Apparent amylose content positively influences the quality of extruded fortified rice kernels.

The present research studies the impact of apparent amylose content (AAC) on the quality of fortified rice kernels (FRK), a health food designed to combat iron deficiency anemia by fortifying with iron, folic acid, and vitamin B12. Five FRK formulations with varying AAC (0.46-23.89 %) were prepared, and AAC influence on the extruder-system parameter and physicochemical, cooking, and textural properties of FRK was investigated. The torque, die-pressure, length, redness, and cooking time increased with an increase in AAC and were in the range of 12.55-22.81 Nm, 58.31-88.96 bar, 4.58-5.09 mm, 0.35-1.15, and 6.1-11.2 min, respectively. The other parameters, such as the breadth, whiteness index, and cooking loss decreased with an increase in AAC. Except for cohesiveness, all other textural properties of cooked FRK increased with an increase in AAC. These correlations of the FRK properties with AAC were confirmed through multivariate analysis. SEM, XRD, FTIR, and rheology supported the observed AAC trends in FRK properties. SEM showed a reduction in pores and cracks with an increase in AAC. The XRD and FTIR showed an increase in crystallinity with an increase in AAC due to better gelatinization leading to rapid retrogradation. This leads to better physical, cooking, and textural properties of FRK.

Characterization of starches isolated from Mexican pulse crops: Structural, physicochemical, and rheological properties.

This work aimed to characterize and compare the physicochemical properties of four pulse starches: bean, chickpea, lentil, and pea. Chemical proximate analysis, elemental composition, morphological grain characterization, crystalline structure, thermal analysis, FTIR analysis, and pasting properties were conducted. The proximate analysis shows that these starches have low fat, mineral, and protein content but high amylose values ranging from 29 to 36 % determined by colorimetry. Despite the high amylose content, the starches did not exhibit the typical behavior of an amylose-rich starch, with high peak viscosity and low breakdown and setback. It was found that this behavior was likely due to the large granule size of the ellipsoidal, spherical, and kidney-shaped granules and the high content of some minerals such as Na, Mg, K, Fe, Mn, P, and Si. The study also found that all pulse starches simultaneously contain monoclinic and hexagonal crystals, making them C-type starches. The findings were verified through the Rietveld analyses of X-ray diffraction patterns and differential scanning calorimetry, in which bimodal endothermic peaks evidenced both types of crystals being gelatinized.

Effect of starch and peanut oil on physicochemical and gel properties of myofibrillar protein: Amylose content and addition form.

Starch and peanut oil (PO) were widely used to improve the gel properties of surimi, however, the impact mechanism of addition forms on the denaturation and aggregation behavior of myofibrillar protein (MP) is not clear. Therefore, the effect of starch, PO, starch/PO mixture, and starch-based emulsion on the physicochemical and gel properties of MP was investigated. The results showed that amylose could accelerate the aggregation of MP, while amylopectin was conducive to the improvement of gel properties. The addition of PO, starch/PO mixture, or starch-based emulsion increased the turbidity, solubility, sulfhydryl content of MP, and improved the gel strength, whiteness, and texture of MP gel. However, compared with starch/PO mixture group, the gel strength of MP with waxy, normal and high amylose corn starch-based emulsion increased by 22.68 %, 10.27 %, and 32.89 %, respectively. The MP containing emulsion had higher storage modulus than MP with starch/PO mixture under the same amylose content. CLSM results indicated that the oil droplets aggregated in PO or starch/PO mixture group, while emulsified oil droplets filled the protein gel network more homogeneously. Therefore, the addition of starch and PO in the form of emulsion could effectively play the filling role to improve the gel properties of MP.

Amylopectin chain length distributions and amylose content are determinants of viscoelasticity and digestibility differences in mung bean starch and proso millet starch.

