Effects of superfine grinding on the quality characteristics of whole-wheat flour and its raw noodle product

Four particle size distributions of whole-wheat flour (WWF) with mean particle sizes (MZ) of 125-μm, 96-μm, 72-μm, and 43-μm were obtained by superfine grinding. Starch damage and Farinograph water absorption were significantly affected by the reduction of particle size, while dough development time, stability, tolerance index and time to breakdown of WWF were little changed. The peak viscosity, trough, and final viscosity of WWF significantly decreased as particle size reduced. Although finer WWFs produced by superfine grinding caused more discoloration of whole-wheat noodle (WWN) after 24 h storage, they still showed brighter noodle appearance (higher L^∗) than coarser WWFs. A significant increase in the cooking yield of WWN was noticed from the 125-μm WWF group to the 43-μm group, perhaps due to increasing damaged starch, while the 72-μm group exhibited the smallest cooking loss of WWN. Additionally, the hardness, cohesiveness, and resilience values of texture profile analysis (TPA) of cooked WWN significantly increased from the 125-μm group to the 72-μm group, and scanning electron microscope (SEM) analysis showed that the 72-μm group revealed the largest coverage of starch granules and degree of protein network connectivity among the WWF groups. The results demonstrated that the superfine grinding technique could improve the quality of WWN by significantly reducing the particle size of WWFs.     

Manufacture and characterization of pasta made with wheat flour rendered gluten-free using fungal proteases and selected sourdough lactic acid bacteria

Wheat flour, which was rendered gluten-free by sourdough lactic acid bacteria fermentation and fungal proteases, was used for manufacturing experimental gluten-free pasta (E-GFp), according to a traditional process with low temperature drying cycle. Chemical, technological, structural, nutritional and sensory features were characterized and compared with those of commercial gluten-free (C-GFp) and durum wheat pasta (C-DWp). As shown through immunological analyses, the residual concentration of gluten of the hydrolyzed wheat flour was below 10 ppm. E-GFp showed rapid water uptake and shorter optimal cooking time compared to the other pastas. Despite the absence of the gluten network, the supplementation with pre-gelatinized rice flour allowed structural properties of E-GFp, which were comparable to those of C-GFp. The in vitro protein digestibility of E-GFp resulted the highest. Probably due to proteolysis during sourdough fermentation; chemical scores, essential amino acid profile, biological value and nutritional index of E-GFp were higher than those of C-DWp. The hydrolysis index (HI) of E-GFp was ca. 30% lower than that found for C-GFp. As shown by sensory analysis, the characteristic of E-GFp were acceptable. The manufacture of E-GFp should be promising to expand the choice of gluten-free foods, which combine sensory and nutritional properties.     

Development of a standard test for dough-making properties of oat cultivars

Bread is consumed all over the world. However, so far, production of large volume bread is only possible with wheat. Alternatives, such as oats, are less suitable but this is partly due to the lack of knowledge about their functionality for other purposes than porridge, which is their most common use. Existing standard tests for the dough making characteristics of wheat flour are not suitable for oat flour, hampering research to optimize oats for bread-making purposes. We therefore set out to develop a test to evaluate oat in relation to mixing and dough making properties using wheat as a model. It was possible to reproduce the profile of various qualities of wheat flour using mixtures of oat flour and gluten in different proportions. Our standard test was based on a dough system composed of 87.2% oat flour and 12.8% gluten and it presented similar properties to a wheat flour with regard to resistance to extension. This dough system was sensitive and reliable (coefficient of variation lower than 10%) for detecting differences among oat cultivars, and it can be used to screen oat varieties and individual oat components in relation to relevant properties for bread-making purposes.     

Quantitative proteomic analysis of wheat grain proteins reveals differential effects of silencing of omega-5 gliadin genes in transgenic lines

Novel wheat lines with altered flour compositions can be used to decipher the roles of specific gluten proteins in flour quality. Grain proteins from transgenic wheat lines in which genes encoding the omega-5 gliadins were silenced by RNA interference (RNAi) were analyzed by quantitative 2-dimensional gel electrophoresis (2-DE). The precise effects of the genetic modifications on the proteome were assessed in four homozygous lines generated with the same RNAi construct. Two of the lines showed >80% decreases in omega-5 gliadins with only small changes in the levels of other gluten proteins. In the other two lines, omega-5 gliadins were not detectable by 2-DE. However, there were notable reductions in all omega-1,2 gliadins. Small decreases in several other gluten proteins were also detected in one of the lines. The other line showed notable decreases in three HMW-GS and an s-type LMW-GS, increases in two m-type LMW-GS and several alpha gliadins, as well as increases in both serpins and triticin. The study demonstrates that the same RNAi construct can have differential effects on the wheat grain proteome and highlights the importance of detailed proteomic analyses of transgenic grain prior to selecting lines for further assessment of flour quality and allergenic potential.     

