Influence of reducing agents on properties of thermo-molded wheat gluten bioplastics

The present work aims to study the influence of reducing agents of sodium bisulfite, sodium sulfite and thioglycolic acid on the equibiaxial extensional deformation of glycerol plasticized wheat gluten and the properties of gluten bioplastics thermo-molded at 125 °C. Moisture absorption, weight loss and water uptake, uniaxial tensile properties (Young's modulus, tensile strength, elongation at break and tensile set), and morphology observations were performed to characterize the physical properties of the thermo-molded gluten bioplastics. The results showed that reducing agents facilitated the viscous flow and restrained the elastic recovery of the plasticized gluten while not hindering the crosslinking reaction of gluten proteins during thermo-molding. On the contrary, reducing agents do not significantly influence moisture absorption, Young's modulus, tensile strength and the morphology of the gluten bioplastics thermo-molded at 125 °C. It is shown that reducing agents are highly effective for tailoring the flow viscosity of the plasticized gluten dough and the mechanical properties of thermo-molded gluten bioplastics.     

Rheological and mechanical properties of bioplastics based on gluten- and glutenin-rich fractions

The present work aims to investigate the dynamic rheology at small strains and the equibiaxial extensional deformation at large strain of the glycerol plasticized dough of gluten- and glutenin-rich fractions and their mixture as well as the uniaxial tension deformation behavior of the compression molded bioplastics. The influence of glutenin-to-gluten ratio (GGR) on the rheological properties of the glycerol plasticized doughs and the crosslinked bioplastics were investigated. The results showed that the glutenin dough exhibits higher moduli and lower loss factor and equibiaxial deformability in comparison with the gluten dough. Addition of a glutenin-rich fraction to the gluten dough can improve elasticity at small deformation and extensional deformational stress at large deformations but result in reductions in extensibility of the compression molded bioplastics.     

Rheological and mechanical properties of bioplastics based on gluten- and glutenin-rich fractions

The present work aims to investigate the dynamic rheology at small strains and the equibiaxial extensional deformation at large strain of the glycerol plasticized dough of gluten- and glutenin-rich fractions and their mixture as well as the uniaxial tension deformation behavior of the compression molded bioplastics. The influence of glutenin-to-gluten ratio (GGR) on the rheological properties of the glycerol plasticized doughs and the crosslinked bioplastics were investigated. The results showed that the glutenin dough exhibits higher moduli and lower loss factor and equibiaxial deformability in comparison with the gluten dough. Addition of a glutenin-rich fraction to the gluten dough can improve elasticity at small deformation and extensional deformational stress at large deformations but result in reductions in extensibility of the compression molded bioplastics.     

Morphology and mechanical properties of thermo-molded bioplastics based on glycerol-plasticized wheat gliadins

Glycerol-plasticized wheat gliadin bioplastics were prepared through thermo-molding method. The effect of glycerol content on the morphology and the mechanical properties of wheat gliadin bioplastics was studied. Morphology, tensile properties (tensile strength and elongation at break), dynamic mechanical properties and rheological properties were evaluated in relation to glycerol content. Experimental results reveal that the morphology, the glass transition temperatures (T_g) of both the gliadin-rich and the glycerol-rich domains and the tensile properties are closely linked to the glycerol content. The time–temperature superposition (TTS) fails to be applied to the dynamic loss modulus G″ (all temperatures) and the dynamic storage modulus G′ (above 80 °C) of wheat gliadin bioplastics.     