This study aimed to reveal the underlying mechanisms of the differences in viscoelasticity and digestibility between mung bean starch (MBS) and proso millet starch (PMS) from the viewpoint of starch fine molecular structure. The contents of amylopectin B2 chains (14.94-15.09 %), amylopectin B3 chains (14.48-15.07 %) and amylose long chains (183.55-198.84) in MBS were significantly higher than PMS (10.45-10.76 %, 12.48-14.07 % and 70.59-88.03, respectively). MBS with higher amylose content (AC, 28.45-31.80 %) not only exhibited a lower weight-average molar mass (91,750.65-128,120.44 kDa) and R1047/1022 (1.1520-1.1904), but also was significantly lower than PMS in relative crystallinity (15.22-23.18 %, p < 0.05). MBS displayed a higher storage modulus (G') and loss modulus (G'') than PMS. Although only MBS-1 showed two distinct and discontinuous phases, MBS exhibited a higher resistant starch (RS) content than PMS (31.63-39.23 %), with MBS-3 having the highest RS content (56.15 %). Correlation analysis suggested that the amylopectin chain length distributions and AC played an important role in affecting the crystal structure, viscoelastic properties and in vitro starch digestibility of MBS and PMS. These results will provide a theoretical and scientific basis for the development of starch science and industrial production of low glycemic index starchy food.

Retrogradation inhibition of starches in staple foods with maltotetraose-forming amylase.

To effectively inhibit the retrogradation of staple foods, the effects of maltotetraose-forming amylase(G4-amylase) on the short and long-term retrogradation of different staple starches such as rice starch (RS), wheat starch (WS), potato starch (PS) were studied. The results indicated that G4-amylase decreased the content of amylose. Amylose contents (21.09%) of WSG4 were higher than that (14.82%) of RSG4 and (13.13%) of PSG4. WS had the most obvious change in the chain length distribution of amylopectin. A chains decreased by 18.99% and the B1 chains decreased by 12.08% after G4-amylase treatment. Compared to RS (662 cP) and WS (693 cP), the setback viscosity of RSG4 (338 cP) and WSG4 (385 cP) decreased. Compared to RS (0.41), WS (0.45), and PS (0.51), the long-term retrogradation rate of RSG4 (0.33), WSG4 (0.31), and PSG4 (0.38) significantly reduced. It indicated that G4-amylase significantly inhibited the long-term retrogradation of WS, followed by RS and PS.

Fast quantitative analysis and chemical visualization of amylopectin and amylose in sweet potatoes via merging 1D spectra and 2D image.

The quantitative analysis and spatial chemical visualization of amylopectin and amylose in different varieties of sweet potatoes were studied by merging spectral and image information. Three-dimensional (3D) hyperspectral images carrying 1D spectra and 2D images of hundreds of the samples (amylopectin, n = 644; amylose, n = 665) in near-infrared (NIR) range of 950-1650 nm (426 wavelengths) were acquired. The NIR spectra were mined to correlate with the values of the two indexes using a linear algorithm, generating a best performance with correlation coefficients and root mean square error of prediction (rP and RMSEP) of 0.983 and 0.847 g/100 mg for amylopectin, and 0.975 and 0.500 g/100 mg for amylose, respectively. Then, 14 % of the wavelengths (60 for amylopectin, 61 for amylopectin) were selected to simplify the prediction with rP and RMSEP of 0.970 and 1.103 g/100 mg for amylopectin, and 0.952 and 0.684 g/100 mg for amylose, respectively, comparable to those of full-wavelength models. By transferring the simplified model to original images, the color chemical maps were created and the differences of the two indexes in spatial distribution were visualized. The integration of NIR spectra and 2D image could be used for the more comprehensive evaluation of amylopectin and amylose concentrations in sweet potatoes.

Differences in rice component distribution across layers and their relationship with taste.

BACKGROUND: Rice taste is closely associated with endosperm composition, which varies among different rice layers. Although clarifying the relationship between this difference and nutritional taste can guide rice breeding and cultivation practices, research on this topic is limited. RESULTS: Here, typical rice varieties having excellent and poor taste characteristics were selected to analyze the distribution characteristics and differences of their components. The varieties with excellent taste exhibited lower apparent amylose content (AAC) and protein content (PC), lesser short-chain (Fa) and long-chain (Fb3 ) amylopectin (AP) and more medium-chain (Fb1+2 ) AP, higher long-to-short chain ratio (Fa:Fb3 ), and higher nitrogen (N), magnesium (Mg) and calcium (Ca) content in layer 1 (L1) than the varieties with poor taste. Layer 2 (L2) played a key role in AAC and PC regulation in the varieties with excellent taste by reducing AAC and appropriately increasing PC, consequently improving rice taste. AP structure in layer 3 (L3) substantially affected the taste of the two types of varieties. The mineral content was the highest in L1, and increased potassium (K), Ca, and Mg content improved taste in all varieties. CONCLUSION: AAC in each layer contributes to rice taste. PC and minerals primarily act on L1 and L2, whereas AP acts on L2 and L3. Therefore, the endosperm formation process should be exploited for improving rice taste. Furthermore, key resources and cultivation should be identified and regulated, respectively, to improve rice taste. © 2023 Society of Chemical Industry.

