Waxy Wheat Starch Research Articles

Improving of noodle quality caused by starch-protein interaction of waxy and strong-gluten wheat flour

Waxy wheat flour (WWF) has good processing properties and can be used to enhance the quality of noodles because of its high amylopectin or low amylose content. The aim of this study was to investigate the correlation between changes in the structural characteristics of waxy wheat starch (WS) and gluten (WG) and changes in noodle quality following molecular interactions with strong-gluten wheat starch (NS) and gluten (NG) by separation and reconstitution methods. The results showed that the noodle quality was better when WWF was added at 15% (w/w). WS promoted the formation of strong crystalline structure of amylopectin, and WG promoted the formation of double-helical short-range molecular structure of starch, and its degree of order was positively correlated with the cohesiveness and water absorption of cooked noodles, and negatively correlated with chewiness. The interaction of WS and WG with NS and NG could improve noodle quality through the change of intermolecular interactions.

Effects of xylanase on starch isolation and functional properties of waxy wheat flour

Waxy wheat starch is difficult to be extracted from waxy wheat flour (WWF) due to the weak gluten quality and the existence of arabinoxylan (AX). The objective of this study was to understand effects of xylanase on starch isolation and functional properties of WWF. WWF with addition of xylanase had a lower water retention capacity, shorter dough development time, and longer dough stability time when compared to the one without xylanase. Addition of xylanase to the WWF dough decreased its viscoelasticity and bound water, increased its extensibility and immobilized water, and transformed it from the elastic to the extensible texture. The xylanase hydrolysis of water-unextractable AX promoted quick formation of gluten and the release of starch granules during wet milling of WWF. Results suggested that WWF could be wet-milled without any challenge by adding xylanase. A role of AX in the dough and during wet milling of WWF was proposed and illustrated.

Characterization of four commercial waxy wheats developed in China

AbstractBackground and ObjectivesAs the interest in use of waxy wheat in food applications continues to grow, it is important to fully understand characteristics of waxy wheats. To the best of our knowledge, there was no previous study reporting a complete characterization of commercial waxy wheats developed in China, especially properties of wheat kernels, dough, wet milling, gluten, and starch. To promote the industrial utilization of waxy wheat, four Chinese commercial waxy wheats were collected and characterized.FindingsFour commercial waxy wheats commercialized in China were sound medium hard wheats. Care must be taken during harvesting and storage of waxy wheats since the waxy wheat flours were very sensitive to the endogenous α‐amylase even at a very low level of enzyme activity. Rapid viscosity analyzer had a good potential for evaluating the sprout damage of waxy wheat. Dough rheological properties and gluten index showed that the four waxy wheats had weak gluten quality, agreeing with wet‐milling performance. The waxy wheat starches had higher onset, peak, and conclusion gelatinization temperatures than normal wheat starch. While the waxy wheat starches showed lower pasting temperature and higher peak viscosity than normal wheat starch.ConclusionsResults suggested that the four commercial waxy wheats varied in kernel characteristics, protein and starch contents, wet‐milling performance, gluten quality, dough rheological properties and pasting properties, which might provide a wide range of applications.Significance and NoveltyThe research work provides useful information for wheat breeders to breed waxy wheat suitable for industrial applications and for scientists to promote the use of waxy wheat flour and starch in food applications.

Microstructures of Starch Granules with Different Amylose Contents and Allomorphs as Revealed by Scattering Techniques.

In this study, as-is (ca. 12% moisture by mass) and hydrated (50% water by mass) granules of waxy potato (WP), waxy wheat (WW), waxy maize, normal maize, and high-amylose maize (HAM) starches were investigated by using small-angle neutron and X-ray scattering (SANS and SAXS), wide-angle X-ray scattering, and ultra-small-angle neutron scattering. The SANS and SAXS data were fitted using the two-phase stacking model of alternating crystalline and amorphous layers. The partial crystalline lamellar structures inside the growth rings of granules were analyzed based on the inter-lamellar distances, thicknesses of the crystalline lamellae and amorphous layers, thickness polydispersities, and water content in each type of layer. Despite having a longer average chain length of amylopectin, the WP and HAM starches, which had B-type allomorph, had a shorter inter-lamellar distance than the other three starches with A-type allomorph. The WP starch had the most uniform crystalline lamellar thickness. After hydration, the amorphous layers were expanded, resulting in an increase of inter-layer distance. The low-angle intensity upturn in SANS and SAXS was attributed to scattering from interfaces/surfaces of larger structures, such as growth rings and macroscopic granule surfaces. Data analysis methods based on model fitting and 1D correlation function were compared. The study emphasized─owing to inherent packing disorder inside granules─that a comprehensive analysis of different parameters was essential in correlating the microstructures with starch properties.

