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BACKGROUND: Starch is a major nutrient in the human diet and has been widely used as an ingredient in many food and non‐food applications. However, the research on the quality characteristics of Tartary buckwheat is lagging behind, and there is a lack of high‐quality special varieties, which makes it difficult to become a popular food. The physicochemical properties of Tartary buckwheat starch may be affected by different environments and varieties, and the stability of planted varieties in different regions is also an important issue in current research. RESULTS: The average amylose content and pasting properties of Dingxi Tartary buckwheat were lower, while the solubility, transparency, relative crystallinity and gelatinization enthalpy were higher compared with the other two regions, and there were significant differences between different varieties. All samples showed typical A‐type structure, and the starch short‐range order structure changed slightly. Amylose content, solubility, transparency, granule size distribution, pasting properties and thermal properties were significantly affected by environment and variety. CONCLUSION: When choosing high‐quality special varieties and products for processing, it contributes to select different buckwheat varieties and planting areas based on various objectives by understanding the effects of environment and varieties on the physicochemical properties of Tartary buckwheat starch. In this study, the four varieties planted in Dingxi and the two varieties in Zhaojue were easy to digest, and the differences of pasting properties and thermal properties are helpful to improve the application of Tartary buckwheat starch in the food industry. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Starches of four varieties of waxy proso millet were examined in terms of granule morphology, amylose, transparency, retrogradation, pasting, and thermal properties. The starches had great numbers of large polygonal granules with smooth edges, small numbers of small spherical granules, and an average granule size of 6.12 µm. Compared with the starches of non-waxy proso millet and maize, the starches of the waxy proso millet varieties had lower amylose contents (0.21%) and higher phosphorus contents (1.85 mg/100 g); higher transparency (29.84%) and lower volume percentages of retrogradation (5.01%); higher peak viscosities (3304 cP), trough viscosities (2422 cP) and breakdowns (882 cP), and lower setbacks (267 cP); and lower onset temperatures ( To) (69.7°C), peak temperatures ( Tp) (75.3°C), final temperatures ( Tc) (80.8°C) and enthalpies (Δ H) (10.55 J/g) in their starch gelatinization. [ABSTRACT FROM AUTHOR]

Buckwheat is a typical medicinal and edible crop with high nutritional value, and the application of appropriate fertilizer can improve the quality of buckwheat starch. The changes of internal structure and physicochemical characteristics of common buckwheat grain starch under low, medium, and high fertilization levels are investigated. With increasing fertilizer amount, the volume proportion is increased, while the granule size distribution is reduced significantly. All of the common buckwheat starch samples show a typical A‐type pattern in X‐ray diffraction detection. Furthermore, with the increase of fertilization level, the amylose content, retrogradation, and the ratio of 1045/1022 cm−1 reduce and then raise, but the relative crystallinity, the ratio of 1022/995 cm−1, light transmittance, solubility, and swelling power increase and then decrease. In comparison to other fertilization levels, common buckwheat starch at the medium level has greater pasting temperatures and gelatinization enthalpy but lower pasting viscosities. These results indicate the medium fertilization level of 180 (N), 115.2 (P), and 84.6 (K) kg h−1 m−2 is more suitable for buckwheat starch quality, which can give information for buckwheat cultivation. [ABSTRACT FROM AUTHOR]

Nitrogen (N) affects common buckwheat quality by affecting starch and amino acids (AAs) content, but its molecular mechanism is still unclear. We selected two common buckwheat varieties with high and low starch content, and designed two treatments with 180 and 0 kg N/ha. Application of high-N led to significant increases in starch, amylose and amylopectin content. Of 1337 differentially expressed proteins (DEPs) induced by high-N conditions. 472DEPs were significantly upregulated and 176DEPs downregulated for Xinong9976. 239DEPs were significantly upregulated and 126DEPs downregulated for Beizaosheng. The six alpha-glucan phosphorylases, three alpha-amylases, one granule-bound starch synthase 1 and one sucrose synthase exhibited higher expression at the 180 kg N/ha than at the 0 kg N/ha. In addition, high-N application promoted arginine, leucine, isoleucine and valine biosynthesis. This study revealed the effect of N on the starch and AA content of common buckwheat and its mechanism. The crucial proteins identified may develop the quality of common buckwheat. [ABSTRACT FROM AUTHOR]

