Impact of mixing time and sodium stearoyl lactylate on gluten polymerization during baking of wheat flour dough

The impact of differences in dough transient gluten network on gluten cross-linking during baking is insufficiently understood. We varied dough mixing times and/or added sodium stearoyl lactylate (SSL; 1.0% on flour dry matter basis) to the recipe and studied the effect on subsequent gluten polymerization during heating. The level of proteins extractable in sodium dodecyl sulfate containing media was fitted using first order kinetics. The extent and rate of gluten polymerization were lower when mixing for 8 min than when mixing for 2 min. This effect was even more outspoken in the presence of SSL. The present observations were explained as resulting from less gliadin incorporation in the polymer gluten network and from interaction of SSL with the gluten proteins. Finally, a higher degree of gluten polymerization during baking increased the firmness of the baked products.     

Combustion of syngas in a pressurized microturbine-like combustor: Experimental results

The different routes for power production from biomass often lead to an intermediary product such as a synthesis gas or syngas, which is typically rich in hydrogen and carbon monoxide. The simple design, fuel flexibility and size, which often matches the amount of waste energy available in industrial sites, makes microturbines an attractive solution for on-site, decentralized power generation using a limited range of alternative fuels such as synthetic gas. The properties of the synthetic fuel differ from properties of natural gas and a detailed experimental study with a separated microturbine-like pressurized combustor is therefore necessary. The present article reviews the experimental results obtained by gradually switching the fuel feed from natural gas to wet syngas in a pressurized, slightly modified lean premix microturbine combustor. Temperature profiles, pressure, emissions and flame imaging were closely monitored to detect possible problems in operability of the combustor caused by the strong difference in fuel characteristics.     

Mechanical examinations on dental implants with porous titanium coating

Due to its good biocompatibility, porous titanium is an interesting material for biomedical applications. Bone tissue can grow inside the porous structure and maintain a long and stable connection between the implant and the human bone. To investigate its long term stability, the mechanical behavior of porous titanium was tested under static and dynamic conditions and was compared to human bone tissue. A promising application of this material is the coating of dental implants. A manufacturing technique was developed and implants were produced. These implants were fatigue tested according to modified ISO 14801 and the micro structural change was examined. The fatigue test was statically modeled using finite element analysis (FEA). The results show that the implants resist a continuous load which is comparable to the loading conditions in the human jaw. The experiments show that the porous titanium has bone-like mechanical properties. Additionally the porous titanium shows an anisotropic behavior of its mechanical properties depending on the alignment of the pores. Finally, other potential applications of porous titanium are outlined.     

Influence of the overall charge and local charge density of pectin on the complex formation between pectin and β-lactoglobulin

The complex formation between β-lactoglobulin (β-lg) and pectin is studied using pectins with different physicochemical characteristics. Pectin allows for the control of both the overall charge by degree of methyl-esterification as well as local charge density by the degree of blockiness. Varying local charge density, at equal overall charge is a parameter that is not available for synthetic polymers and is of key importance in the complex formation between oppositely charged (bio)polymers. LMP is a pectin with a high overall charge and high local charge density; HMP_B and HMP_R are pectins with a low overall charge, but a high and low local charge density, respectively. Dynamic light scattering (DLS) titrations identified pH_c, the pH where soluble complexes of β-lg and pectin are formed and pH_?, the pH of phase separation, both as a function of ionic strength. pH_c decreased with increasing ionic strength for all pectins and was used in a theoretical model that showed local charge density of the pectin to control the onset of complex formation. pH_? passed through a maximum with increasing ionic strength for LMP because of shielding of repulsive interactions between β-lg molecules bound to LMP, while attractive interactions were repressed at higher ionic strength. Potentiometric titrations of homo-molecular solutions and mixtures of β-lg and pectin showed charge regulation in β-lg–pectin complexes. Around pH 5.5–5.0 the pK_as of β-lg ionic groups are increased to induce positive charge on the β-lg molecule; around pH 4.5–3.5 the pK_a values of the pectin ionic groups are lowered to retain negative charge on the pectin. Since pectins with high local charge density form complexes with β-lg at higher ionic strength than pectins with low local charge density, pectin with a high local charge density is preferred in food systems where complex formation between protein and pectin is desired.     

Going green to be seen: Status, reputation, and conspicuous conservation.

Why do people purchase proenvironmental “green” products? We argue that buying such products can be construed as altruistic, since green products often cost more and are of lower quality than their conventional counterparts, but green goods benefit the environment for everyone. Because biologists have observed that altruism might function as a “costly signal” associated with status, we examined in 3 experiments how status motives influenced desire for green products. Activating status motives led people to choose green products over more luxurious nongreen products. Supporting the notion that altruism signals one’s willingness and ability to incur costs for others’ benefit, status motives increased desire for green products when shopping in public (but not private) and when green products cost more (but not less) than nongreen products. Findings suggest that status competition can be used to promote proenvironmental behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Xylanase-mediated in situ production of arabinoxylan oligosaccharides with prebiotic potential in whole meal breads and breads enriched with arabinoxylan rich materials

Multiple studies have revealed the prebiotic activity of cereal derived arabinoxylan oligosaccharides (AXOS). This study investigated the in situ production of AXOS during bread making. In the first part, the AXOS producing capacity of different xylanases was compared in whole meal bread making. Three mesophilic xylanases originating from Bacillus subtilis, Aspergillus niger and Hypocrea jecorina, and one thermophilic xylanase from H. jecorina (HjXynA), were used in different dosages. At dosages that did not impair dough manageability, HjXynA solubilised and cleaved the arabinoxylan fraction to the largest extent, resulting in an AXOS content of 2.1% (dry basis) and an average degree of polymerisation (avDP) of 9. In the second part, the impact of HjXynA on the AXOS levels in dietary fibre enriched breads was studied. Rye or wheat bran fortified breads treated with HjXynA yielded good quality breads with AXOS levels above 2.0% with an avDP of 26 and 19, respectively.     