Influence of reducing agents on properties of thermo-molded wheat gluten bioplastics

The present work aims to study the influence of reducing agents of sodium bisulfite, sodium sulfite and thioglycolic acid on the equibiaxial extensional deformation of glycerol plasticized wheat gluten and the properties of gluten bioplastics thermo-molded at 125 °C. Moisture absorption, weight loss and water uptake, uniaxial tensile properties (Young's modulus, tensile strength, elongation at break and tensile set), and morphology observations were performed to characterize the physical properties of the thermo-molded gluten bioplastics. The results showed that reducing agents facilitated the viscous flow and restrained the elastic recovery of the plasticized gluten while not hindering the crosslinking reaction of gluten proteins during thermo-molding. On the contrary, reducing agents do not significantly influence moisture absorption, Young's modulus, tensile strength and the morphology of the gluten bioplastics thermo-molded at 125 °C. It is shown that reducing agents are highly effective for tailoring the flow viscosity of the plasticized gluten dough and the mechanical properties of thermo-molded gluten bioplastics.     

Preparation and properties of wheat gluten based bioplastics with fish scale

The objective of this study was to prepare the wheat gluten based bioplastics with fish scale (FS) through compression molding. The tensile strength of the wheat gluten/FS composites (the range of 6.5–7.5 MPa) was higher than that of the neat wheat gluten-based bioplastic (3.40 MPa). There was a good dispersion of the fish scale powder embedded within the wheat gluten matrix. Dynamic mechanical analysis results showed that the tan delta max peak height and storage modulus of the wheat gluten-based bioplasic was reduced by adding the fish scale. Moreover, the addition of the fish scale caused a weight loss and the surface of the wheat gluten based bioplastic after 120 h of accelerated weathering were differed from the neat wheat gluten based bioplastic. These results may help to find a new applications for fish scale waste to control the degradation rate of a wheat gluten based bioplastic in the agricultural field.     

Milling and baking properties of field grown wheat expressing HMW subunit transgenes

Milling and baking tests were carried out on three transgenic wheat lines and their parental varieties grown in the field at two UK sites. The transgenic and control lines were essentially similar in their milling properties but the subunit 1Ax1 and 1Dx5 transgenes had different effects on breadmaking. The subunit 1Dx5 transgene resulted in a low loaf volume and poor crumb structure when expressed in lines with two or five endogenous HMW subunits, and this was accompanied by a greatly increased elastic modulus of the gel protein fraction. In contrast, the 1Ax1 transgene resulted in improved breadmaking quality and a more modest increase in the gel protein elastic modulus when expressed in the two subunit background. Blending of flour from a line expressing the 1Dx5 transgene with flour from a normal breadmaking wheat variety resulted in decreased breadmaking quality, even at a ratio of 1:9. The difference in the results obtained with the 1Ax1 and 1Dx5 transgenes may relate to the presence of an additional cysteine residue in the protein encoded by the latter, which promotes a more highly cross-linked glutenin network.     

Association analysis reveals effects of wheat glutenin alleles and rye translocations on dough-mixing properties

The glutenin loci of wheat (Triticum aestivum L.) are important determinants of bread-making quality, although the effects of alleles at those loci are incompletely understood. We applied an association analysis method to assess the effects of glutenin alleles and 1RS wheat–rye (Secale cereale L.) translocations on dough-mixing properties in 96 wheat cultivars and advanced lines grown at three Colorado locations while accounting for population structure and relatedness of individuals in the population. The results indicated that (1) in the majority of cases, controlling relatedness of individuals reduced the significance of associations between glutenin loci and Mixograph traits; (2) the Glu-D1 and Glu-B3 loci and 1RS translocations had greater impacts on dough-mixing properties compared to other glutenin loci; (3) Glu-B1w, Glu-D1d, and Glu-B3b were consistently associated with greater (more favorable) Mixograph peak time (MPT) than other alleles at the respective loci, whereas Glu-B1e, Glu-D1a, and Glu-B3c were associated with reduced MPT; (4) the 1BL.1RS translocation was associated with a decrease in Mixograph properties. Our results indicate that taking multiple-level relatedness of individuals into account can improve the results of association analysis for wheat-quality traits.     

