted onto C6, and that the length of the grafted segment decreased with increasing amylopectin content in general, and in particular for waxy starch. The high molecular weight and branched structure of amylopectin reduced the mobility of the polymer chains and increased viscosity, which could explain the graft reactions and performance of the starch-based SAPs. [Copyright &y& Elsevier]