Effects of irrigation schemes on the components and physicochemical properties of starch in waxy wheat lines

The waxy wheat shows special starch quality due to low amylose content. However, less information is available concerning the physicochemical properties of starch in different waxy wheat under different irrigation. In this study, two wheat near-isogenic lines (NILs) and a normal wheat cultivar were used to investigate the contents, size distribution and crystallinity of starch by biochemical methods, laser-diffraction and X-ray diffraction analysis. The amylose content in wheat grains was the lowest in waxy wheat lines, SJZ8-N, followed by the partly waxy wheat lines, SJZ8-P, and the highest in the normal wheat, SJZ8, with significant differences among wheat lines. Waxy wheat starch had more B-type granules and a higher degree of crystallinity than normal wheat starch, with the order as SJZ8-N > SJZ8-P > SJZ8. When compared with the conventional and water-saving irrigation, the rainfed treatment showed the lowest starch content, amylose content (except SJZ8-N), amylopectin content and relative crystallinity in the three wheat lines indicating that water deficiency was not benefited starch accumulation and crystal formation in wheat grains. It was concluded that (1) wheat lines not only differed in amylose content but also in size distribution and crystallinity of starch; (2) irrigation markedly influenced the physicochemical characteristics of wheat starch; therefore, the irrigation schemes could be adjusted to achieve high-quality wheat production.

The influence of repeated versus continuous dry-heating on the performance of wheat starch with different amylose content

Normal and waxy wheat starches were subjected to dry-heat treatment for physical modification. The influence of repeated (RDH) versus continuous dry-heating (CDH) on the performance of wheat starch with different amylose content was investigated. Native waxy starch illustrated greater crystallinity, solubility, swelling power, peak viscosity and thermal properties than normal wheat starch. The dry-heating could not transform the crystalline structure, wheat starches remained A-type. Additionally, dry-heated samples showed lower transition temperatures and pasting properties, but higher crystallinity and solubility. Dry-heating increased gelatinization enthalpy in normal wheat starch, but reduced this value in waxy ones. Furthermore, RDH can highly influence starch characteristics due to the cooling procedure compared to CDH under the same duration. The differences between RDH and CDH starches were expected to be suitable for varied food and non-food industries.

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

Effects of repeated annealing treatments (8 cycles, 12 h each) or continuous annealing treatments (12–96 h) at 50 °C on structural, physicochemical, and digestive properties of normal and waxy wheat starches were investigated. Wheat starches retained the original crystalline structure of A-type after annealing. Annealing treatments increased crystallinity, short chain of amylopectin, viscosity, and gelatinization temperatures of starch. However, molecular weight, long chain of amylopectin, solubility, and swelling power of starch decreased after annealing. Additionally, annealing reduced the in vitro digestibility of wheat starches. The changes in properties of starch varied depending on starch type, normal or waxy, and annealing methods, repeated or continuous. The repeated annealing was found to be more effective in modification of normal wheat starch properties. However, continuous annealing efficiently modified properties of the waxy wheat starch. The obtained results may help in choosing appropriate applications of annealed wheat starches in the food industry.

Gelatinization, pasting and retrogradation properties of hydroxypropylated normal wheat, waxy wheat, and waxy maize starches

Normal wheat starch (NWS), waxy wheat starch (WWS), and waxy maize starch (WMS) were hydroxypropylated with 3–9% propylene oxide (PO). The objectives of this study were to correlate morphology changes to pasting properties of hydroxypropylated starches and establish the relationship between molar substitution (MS) and degree of retrogradation of the hydroxypropylated starches. Gelatinization temperatures and enthalpy of the starches decreased after hydroxypropylation, and the extent of decrease was positively correlated to MS. Hydroxypropylation reduced retrogradation of the gelatinized starches during cold storage as determined by differential scanning calorimetry, but the effects varied among the starches. For the same level of PO (3 and 5%) reaction, hydroxypropylated WWS retrograded less than WMS. WWS and WMS had no retrogradation after reacted with 6% PO. However, a higher level of PO (9%) was needed to react with NWS, an amylose containing starch, to achieve no retrogradation. Hydroxypropylation promoted the swelling of the starch granules as observed by light microscopy, and Micro Visco-Amylograph results showed that hydroxypropylated starches had lower pasting temperatures and improved hot and cold viscosities.