Using the Gluten Peak Tester as a tool to measure physical properties of gluten

The functional properties of wheat are largely dictated by composition and interactions of the gluten proteins. All flours contain gliadin and glutenin, but produce baked products of varying quality, which provides evidence that gluten proteins from different wheats possess different properties. A common method to study differences in gluten properties, which is utilized in this study, is fractionation/reconstitution experiments to understand how various gliadin to glutenin ratios and how fractions from different wheat sources affect gluten aggregation properties. Gliadin and glutenin from a vital wheat gluten were fractionated with 70% ethanol and reconstituted at various gliadin to glutenin ratios. Gliadin and glutenin from a Canadian eastern soft, eastern hard and western hard wheat (14% moisture) were fractionated and substituted between flours at the native gliadin to glutenin ratio. Gluten combinations were evaluated with a Gluten Peak Tester at constant temperature and mixing. Varying gliadin to glutenin ratio showed that 50:50 is optimal for fast gluten aggregation while amount of glutenin dictates strength. Substitution experiments showed that replacing good quality gluten fractions with those from a lower quality wheat decreases gluten quality, and vice versa. Data also showed that cultivar specific differences in gliadin and glutenin are more important in dictating gluten strength (torque), while gliadin to glutenin ratio dictates aggregation time (PMT) independent of the source of fractions. The study demonstrated the ability of the improved method to evaluate gluten aggregation by controlling for all variables except the one being tested. The data also revealed information about gluten aggregation properties never before seen.     

Preparation and properties of a white protein fraction recovered at high yield from potato haulms

Summary More than 50% of protein free of chlorophyll has been recovered from potato haulm juice after two successive pH treatments. The white protein coagulum is rich in lysine and in hydrophobic and aromatic amino acids. A low relative proportion of polypeptides of high molecular weight suggests that proteins were partially degraded during fractionation. Protein digestibility and other components of the final preparation were also studied.     

Investigation of the stripping process of the reactive dyes using organic sulphur reducing agents in alkali condition

This paper focuses on the stripping application of the reactive dyes using different recipes set up with different reducing agents and working parameters. We tried to develop alternative stripping methods using two kinds of thioureadioxide because of several disadvantages of sodium dithionite. The pretreated woven fabrics were dyed at 0.25%, 1%, 4% owf% using five commercial reactive dyes by exhaust method. Totally, 180 specimens were dyed. Then, these specimens were stripped using alternative recipes. In these recipes, we investigated the effects of types of the reducing agents, the concentration of the reducing agents and caustic, process temperature and the presence of leveling agent on the stripping efficiency. In order to examine the efficiency of the stripping processes, we measured the colorimetric values (L*, ΔL, ΔE) of pretreated, dyed and the stripped samples using commercial spectrophotometer and international measurement method. The experimental results were statistically evaluated using analysis of variance (ANOVA) with significance level ofα=0.05. According to the measured and calculated spectral results, we achieved to develop alternative methods using thioureadioxide instead of sodium dithionite. In terms of ANOVA, we found out that only concentration of caustic itself did not have significant effects on the efficiency of stripping.     

小麦谷蛋白亚基及其基因多态性研究进展

本文主要介绍了小麦高、低分子量谷蛋白亚基及其控制基因的研究进展情况,包括各种不同的研究技术以及相应的研究结果。除了传统的SDS-PAGE技术以外,分子标记技术以及免疫化学技术都在该领域中得到日益广泛的应用,并取得了关于亚基及基因的多态性和快速鉴别方法等一系列重要的研究进展。     

Laccase-mediated enhancement of the properties of regenerated fibers from wheat gliadin

In this study, laccase-mediated crosslinking was used to develop regenerated protein fibers from wheat gliadin with good mechanical properties and water stability. The oxygen consumption during laccase catalyzed oxidation of gliadin, molecular weight of gliadin, mechanical properties, water stability, thermal properties and morphology of gliadin fibers were tested to prove the effect of laccase as the crosslinker of gliadin. The rapid decrease of dissolved oxygen in gliadin solution indicated laccase was active in oxidizing gliadin. The results of SDS-PAGE and SEC demonstrated that laccase-mediated crosslinking reaction effectively occurred. The mechanical properties and water stability of the gliadin fibers with laccase treatment significantly were improved. The fibers from gliadin with laccase treatment exhibited a much smoother and more uniform surface was observed by SEM for the laccase-mediated modified gliadin fibers.     

