Effect of steaming on the rheological characteristics of wheat flour dough

 The effect of steaming on the various rheological characteristics of wheat flour dough was studied. Steaming of flours at atmospheric pressure for 15 min completely denatured the gluten and reduced the water absorption capacity from 58.4% to 45.0%. Even steaming for just 5 min increased the resistance to extension considerably from 500 BU (Brabender Units) to 1000 BU and the ratio figure (resistance to extension/extensibility) from 4.2 to 27.4, indicating stiffening of the dough. The dough made from steamed flour had a higher hardness value of 91.1 N than the dough made from raw wheat flour which had a value of 51.1 N. The pasting characteristics of flour steamed for 15 min measured in a Rapid Visco Analyser showed increased peak viscosity from 218 rapid visco units (RVU) to 257 RVU as well as increased cold paste viscosity from 175 RVU to 200 RVU and increased hot paste viscosity from 94 RVU to 108 RVU for flour steamed for 15 min. Received: 4 August 1998 / Revised version: 23 October 1998     

Indian Wheat Cultivars: Correlation between Quality of Gluten Proteins,Rheological Characteristics of Dough and Tandoori Roti Quality

Physico-chemical, rheological characteristics and quality of tandoori roti were determined for whole wheat flours from eight commercial wheat cultivars grown at one location. Tandoori roties baked from these flours indicated wide differences in baking performance. Among the varieties, Cpan-3004, GW-180 and K-8804 and WL-1562 were found suitable for the preparation of tandoori roti. These four varieties had higher water absorption capacity (718–735 ml kg^-1) when measured in a farinograph at an optimum tandoori dough consistency of 400 BU. The doughs from these varieties also had higher cohesiveness (0·38–0·45) and extensibility (114–121 mm) than other varieties. Total protein, gluten as well as total glutenin (soluble and insoluble) contents were found to be maximum in these four varieties. Varieties having Glu-1 score of 6 were found to be more suitable for roti preparation. The prediction equation derived for correlating total protein and total glutenin in flour with overall sensory score of roti was found highly significant (R² = 0·92). The results suggest that the medium hard wheats are suitable for the preparation of tandoori roti. © 1997 SCI.     

The growth and conductivity of nanostructured ZnO films grown on Al-doped ZnO precursor layers by pulsed laser deposition

The structure and electrical properties of nanostructured Al-doped ZnO (AZO)/ZnO bilayers grown as potential solar cell electrodes by pulsed laser deposition on (0001) sapphire substrates are investigated. Transmission and scanning electron microscopy and X-ray diffraction show a narrow temperature window around 350–450 °C where nanostructures are formed. 2-D mapping of electrical conductivity by tunnelling atomic force microscopy showed that these nanostructures provided low resistance pathways, but that the overall film resistivity increased for substrate temperatures above 350 °C. The reasons for this are discussed.     

Strontuim titanate aided water splitting: An overview of current scenario

Addressing the ever-growing global energy demands and environmental concerns by switching over to sustainable and renewable energy resources have been the thrust area of research in the past few decades. Harnessing the abundant solar energy has been the most viable option in this regard. Perovskites, especially strontium titanate have been among the most explored photocatalytic catalytic systems due to their unique properties. The present review summarises the state of art in the solar assisted water splitting using strontium titanate as catalyst. Strategies adopted in enhancing the visible light sensitivity and performance has been discussed giving emphasis to the mechanistic pathway     

Solubilization,micellar transition and biocidal assay of loaded antioxidants in Tetronic® 1304 micelles

The current study scrutinizes the solubilization behaviour of pharmaceutically active antioxidants, namely hydrocinnamic acid (HCA), cinnamic acid (CA) and phenyl propiolic acid (PPA), in the micelles of polyethylene oxide‐polypropylene oxide (PEO‐PPO) based star‐block copolymer: Tetronic® 1304 (T1304). A correlation between the molecular orbital energy levels of PEO‐PPO units of T1304 and the active parts of the antioxidants are well explained using a simulation study. The antioxidants modulate core–shell micelles of T1304 with enhanced solubilization dependent on their unsaturation and hydrophobicity, as depicted from UV–visible spectroscopy. Antioxidants as an additive induce micellization in 5% w/v T1304 thereby modulating the phase behaviour, as indicated by the decrease in the cloud point. The cloud point results are well complemented by steady state fluorescence spectroscopy findings, depicting a decrease in critical micelle temperature due to the solubilization of antioxidants into the T1304 micelles. A significant difference between the hydrodynamic diameter (D_h) of unloaded and loaded polymer micelles with antioxidants is observed from dynamic light scattering, ensuring the solubilization of the antioxidants in T1304 micelles. These results can apparently be attributed to the interaction and the charge induced by the antioxidants on non‐ionic T1304 micelles which increase the micellar size. Furthermore, the role of unsaturation and hydrophobicity of the employed antioxidants in 5% T1304 demonstrates the solution viscosity (η) change as a function of temperature. In addition, small‐angle neutron scattering depicts the shape transition (spherical to ellipsoidal to polymersomes) with temperature. The antioxidant loaded 5% T1304 micellar systems exhibit brilliant biocidal activity against the tested microbes, suggesting their antimicrobial application. © 2019 Society of Chemical Industry     

