Molecular Characteristics of New Wheat Starch and Its Digestion Behaviours

In order to understand the effect of starch molecular characteristics on the gel structure, which subsequently influence the gel digestion behaviours, three wheat starches, control （conventional wheat starch）, two new wheat cultivars with different genetic backgrounds （by knocking out SBE IIb and SBE IIa, respectively） were used in this study. In comparison with control, slight differences in the morphology of the starch granules of new wheat 1 were observed, whereas the starch granules of new wheat 2 had irregular shapes both for A-type granules and B-type granules. Starch molecular weight size was determined by SE-HPLC, and the results indicate that there was a subtle increase in the amylose content in the starch of new wheat 1 compared to that of control. The starch of new wheat 2 had the highest amylose content, and the molecular weight （MW） of its amylopectin was the lowest among the three starches. Fourier transform infrared spectroscopy （FTIR） was employed to investigate starch gel structure and the results suggest that the molecules of starch gel from new wheat 2 are more likely to re-associate to form an organized conformation. The digestion behaviours of the three starch gels were measured using a mixture of pancreatin a-amylase and amyloglucosidase. The results indicated that the starch gels of control and new wheat 1 had very high digestibility of 91.7 and 91.9%, respectively, whereas the digestibility of wheat 2 starch gel was only 36.2%. In comparison with the digestion curve pattems of control and new wheat 1 starch gels, the new wheat 2 exhibited a much lower initial velocity. These results indicated that the molecules in the starch of new wheat 2 are more readily to re-associate to form an organized structure during gel formation because of its unique molecular characteristics.

Research on Physical and Chemical Properties of Corynebacterium glutamicum in Fermentation Process of the Glucose of Wheat Starch

[Objective] This study aimed to investigate the physical and chemical char- acteristic of Corynebacterium glutamicum in fermentation process of the glucose of wheat starch. [Method] The purity of glutamic acid in fermentation period, optical density and cell viability of bacteria were detected as indicators for regression com- parison and analysis. [Result] The relative error d=-3.316 6% within the experimental range of Warburg trace breathing apparatus and double function analyzer. The linear relationship was s1=（1-d）s2. During the fermentation process of the glucose of wheat starch, the average cell activity was 6.24 μA and the maximum cell activity was 6.61 μA. [Conclusion] Compared with optical density, cell viability can more accurate- ly reflect the physical and chemical properties of Corynebacterium glutamicum in fermentation process of the glucose of wheat starch. There was certain correlation between cell membrane phospholipids and cell viability.

Effect of steam-flaking on chemical compositions,starch gelatinization,in vitro fermentability,and energetic values of maize,wheat and rice

Intact and steam-flaked grains of maize,wheat and rice（with whole hulls） were analyzed for chemical composition,starch gelatinization degree（SGD） and in vitro fermentation characteristics to investigate the influence of cereal type and steam-flaking（SF） processing on their nutritive values.The treatments were arranged in a 3×2 factorial design.Obvious differences（P〈0.001） in chemical composition and energetic values were observed among the different cereal types.SGD and gas production（GP） rate was significantly increased（P〈0.001） by SF processing.SF processing also increased（P〈0.01） the proportion of propionic acid and decreased the acetic：propionic acid ratio in vitro.Steam-flaking also increased organic matter digestibility and the energetic value of the cereal grains,especially rice.Based on these results,rice probably is more amendable to SF processing than maize and wheat.In conclusion,it is feasible to partially substitute maize grain with wheat or rice in ruminant diets,and steam-flaking can significantly improve the nutritional value of wheat and rice grains.

Characterization of A-and B-type starch granules in Chinese wheat cultivars

Starch is the major component of wheat flour and serves as a multifunctional ingredient in food industry. The objective of the present study was to investigate starch granule size distribution of Chinese wheat cultivars, and to compare structure and functionality of starches in four leading cultivars Zhongmai 175, CA12092, Lunxuan 987, and Zhongyou 206. A wide variation in volume percentages of A- and B-type starch granules among genotypes was observed. Volume percentages of A- and B-type granules had ranges of 68.4–88.9% and 9.7–27.9% in the first cropping seasons, 74.1–90.1% and 7.2–25.3% in the second. Wheat cultivars with higher volume percentages of A- and B-type granules could serve as parents in breeding program for selecting high and low amylose wheat cultivars, respectively. In comparison with the B-type starch granules, the A-type granules starch showed difference in three aspects：（1） higher amount of ordered short-range structure and a lower relative crystallinity,（2） higher gelatinization onset（To） temperatures and enthalpies（ΔH）, and lower gelatinization conclusion temperatures（Tc）,（3） greater peak, though, and final viscosity, and lower breakdown viscosity and pasting temperature. It provides important information for breeders to develop potentially useful cultivars with particular functional properties of their starches suited to specific applications.

Non-Carbohydrate Components on the Surface of Starch Granules According to the Hardness of Wheat

An attempt was made to demonstrate the usefulness of pre-knowledge of the quality and quantity analysis of non-carbohydrate components of starch surface, such as proteins and lipids, in starch isolated from wheat with varying degrees of hardness, for receiving glucose hydrolysates. The chemical composition of starches isolated from wheat grains of different hardness was examined. The amount of protein fraction (surface proteins, puroindolins and internal proteins), total and surface lipids, apparent amylose, phosphorous and pentosans contents were evaluated. It was found that starches, depending on the hardness of wheat grain, have a different chemical composition. A clear influence of wheat hardness on lipid and proteins content on the surface of starch grains and on apparent amylose was proved. It was showed that the presence of polar lipids (glyco and phospholipids) on the surface of starch was connected with their role in binding of surface proteins fraction (friabilins) to starch grains. There was a clear positive correlation between the amount of lipid fraction on starch surface and the amount of protein fraction, depending on wheat hardness. Starches from soft wheat varieties were characterized by higher amounts of proteins and lipids on their surface. In addition, it was determined that basing on the knowledge of mechanical properties of wheat grains, namely its hardness and initial starch chemical content analysis, one may predict its further directions of processing, including evaluation, whether the starch from a given wheat variety would be appropriate for obtaining hydrolysates with good physicochemical properties.

Analysis on Carotenoids Content and Other Quality Traits of 185 Wheat Varieties

In order to provide the reference of improving the nutritional quality traits in carotenoids and screening its resources of wheat varieties, 185 wheat varieties or lines were selected as materials to test the carotenoids content, lipoxygenase activity, whiteness, yellowness and some other quality traits of whole mill in wheat.The results showed that there were highly significant variations in lipoxygenase activity,carotenoids content, whiteness and yellowness among those sample of wheat varieties; carotenoids content was significantly and positively correlated with yellowness.Cluster analysis was performed based on carotenoids content clustered all the varieties or lines into three major groups. Additionally, carotenoids were discussed in the application of nutritional quality improvement in wheat.