Enzymatic Modification of Starch Using Recombinant Genes from Sorghum in Escherichia coli: Insights and Potential Applications.

SBEIIb (Sobic.004G163700), SSSIIa (Sobic.010G093400), and GBSSI (Sobic.010G022600) genes that regulate starch synthesis in sorghum endosperm were transferred into Escherichia coli by transgenic technology. SBEIIb, SSSIIa, and GBSSI enzymes were separated and purified through a Ni column and analyzed by electrophoresis with molecular weights and activities of 91.57 84.57, and 66.89 kDa and 551 and 700 and 587 U/µL, respectively. Furthermore, they were applied to starch modification, yielding interesting findings: the A chain content increased from 25.79 to 89.55% for SBEIIb-treated waxy starch, while SSSIIa extended the A chain to form DPs of the B chain, with A chain content decreasing from 89.55 to 37.01%, whereas GBSSI was explicitly involved in the synthesis of B1 chain, with its content increasing from 9.59 to 48.45%. Modified starch was obtained, which could be accurately applied in various industries. For instance, we prepared a sample (containing 89.6% A chain content) with excellent antiaging and antidigestion properties through SBEIIb modification. Moreover, higher RS3 (34.25%) and SDS contents (15.75%) of starch were obtained through the joint modification of SBEIIb and SSSIIa. These findings provide valuable insights for developing sorghum starch synthesis-related enzymes and offer opportunities for improving starch properties through enzymatic approaches.

The potential exploitation of the Malay-red apple (Syzygium malaccense) seed as source of a phosphorylated starch.

This work presents the characterization of a novel naturally phosphorylated starch extracted from an unconventional and non-utilized source, the seeds of the stone fruit Syzygium malaccense. The morphology and chemical characteristics of the extracted starch were examined by scanning electron microscopy, FTIR, 1H/13C/31P NMR and 13C-CP/MAS-NMR, HPAEC-PAD chromatography, XRD, DSC, and RVA. The extraction yielded a highly pure starch (95.6 %) with an average granule size of 13 µm. The analysis of the starch components revealed an amylose content of 28.1 % and a predominance (65 %) of B-chains (B1-B3 65 %) in the amylopectin, as shown through HPAEC-PAD chromatography. The X-ray diffractogram was compatible with B-type starch, which was confirmed by the deconvolution of the C1 peak in the 13C-CP/MAS-NMR. X-Ray diffractogram also showed that S. malaccense has 28.5 % of crystallinity. DSC analysis showed values of 82.6 °C and -12.41 J g-1 for Tc and ΔH, respectively, which is compatible with a highly ordered starch granule structure. The values observed for peak (4678 mPa•s), trough (3055 mPa•s), and final viscosity (6526 mPa•s) indicated that S. malaccense may be used as a thickener in hot food.

"Structure-function" analysis using starches isolated from Lycoris chinensis bulbs of different developmental stages.

In this study, Lycoris chinensis bulbs of four developmental stages were compared for starch characteristics. Based on correlation analysis and hierarchical cluster analysis, the relationships among 36 traits were discussed. Compared to commonly consumed starches, L. chinensis starch had higher amylose content (33.4-43.2 %) and weight-average molar mass (36410-82,781 kDa), lower gelatinization temperature (61.8-68.1 °C), gel hardness (19.0-39.5 g) and viscosities. Among developmental stages, starches varied significantly in characteristics. As compared to juvenile stage (S1), mature bulbs (S4) had higher amylose content, lower gelatinization temperature, weight-average molar mass and degree of polymorphism. Correlation analysis revealed that the molecular weight-related traits had significantly positive correlations to gelatinization temperature (Tp, p < 0.05), positive but weak correlations to traits of particle size distribution, significantly negative correlations to AAC and many parameters of viscosity properties (p < 0.05). Based on the results of correlation analysis and hierarchical cluster analysis, the 36 traits of starch characteristics were proposed to be divided into three groups: particle size-related traits, molecular weight-related traits and AAC-related traits. The information presented in the current study are useful for future studies on starches of Lycoris and other bulb species, and instructive for future studies in investigating the "Structure-Function" relationship in starch.

