Total phenolic, flavonoid content, and antioxidant activity of flour, noodles, and steamed bread made from different colored wheat grains by three milling methods

The objective of this study was to evaluate the effects of wheat variety, food processing, and milling method on antioxidant properties. Black wheat variety Heibaoshi 1 had the highest total phenolic content(659.8 μg gallic acid equivalents g-1), total flavonoid content(319.3 μg rutin equivalents g-1), and antioxidant activity, whereas light purple wheat variety Shandongzimai 1 had the lowest total flavonoid content(236.2 μg rutin equivalents g-1) and antioxidant activity. Whole wheat flour and partially debranned grain flour had significantly higher total phenolic contents, total flavonoid contents, and antioxidant activity than refined flour(P < 0.05). Compared with flour, total phenolic contents, total flavonoid contents and antioxidant activity decreased in noodles and steamed bread, whereas noodles had slightly higher total phenolic and flavonoid content than steamed bread. Antioxidant activities(by ferric reducing ability of plasma assay) of steamed bread made from whole wheat flour, partially debranned grain flour, and refined flour were 23.5%, 21.1%, and 31.6% lower, respectively, than the corresponding values of flour. These results suggested that black whole wheat flour and partially debranned grain flour are beneficial to human health.

Comparison of algorithms for monitoring wheat powdery mildew using multi-angular remote sensing data

Powdery mildew is a disease that threatens wheat production and causes severe economic losses worldwide. Its timely diagnosis is imperative for preventing and controlling its spread. In this study, the multiangle canopy spectra and disease severity of wheat were investigated at several developmental stages and degrees of disease severity. Four wavelength variable-selected algorithms: successive projection(SPA), competitive adaptive reweighted sampling(CARS), feature selection learning(Relief-F), and genetic algorithm(GA), were used to identify bands sensitive to powdery mildew. The wavelength variables selected were used as input variables for partial least squares(PLS), extreme learning machine(ELM), random forest(RF), and support vector machine(SVM) algorithms, to construct a suitable prediction model for powdery mildew. Spectral reflectance and conventional vegetation indices(VIs) displayed angle effects under several disease severity indices(DIs). The CARS method selected relatively few wavelength variables and showed a relatively homogeneous distribution across the 13 viewing zenith angles.Overall accuracies of the four modeling algorithms were ranked as follows: ELM(0.70–0.82) > PLS(0.63–0.79) > SVM(0.49–0.69) > RF(0.43–0.69). Combinations of features and algorithms generated varied accuracies, with coefficients of determination(R^(2)) single-peaked at different observation angles. The constructed CARS-ELM model extracted a predictable bivariate relationship between the multi-angle canopy spectrum and disease severity, yielding an R^(2)> 0.8 at each measured angle. Especially for larger angles,monitoring accuracies were increased relative to the optimal VI model(40% at-60°, 33% at +60°), indicating that the CARS-ELM model is suitable for extreme angles of-60° and +60°. The results are proposed to provide a technical basis for rapid and large-scale monitoring of wheat powdery mildew.

Accumulation of glycolipids in wheat grain and their role in hardness during grain development

Grain hardness is an important parameter for wheat quality. To understand the role of glycolipids in the formation of grain hardness, the glycolipid contents in wholegrain wheat flour and the starch granule surfaces of oven-dried and freeze-dried hard and soft wheat grain were analyzed. Changes in endosperm structure and amyloplast membrane integrity during grain development were also examined by electron microscopy. The monogalactosyldigylcerol(MGDG) and digalactosyldigylcerol(DGDG) contents of the starch surface were significantly higher in soft wheat than in hard wheat, regardless of the drying method or developmental stage. Throughout grain development, MGDG content was significantly higher in the starch surface of freeze-dried hard wheat than in the starch surface of oven-dried hard wheat. In contrast, the MGDG content of the starch surface was significantly higher in freeze-dried soft grain at 14 and 35 days after anthesis. No significant difference was observed in puroindoline protein(PIN) accumulation in wholegrain flour from wheat that was dried using the two methods, whereas PIN accumulation on the starch surface of freeze-dried grain was lower than that on the starch surface of oven-dried grain.The gap between the amyloplast membrane and starch granules was larger in hard wheat than in soft wheat, as shown by transmission electron microscopy. For the same wheat cultivar, this gap was larger for oven-dried than for freeze-dried grain. The content of polar lipids in the starch surface was closely related to grain hardness, and the breakdown of the amyloplast membrane may determine the location of polar lipids on the starch surface.

Diurnal Changes in the Transcription Profiles of Genes Encoding Starch Synthesis-related Enzymes in Wheat Grains under Field Conditions

[Objective] During the filling stage of plant growth and development, storage starch is diurnally synthesized and accumulated in the grains from cereal crops, but the underlying molecular mechanism is unclear. [Method] In this study, grains from the bread wheat cultivar Zhoumai 18 grown in fields were harvested at 15 d after anthesis, and quantitative real-time reverse transcription polymerase chain reaction(qPCR) was used to measure the transcriptional levels of 26 genes encoding starch synthesis-related enzymes at 2 h intervals throughout a diurnal cycle. [Result] Our findings indicated that storage starch was persistently synthesized in wheat grains throughout a 24 h period. The diurnal patterns of the transcriptional levels of 26 genes in wheat grains were classified into two groups. The 13 genes in Group 1 were temporally and highly expressed in wheat grains,and their encoded proteins could play crucial roles in starch synthesis. The other 13 genes in Group 2 were characterized by low or no transcription in wheat grains throughout a diurnal cycle, suggesting their function in the synthesis or degradation of transitory starches in wheat grains. [Conclusion] These results provide information on the molecular mechanism of storage starch synthesis in higher plants.