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In the double rice cropping system, early/late season rice cultivars can be grown in both early and late seasons. However, the functional properties and starch structures of early/late-season rice between the early and late seasons are still unclear. Here, we conducted a field experiment with two typical early/late season rice cultivars. Compared to early rice, late rice had higher hardness and stickiness and lower peak viscosity, breakdown, and pasting temperature. The higher hardness, lower peak viscosity and breakdown of late rice were dominated by its higher amylose content (i.e., the proportion of amylose chains, DP 100–10000). The lower crystallinity and ratio of 1045/1022 cm−1 of late rice was due to its long and very long amylopectin branch chains (DP 25–70), resulting in a lower pasting temperature. We considered that the higher stickiness of late rice was due to a higher proportion of short and medium amylopectin branch chains (DP 6–24). Furthermore, the setback (short-term retrogradation) showed a significant difference between cultivars, which might be related to the difference in long amylopectin branch chains (DP 37–70) and their intermolecular interactions with amylose molecules. These findings are expected to provide important information for improving rice palatability and developing the rice industry of early/late season rice in the double rice cropping system. [Display omitted] • Early and late rice have different cooked rice textures and pasting properties. • The high hardness of late rice was dominated by its high amylose content. • The high stickiness of late rice depends on more short and medium branch chains. • Late rice has a less crystalline structure, resulting in a low pasting temperature. [ABSTRACT FROM AUTHOR]

• FATI facility increased canopy temperature by 1.4–2.1 °C in a double rice cropping system. • Experimental warming changed the starch fine structure of indica rice. • Experimental warming deteriorated cooking and eating quality of indica rice starch. To evaluate the actual response of rice starch physicochemical properties to climate warming, a field warming experiment was conducted with four indica rice cultivars using free-air temperature increase (FATI) facility in a double rice cropping system. FATI facility increased rice canopy temperature by 1.4–2.1 °C during the entire growth period. The responses of starch physicochemical properties to experimental warming were basically consistent for both early and late rice. On average, experimental warming increased the starch relative crystallinity, granule average diameter, and amylopectin average chain length by 14.3%, 6.9%, and 2.4%, respectively. These resulted in starch with lower swelling power, water solubility, and pasting viscosity, but higher gelatinization temperatures and gelatinization enthalpy. Our study indicated that experimental warming affected the rice starch physicochemical properties, and would provide some useful information on how to guide the rice starch end use in food and non-food industries under climate warming. [ABSTRACT FROM AUTHOR]

The starch multiscale structure, physiochemical properties, grain quality and cooked rice texture of high-quality early and late indica were analyzed under nitrogen panicle fertilizer (low panicle fertilizer, LPF; middle panicle fertilizer, MPF; high panicle fertilizer, HPF) treatments and their internal relations were investigated. Compared to the MPF treatment, the starch granules in HPF and LPF had more surface-proteins and irregular voids for high-quality early and late indica rice cultivars, respectively. Nitrogen panicle fertilization application increased amylopectin medium and long chains as well as protein content, resulting in higher relative crystallinity and gelatinization temperatures. Moderate changes in starch multistructures and physicochemical properties such as branching degree, amylopectin medium chain, and pasting viscosities derived from MPF treatment significantly improved processing, appearance qualities and cooked rice texture. Additionally, the decrease in starch branching, gelatinization temperatures, and granule uniformity along with an increase in large granules, breakdown, and △H gel under MPF treatment were the main reasons for improving rice textural properties. • Middle nitrogen panicle fertilization (MPF) improved cooked rice texture. • MPF treatment improved processing quality by increasing amylopectin medium and long chains. • MPF improved appearance quality by increasing starch pasting properties. • The improvement in cooked rice texture was due to increasing ∆H gel under MPF. • Protein attached to starch granules surface under HPF treatment decreased ∆H gel. [ABSTRACT FROM AUTHOR]

Nitrogen management, especially panicle nitrogen fertilization (PNF), can affect cooked rice textures by altering starch quality, but the details are unclear. In this study, the starch multi-level structures, physicochemical properties and cooked rice textures of indica under different nitrogen managements were analysed and their internal relations were investigated. With an increase in PNF, large granules, amylopectin short chains, amylose content, thermal temperatures, setback, and hardness first exhibited decreasing trends and then increasing trends, which were relatively lower under moderate PNF (N3), whereas α-1,6 linkage, relative crystallinity, protein content, enthalpy of gelatinization (△H gel), peak viscosity, breakdown and stickiness exhibited the opposite trends. N3 treatment significantly increased △H gel and breakdown and decreased setback, hardness and chewiness, suggesting that it might contribute to better starch thermal stability and pasting properties, ultimately improving cooked rice texture. Nitrogen management affected the texture of cooked rice mainly by improving starch multi-level structures, thermal and pasting viscosities. [Display omitted] • Moderate panicle nitrogen fertilization (N3) treatment decreased the starch large granule. • N3 treatment increased the α-1,6 linkage, amylopectin long chains and relative crystallinity. • N3 treatment improved the starch thermal stability, pasting viscosities and taste of cooked rice. • The amylopectin long chain, breakdown and gelatinization enthalpy altered the taste of cooked rice. [ABSTRACT FROM AUTHOR]