Structure and physicochemical properties of two waxy wheat starches

The objective of this study was to determine the primary influences of amylopectin (AP) on starch properties using two waxy wheat starches with different pasting properties. Compared with Yang Nuo Mai 1 (YNM1) starch, Ning Nuo Mai 1 (NNM1) starch had a greater average granule diameter, hot water solubility, gelatinization enthalpy, higher pasting viscosity, but lower retrogradation enthalpy. NNM1 starch had a greater proportion of AP long chains, and lower proportion of AP short chains. Therefore, NNM1 starch had a greater degree of crystallinity as well as stronger resonance intensities at the C1, C2, C3, C5, and C6 by solid-state 13C CP/MAS NMR. These results suggested that the proportion of long AP chains (DP ≥ 37) is the main influencing factor in determining waxy starch physicochemical properties. In addition, the proportion of short AP chains (DP 13–24) plays a role in promoting retrogradation of waxy wheat starch.

Structure and functional properties of waxy starches

A comprehensive study was conducted to elucidate structural and functional properties of waxy starches. The specific objectives were to examine the relationship between gelatinization/pasting properties and morphology of starch cooks, determine how the retrogradation properties are affected by chain-length distribution, and use a novel sensory approach to assess freeze-thaw stability of starch pastes. Waxy potato starch had a greater degree of granule swelling, higher paste viscosities, and better paste clarity than waxy starches from maize, wheat, rice, and tapioca. Waxy starches typically had greater paste viscosities than their normal counterparts, but the exception was potato starches. Waxy potato starch, which had no amylose, had lower paste viscosity than normal potato starch. Both waxy rice and waxy tapioca starches had less retrogradation tendency, which was closely related to the higher proportion of chains with DP 6–11 and the lower proportion of chains with DP 12–24. The sensory evaluation in this study allowed for an easier assessment of water separation as compared to the conventional centrifuge methods. Waxy maize and waxy potato starches had noticeable water separation from the paste after 1–2 freeze-thaw cycles, whereas both waxy rice and waxy tapioca starches could survive 6 freeze-thaw cycles without apparent syneresis. Waxy wheat, waxy rice and waxy tapioca starches are potential starting materials from which clean-label functional starches may be produced.

Settling volume and morphology changes in cross-linked and unmodified starches from wheat, waxy wheat, and waxy maize in relation to their pasting properties

Normal wheat, waxy wheat and waxy maize starches were cross-linked with 0.01, 0.03 and 0.06% (sb) phosphorus oxychloride. The objective of this study was to correlate the morphology changes and settling volume to the pasting properties of those cross-linked and unmodified starches. Pasting and microscopic data for waxy maize starch and its cross-linked products was similar to waxy wheat starch, except changes occurred at ∼5 °C higher in temperature. At 6% solids, waxy wheat starch cross-linked with 0.01% POCl3 had a greater settling volume and a higher pasting viscosity than the cross-linked waxy maize starch, but at 7 and 8% solids, waxy maize starch cross-linked with 0.03% and 0.06% POCl3 had a higher pasting viscosity. At 6% starch solids, particle volume fraction appeared to be the dominant factor controlling consistency, but at higher starch solids contents, the deformability (rigidity) of swollen granules became important in controlling viscosity.

Interplay between starch and proteins in waxy wheat

Most of the unique properties of waxy wheat have been associated with the lack of amylose, that in turn may affect the mutual interactions between starch and proteins. To address this particular aspect, we carried out molecular, rheological, and calorimetric studies on flours from two waxy wheat lines that were compared with a non-waxy one. Dough thermal properties and water binding capacity were investigated by Differential Scanning Calorimetry (DSC) and by thermogravimetric analysis, respectively. Protein solvation, aggregation, and thiol accessibility were also investigated, together with dough mixing properties and stickiness. Proteins in waxy wheat samples needed more water to complete solvation, likely because of the water-retaining capacity of waxy wheat starch. In waxy wheat dough, water was tightly bound to starch, and DSC studies indicated an increase in gelatinization temperature. Moreover, the low water mobility in waxy wheat resulted in low and retarded gluten hydration and in high stickiness. In samples with the highest stickiness, protein aggregates were stabilized mainly by hydrophobic interactions. Differences between waxy wheat lines may be attributed to a different structural organization of components within each class of biopolymers.

