Comparison of Endosperm Starch Granule Development and Physicochemical Properties of Starches from Waxy and Non-Waxy Wheat

Characterization and structure-functionality analysis of starch in different layers of Lycoris chinensis bulb scales

According to literature, the size distribution of starch granules varies significantly in different layers of Lycoris chinensis bulb scales, however its effect on structural and physicochemical properties of starch still remains unclear. In this study, outer, middle and inner layers of bulb scales of L. chinensis were compared for starch characteristics. Also, the structure-functionality association was investigated based on correlation analysis and hierarchical cluster analysis, using 37 starch quality traits. Compared to commonly consumed starches with similar amylose content, L. chinensis starch gel had lower hardness and viscosities. Among layers, starches varied significantly in particle size, physicochemical and structural properties. As compared to middle and inner scales, the starch in outer scales had higher amylose content, hardness and viscosities, but lower gelatinization temperature, weight-average molar mass and degree of polymorphism. Correlation analysis revealed significant correlations among traits, and interestingly, gelatinization temperature (Tp) was found positively correlated to traits of molecular weight (p < 0.05). The 37 traits of starch characteristics can be divided into three subgroups, as supported by the results of Pearson correlation analysis and hierarchical cluster analysis. In general, the information presented in the current study are useful for Lycoris bulb starch utilization and insightful for a better understanding of structure-functionality association of starch.

Endosperm and amyloplast development in waxy wheat cultivars

The endosperm is an essential part of wheat grains, and the accumulation of amyloplasts in endosperm determines the quality of wheat. Because waxy wheat has a special starch quality, there is a need to understand differences in endosperm and starch morphologies among waxy wheat cultivars. This study investigated differences in the endosperm and amyloplasts of two near-isogenic lines (Shimai19-P and Shimai19-N) and the wheat cultivar Shimai19 during various growth stages using light microscopy and scanning electron microscopy. At 8 days after pollination (DAP), with endosperm development, the amyloplast distributions in the different endosperm regions of the three wheat varieties were in the following order: center of ventral endosperm > subaleurone of ventral endosperm > center of dorsal endosperm > modified aleurone > subaleurone of dorsal endosperm. At 16 DAP, small amyloplasts appeared in the endosperm cells in all three wheat cultivars; subsequently, endosperm cell development until maturity was more rapid in Shimai19-N than in the other varieties. This study revealed variations in amyloplast accumulation among endosperm regions and waxy wheat varieties during wheat grain development, which improved the understanding of nutrient accumulation and nutrient transfer of wheat grains.

Comparison of the physicochemical properties of starches from maize reciprocal F1 hybrids and their parental lines

Heterosis on maize yield and quality is highly variable and depends on parental selection. This study investigated and compared the starch structure and physicochemical properties among four sweet-waxy maize lines, four waxy maize lines, and their eight reciprocal F1 hybrids. Compared with the sweet-waxy maize, waxy maize and F1 hybrids had lower extent of branching of amylopectin and relative crystallinity, and larger starch granule size. Waxy maize starch had higher breakdown viscosity and retrogradation percentage, and lower setback viscosity and gelatinization enthalpy than the sweet-waxy maize starch. Meanwhile, the peak and setback viscosities, and retrogradation enthalpy of most F1 hybrid starches were higher than those of their female parent, while gelatinization enthalpy was the opposite. The F1 hybrid starches had higher onset temperature and retrogradation percentage and lower gelatinization enthalpy than their male parent in general. In conclusion, this study provides a framework for the production of new hybrids.

Effects of Altitudinal Gradient on Physicochemical and Rheological Potential of Quinoa Cultivars

The protein, carbohydrate, and fat characteristics of quinoa grains reflect in their techno-functional potential. This aspect has been little studied in quinoa, while some physicochemical and rheological characteristics have been generalized for all cultivars under all primary production conditions. The aim of this research is to determine the agro-industrial potential of different quinoa cultivars evaluated under different environments through physicochemical and rheological responses. This study has a factorial design with a first level corresponding to cultivars and a second level to production zones. The results showed that the cultivars present high compositional variability. It was also found that the altitudinal gradient changes protein and starch composition, protein secondary structure, and starch structural conformation. In addition, significant variations were found in viscosity, breakdown, and dispersion setback for all treatments. However, there were no differences between treatments before heating/cooling and after heat treatment.

Rice starch accumulation at different endosperm regions and physical properties under nitrogen treatment at panicle initiation stage

The quality of rice grain is characterized by the component, structure and physicochemical properties of starch accumulated in endosperm cell. Nitrogen uptake strongly affects rice growth and starch development. In this study, Nangeng 9108 was used to investigated the accumulation of starch in different positions of the endosperm and physical properties of starch under nitrogen treatment of panicle initiation (PI) stage. Compared with the control group (CG), nitrogen treatment group (NTG) featured a higher number of grains per panicle and 1000-grain weight. Nitrogen treatment significantly increased starch accumulation among different regions during endosperm development, which was expressed as central endosperm cells > sub-aleurone cells of abdominal endosperm > sub-aleurone cells of dorsal endosperm. The amyloplast increased by constricting and budding-type division, generated a bead-like structure and derived some vesicles. The particle size of the starch granules obtained from the NTG was smaller and the apparent amylose content was lower than those of the CG, resulting in higher relative crystallinity. Nitrogen treatment promoted double helical components and provided a higher degree of order at short-rang scale for the starch granules. This study indicated that nitrogen significantly affected the accumulation and physicochemical properties of starch in the endosperm.

