Absorption Index (absorption + index)

Distribution by Scientific Domains
Chemistry66%
Physics and Astronomy33%

Kinds of Absorption Index

  • water absorption index
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    Selected Abstracts

    Changes in the biochemical and functional properties of the extruded hard-to-cook cowpea (Vigna unguiculata L. Walp)

    INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 4 2010
    Karla A. Batista
    Summary Changes in the biochemical and functional properties of the hard-to-cook cowpea bean after treatment by the extrusion process are reported. The extrusion was carried out at 150 °C, with a compression ratio screw of 3:1, a 5-mm die, and a screw speed of 150 r.p.m. The extrusion caused the complete inactivation of the ,-amylase and lectin and it also reduced the trypsin inhibitor activity (38.2%) and phytic acid content (33.2%). The functional properties were also modified by the process, an increase of 2.5 times in the water absorption index and 3.1% in the water solubility were observed. The digestibility of the hard-to-cook flour of the cowpea bean was improved after the extrusion, with a 55.9% increase in protein digestibility and a 5.9% increase in starch digestibility. [source]

    Effect of extrusion parameters on flavour retention, functional and physical properties of mixtures of starch and d -limonene encapsulated in milk protein

    INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 2006
    Sri Yuliani
    Summary The purpose of this research was to investigate the retention of flavour volatiles encapsulated in water-insoluble systems during high temperature,short time extrusion process. A protein precipitation method was used to produce water-insoluble capsules encapsulating limonene, and the capsules were added to the extruder feed material (cornstarch). A twin-screw extruder was used to evaluate the effect of capsule level of addition (0,5%), barrel temperature (125,145 °C) and screw speed (145,175 r.p.m.) on extruder parameters (torque, die pressure, specific mechanical energy, residence time distribution) and extrudate properties [flavour retention, texture, colour, density, expansion, water absorption index, water solubility index (WSI)]. Capsule level had a significant effect on extrusion conditions, flavour retention and extrudate physical properties. Flavour retention increased with the increase in capsule level from 0% to 2.5%, reached a maximum value at capsule level of 2.5% and decreased when the capsule level increased from 2.5% to 5%. The die pressure, torque, expansion ratio, hardness and WSI exhibited the opposite effect with the presence of capsules. [source]

    EFFECTS OF EXTRUSION CONDITIONS ON PHYSICOCHEMICAL PROPERTIES OF A MUTANT RICE CULTIVAR, GOAMI2 , HIGH IN NONDIGESTIBLE CARBOHYDRATES

    JOURNAL OF FOOD QUALITY, Issue 5 2008
    I. CHOI
    ABSTRACT A mutant rice Goami2, a cultivar high in nondigestible carbohydrates (NDCs), was extrusion-cooked at feed moisture (20, 25%), screw speed (200, 300 rpm) and barrel temperature (110, 120 and 130C). Effects of extrusion conditions on the physical and functional properties were investigated. NDCs were determined by total dietary fiber (TDF) and resistant starch (RS) contents. Increasing moisture resulted in an increment of density, water absorption index (WAI) and hardness, and a decrement in expansion and water solubility index (WSI). A higher barrel temperature decreased the hardness and increased the WSI probably due to a higher proportion of gelatinized starch. Extrusion caused a reduction in TDF in the extrudates, as well as a significant decrease in RS contents. However, extrudates processed at moisture (%), screw speed (rpm) and barrel temperature (C) combinations of 25/200/110 and 25/200/120 showed no significant difference in TDF contents compared with its raw rice. Multiple regression models showed that feed moisture had the most pronounced effect on extrudate qualities, followed by barrel temperature and screw speed. PRACTICAL APPLICATIONS Rice, being one of the primary dietary sources of carbohydrates worldwide, is the major energy and nutritional sources. In recent years, demands have been increasing for rice with a wide range of value-added properties, such as enhanced nutrient, aroma, color and rice kernel shape, including functional properties. Goami2 is a mutant rice of Ilpumbyeo, a high japonica rice cultivar, and has been revealed to have higher nondigestible fractions. However, Goami2 rice has unsuitable properties for traditional cooking because of the difficulty of gelatinization, which might result in a hard texture of cooked rice compared with that of ordinary rice. On the basis of its nutritional and functional benefits, exploiting the possible utilization of Goami2 for processed food products would increase the potential consumption of Goami2 for various food products. [source]

    Physico-chemical and Sensory Characteristics of Flavored Snacks from Extruded Cassava/Pigeonpea Flour

