Genes play a pivotal role in regulating the germination of cereal grains; however, there is limited research on the impact of germination genes on the physicochemical properties of germinated cereal starch. We investigated the effects of the OsGA20ox1 gene on the multiscale structural features and adhesion behavior of germinated brown rice starch. Compared to the knockout lines group, the wild type exhibited a decrease in double-helix content (62.74 %), relative crystallinity (47.39 %), and short-range molecular ordering (2.47 %), accompanied by enhanced erosion on the surface of starch granules. The damage to glycosidic bonds at the double-helix level and the heightened structural amorphization (90.95 %) led to reduced entanglement and interaction among starch molecules, ultimately resulting in reduced characteristic viscosity. Further transcriptomic analysis revealed that OsGA20ox1 could regulate the expression of starch-related enzyme genes in the starch metabolism pathway during germination of brown rice. This study contributes to understanding the role of germination genes in promoting the physicochemical properties of starch in germinated grains, thereby opening up new avenues for the improvement of plant-based starch, and paving the way for further research in this field.

Resistant starch (RS) is a dietary fiber that resists starch hydrolysis in the small intestine, and is fermented in the colon by microorganisms. RS not only has a broad range of benefits in the food and non-food industries but also has a significance impact on health promotion and prevention of non-communicable diseases. RS types 3 and 5 have been the focus of research from an environment-friendly perspective. RS3 is normally formed by recrystallization after physical modification, whereas RS5 is obtained by the complexation of starch and fatty acids through the thermomechanical methods. This review provides updates and approaches to RS3 and RS5 preparations that promote RS content based on green technologies. This information will be useful for future research on RS development and for identifying preparation methods for functional food.

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.

Mangoes contain several components that are beneficial for health, in addition to being potential sources of starch for the food industry. However, a substantial amount of fruit is lost in the field because it does not meet commercial standards, resulting in food losses and environmental damage. Herein, the physicochemical properties of mango flours and starches obtained from different parts of the fruit of two cultivars were evaluated. Mango peel flours have higher levels of proteins, fibers, minerals, carotenoids, ascorbic acid, and antioxidant activity than pulp flours, in addition to a higher yellowing index and water and oil-holding capacity, and can be used as a functional flour. The pulp flours, with the higher starch content, showed characteristics that make them valuable as a potential ingredient in soft baking and gluten-free products. Mango starches have circular and oval shapes, with a bimodal distribution. All starches showed an A-type crystallinity pattern. Pulp starches showed a higher peak viscosity and breakdown, with a lower setback, and can be used as a thickening or gelling agent. The higher thermal stability of kernel starch suggests its application in sauces, baking, dairy products, and canned foods.

UNASSIGNED: Bread wheat is one of the most important food crops associated with ensuring food security and human nutritional health. The starch quality is an important index of high-quality wheat. It is affected by a complex series of factors; among which, suitable sowing time is a key factor.
UNASSIGNED: To analyze the integrative effects of sowing time on the starch quality of high-quality wheat, in the present study, we selected a high-quality bread wheat cultivar Jinan 17 and investigated the effect of different sowing times on the starch properties and the related genes by analyzing X-ray diffraction patterns, apparent amylose content, thermal properties, pasting properties, in vitro starch digestibility, and qRT-PCR. Meanwhile, we also investigated the agronomic and yield performance that may be associated with the starch properties.
UNASSIGNED: Delayed sowing had little effect on starch crystalline morphology, but there was a tendency to reduce the formation of crystals within wheat starch granules: (1) delayed sowing for 15 days altered the thermal properties of starch, including onset, peak and termination temperatures, and enthalpy changes; (2) delayed sowing for 30 days changed the thermal characteristics of starch relatively insignificant; (3) significant differences in pasting characteristics occurred: peak viscosity and hold-through viscosity increased, while final viscosity, breakdown viscosity, and setback viscosity tended to increase and then decrease, suggesting that delayed sowing caused changes in the surface of the starch granules resulting in a decrease in digestibility. Analysis of related genes showed that several key enzymes in starch biosynthesis were significantly affected by delayed sowing, leading to a reduction in apparent straight-chain starch content. In addition to starch properties, thousand-kernel weight also increased under delayed sowing conditions compared with normal sowing.
UNASSIGNED: The impact of delayed sowing on starch quality is multifaceted and complex, from the fine structure, and functional properties of the starch to the regulation of key gene expression. Our study holds significant practical value for optimizing wheat planting management and maximizing the potential in both quality and yield.

