Soft and Hard Textured Wheat Differ in Starch Properties as Indicated by Trimodal Distribution, Morphology, Thermal and Crystalline Properties

Abstract

Starch and proteins are major components in the wheat endosperm that affect its end product quality. Between the two textural classes of wheat i.e. hard and soft, starch granules are loosely bound with the lipids and proteins in soft wheat due to higher expression of interfering grain softness proteins. It might have impact on starch granules properties. In this work for the first time the physiochemical and structural properties of different sized starch granules (A-, B- and C-granules) were studied to understand the differences in starches with respect to soft and hard wheat. A-, B- and C-type granules were separated with >95% purity. Average number and proportion of A-, B-, and C-type granules was 18%, 56%, 26% and 76%, 19%, 5% respectively. All had symmetrical birefringence pattern with varied intensity. All displayed typical A-type crystallites. A-type granules also showed V-type crystallinity that is indicative of starch complexes with lipids and proteins. Granules differing in gelatinization temperature (ΔH) and transition temperature (ΔT), showed different enthalpy changes during heating. Substitution analysis indicated differences in relative substitution pattern of different starch granules. Birefringence, percentage crystallinity, transmittance, gelatinization enthalpy and substitution decreased in order of A>B>C being higher in hard wheat than soft wheat. Amylose content decreased in order of A>B>C being higher in soft wheat than hard wheat. Reconstitution experiment showed that starch properties could be manipulated by changing the composition of starch granules. Addition of A-granules to total starch significantly affected its thermal properties. Effect of A-granule addition was higher than B- and C-granules. Transmittance of the starch granules paste showed that starch granules of hard wheat formed clear paste. These results suggested that in addition to differences in protein concentration, hard and soft wheat lines have differences in starch composition also.

Physicochemical, Thermal, Crystallographic, and Morphological Properties of Biodynamic Black Rice Starch, and of Residual Fractions From Aqueous Extraction

“…This agrees with previous results provided by Zhu et al Minor peaks were also observed at 2 θ ≈ 20° and 27°. The peak observed at 2 θ ≈ 20° indicates the presence of some V‐type starch crystals in rice varieties, which may indicate starch complexes containing lipids and proteins . The residual fractions (1 and 2) and black rice starch in our systems had similar crystallinity (≈22%), with no significant differences ( p > 0.05) between the samples.…”

Transfer of a starch phenotype from wild wheat to bread wheat by deletion of a locus controlling B-type starch granule content

“…This result is predicted by the work of Eliasson and Larsson (1983) , Ao and Jane (2007) , and Wei et al (2010) who showed that the gelatinization enthalpy of wheat starch is independent of the granule size distribution. However, others have found higher gelatinization enthalpies for A-type than for B-type starch granules in wheat ( Chiotelli and Le Meste, 2002 ; Li et al , 2013 ; Kumar et al , 2016 ).…”

Improvement of Quality Properties and Shelf Life Stability of New Formulated Muffins Based on Black Rice

“…Approximately 30% of the wheat starch granules were spherical, medium-sized (3–10 μm), while 10% were really small grains (under 3 μm) with irregular forms (as it can be seen in Figure 2 a). The heterogeneity of the wheat flour starch granules could be attributed to the wheat variety (soft or hard wheat), the amylose content, and especially the moment in which is formed during anthesis or their different times of formation during grain development [ 34 , 35 , 36 , 37 , 38 ]. There are also many studies that confirm the presence of amylose in the peripheral region of the starch granules as it was likewise assessed in our study.…”