The impact of the protein network on the pasting and cooking properties of dry pasta products

Durum wheat semolina gluten and starch as well as processing conditions determine pasta cooking quality. This study investigated whether, for good organoleptic properties, a permanent protein network needs to be formed during pasta drying or can still be formed during cooking. The cooking quality of 16 spaghetti samples was related to the levels of sodium dodecyl sulphate extractable protein (SDSEP), starch gelatinisation temperatures as well as to the swelling properties of milled dry spaghettis. SDSEP levels in dry and cooked products varied between 31% and 56%, and 12% to 21% of total protein contents, respectively. The highest quality spaghettis had relatively higher levels of SDSEP in the dry product, low starch gelatinisation temperatures and swelling powers, and rigid particles. The lowest quality spaghettis had lower levels of SDSEP and higher gelatinisation temperatures. This work implies that high pasta quality results from an optimal degree of protein polymerisation during drying and/or the subsequent cooking.     

Effect of Internal Current Flow During the Sintering of Zirconium Diboride by Field Assisted Sintering Technology

Effect of electric current on sintering behavior and microstructure evolution of zirconium diboride (ZrB₂) was investigated using three different configurations of Field Assisted Sintering Technology/Spark Plasma Sintering. The current flow through the ZrB₂ compact was controlled by modifying the interface between the graphite punches and the electrical conductive powder. Boron nitride discs, graphite foils or direct contact with the graphite punches were the three different interfaces used in order to deflect, conduct or promote, respectively, the current during the sintering process of the electrically conductive ZrB₂ ceramics. The current flow during the sintering process triggered the elimination/reduction in B₂O₃, leading to faster diffusion rates at high temperatures and limiting the formation of B₄C secondary phase. This allows to control the final density, grain size (from 19.6 to 43.2 μm) and secondary phase formation (from 5.95 to 11.61 vol%) as well as the electrical resistivity (from 7.7 to 9.4 μΩ·cm) of the specimens.     

The Antibiotic Doxycycline Impairs Cardiac Mitochondrial and Contractile Function

Tetracycline antibiotics act by inhibiting bacterial protein translation. Given the bacterial ancestry of mitochondria, we tested the hypothesis that doxycycline—which belongs to the tetracycline class—reduces mitochondrial function, and results in cardiac contractile dysfunction in cultured H9C2 cardiomyoblasts, adult rat cardiomyocytes, in Drosophila and in mice. Ampicillin and carbenicillin were used as control antibiotics since these do not interfere with mitochondrial translation. In line with its specific inhibitory effect on mitochondrial translation, doxycycline caused a mitonuclear protein imbalance in doxycycline-treated H9C2 cells, reduced maximal mitochondrial respiration, particularly with complex I substrates, and mitochondria appeared fragmented. Flux measurements using stable isotope tracers showed a shift away from OXPHOS towards glycolysis after doxycycline exposure. Cardiac contractility measurements in adult cardiomyocytes and Drosophila melanogaster hearts showed an increased diastolic calcium concentration, and a higher arrhythmicity index. Systolic and diastolic dysfunction were observed after exposure to doxycycline. Mice treated with doxycycline showed mitochondrial complex I dysfunction, reduced OXPHOS capacity and impaired diastolic function. Doxycycline exacerbated diastolic dysfunction and reduced ejection fraction in a diabetes mouse model vulnerable for metabolic derangements. We therefore conclude that doxycycline impairs mitochondrial function and causes cardiac dysfunction.     

Sintering of a sodium-based NASICON electrolyte: A comparative study between cold,field assisted and conventional sintering methods

Scandium-substituted NASICON (Na_3.4Sc_0.4Zr_1.6Si₂PO₁₂) is a promising electrolyte material for sodium-ion solid state batteries, with the highest ionic conductivity reported to date for a NASICON material. Low-temperature densification and control of microstructure are important factors to enable the low-cost manufacturing of such new battery type. Non-conventional sintering techniques such as Field Assisted Sintering Technology / Spark Plasma Sintering (FAST/SPS) and Cold Sintering are therefore investigated and compared to conventional free sintering. FAST/SPS enables to get rapidly dense samples (99% TD) at lower temperatures than the ones required by conventional sintering routes and with similar electrical properties. Cold sintering experiments, involving the addition of aqueous solutions as sintering aids and high mechanical pressure, enable a moderate densification, but at temperatures as low as 250 °C. Further heat treatments still below the conventional sintering temperature increased the achieved density and ionic conductivity.