Recent findings suggest that optimal application of nitrogen fertilizers can effectively improve the quality of proso millet (PM). Here, we aimed to investigate the pathways associated with starch synthesis and metabolism to elucidate the effect and molecular mechanisms of nitrogen fertilization in starch synthesis and properties in waxy and non-waxy PM varieties using transcriptomic techniques. Co-expression network analysis revealed that the regulation of starch synthesis and quality in PM by nitrogen fertilizer mainly occurred in the S2 and S3 stages during grain filling. Nitrogen fertilization inhibited glycolysis/gluconeogenesis and starch biosynthesis in grains, but increased starch degradation to maltose and dextrin and then to glucose. Moreover, nitrogen fertilization increased starch accumulation by upregulating the expression of SuS and malZ genes, thereby increasing the total starch content in grains. In contrast, nitrogen fertilization suppressed the expression of GBSS gene and decreased amylose content in PM grains, resulting in a relatively higher crystallinity, light transmittance, and breakdown viscosity in the two PM varieties. Overall, these results provided transcriptomics insights into the molecular mechanisms by which nitrogen fertilization regulates starch quality in PM, identified key genes that associated with the starch properties, and provided new insights into the quality cultivation of PM. [Display omitted] [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Starches were isolated from five coarse grains. • The starches showed significantly different granule morphology and sizes. • The starches exhibited different structural properties and crystalline structure. • The starches exhibited different thermal and pasting properties. Abstract Starch, one of the most important components of coarse grains, has received widespread attention because of its prominent potential health benefits. In the present study, we isolated starches from the grains of sorghum, tartary buckwheat, common buckwheat, mungbean, and pea and studied their structural and physicochemical properties. These five starches all showed the distinctive "Maltese cross" effect (birefringence) but significantly differed in morphology, size, and complexity of granules. Sorghum starch exhibited the lowest amylose content and highest weight-average molar mass. Mungbean contained more short amylopectin [degree of polymerization (DP) 6–12 = 23.4%]. Pea starch exhibited the highest amylose content, highest amylopectin average chain length, and lowest weight-average molar mass. The starches of sorghum, tartary buckwheat, and common buckwheat showed A-type crystallinity, whereas those of mungbean and pea showed C-type crystallinity. Our results provide useful information for the application of coarse grain starches in diverse industries. [ABSTRACT FROM AUTHOR]

Field experiments were conducted to evaluate the morphology, granule size, fine structure, thermal properties, and pasting properties of starch from a waxy (139) and a non-waxy (297) varieties of proso millet grown in Yulin (YY) and Yangling (YL). Compared with the starches from the two varieties grown in YY, the starches from the two varieties grown in YL exhibited higher relative crystallinities, 1045/1022 cm−1 ratio, and amounts of amylopectin long branch chains (AP L) but lower 1022/995 cm −1 ratio, amounts of amylopectin short branch chains (APs), and APs/AP L ratios. Starches from YL also synthesized long branch-chain amylopectin to enhance intermolecular interactions and form a stable granular structure, which resulted in increased starch gelatinization temperature, enhanced shear resistance, and reduced setback viscosity. Starch from the waxy (139) variety has good application prospects in the food industry because of its high gelatinization temperature and light transmittance and low setback value, which can be ascribed to its extremely low amylose content, polydispersity index, high molecular weight, and dispersed molecular density. It may serve as a reference for applying proso millet starches in the food industry and developing breeding programs to improve starch quality. • Proso millet were grown in different ecological regions, Yulin (YY) and Yangling (YL). • Compared with YY, starch from YL showed higher amylose content and ratio of long chain. • High weight-average molecular weight increased the gelatinization temperature. • High amylose content or large granules of starch increased setback viscosity. • Starch of waxy (139) variety had good application prospects in the food industry. [ABSTRACT FROM AUTHOR]

In this study, changes in structural and physicochemical properties of pea starch treated with Bacillus-produced α-amylase were determined. The results showed that enzymatically modified pea starch had lower amylose content and granule size but higher branching degree and relative crystallinity. After enzyme hydrolysis, the distribution of A and B1 chains slightly decreased, while the distribution of B2 and B3 chains increased lightly. Enzymatic hydrolysis preferentially occurred in the amorphous region and cannot change the crystalline structure of pea starch. Moreover, pea starch showed lower light transmittance, peak viscosity, breakdown viscosity, pasting temperature, shear viscosity, storage modulus and loss modulus, while the oil adsorption capacity and gelatinization enthalpy significantly increased with increasing α-amylase hydrolysis time. Correlation analysis indicated that α-amylase hydrolysis had different effects on different pea varieties. This research could provide ideas for exploring new applications for enzymatically modified pea starch in food industry. This study found that Bacillus-produced α-amylase significantly changed the amylose content, granule size and viscosity of pea starch, which was helpful to further investigate the modified starch. This technology is expected to widen the applications of pea starch modified by Bacillus-produced α-amylase in food industry, for example as thickener, stabilizer and beverage, to improve the texture, stability and shelf-life of various food products. • Bacillus-produced α-amylase significantly decreased amylose content of pea starch. • The enzymatically modified pea starch had lower granule size. • The enzymatically modified pea starch showed higher gelatinization enthalpy. • Bacillus-produced α-amylase was helpful to widen the application of pea starch. [ABSTRACT FROM AUTHOR]