Effect of high hydrostatic pressure and retrogradation treatments on structural and physicochemical properties of waxy wheat starch

In this study, the effects of high hydrostatic pressure and retrogradation (HHPR) treatments on in vitro digestibility, structural and physicochemical properties of waxy wheat starch were investigated. The waxy wheat starch slurries (10%, w/v) were treated with high hydrostatic pressures of 300, 400, 500, 600MPa at 20°C for 30min, respectively, and then retrograded at 4°C for 4d. The results indicated that the content of slowly digestible starch (SDS) in HHPR-treated starch samples increased with increasing pressure level, and it reached the maximum (31.12%) at 600MPa. HHPR treatment decreased the gelatinization temperatures, the gelatinization enthalpy, the relative crystallinity and the peak viscosity of the starch samples. Moreover, HHPR treatment destroyed the surface and interior structures of starch granules. These results suggest that the in vitro digestibility, physicochemical, and structural properties of waxy wheat starch are effectively modified by HHPR.

Effects of removal of surface proteins on physicochemical and structural properties of A- and B-starch isolated from normal and waxy wheat.

The effects of protein removal on the physicochemical and structural properties of normal and waxy wheat and their A- and B-type granule fractions were investigated. No evident changes were observed in the morphological, birefringence pattern and X-ray diffraction pattern after treatment, but there was evidence showing that the relative crystallinity, swelling power and percentage syneresis of all samples were significant increased. Protein removal treatment increased the peak, setback, final viscosity, breakdown viscosity of normal and waxy native wheat starch, and their A- and B-type starch granule fractions, whereas it decreased the pasting temperature, peak time and trough viscosity. Meanwhile, the thermal transition temperatures (To, Tp, Tc) and gelatinization temperature range (ΔTr) of normal and waxy wheat and their isolated A- and B-type granules were increased, but the enthalpy decrease slightly. The different genetic factors and amylose content in normal and waxy wheat starch and their A- and B-type wheat starch granules fractions were related to the different physicochemical and structural characteristics of those starches.

Understanding how the aggregation structure of starch affects its gastrointestinal digestion rate and extent

Regulating the starch gastrointestinal digestion rate by control of its aggregation structure is an effective way, but the mechanism is still not clear. Multi-scale structure of waxy and normal wheat starches were studied by confocal laser scanning and scanning electron microscopes, as well as wide-angle and small-angle X-ray techniques in this study. In vitro digestion kinetics of those two starches and structure–digestion relationship were also discussed. Both waxy and normal starches show A-type diffraction pattern, but waxy variety shows a slightly higher crystallinity. Small-angle X-ray scattering results show that waxy wheat starch has higher scattering peak intensity (Imax) and a larger crystallinity lamellar repeat distance (Lp) compared with the normal wheat starch. We suggested that the higher digestion rate of waxy starch at initial stage is mainly due to more small-size particles, but the higher crystallinity and the larger crystalline lamellar size limit the digestion extent.

Functional Characteristics of Bread Wheat (Triticum aestivum L.) Near‐Isogenic Lines Differing at the Waxy (Wx) Locus

The Waxy (Wx) gene in hexaploid wheat (Triticum aestivum L.) encodes granule‐bound starch synthase (GBSS1), which is involved in the synthesis of amylose, a mostly linear glucan polymer that makes up ∼25% of wheat starch. A null mutation of the Wx gene in each of the three genomes is associated with starch almost entirely consisting of the branched glucan polymer amylopectin (waxy starch), with corresponding changes in functionality. However, the rheological behavior of partially waxy starch remains unclear. The objective of this study was to characterize flour and baking quality in 16 near‐isogenic lines, null at the Wx locus on zero, one, two, or all three genomes, grown in four different environments. Across allelic groups, significant variations in amylose concentrations, flour paste viscosity, loaf structure and texture, dough stability, and proximate variables were observed. Because waxy wheat starch has greater water absorbance and resistance to retrogradation than normal starch, its inclusion in flour blends has been suggested as a means of improving the texture and appearance of bakery products and noodles. The results indicate that wheat encoding <3 functional homeologs of GBSS1 produces starch that has potential in the production of certain food items, such as Asian noodles. However, further research is necessary to determine the optimal amylose‐to‐amylopectin ratio to improve baking quality.