Effect of blending of raw and steamed wheat flour on the rheological characteristics of dough

 The blended dough made from raw wheat flour and wheat flour steamed for 15 min at a ratio of 1 : 1, along with minor ingredients (salt, oil) showed reduced farinograph water absorption capacity. The stability of the blended dough with oil was reduced while the mixing tolerance index increased. The inclusion of salt in the blend increased the resistance to extension and also the area under the curve. The hardness and cohesiveness measured by means of texture profile analysis decreased with the inclusion of oil in the blend, while increasing with the addition of salt. The Rapid Visco Analyser used to measure pasting characteristics showed a peak viscosity which increased for the blend with salt, but decreased for that with oil. Similarly, the hot paste viscosity, cold paste viscosity and area under the curve increased for the blend with salt, but decreased for the blend with oil. Received: 5 February 1999 / Revised version: 21 April 1999     

Supramolecular Assemblies of Thioflavin T with Cucurbiturils: Prospects of Cooperative and Competitive Metal Ion Binding

Of late, molecular-recognition-guided supramolecular assembly and its relevance in the development of highly stable and active photofunctional materials have drawn much attention. In this review, the non-covalent interaction of a biologically important dye, thioflavin T (ThT), with cucurbituril macrocycles, especially, cucurbit[7]uril (CB7) and cucurbit[8]uril (CB8), and the response of the resulting molecular assemblies towards the metal ions have been discussed. The interaction of ThT with CB7 leads to significant enhancement in the fluorescence yield, lifetime and modifications in the spectral features of ThT. These changes are assigned to the formation of 1 : 1 and 2 : 1 (CB7⋅ThT) complexes. However, with CB8 a distinct evolution of a hitherto unexplored strong excimer emission band having maximum at 570 nm is observed. The strong ion–dipole interactions provided by the carbonyl portals of the CB8 adequately support the stabilization of two π-stacked ThTs, both in 1 : 2 (CB8⋅ThT) and 2 : 2 stoichiometric ratio. In case of the 1 : 1 (CB7⋅ThT) system, the metal ion addition leads to the usual competitive binding interaction and decreases the fluorescence intensity. However, the addition of the same metal ion to the 2 : 1 (CB7⋅ThT) complex results in a novel cooperative metal ion binding to the complex, leading to the formation of a highly fluorescent supramolecular capsule. Further addition of amantadine hydrochloride induces rupture of the capsular complex, projecting potential application in targeted drug delivery. The 2 : 2 (CB8⋅ThT) complex responds to the metal ion presence in a competitive way, which allows demonstration of a fluorescence on–off mechanism.     

Carnosine Inhibits Aβ42 Aggregation by Perturbing the H‐Bond Network in and around the Central Hydrophobic Cluster

Aggregation of the amyloid‐β peptide (Aβ) into fibrillar structures is a hallmark of Alzheimer's disease. Thus, preventing self‐assembly of the Aβ peptide is an attractive therapeutic strategy. Here, we used experimental techniques and atomistic simulations to investigate the influence of carnosine, a dipeptide naturally occurring in the brain, on Aβ aggregation. Scanning force microscopy, circular dichroism and thioflavin T fluorescence experiments showed that carnosine does not modify the conformational features of Aβ42 but nonetheless inhibits amyloid growth. Molecular dynamics (MD) simulations indicated that carnosine interacts transiently with monomeric Aβ42 by salt bridges with charged side chains, and van der Waals contacts with residues in and around the central hydrophobic cluster (¹⁷LVFFA²¹). NMR experiments on the nonaggregative fragment Aβ12–28 did not evidence specific intermolecular interactions between the peptide and carnosine, in agreement with MD simulations. However, a close inspection of the spectra revealed that carnosine interferes with the local propensity of the peptide to form backbone hydrogen bonds close to the central hydrophobic cluster (residues E22, S26 and N27). Finally, MD simulations of aggregation‐prone Aβ heptapeptide segments show that carnosine reduces the propensity to form intermolecular backbone hydrogen bonds in the region 18–24. Taken together, the experimental and simulation results (cumulative MD sampling of 0.2 ms) suggest that, despite the inability of carnosine to form stable contacts with Aβ, it might block the pathway toward toxic aggregates by perturbing the hydrogen bond network near residues with key roles in fibrillogenesis.     

Optical properties of polymer nanocomposites

Nanomaterials have emerged as an area of interest motivated by potential applications of these materials in light emitting diodes, solar cells, polarizers, light-stable colour filters, optical sensors, optical data communication and optical data storage. Nanomaterials are of particular interest as they combine the properties of two or more different materials with the possibility of possessing novel mechanical, electronic or chemical behaviour. Understanding and tuning such effects could lead to hybrid devices based on these nanocomposites with improved optical properties. We have prepared polymer nanocomposites of well-defined compositions and studied the optical properties of powders and their thin films. UV-vis absorption spectroscopy on nanocomposite powders and spectroscopic ellipsometry measurements on thin films was used to study the effect of interfacial morphology, interparticle spacing and finite size effects on optical properties of nanocomposites. Systematic shift in the imaginary part of the dielectric function can be seen with variation in size and fraction of the gold nanoparticle. The thickness of the film also plays a significant role in the tunability of the optical spectra.