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Foods with high amylose and resistant starch (RS) contents have great potential to enhance human health. In this study, cassava soluble starch synthase MeSSIII-1 gene mutants were generated using CRISPR/Cas9 system. The results showed that the storage roots of messiii-1 mutants had higher contents of amylose, RS, and total starch than those in CK. The rates of small and large-sized starch granules were increased. Additionally, amylopectin starch in messiii-1 mutants had a higher proportion of medium- and long- chains, and a lower proportion of short-chains than those in CK. The onset, peak, and conclusion temperatures of starch gelatinization in messiii-1 mutants were significantly lower than those in CK, and the peak viscosity, trough viscosity and final viscosity all increased. MeSSIII-1 mutation could increase the contents of sucrose, glucose, and fructose in cassava storage roots. We hypothesize that these soluble sugars serve a dual role: they provide the necessary carbon source for starch synthesis and act as sugar signals to trigger the transcriptional reprogramming of genes involved in starch biosynthesis. This process results in a collective enhancement of amylose, RS, and total starch contents, accompanied by changes in starch granule morphology, fine structure, and physicochemical properties. [Display omitted] [ABSTRACT FROM AUTHOR]

The objective of this work was to study the effects of heat-moisture treatment (HMT) of freshly harvested mature high-amylose maize (HAM) kernels on its starch structure, properties, and digestibility. Freshly harvested HAM kernels were sealed in Pyrex glass bottles and treated at 80 °C, 100 °C, or 120 °C. HMT of HAM kernels had no impact on its starch X-ray diffraction pattern but increased the relative crystallinity. This result together with the increased starch gelatinization temperatures and enthalpy change indicated starch molecules reorganization forming long-chain double-helical crystalline structure during HMT of HAM kernels. The aggregation of starch granules were observed after HMT, indicating interaction of starch granules and other components. This interaction and the high-temperature crystalline structure led to reductions in the starch digestibility, swelling power, solubility, and pasting viscosity of the HAM flours. Some starch granules remained intact and showed strong birefringence after the HAM flours were precooked at 100 °C for 20 min and followed by enzymatic hydrolysis, and the amount of undigested starch granules increased with increasing HMT temperatures. This result further supported that HMT of HAM kernels with high moisture level could increase the starch thermal stability and enzymatic resistance. • HMT of freshly harvested HAM kernels increased its starch gelatinization temperatures. • HMT of HAM kernels promoted molecules interactions and then increased starch thermal stability and enzymatic resistance. • Whole maize flour with high resistant-starch content could be achieved by this technology. [ABSTRACT FROM AUTHOR]

The objective of this study was to understand dosage effects of the Waxy gene on the structures of amylose and amylopectin and on the properties of corn starch. Reciprocal crossing of isogenic normal and waxy corn lines was conducted to develop hybrids with different dosages (0, 1, 2, 3) of Waxy gene in the endosperm. The amylose content of starch and proportions of branch chains of DP 17–30 and extra-long branch chains (DP > 100) of amylopectin were positively correlated with the Waxy -gene dosage. Proportions of short (DP < 17) and long branch-chains (DP 30–80), however, were negatively correlated with the Waxy -gene dosage. The gelatinization conclusion-temperature and temperature-range of the starch were negatively correlated with the Waxy -gene dosage, indicating that amylose facilitated dissociation of the surrounding crystalline regions. These results helped us understand the function of granule-bound starch synthase I in the biosynthesis of amylose and amylopectin and impacts of Waxy -gene dosages on the properties of corn starch. [ABSTRACT FROM AUTHOR]

In this study, a range of barley allelic mutants lost ADPG binding structure of starch synthase IIa (SSIIa) were created through targeted mutagenesis of SSIIa by RNA-guided Cas9. The transcriptomic and qRT-PCR results showed the increased mRNA expression of HvGBSSI and the decreased HvSSIIa and HvSBEI levels in ssIIa mutant grains, which were consistent with the expressions of GBSSI, SSS and SBE enzymatic activities, respectively. However, the increased expressions of HvSSI cannot effectively compensate for the loss of HvSSIIa. The metabolic pathway analysis showed that the mutation of SSIIa led to increased ADP-glucose synthesis in barley grains. The ssIIa mutant grains had two and six times amylose, and RS contents in control grains, respectively, and significantly changed starch structure and functions compared to the controls. No metabolite changes could compensate for the decrease of starch biosynthesis in the ssIIa null mutant. [Display omitted] [ABSTRACT FROM AUTHOR]

Highlights: [•] The effect of UV-irradiation on four starches of various origin has been studied. [•] UV-irradiation decreased the water content, degree of crystallinity and changed the molecular weight. [•] The potato starch was less photostable than corn, waxy corn and wheat starches. [•] Only in potato starch the aggregation due to macroradicals recombination occurs. [ABSTRACT FROM AUTHOR]

Abstract: Thermal, pasting, and gelling properties of wheat and potato starches were studied in the presence of sucrose, glucose, glycerol, and hydroxypropyl β-cyclodextrin (HPβ-CD). Swelling factor of both starches slightly increased up to 20% sucrose and glucose but decreased at 40% concentration (sucrose>glucose). Glycerol did not affect swelling factor of wheat starch even at 40% concentration but decreased it in potato starch. Amylose leaching of wheat and potato starches tends to decline above 5% and 1% concentration of sucrose and glucose, respectively. However, similar to swelling factor the extent of amylose leaching in wheat starch was unaffected in the presence of glycerol. Gelatinization temperature and enthalpy of both starches were increased by sucrose, glucose and glycerol in the order of sucrose>glucose>glycerol. Glucose increased peak viscosity of the two starches more than other polyols. Cold paste viscosity increased in wheat starch following the order: glucose>sucrose>glycerol but sucrose was most effective in potato starch. Gel hardness of wheat starch was increased following the order glucose>sucrose>glycerol but sucrose was more effective in potato starch. All above results indicate the occurrence of starch–polyhydroxy interaction which reinforces the starch granules depending on the botanical source of starch and the type and concentration of polyhydroxy compound. The influence of HPβ-CD on the swelling factor, amylose leaching, and dissociation parameters of amylose–lipid complex in wheat starch is consistent with the disruption of amylose–lipid complex. This greatly affects the gelatinizing, pasting, and gelling properties of wheat starch. [Copyright &y& Elsevier]

Abstract: In this study, moisture, ash, amylose, phosphorous content, and the gelatinization profiles of starches isolated from Colocasia esculenta (taro), and Xanthosoma sagitifolium (tannia) storage organs were evaluated. The gelatinization profile and the changes in the heat flow or enthalpy during the gelatinization process were evaluated by DSC methodology. The phosphorous and amylose content were also analyzed by a colorimetric method. The results show that the amylose content of the starch isolated from Xanthosoma sagittifolium is higher than those shown by Colocasia esculenta and Manihot esculenta Crantz starches. The phosphorous content was higher in Xanthosoma sagittifolium than Colocasia esculenta or the commercial Manihot esculenta C. starches. The gelatinization profile range is wider in Manihot esculenta C. than the other two starches. Differences in these parameters may affect the functional properties of the products formulated with these starches. The most significant relationship between parameters was found between the amylose and gelatinization profile and enthalpic change and ash. [Copyright &y& Elsevier]

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. • Supplemental irrigation (SI) kept grain yield and improved quality. • SI had minor effect on starch molecular structure. • SI significantly decreased granular crystallinity and increased B-type granules. • SI increased resistant starch content. • SI likely affected hormonal (abscisic acid) control of starch biosynthesis. [ABSTRACT FROM AUTHOR]