633 research outputs found
New approaches for semolina characterization
No full textSemolina from durum wheat is considered the most suitable raw material for pasta-making. Protein quantity and quality are important factors affecting pasta properties, while the role of starch has received less attention. In this study two semolina samples (organic and conventional), different in protein and starch characteristics, were analyzed using both conventional and new approaches. Starch organization was studied by using DSC, MVA test, and X-ray diffraction. Rheological properties of dough during heating and cooling were investigated using Mixolab ® and Farinograph ®. Despite a lower protein and gluten content, the dough from organic semolina was stronger than conventional semolina. The organic semolina was characterized by a higher total starch content, with a higher pasting viscosity, larger gelatinization temperature range, and a higher H value. Exposure of semolina to iodine vapour exhibited differences in the organization of the starch granules. Both the new approaches used to investigate dough behaviour under heating and cooling showed similar trends. More differences between the semolina samples appeared during the heating and cooling steps: the organic semolina showed a higher consistency than conventional semolina. These preliminary results suggest that there are differences in the starch properties between semolina that require further studies
Starch Characterization of Rice Pasta : Comparison between Extrusion-cooking and Conventional Pasta-Making Process
No full textCharacterization of a rice-based pasta : comparison with conventional semolina pasta
No full textGood quality gluten-free products continue to be in demand among the celiac community. In this study we characterized the quality characteristics of gluten-free pasta made using milled and brown rice flour. Two processes were applied to produce pasta from these flours, with similar moisture contents of 40% in dough. In one case, the rice flour was processed in a conventional plant (pilot-scale) for semolina pasta where the dough temperature inside the continuous extruder was maintained at 55°C. In the second process, two extrusion steps were used: rice dough was first heated and extruded at 115° C for about 2 minutes; then the pre-treated dough was extruded again in the continuous extruder at 55°C. All samples were then dried using a low-temperature drying cycle (50 °C for 14 hours). The characteristics of rice pasta were compared with those of semolina pasta obtained by using the conventional continuous extrusion and dried using the same cycle. The weight-increase of cooked pasta, the solids loss into the cooking water and the color of the pasta were evaluated. Starch modifications induced by the pasta-making process were analyzed by using a micro-viscoamylograph test. As expected, the brown rice flour and pasta were darker compared to either white rice flour or semolina, as evidenced by a higher L, a, b values. The pasta making process did not affect the color of the samples. Following cooking, semolina pasta had the highest weight gain. White rice flour pasta made using non-conventional process had a higher weight gain than pasta from either of the brown rice pasta samples. As expected, semolina pasta had the lowest solids loss following cooking; but white rice pasta made using the non-conventional process also had similar low weight loss. Flours from rice were characterized by a lower peak viscosity compared to semolina. Starch gelatinization temperature decreased in the pasta compared to the respective flours. Furthermore, the pasting profiles were significantly influenced by the pasta making procedure. These results suggest that while good quality pasta can be made using rice flour, the structure of the pasta, as influenced by starch gelatinization, is different likely resulting in differences in weight gain and cooking losses. Further studies are underway to better understand the structure that governs a good quality rice-based pasta
Video Haze Removal And Poisson Blending Based Mini-Mosaics For Wide Area Motion Imagery
No full textThis poster is related to the following paper:
R. Aktar, V. B. S. Prasath, H. Aliakbarpour, U. Sampathkumar, G. Seetharaman, K. Palaniappan. Video Haze Removal And Poisson Blending Based Mini-Mosaics For Wide Area Motion Imagery. IEEE Applied Imagery Pattern Recognition (AIPR), Washington DC, USA.</p
Gluten structural evolution during pasta processing of refined and whole wheat pasta from hard white winter wheat: the influence of mixing, drying, and cooking
No full textAn attempt was made to evaluate gluten structural changes in refined and whole wheat pasta from hard white winter wheat to elucidate the impact of whole wheat components on the formation and structure of the gluten network in pasta. Attenuated total reflectance–FTIR spectroscopy was used to track gluten secondary structure through most of the major steps in pasta processing: raw material, mixing, drying, and cooking. Protein solubility, accessible thiols, and SDS-PAGE data were also collected to provide additional information on the nature of protein interactions and network composition. Few secondary structural differences were observed between refined and whole wheat flours from hard white wheat. However, mixing induced a significant shift to β-sheet structures in refined dough that was not equally matched by whole wheat dough. Drying under both high temperature, short time (HT) and low temperature, long time (LT) conditions resulted in a reversion to structural distributions similar to those for flour in both pastas. However, greater protein denaturation in HT samples was indicated by lower protein solubility also in the presence of denaturants and disulfide reducing agents. Cooking generated a substantial increase in β-sheet structures for both pasta systems. This structure was greatest in refined and LT samples. Thiol accessibility data indicate the presence of a highly aggregated, compact gluten network in refined pasta, mostly driven by hydrophobic association. Conversely, the network in whole wheat pasta was more loosely associated and dependent on disulfide bonding, both of which fit well with the secondary structural data