Effect of operating conditions on structure and digestibility of spray-dried corn starch.

Spray drying has been widely applied in food industry due to its efficiency and low cost. Exploring feasibility to prepare resistant starch (RS) via spray drying could open up new route to produce starch-based products with low glycemic index efficiently. In this study, effects of spray drying operating conditions on the structure and digestibility of recrystallized spray-dried corn starch (RSDCS) were explored. Apparent amylose content (AAC) and swelling power (SP) of the RSDCSs increased after the spray drying and recrystallization. Particle size of the RSDCSs decreased significantly with increase of compressed air flow and decrease of starch suspension concentration. Furthermore, the short-range order, long-range order, and content of RS in the RSDCSs decreased with increase of compressed air flow and starch suspension concentration. The Pearson's correlation analysis showed that digestive properties of the RSDCSs were mainly related to the short-range ordered structure and crystalline structure. Moreover, Mantel analysis revealed that operating conditions changed the digestibility of the RSDCSs through impacting crystalline structure, AAC and SP. The highest content of RS in the RSDCSs (23.08%) was increased near 2.6 times comparing to that of native corn starch (9.02%).

Role of short germination and milling on physical properties, amino acid and metabolomic profiles of high amylose rice fractions.

Short germination is a process that can improve bioactive compounds in rice. This work aimed investigate the physical properties, phenolic compounds (PC), antioxidant activity and amino acids composition of husk + bran, brown and milled rice with high amylose content after short germination (16 h). α-amylase activity (Falling Number, FN) and enthalpy (ΔH) were unchanged (p < 0.05). RVA curve profiles were similar, even though after short germination and milling. Globally, metabolomics analysis identified 117 PC, in which 111 (bound), 104 (free) and 21 revealed in both extracts. p-Coumaric, trans-ferulic and ferulic acids were the most abundant PC revealed in all fractions. The portion husk + bran showed the highest level of total antioxidant activity (709.90 µmol TE) in both free and bound fractions. In terms of total amino acids, there was no statistical difference (p < 0.05) among non-germinated and germinated samples, contrary to free amino acids content. Glutamic acid (Glu) presented the highest values combining short germination and milling (1725-1900 mg/100 g) consequently, leads to higher value of GABA (12.21 mg/100 g). The combination of short germination and milling demonstrated a good strategy to improve the nutritional quality of rice, unless the thermal and pasting properties have been altered, contribute to potential health benefits on human nutrition.

Hydrogel properties of non-conventional starches from guabiju, pinhão, and uvaia seeds.

The physicochemical properties of starch vary depending on the botanical sources, thereby influencing the gelatinisation/retrogradation properties and subsequently affecting the hydrogels characteristics. This study aimed to assess the influence of botanical sources influence on starch and hydrogel properties using non-conventional starch derived from guabiju, pinhão, and uvaia seeds. Hydrogels were prepared by starch gelatinisation followed by 6 h ageing period at room temperature (20 ± 2 °C) and subjected to five freeze-thaw cycles. Pinhão starch exhibited a higher viscosity peak and breakdown, along with a lower final viscosity and setback, compared to guabiju and uvaia starches. The significantly different pasting properties influenced the porous microstructure, water absorption (p-value: 0.01), and resistance of the hydrogels (p-value: 0.01). The guabiju starch hydrogels showed a uniform pore structure without cavities, whereas pinhão and uvaia starch hydrogels exhibited agglomerated and spongy pore structures. Furthermore, the guabiju starch hydrogel demonstrated the lowest water absorption (4.56 g/g) and the highest compression resistance (1448.50 g) among all the studied starch hydrogels. In contrast, the pinhão starch hydrogel showed the highest water absorption (7.43 g/; p-value: 0.01) among all studied starch hydrogels. The hardness of uvaia starch hydrogel did not differ significantly from the guabiju and pinhão starch hydrogel. The different non-conventional starches reveal important variations in the hydrogels characteristics. This provides insights into how amylose and amylopectin interact and present alternatives for using these unique starch-based hydrogels in diverse applications.

Morphological, textural analysis and freeze-thaw stability of starches from legume grow in Cameroon.

