DYNAMIC VISCOELASTIC PROPERTIES OF PASTA AS A FUNCTION OF TEMPERATURE AND WATER CONTENT*

Pasta samples were tested in the linear viscoelasticity range using a dynamic mechanical thermal analyzer over the temperature range of 25 to 95C and the water content range of 12 to 20% (weight of water/weight of solids). To obtain wholesome pasta samples at different moisture levels, the intermittent sorption technique was used. The behavior of G′ and tanδversus temperature curves exhibited a transition, which was determined to be the glass transition by making comparisons to the literature values of glass transition for starch and semolina extrudates. At 12.5% water content, glass transition initiated at 48.7C. With increase in water content values, the initiating glass transition temperature decreased. At 19.7% water content, glass transition was observed in the temperature range of 36.9 to 57.3C. Although pasta contains about 13% protein fraction, it did not seem to affect the major part of glass transition range because the pasta proteins become mobile at temperatures greater than 80C and water content greater than 17%.     

Elastic properties of RCC under flexural loading-experimental and analytical approach

In structural analysis, especially in indeterminate structures, it becomes essential to know material and geometrical properties of members. The codal provisions recommend elastic properties of concrete and steel and these are fairly accurate enough. The stress–strain curve for concrete cylinder or a cube specimen is plotted. The slope of this curve is modulus of elasticity of plain concrete. Another method of determining modulus of elasticity of concrete is by flexural test of a beam specimen. The modulus of elasticity most commonly used for concrete is secant modulus. The modulus of elasticity of steel is obtained by performing a tension test of steel bar. While performing analysis by any software for high rise building, cross area of plain concrete is taken into consideration whereas effects of reinforcement bars and concrete confined by stirrups are neglected. The aim of study is to determine elastic properties of reinforced cement concrete material. Two important stiffness properties such as AE and EI play important role in analysis of high rise RCC building idealized as plane frame. The experimental programme consists of testing of beams (model size 150 × 150 × 700 mm) with percentage of reinforcement varying from 0.54 to 1.63%. The experimental results are verified by using 3D finite element techniques. This study refers to the effect of variation of percentage of main longitudinal reinforcement and concrete grade. Effect of confinement is not considered and it appears in a separate study.     

Magnetic properties of Ni-Zn ferrites doped with Ti4+ ions

Abstracts are not published in this journal This revised version was published online in November 2006 with corrections to the Cover Date.     

Studies on the value of protein reducing substances in buffalo milk

The values for protein reducing substances (PRS) of buffalo milk collected during the summer, rainy and winter seasons and subjected to thermal treatments have been determined. Analysis of model blends of reconstituted skim milk and buffalo milk for PRS values showed the suitability of the parameter as an indicator of the presence of reconstituted skim milk in both fresh and thermally treated buffalo milk.     

HYDRODYNAMICS AND MASS TRANSFER IN DOWNFLOW BUBBLE COLUMN

Gas holdup, effective interfacial area and volumetric mass transfer coefficient were measured in two and three phase downflow bubble columns. The mass transfer data were obtained using the chemical method of sulfite oxidation, and the gas holdup was measured using the hydrostatic technique. Glass beads and Triton 114 were used to study the effects of solids and liquid surface tension on the gas holdup and the mass transfer parameters a and k_L a . The gas holdup in three phase systems was measured for non-wettable (glass bead) and wettable (coal and shale particles) solids.

The mass transfer data obtained in the downflow bubble column were compared with the values published for upflow bubble columns. The results indicate that in the range of superficial gas velocities (0.002-0.025) m/s investigated, the values of the mass transfer coefficient were of the same order of magnitude as those observed in upflow systems, but the values of interfacial area were at least two fold greater. Also, the results showed that the operating variables and the physical properties had different influences on a and k_L a in the downflow bubble column. Correlations for a and k_L a for the downflow bubble column are proposed which predict the data with adequate accuracy in the range of operating conditions investigated.     