杂交小麦F1与F2品质组配规律及高分子量谷蛋白亚基组成规律的研究初报

为了探明杂交小麦F1与F2代品质的组配规律及高分子量谷蛋白亚基组成规律,选取不同品质类型的14个亲本材料,以8种设计,按照强筋×强筋、强筋×中筋、强筋×弱筋、中筋×强筋、中筋×中筋、弱筋×强筋、弱筋×中筋、弱筋×弱筋等方式组配不同杂交组合,分别测定其中8种F2代的品质以及亲本、F1代、F2代的高分子量谷蛋白亚基组成,结果表明,以优质和含有优质亚基的品种作母本对杂交小麦F2品质改良有重要作用,同时在亚基中出现了5 10亚基,其对品质有重要的影响。F1代籽粒中出现了高分子量谷蛋白亚基共显现象和不完全表达或缺失现象。经观察发现,缺失的带基本都是父本的亚基带。     

Preparation and properties of waterborne poly(urethane-urea) ionomers effect of the type of neutralizing agent

A series of waterborne poly(urethane-urea) anionomers were prepared from isophorone diisocyanate (IPDI), polycaprolactone diol (PCL), dimethylol propionic acid (DMPA), ethylene diamine (EDA), and triethylamine (TEA), NaOH, or Cu(COOCH₃)₂ as neutralizing agent. This study was performed to decide the effect of neutralizing agent type on the particle size, viscosity, hydrogen bonding index, adhesive strength, antistaticity, antibacterial and mechanical properties. The particle size of the dispersions decreased in the following order: TEA based samples (T-sample), NaOH based samples(N-sample), and Cu(COOCH₃)₂ based sample (C-sample). The viscosity of the dispersions increased in the order of C-sample, N-sample, and T-sample. Metal salt based film samples (N and C-sample) had much higher antistaticity than TEA based sample. By infrared spectroscopy, it was found that the hydrogen bonding index (or fraction) of samples decreased in the order of T-sample, N-sample, and C-sample. The adhesive strength and tensile modulus/strength decreased in the order of T-sample, N-sample, and C-sample. The C-sample had strong antibacterial halo, however, T- and N-samples did not.     

Physicochemical properties and garification (gari yield) of selected cassava cultivars in Rivers State,Nigeria

Gari was processed from six different cassava cultivars TMS 3575, TMS 3044, hormone treated variety (HTV), TMS 30555, TMS 40944 and TMS 30572. Chemical analyses of the gari samples showed pH values of: 4.0, 4.0, 3.9, 3.6, 3.4, 3.6 and total titratable acidity of 0.99, 0.99, 0.98, 0.85, 0.96, 0.85 (% lactic acid) for TMS 3575, 3044, HTV, 30555, 30572, and 40944 respectively. Physical characteristics of the samples showed the swelling index of 264.5%, 223.5%, 364.0%, 321.3%, 241.3% and 232.7%, water absorption capacity of 1.0 ml g-1, 0.8, 1.5, 1.9, 1.7, 1.9 ml g-1 sample, relative bulk density of 0.29, 0.30, 0.15, 0.17, 0.15 (g cm-3) and gari yield of 34%, 21%, 33%, 24%, and 23%, for cultivars, TMS 3575 (2), 3044, HTV, 30555, 30572, 40944 respectively. Sensory evaluation showed a significant difference (p < 0.05) in quality and overall acceptability among the samples while Tukey test showed a difference ( p< 0.05) between HTV and between 3575 and 3044. The cassava pulp from the cultivars and their corresponding gari had HCN content (mg/100 g) ranging from 7.9 to 9.3 for pulp and 1.1 to 1.5 for gari, respectively. The 72 hours fermentation period reduced the HCN in all cultivars by 85%, which is considered to be a safe level for human consumption.     