微波消解-原子荧光光谱法测定豆粉中总汞的不确定度评定

为了得到准确而完善的检测结果,对微波消解-原子荧光光谱法测定豆粉中总汞结果的不确定度进行了评定,结合各不确定度分量对测定方法中不确定度的主要来源进行了分析。结果表明:样品的前处理方法以及试样的重复性对获得准确测定结果尤为重要,标准曲线的配制也是重要的不确定度来源,同时需要确保仪器的稳定性,而试样定容和样品称样引入的不确定度极低,可以忽略。通过不确定度的评定,明确了测定过程中主要误差的来源,为降低检测过程中的误差提供了依据。     

腰果酚基增塑剂对乙酰木粉复合材料的性能影响(英文)

利用熔融挤出-注塑的方法制得乙酰化木粉(AWF)/低密度聚乙烯(LDPE)复合材料,在制备过程中分别将腰果酚基乙酸酯(CA)和环氧腰果酚基乙酸酯(ECA)增塑剂添加到复合材料中。对复合材料的力学性能、吸水率、表面能、增塑剂热迁移和热机械性能(TMA)进行了研究。结果表明:随着增塑剂含量的增加,材料的力学性能不断下降,但整体而言由CA制备的复合材料的力学强度相比更高;吸水率测试显示材料的疏水性能在增塑剂质量分数为5%时差别不大,但添加量为15%时由CA制备的材料具有更好的疏水性;接触角测试也验证了其界面极性最小。在85℃及100 min内ECA的热迁移常数(4.35×10-4)相比CA的(5.48×10-4)要小,同时随着时间延长至3 700 min时ECA在材料中的保留更好。TMA结果显示随着温度的增大材料的膨胀加剧,加入15%的ECA的复合材料在高温段的线膨胀系数(3 758μm/(m·℃))要明显高于对应的加入CA的材料的线膨胀系数(3 182μm/(m·℃))。     

Influence of high molecular weight glutenin subunit substitution on rheological behaviour and bread-baking quality of near-isogenic lines developed from Chinese wheats

Three near‐isogenic lines (NILs) of wheat involving Glu‐B1 and Glu‐D1 alleles were used to study the genetic contribution of high molecular weight glutenin subunits (HMW‐GS) to gluten strength. The HMW‐GS composition of each NILs was determined by SDS‐PAGE. No significant differences were found in grain protein contents among the NILs. Gluten strength and dough‐mixing properties were measured by the Farinograph, the Extensograph, and SDS‐sedimentation (SDS‐SE). Results indicated that line 2, containing the Glu‐1B 14 + 15 and Glu‐1D 5 + 10 combination of subunits, had higher values for flour quality, dough rheological parameters, and bread‐baking quality when compared with lines 8 and 13. Line 8, containing Glu‐1B 7 + 9 and Glu‐1D 5 + 10, was better than line 13 with the Glu‐1B 14 + 15 and Glu‐1D 10 combination. Some major parameters appeared significantly different. The presence of Glu‐1B 14 + 15 was associated with higher dough strength based on SDS‐SE volume and several rheological parameters when compared with Glu‐1B 7 + 9. Lines with subunit 10 at Glu‐D1 performed significantly worse than those with 5 + 10 in gluten index, SDS‐SE volume, Farinograph stability time, Extensograph area and bread‐baking quality.     

Variation in pigment content of flour color in bread wheat (Triticum aestivum L.)

Summary Variation in pigment content of the flour of bread wheats (Triticum aestivum L.) was studied in the progenies of F₁ and F₂ of three crosses and their reciprocals. Reciprocal differences in pigment content were observed in the F₁ and F₂ means. Low pigment content was found to be partially dominant or over dominant in the crosses studied. There was evidence of substantial mid-parent F₁ heterosis in all crosses and betterparent F₁ heterosis in three crosses. In the F₂, heritability estimates were moderate to high. The F₂ frequency distributions were not normal. Estimation of effective factor pairs indicated the presence of one or two major gene pairs involved in the expression of pigment content in the flour. Action of modifiers was also assumed in one cross and its reciprocal. A factorial approach to metrical character suggested that the F₂ segregation ratios of low pigment content to high pigment content were 3:1, 15:1, 13:3 and 9:7 for the different crosses. Utilization of the findings in a wheat breeding program is briefly discussed.     

玉米粉皮胚含量测定器的研制及测定方法的探讨

通过大量试验研制出与国际法（ＧＢ１０４６３－８９）配套的仪器－玉米粉皮胚含量测定器，并对国际法进行了适当改进，提高了方法的准确度。     

沙蒿胶对荞麦面包品质的影响

将沙蒿胶不同添加量对面包比容、硬度、水分含量、高径比及感官品质的影响进行了研究.结果表明,在面包中添加0.5%沙蒿胶时,面包保水性较好,比容最大,同时也可延缓面包老化,对改善面包形状具有一定作用.