CHEMICAL COMPOSITION AND ANTIOXIDANT ACTIVITY OF SAPOTA (ACHRAS SAPOTA LINN.) FRUIT

Sapota (Achras sapota Linn.) belongs to the family Sapotaceae and is assigned for various properties in the traditional system of Indian medicine. For the first time, nutritional quality and antioxidant activity of sapota juice with reference to its chemical composition have been investigated employing various well‐established in vitro methods. Chemical composition analysis of sapota juice revealed that it is one of the rich sources of sugars, proteins, ascorbic acid, phenolics, carotenoids and minerals like iron, copper, zinc, calcium and potassium. Apart from the nutritional components just given, sapota juice showed potential antioxidant activity against 1,1‐diphenyl‐2‐picrylhydrazyl free radicals and superoxide radicals. Sapota juice potentially inhibited the free radical‐mediated lipid peroxidation in a liposome model system. Total reducing‐power assay revealed the potential reducing power of sapota juice. The multiple radical‐scavenging potential of sapota juice was found to be due to its nutraceutical components, viz., phenolics, carotenoids and ascorbic acid.     

Chemically deposited TiO2/CdS bilayer system for photoelectrochemical properties

In the present investigation, TiO₂, CdS and TiO₂/CdS bilayer system have been deposited on the fluorine doped tin oxide (FTO) coated glass substrate by chemical methods. Nanograined TiO₂ was deposited on FTO coated glass substrates by successive ionic layers adsorption and reaction (SILAR) method. Chemical bath deposition (CBD) method was employed to deposit CdS thin film on pre-deposited TiO₂ film. A further study has been made for structural, surface morphological, optical and photoelectrochemical (PEC) properties of FTO/TiO₂, FTO/CdS and FTO/TiO₂/CdS bilayers system. PEC behaviour of FTO/TiO₂/CdS bilayers was studied and compared with FTO/CdS single system. FTO/TiO₂/CdS bilayers system showed improved performance of PEC properties over individual FTO/CdS thin films.     

PARTICLE-SIZE ANALYSIS OF TOMATO POWDER

Particle‐size information is a measure of the quality of processed food products. In this investigation, a study has been made for the particle‐size analysis (PSA) of blanched and unblanched samples of tomato powder. The outcome indicates that the standard percentile reading D (v, 0.5), D (v, 0.1) and D (v, 0.9) for blanched and unblanched tomato‐powder samples are 260.30, 308.78 and 100.49 μm and 108.57, 609.24 and 521.76 μm, respectively. Volume mean diameter [D 4,3] is higher for unblanched sample (335.87 μm) compared with blanched tomato powder (288.41 μm). Surface area mean diameter [D 3,2] is also higher for unblanched sample (200.51 μm) than blanched tomato powder (158.71 μm). Furthermore, the specific surface area (Aw) is higher for blanched sample (0.0378 m²/g) as compared with unblanched sample (0.0299 m²/g). The blanching treatment slightly affects the grinding/milling quality/size‐reduction characteristics and results in uniform particle size, which is depicted by a narrow range of particle‐size distribution of tomato‐powder samples. Blanched tomato powder is finer as compared with unblanched tomato powder. The narrow range of particle sizes of the blanched sample of tomato powder shows stability during particle‐size settlement, as it is a very important and much desirable parameter for its use in processing of another product preparation.     

PACKAGING, HANDLING and STORAGE of LIPOXYGENASE-FREE FULL-FAT SOY FLOUR

Lipoxygenase-free full-fat soy flour was prepared by hot water blanching and hot-air-oven heat treatment to raw soybeans. Whole soybeans, splits and flours of raw and treated soybeans were used to evaluate their packaging and handling characteristics in polythene bags up to 400 μm thickness. Storage quality of differently processed soy flours was judged in polythene bags of 100 μm. Polythene bags of 50 μm film thickness were judged suitable by stack load test for packaging of whole soybean, soy-splits and soy flours. For safe handling, however, the minimum film thickness of 200 μm was found to be safe as decided by the drop test. 100 μm film thickness of polythene bags was considered appropriate for safe storage up to 45 days in ambient conditions (5-36C; 6–97% rh) on account of FFA rise and change in moisture content. the lipoxygenase-free full-fat soy flour produced by dry heat was found to have better storage quality over raw and blanched soy flour. Overall, the polythene bag film thickness of 200 μm is considered for safe packaging, handling and storage of full-fat soy flour up to 45 days under ambient conditions.