Gluten structural evolution during pasta processing in refined and whole grain pasta : the influence of mixing, drying, and cooking
No full textRecent investigations of gluten secondary structure in whole grain bread dough indicate that preservation of β-turns is critical for quality. The question is whether this is true for other products. An attempt was made to evaluate gluten structural changes in refined and whole grain pasta to elucidate the impact of whole grain components on the formation and structure of the gluten network in pasta. ATR-FTIR spectroscopy was used to track gluten secondary structure through most of the major processing steps in pasta processing: raw material, mixing, drying, and cooking. Protein solubility, thiol accessibility, and SDS-PAGE data were also collected to provide additional information on the nature of protein interactions and network composition. Few secondary structural differences were observed between refined and whole grain flours from hard white winter wheat. However, mixing induced a significant shift to β-sheets in refined dough that was not equally matched by whole grain dough. Drying under both high temperature-short time (HT) and low temperature-long time (LT) conditions resulted in a reversion to structural distributions similar to those for flour in both pastas. However, greater protein denaturation in HT dried samples was indicated by lower protein solubility in urea with dithiothreitol and by SDS-PAGE profiles. Cooking generated a substantial increase in β-sheets for all pastas. This structure was greatest in refined and LT samples. Further analysis of accessible thiols indicated the presence of a highly aggregated, compact gluten network in refined pasta driven by hydrophobic association, whereas the network in whole grain pasta was more loosely associated and dependent on disulphide bonding, both of which fit well with the secondary structural data. This suggests that β-sheets may be more important to pasta quality, especially texture, than β-turns
Reproductive biology of a natural mangrove hybrid <i>Rhizophora annamalayana</i> and its parent species (<i>R. apiculata</i> and <i>R. mucronata</i>) (Rhizophoraceae)
No full textAbstract
Rhizophora annamalayana is a natural mangrove hybrid with a rare seed set; the species is fast disappearing. We investigated possible causes of rare fruit set and explored ways of overcoming reproductive difficulties in this mangrove. Flowers open in the early morning in the hybrid and its parent species. Anthers dehisced after flower opening only in Rhizophora mucronata and Rhizophora apiculata. Anthesis and anther dehiscence took up to 5 days in all three species. Stigma receptivity peaked during anthesis; receptivity was lost within 8 h in R. annamalayana and R. mucronata. In R. apiculata, anthesis occurred inside the flowers, confirming that cleiostogamy occurred. Pollen of R. mucronata was 100% viable. Viability was 53% in R. apiculata. In R. annamalayana, only 3% of pollen was viable. R. mucronata flowers offered pollen and nectar to visitors, which were mainly Lucilia caesar (flies, bees, ants, etc.). Pollinators of R. annamalayana were restricted to Monobia quadridens, Vespa tropica and Ocybadistes walkeri. R. annamalayana reproduced by cross-pollination.</jats:p
Analysis of HCS in STI-based LDMOS transistors
No full textA numerical investigation of the hot-carrier behavior of a lateral DMOS transistor with shallow trench isolation (STI) is carried out. The measured drain-current degradation induced by hot-carrier stress (HCS) is nicely reproduced by TCAD results revealing that interface traps are mainly formed at the STI corner close to the channel. The effect of typical device design variations on hot-carrier degradation is analyzed
Investigation on the temperature dependence of the HCI effects in the rugged STI-based LDMOS transistor
No full textThe rugged LDMOS transistors showing a current "enhancement" in their high current-voltage regime are investigated under electrical stress conditions. A new hot-carrier-injection (HCI) effect is observed for the n-channel devices, in that the temperature dependence of the device parameter drift changes with operating conditions: under high injection conditions, an increasing linear current drift DId,lin and a positive threshold voltage shift DVt are found under increasing temperature, whereas at low gate voltage DVt is temperature independent and DId,lin decreases with increasing temperature. A numerical investigation is carried out, revealing that traps at the gate oxide close to the source side of the channel are mainly responsible for the degradation under high injection, where the increase of the normal electric field is mainly driven by the local temperature. A temperature-dependent slope of the DVt curves is observed. Under low injection, the drift is dominated by traps located in the drain extension region at the corner of the ST
Investigation on saturation effects in the rugged LDMOS transistor
No full textA numerical investigation on the behavior of the rugged LDMOS transistor operating in the high current-voltage pulsed regime is carried out with the aim of clarifying the physical origin of the drain-current “enhancement” visible in the output characteristics at high drain and gate biases. The socalled “quasi-saturation” effect and the current enhancement are explained in terms of the strong nonlinear behavior of the drift resistance, which is heavily affected by the carrier velocity saturation and by the impact-generated electron-hole pairs. At high gate and drain voltages, the reduction of the drift resistance caused by the latter effect raises the electrostatic potential near the channel end and drives herewith the intrinsic MOSFET into a second saturation condition
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