Nitrogen has a critical influence on the yield and quality of proso millet. However, the exact impact of nitrogen on the cooking quality of proso millet is not clear. In this study, the cooking quality and starch properties of two proso millet varieties (waxy-Shaanxi millet [wSM] variety and non-waxy-Shaanxi millet [nSM] variety) were compared and analyzed under nitrogen fertilizer treatment (N150, 150 kg/hm2) and a control group without nitrogen application (N0, 0 kg/hm2). Compared with the N0 group, the N150 treatment significantly increased protein content, amylose levels, and total yield. Employing rapid visco analyser and differential scanning calorimetry analyses, we observed that under the N150 treatment, the peak viscosity and breakdown viscosity of proso millet powder were diminished, while the setback viscosity and enthalpy values (ΔH) increased. In addition, nitrogen treatment increased the solids content in the obtained rice soup and significantly hardened the texture of the rice. At the same time, we noticed that the absorption capacity of starch in water and oil was enhanced. These results showed that nitrogen fertilizer had significant effects on the cooking quality and starch properties of proso millet.

Pulsed electric field (PEF) technology was used to extract starch from Q. robur flours using low-intensity electric fields (0 and 0.1 kV/cm) and study the impact of PEF on the structure and properties of acorn starch concerning commercial starch. PEF technology is an advantageous method for starch extraction than the aqueous steeping from an industrial perspective since reduces extraction time and allows for continuous processing of larger suspension volumes. PEF technology preserved the amylose and amylopectin contents, hydrogen bonds, and diffraction patterns, as well as the starch native properties. Hence, PEF could be used to obtain native starches, but future studies should verify its economic viability. Acorn starches have lower damaged starch content, gelatinization temperatures, enthalpies, improved pseudoplastic behavior, reduced in-vitro digestibility, and lower resistance to deformation compared to commercial corn starch. The higher solubility and swelling power of acorn starches up to 80 °C make them a suitable food additive in fermented yogurt and milk products and thus help to value acorn and acorn starches. Hence, acorns can be used to obtain native starches, a food ingredient with a wide range of food and non-food usage, using PEF.

Interests in using high-amylose maize (HAM) flour and starch for low glycemic index foods continue to grow. The objective of this work was to understand resistant-starch formation during drying the HAM kernels. Freshly harvested HAM kernels with 28.2 % initial moisture were subjected to sun drying (~30 °C) or hot-air drying at 50 °C, 70 °C, 90 °C, or 110 °C. The enzymatic digestibility of HAM flour decreased from 63.6 % to 41.1 % as the drying temperature increased from 30 °C to 110 °C. The swelling power, solubility, and overall viscosity of HAM flours milled from kernels dried at 110 °C decreased, whereas the peak and conclusion gelatinization temperatures, enthalpy change, and relative crystallinity increased compared to those of flours from kernels dried at 30 °C, 50 °C, 70 °C, and 90 °C. Light microscopic and scanning electron microscopic images showed that starch granule aggregation in HAM flour increased with increasing drying-temperatures. The aggregates remained after 16 h enzymatic hydrolysis of cooked HAM flours. These results suggested that the increase of enzymatic resistance of HAM flour resulted from the formation of high temperature-resistant ordered structures in starch granules and the starch aggregates less accessible to enzymatic hydrolysis.

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.

Besides increasing grain yield, improving rice (Oryza sativa L.) quality has been paid more and more attention recently. Cooking and eating quality (CEQ) is an important indicator of rice quality. Since CEQs are quantitative traits and challenging for measurement, efforts have mainly focused on two major genes, Wx and SSIIa. Chalkiness and floury endosperm significantly affect the eating quality of rice, leading to noticeable changes in CEQ. Due to the easily observable phenotype of floury endosperm, cloning single gene mutations that cause floury endosperm and evaluating changes in CEQs indirectly facilitate the exploration of the minor genes controlling CEQ. In this study, eight mutants with different degrees of floury endosperm, generated through ethylmethane sulfonate (EMS) mutagenesis, were analyzed. These mutants exhibited wide variation in starch morphology and CEQs. Particularly, the z2 mutant showed spherical starch granules significantly increased rapid visco analyzer (RVA) indexes and urea swelling, while the z4 mutant displayed extremely sharp starch granules and significantly decreased RVA indexes and urea swelling compared to the wild type. Additionally, these mutants still maintained correlations with certain RVA profiles, suggesting that the genes PUL, which affect these indexes, may not undergo mutation. Cloning these mutated genes in the future, especially in z2 and z4, will enhance the genetic network of rice eating quality and hold significant importance for molecular marker-assisted breeding to improve rice quality.