Starches from some legume grown in Cameroon were evaluated for their granule structure and size, turbidity, firmness and gel strength, thermal and freeze-thaw properties. Amylose contents were in the range of 26.21%-44.85%. Morphological analysis of the starch granules showed bimodal distribution, multiple sizes and shapes from small spherical to the bigger kidney shape. Significant differences were observed among starch in light transmittance, firmness and gel strength. The thermal parameters of starches were evaluated using differential scanning calorimeter and significant differences were observed. The peak gelatinisation temperature was positively correlated to starch granule size but the amylose content showed no evidence of their impact on legume starch properties studied. The data reported can be useful to facilitate the selection of variety of legume and conditions closer to the desired application.

Avocado seed starch: Effect of the variety on molecular, physicochemical, and digestibility characteristics.

Agro-industrial residues can increase environmental pollution owing to poor knowledge of the use of some components, such as dietary fiber, protein, starch, minerals, and bioactive compounds, which can be used in the food industry. This study compared the molecular, physicochemical, and digestibility characteristics of three avocado seed starches (Criolla, Fuerte, and Hass). Starch was extracted through successive washing and sedimentation. The morphology, size distribution, thermal properties, pasting properties, infrared spectra with Fourier transform, size distribution of amylopectin chains, and digestibility of the three avocado seed strains were analyzed. The starch grains were oval and spherical in shape. The average size of Criolla avocado starch (24.55 µm) was the largest, followed by Hass and Fuerte starches (21.37 µm). Higher gelatinization enthalpy (8.55 J/g), gelatinization temperature (75.28 °C), and pasting temperature (75.57 °C) were observed for Fuerte avocado starch, followed by Hass and Criolla starches. Hass avocado starch exhibited higher maximum (836.27 mPa.s), final (1407.37 mPa.s), setback (588.78 mPa.s), and breakdown (17.68 mPa.s) viscosities than Criolla and Fuerte avocado starches. In addition, the probed avocado starches exhibited high content of resistant starch (60.06-68.90%). Therefore, it was demonstrated that differences in the chemical composition and structure of avocado starch can affect the digestibility of native starch.

Understanding the structural contributions to the functional properties of chestnut starch high in resistant starch type-2.

BACKGROUND: Chestnut has recently attracted attention because of its exceptional functional properties, which are mainly influenced by the structural properties of chestnut starch (CS). In this study, ten varieties of chestnut from the northern, southern, eastern, and western regions of China were selected, and their functional properties, including thermal properties, pasting properties, in vitro digestibility, and multi-scale structural characteristics were characterized. The relationship between structure and functional properties was clarified. RESULTS: In the varieties that were studied, the pasting temperature of CS was in the range of 67.2-75.2 °C and the pastes displayed diverse viscosity characteristics. Slowly digestible starch (SDS), and resistant starch (RS) of CS were in the range of 17.17-28.78% and 61.19-76.10%, respectively. Chestnut starch from north-eastern China exhibited the highest RS content of 74.43-76.10%. Structural correlation analysis revealed that smaller size distribution, fewer B2 chains, and thinner lamellae thickness contributed to higher RS content. Meanwhile, CS with smaller granules, more B2 chains, and thicker amorphous lamellae displayed lower peak viscosities, stronger resistance to shear, and higher thermal stability. CONCLUSION: Overall, this study clarified the relationship between the functional properties and the multi-scale structure of CS, revealing the structural contributions to its high RS content. These findings provide significant information and basic data for use in the creation of nutritional chestnut food. © 2023 Society of Chemical Industry.

Non-conventional starches isolated from agronomic-improved beans (Phaseolus vulgaris L.): a study of their structure and physicochemical properties.

BACKGROUND: Non-conventional starch sources are promising alternative food ingredients. Different bean varieties with agronomic improvements are constantly being developed and cultivated in the Northwestern Argentinean region (NOA) to increase yields and obtain high-quality seeds. However, the main attributes of their starches have not been studied. In this work, starches from four agronomic-improved bean cultivars were isolated and their structure and physicochemical properties were evaluated. RESULTS: High-purity starches were obtained, as shown by their low protein and ash content. Starch granules presented smooth surfaces with spherical to oval shapes, with a marked 'Maltese cross' and heterogeneous sizes. Their amylose content revealed a mean value of 318 g kg-1 and all presented resistant > slowly digestible > rapidly digestible starch fractions. Their Fourier transform infrared spectra were similar and X-ray diffraction analysis showed a CA -type pattern in all cases despite their different sources. Among thermal properties, Escarlata starch showed the lowest gelatinization peak temperature (69.5 °C) and Anahí starch the highest (71.3 °C). Starch pasting temperature varied from 74.6 to 76.9 °C, whereas peak viscosity and final viscosity showed a similar tendency, with Leales B30 < Anahí < Escarlata < Cegro 99/11-2 and Leales B30 < Anahí = Escarlata < Cegro 99/11-2, respectively. CONCLUSION: This study provides the basis for a better understanding of the characteristics of agronomic-improved NOA bean starches, enabling their use in product formulation as an alternative to starches from conventional sources. © 2023 Society of Chemical Industry.