Correlation of glutenin macropolymer with viscoelastic properties during dough mixing

Although significant correlations exist for glutenin macropolymer (GMP) quantity and rheological properties/bread making quality of dough, little information about these links is available. The relationship between GMP contents measured by UV absorption method/RP-HPLC and dough viscoelastic properties determined by TA-XT2i texturometer from three wheat varieties (Xiaoyan6, Yumai56 and Zhengnong8805) during mixing was investigated. GMP contents of doughs decrease significantly (P<0.05) during mixing. During the initial mixing stage, amounts of the HMW-GS and LMW-GS and GMP decrease significantly (P<0.05). Their contents begin to increase beyond peak dough development time (DDT). This indicates that during further mixing after peak DDT some glutenin subunits are incorporated into GMP by repolymerization. The HMW/LMW-GS ratio has a significant effect on load-deformation properties (area, resistance and extensibility) of dough. The varieties behaved differently in relation to the contribution of their HMW-LMW-GS ratio to the rheological properties.     

小麦谷蛋白聚合体含量和粒度相对分布及其与品质性状的关系

为了给小麦早代品质筛选提供科学有效的生化指标,以黄淮麦区57个小麦品种为材料,对其籽粒品质性状、谷蛋白总聚合体(TGP)含量、大聚合体(GMP)含量及谷蛋白聚合体粒度相对分布(GMP/TGP)等进行了分析.结果表明:(1)供试品种的籽粒硬度、全麦粉蛋白质含量变化幅度较小,SDS-沉淀值变化幅度较大,按这三个品质指标可将57个品种聚为三大美;(2)供试品种的TGP和GMP含量变异较大,其变化幅度分别为3.63%～8.38%和0.95%～3.63%,变异系数分别为19.68%和26.94%,且多数强筋粉小麦品种的TGP和GMP含量都大于弱筋粉小麦品种;(3)对品质性状与生化性状的相关和回归分析结果表明,全麦粉GMP含量(X3)、蛋白质含量(X1)是影响其SDS-沉淀值(Y1)的关键生化性状,其回归方程为:Y1=6.396X1 6.430X3-47.276;全麦粉TGP含量(X2)是影响小麦籽粒硬度(Y2)的主要生化性状,其回归方程为:Y2=2.050X2 42.947.这些研究结果可为黄准麦区小麦品质育种的亲本选配及后代材料品质筛选提供一些重要信息.     

麦谷蛋白亚基对小麦品质特性的影响及其遗传转化

麦谷蛋白是小麦籽粒贮藏蛋白的重要组成部分,其亚基类型及组成与小麦品质密切相关,为了更进一步了解其与小麦蛋白质品质特性的关系,综合论述了小麦谷蛋白亚基的分类、结构及其不同亚基与小麦品质的关系,并对利用基因工程遗传转化方法改变小麦谷蛋白亚基组成从而提高小麦加工品质的现状及应用前景进行了讨论。     

Chemical composition and functional properties of blends of maize and bambara groundnut flours for cookie production

Chemical composition and functional properties of flour blends containing various levels of maize (100–0%) and bambara groundnut (0–100%) were studied. The resultant blends were high in protein, carbohydrate and caloric value. The blends contained fair amounts of Ca, P and K but were low in Na and Fe. The oil and water absorption capacities of the blends were fairly high ranging from 3.65 to 3.81 g oil/g sample and 3.40 to 3.80 g water/g sample, respectively. The gelation concentration of the blends tended to increase with increase in amount of maize flour in the blend. On the other hand, increasing the level of maize flour in the blends considerably reduced the foaming capacities of the blends. The flour blends had good emulsifying properties. Cookies prepared from the blends contained proteins ranging from 10.9 to 21.65% The cookies had good spread and were significantly lighter than the wheat control cookies. Sensory evaluation scores for cookies showed that the best level of combination was 75% maize flour and 25% bambara groundnut flour.