Factors Governing Pasting Properties of Waxy Wheat Flours

Waxy wheat (Triticum aestivum L.) contains endosperm starch lacking in amylose. To realize the full potential of waxy wheat, the pasting properties of hard waxy wheat flours as well as factors governing the pasting properties were investigated and compared with normal and partial waxy wheat flours. Starches isolated from six hard waxy wheat flours had similar pasting properties, yet their corresponding flours had very different pasting properties. The differences in pasting properties were narrowed after endogenous α‐amylase activity in waxy wheat flours was inhibited by silver nitrate. Upon treatment with protease, the extent of protein digestibility influenced the viscosity profile in waxy wheat flours. Waxy wheat starch granules swelled extensively when heated in water and exhibited a high peak viscosity, but they fragmented at high temperatures, resulting in more rapid breakdown in viscosity. The extensively swelled and fragmented waxy wheat starch granules were more susceptible to α‐amylase degradation than normal wheat starch. A combination of endogenous α‐amylase activity and protein matrix contributed to a large variation in pasting properties of waxy wheat flours.

Effect of fatty acids on functional properties of normal wheat and waxy wheat starches: A structural basis

The effects of three saturated fatty acids on functional properties of normal wheat and waxy wheat starches were investigated. The complexing index (CI) of normal wheat starch–fatty acid complexes decreased with increasing carbon chain length. In contrast, waxy wheat starch–fatty acid complexes presented much lower CI. V-type crystalline polymorphs were formed between normal wheat starch and three fatty acids, with shorter chain fatty acids producing more crystalline structure. FTIR and Raman spectroscopy presented the similar results with XRD. The formation of amylose–fatty acid complex inhibited granule swelling, gelatinization progression, retrogradation and pasting development of normal wheat starch, with longer chain fatty acids showing greater inhibition. Amylopectin can also form complexes with fatty acids, but the amount of complex was too little to be detected by XRD, FTIR, Raman and DSC. As a consequence, small changes were observed in the functional properties of waxy wheat starch with the addition of fatty acids.

Effects of the order of addition of reagents and alkali on modification of wheat starches

The objective of this research was to determine if adding reactive reagents to wheat starch granules before addition of alkali (the TRF method) would produce products that are different than those obtained with the conventional procedure (adding alkali before addition of reagent). Laboratory-isolated (LI) and commercial (C) normal (NWS) and waxy (WWS) wheat starches were each reacted with 6 reagents (acetic-adipic mixed anhydride (AAMA), phosphoryl chloride (POCl3), sodium trimetaphosphate (STMP), acetic anhydride (AA), succinic anhydride (SA), octenylsuccinic anhydride (OSA)). Data obtained were similar to those previously obtained with maize starches (Sui, Huber, & BeMiller, 2013). Almost no starch polymer molecule modification occurred when the TRF method and AAMA or AA were used; less than a third as much reaction when SA was the reagent used, and about the same amount of reaction when POCl3, STMP, or OSA were the reagents used (for different reasons).

Molecular order and functional properties of starches from three waxy wheat varieties grown in China

Molecular order and functional properties of starch from three waxy wheat varieties grown in China were investigated by a combination of various technical analyses. The total starch content of the waxy wheat ranged between 54.1% and 55.0%, and the amylose content of the starch was between 0.71% and 1.63%. Average particle diameter of the three starches varied between 16.5 and 17.4μm. Three waxy wheat starches presented the typical A-type X-ray diffraction pattern, with relative crystallinity between 38.7% and 40.0%. No significant differences were observed in relative crystallinity, IR ratios of 1047/1022cm−1 and 1022/995cm−1, and FWHH of the band at 480cm−1, indicating the similarity in long-range order of crystallites and short-range order of double helices of three starch granules. Small differences were observed in swelling power, gelatinization parameters, pasting viscosities, and in vitro enzymatic digestibility of three waxy wheat starches. Under the stored condition, no retrogradation occurred for three waxy wheat starches.