The KEGG and GO enrichment analysis of proteomics revealed the molecular mechanism of starch synthesis and accumulation driven by nitrogen fertilizer in common buckwheat grain filling. [Display omitted] • High N level significant increased starches content of common buckwheat. • The number of upregulated DEPs induced by N increased with the filling progress. • N induced six PYGs, one SUS and two AMYs significant upregulation at 30d. • Linear relationship between key protein expression and starch content. • N promoted arginine and lysine biosynthetic proteins types at late filling stage. The accumulation of starches and amino acid content of common buckwheat is promoted by Nitrogen (N), but the molecular mechanism is not clear. N applications with 0 (control group) and 180 kg/ha were designed. High-N significantly improved grain fullness and increased the starch, amylopectin and amylose content. The number of upregulated differentially expressed proteins (DEPs) induced by N gradually increased with the filling progress. N resulted in 139, 341 and 472DEPs significant upregulation at 10d, 20d and 30d and they were mainly related to the 'Starch and sucrose metabolism', 'Protein processing in endoplasmic reticulum' and 'Ribosome' by kyoto encyclopedia of genes and genomes analysis. High-N induced one sucrose synthase, two alpha-amylases and six alpha-glucan phosphorylases significant upregulation at 30d and one alpha-amylases upregulation at 10d, and the expression levels of these proteins showed a significant linear relationship with starch and amylose contents. N promoted the arginine and lysine biosynthesis at the late filling stage. These results elucidated that the mechanism of N promoted common buckwheat starches and amino acid accumulation. The identified crucial proteins may improve buckwheat quality. [ABSTRACT FROM AUTHOR]

• Increased nitrogen level reduced amylose content but increased ash content. • All the common buckwheat starches showed typical A-type XRD pattern. • High relative crystallinity were observed under high nitrogen level. • Samples had higher gelatinization enthalpy with increasing nitrogen level. • Nitrogen fertilizer led to a decrease in the storage modulus and loss modulus. Nitrogen is an essential element for the yield and quality of grain. In this study, the structural and physicochemical properties of two common buckwheat varieties under four nitrogen levels (0, 90, 180, 270 kg N ha−1) at one location in two years were investigated. With increasing nitrogen level, the contents of moisture and amylose decreased but the contents of ash and crude protein increased. Excessive nitrogen application significantly increased the granule size, but reduced the light transmittance, water solubility, swelling power, absorption of water and oil. All the samples showed a typical A – type pattern, while high relative crystallinity and low order degree were observed under high nitrogen level. The samples under high nitrogen level had lower textural properties, pasting properties and rheological properties but higher pasting temperature and gelatinization enthalpy. These results indicated that nitrogen fertilizer significantly affected the structural and physicochemical properties of common buckwheat starch. [ABSTRACT FROM AUTHOR]

Two pea varieties were used to investigate the changes in the structural and physicochemical properties of pea starch during germination. The results showed that there were more obvious crimples on the surface of the germinated pea starch granules than native starch. Germination treatment led to significant increases in the amylose content and granule size distribution, while volume proportion of germinated pea starch significantly decreased. All the pea starches showed a typical C-type crystalline structure but the relative crystallinity slightly decreased during germination. Compared with the native starches, the light transmittance and absorption capacities of water and oil all firstly increased and then decreased with the increase of germination time. Moreover, there were obvious increases in the peak viscosity, trough viscosity and final viscosity, while the pasting temperature significantly decreased as germination prolonged to 4 d. The gelatinization temperature of pea starch firstly decreased and then increased during germination, while germinated pea starch showed higher gelatinization enthalpy than that of native starch. In conclusion, the structural and physicochemical properties of pea starch could be significantly affected under germination treatment, which may provide a theoretical basis to promote the utilization of germinated pea starch in the food industry. [Display omitted] • Germinated pea starch showed more crimples on the surface of starch granules. • Germination increased the amylose content but decreased the volume proportion. • All the germinated pea starch showed a typical C-type crystalline structure. • Pasting temperature significantly decreased with increasing germination time. • Germinated pea starch showed higher gelatinization enthalpy than native starch. [ABSTRACT FROM AUTHOR]

Nitrogen fertilizer is a crucial factor affecting the growth and grain quality of Tartary buckwheat. This study was to investigate the synthesis, accumulation, and physicochemical properties of Tartary buckwheat starches under four nitrogen levels (0, 90, 180, 270 kg N ha−1). The results showed that activities of four key enzymes, starch contents all first increased and then decreased with increasing nitrogen levels, and peaked at 180 kg N ha−1. All the starches showed typical A-type, while higher nitrogen levels significantly increased the relative crystallinity. The viscosities significantly decreased, onset, peak, and conclusion first decreased and then increased, while pasting temperature and gelatinization enthalpy increased with increasing nitrogen levels. Nitrogen fertilizer and year had significant effects on the synthesis, accumulation and physicochemical properties of Tartary buckwheat starch, and the nitrogen level of 180 kg N ha−1 was more suitable for planting in the northern area of the Loess Plateau. • Activities of key enzymes for starch synthesis first increased and then decreased. • Amylose content positively correlated with granule bound starch synthase activity. • Tartary buckwheat starches under different nitrogen levels all showed A-type. • Gelatinization enthalpies significantly increased with increasing nitrogen levels. • Nitrogen level of 180 kg N ha−1 was recommended for Tartary buckwheat planting. [ABSTRACT FROM AUTHOR]