Effects of biochar on rice yield, grain quality and starch viscosity attributes.

BACKGROUND: Biochar can play a key role in improving paddy soil and productivity. However, there is limited information on the effects of biochar on rice quality and starch gelatinization. In this study, four rice straw biochar dosage treatments (0, 20, 40 and 60 g kg-1 ; CK, C20, C40 and C60, respectively) were set up to investigate rice yield components, rice processing, appearance and cooking quality, and starch gelatinization. RESULTS: Addition of biochar increased the effective panicle, grain number per panicle and seed setting rate. However, it decreased the 1000-grain weight, resulting in an increase in yield. In 2019, all the biochar treatments improved the head rice rate (9.13-11.42%), whereas in 2020 only the C20 treatment improved. Low biochar dosage had little effect on grain appearance. High biochar dosage significantly decreased the chalky rice rate by 21.47% and chalkiness by 19.44% in 2019. However, it significantly increased the chalky rice rate and chalkiness by 118.95% and 85.45% in 2020, respectively. Biochar significantly lowered the amylose content except for the C20 and C40 treatments in 2020, and the gel consistency. The C40 and C60 treatments significantly increased the peak and breakdown viscosities and decreased the setback viscosity compared with CK. Correlation analysis showed that starch gelatinization characteristics were significantly correlated with the head rice rate, chalky rate and amylose content. CONCLUSION: A lower biochar dosage can improve the yield and milled rice rate and maintain a higher quality of appearance, whereas a higher biochar dosage can significantly improve starch gelatinization. © 2023 Society of Chemical Industry.

Structure and genetic regulation of starch formation in sorghum (Sorghum bicolor (L.) Moench) endosperm: A review.

This review focuses on the structure and genetic regulation of starch formation in sorghum (Sorghum bicolor (L.) Moench) endosperm. Sorghum is an important cereal crop that is well suited to grow in regions with high temperatures and limited water resources due to its C4 metabolism. The endosperm of sorghum kernels is a rich source of starch, which is composed of two main components: amylose and amylopectin. The synthesis of starch in sorghum endosperm involves multiple enzymatic reactions, which are regulated by complex genetic and environmental factors. Recent research has identified several genes involved in the regulation of starch synthesis in sorghum endosperm. In addition, the structure and properties of sorghum starch can also be influenced by environmental factors such as temperature, water availability, and soil nutrients. A better understanding of the structure and genetic regulation of starch formation in sorghum endosperm can have important implications for the development of sorghum-based products with improved quality and nutritional value. This review provides a comprehensive summary of the current knowledge on the structure and genetic regulation of starch formation in sorghum endosperm and highlights the potential for future research to further improve our understanding of this important process.

Shading affects the starch structure and digestibility of wheat by regulating the photosynthetic light response of flag leaves.

Heavy haze-induced decreases in solar radiation represent an important factor that affects the structural properties of starch macromolecules. However, the relationship between the photosynthetic light response of flag leaves and the structural properties of starch remains unclear. In this study, we investigated the impact of light deprivation (60 %) during the vegetative-growth or grain-filling stage on the leaf light response, starch structure, and biscuit-baking quality of four wheat cultivars with contrasting shade tolerance. Shading decreased the apparent quantum yield and maximum net photosynthetic rate of flag leaves, resulting in a lower grain-filling rate and starch content and higher protein content. Shading decreased the starch, amylose, and small starch granule amount and swelling power but increased the larger starch granule amount. Under shade stress, the lower amylose content decreased the resistant starch content while increasing the starch digestibility and estimated glycemic index. Shading during the vegetative-growth stage increased starch crystallinity, 1045/1022 cm-1 ratio, starch viscosity, and the biscuit spread ratio, while shading during the grain-filling stage decreased these values. Overall, this study indicated that low light affects the starch structure and biscuit spread ratio by regulating the photosynthetic light response of flag leaves.