Effects of low temperature at stem elongation stage on the development, morphology, and physicochemical properties of wheat starch

The low temperature in spring is a meteorological problem in wheat production because it leads to yield reduction and alteration of wheat quality. In this study, an artificial low-temperature treatment (LTT) at the stem elongation stage was implemented to investigate the starch granule development and physical and chemical properties of wheat starch. Results showed that the agronomic traits of spike, such as spike length, spikelet number per spike, and grain number per spikelet, decreased after LTT. LTT promoted the development of starch granules in developing grains at 15 days post-anthesis, resulting in increased B-type granules and reduced C-type granules with an irregular shape in mature grains. The swelling power of the starch granules was reduced, but their solubility was enhanced by LTT. The proportion of the amorphous structure within the granules increased, but the crystalline component decreased after LTT, leading to a significant reduction in the relative degree of crystallinity and double- and single-helix structures. Three types of hydrolysis showed that starch in LTT was easy to hydrolyze, resulting in a high degree of hydrolysis. The findings suggest that low temperature at the stem elongation stage can not only reduce the yield parameters of spike but also alter starch accumulation, thereby affecting the processability and structure characteristics of starch in wheat grains.

Effects of high temperature during two growth stages on caryopsis development and physicochemical properties of starch in rice

Global warming may affect the development of rice at different growth stages, thereby decreasing rice yield and deteriorating grain quality. The difference in rice responses to high temperature during primordial differentiation (PD) and pollen filling (PF) stages has been rarely studied. In this paper, two temperature treatments (40 °C and 30 °C) at the two stages (PD and PF) were imposed to four rice groups under the controlled temperature chambers. Compared with rice under normal temperature, high temperature-stressed rice showed accelerated growth rate, smaller caryopsis and decreased yield. Moreover, high temperature affected the starch physicochemical properties, resulting in lower apparent amylose content and higher order degree, gelatinization temperatures, and thereby increased peak, trough and final viscosities in starch. High temperature during PD stage inhibited cell development and starch deposition, thus leading to small starch granule and low retrogradation. However, temperature-stressed rice during PF stage showed increased starch accumulation and larger granule size. Therefore, effects of high temperature during the two stages on caryopsis development and starch properties were partly similar but also notably different. These results enriched and deepened the study of high temperature-stressed rice and served as an important reference for the processing and utilization of rice starch in food industry.

Phosphorus Alters Starch Morphology and Gene Expression Related to Starch Biosynthesis and Degradation in Wheat Grain

Phosphorus is an essential plant macronutrient which profoundly affects the yield and quality of wheat starch. In this study, scanning electron microscopy showed that P fertilizer amount (0, 46, and 92 kg P ha-1) had no significant effect on the shape of starch granules in wheat (cv. Xindong 20) grain. However, confocal laser scanning microscopy with 3-(4-carboxybenzoyl) quinoline-2-carboxaldehyde and methanolic merbromin stains indicated that P amount influenced the microstructure of the starch granules. Starch granules from the 46 kg P ha-1 treatment released significantly more reducing sugars than those from the 0 and 92 kg P ha-1 treatments during digestion with alpha-amylase and amyloglucosidase digestion. Phosphorus application (especially the 46 kg P ha-1 treatments) significantly increased the relative expression of genes related to starch synthesis (especially during early to mid-grain filling) and starch degradation (especially during mid- and late grain filling). Phosphorus application also increased the transcript abundance of amylase genes at the periphery of the endosperm. We propose that P application, especially the 46 kg P ha-1 treatment, enhanced channels in wheat starch granules. These channels facilitated the transport of substances required for starch biosynthesis, thus increasing starch accumulation in wheat endosperm. These results provide insight into the potential mechanisms through which P influences the microstructure and biosynthesis of wheat starch.

The Impact of Heat-Moisture Treatment on Physicochemical Properties and Retrogradation Behavior of Sweet Potato Starch

Starch isolated from sweet potato was subjected to different levels of HMT at 15, 20, 25, 30, and 35 %. HMT showed negligible effect on the swelling power of starch. The swelling power was decreased with the increasing of the initial moisture content of the starch. The apparent amylose contents of HMT starches decreased from 24.11 % to 20.56 % with the initial moisture content increasing from 15 % to 35 %. The pasting temperatures enhanced from 73.1 to 81°C (p < 0.05) with the rapidly digestible starch (RDS) contents decreasing from 86.97 to 70.24 % (p < 0.05). Avrami equation analysis showed that HMT reduced the rate of starch retrogradation. The Avrami exponents of native and HMT-35 starches were 0.70 and 0.98 with the recrystallization rates 0.22 and 0.10, respectively. HMT could restrain the starch retrogradation and these results could provide theoretical guidance on sweet potato starch modification.