    JOURNAL OF FOOD SCIENCE, Issue 1 2003
    R. Rampersad
    ABSTRACT: The effects of pigeonpea flour (PF) addition to cassava flour (CF) on the sensory and physico-chemical quality of extrudates were investigated. Products with added PF were more yellow, had higher protein, bulk density, and water absorption index with lower expansion and water absorption index. Extrudate with 95% CF/5% PF had a suitable crisp to hard texture. All enrobed products were liked moderately to very much in overall acceptability. Chocolate extrudates were most liked (p < 0.01) for flavor and color over paprika, hickory, and cheese/onion. [source]

    PHYSICOCHEMICAL PROPERTIES OF TEXTURIZED MEAT ANALOG MADE FROM PEANUT FLOUR AND SOY PROTEIN ISOLATE WITH A SINGLE-SCREW EXTRUDER ,

    JOURNAL OF TEXTURE STUDIES, Issue 4 2004
    E.L. PARMER JR.
    ABSTRACT The objective of this study was to establish conditions for the texturization of soy protein isolate and peanut flour mixture using a single-screw extruder. The effects of feed moisture, screw-speed, and barrel temperature on the characteristics of the texturized products were studied. Feed moisture was the most important factor affecting the texture. Feeding ingredients with 22% moisture had the highest water absorption and expansion indices, and Hunter L value (P < 0.05). When the screw speed was above 180 RPM, the meat analog had a 12% decrease in the expansion index and a 5% decrease in moisture content (P < 0.05). When the barrel temperature was increased to 165C, there was a 12% decrease in the water absorption index, and a 23% decrease in the expansion index of the meat analogs (P < 0.05). Overall, an acceptable meat analog could be successfully produced with 22% moisture in the raw ingredient, screw speed at 140 RPM, and barrel temperatures at 150, 155, and 160C for the three temperature zones respectively. [source]

    Stellar populations and surface brightness fluctuations: new observations and models

    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2001
    John P. Blakeslee
    We investigate the use of surface brightness fluctuations (SBF) measurements in optical and near-IR bandpasses for both stellar population and distance studies. New V -band SBF data are reported for five galaxies in the Fornax cluster and combined with literature data to define a V -band SBF distance indicator, calibrated against Cepheid distances to the Leo group and the Virgo and Fornax clusters. The colour dependence of the V -band SBF indicator is only ,15 per cent steeper than that found for the I band, and the mean ,fluctuation colour' of the galaxies is We use new stellar population models, based on the latest Padua isochrones transformed empirically to the observational plane, to predict optical and near-IR SBF magnitudes and integrated colours for a wide range of population ages and metallicities. We examine the sensitivity of the predicted SBF,colour relations to changes in the isochrones, stellar transformations, and initial mass function. The new models reproduce fairly well the weak dependence of V and I SBF in globular clusters on metallicity, especially if the more metal-rich globulars are younger. Below solar metallicity, the near-IR SBF magnitudes depend mainly on age, while the integrated colours depend mainly on metallicity. This could prove a powerful new approach to the age,metallicity degeneracy problem; near-IR SBF observations of globular clusters would be an important test of the models. The models also help in understanding the and fluctuation colours of elliptical galaxies, with much less need for composite stellar populations than in previous models. However, in order to obtain theoretical calibrations of the SBF distance indicators, we combine the homogeneous population models into composite models and select out those ones with fluctuation colours consistent with observations. We are able to reproduce the observed range of elliptical galaxy colours, the slopes of the V and I SBF distance indicators against (fainter SBF in redder populations), and the flattening of the I -band relation for The models also match the observed slope of I -band SBF against the Mg2 absorption index and explain the steep colour dependence found by Ajhar et al. for the HST/WFPC2 F814W-band SBF measurements. In contrast to previous models, ours predict that the near-IR SBF magnitudes will also continue to grow fainter for redder populations. The theoretical V -band SBF zero-point predicted by these models agrees well with the Cepheid-calibrated V -band empirical zero-point. However, the model zero-point is 0.15,0.27 mag too faint in the I band and 0.24,0.36 mag too faint in K. The zero-points for the I band (empirically the best determined) would come into close agreement if the Cepheid distance scale were revised to agree with the recent dynamical distance measured to NGC 4258. We note that the theoretical SBF calibrations are sensitive to the uncertain details of stellar evolution, and conclude that the empirical calibrations remain more secure. However, the sensitivity of SBF to these finer details potentially makes it a powerful, relatively unexploited, constraint for stellar evolution and population synthesis. [source]

    Optical and electronic conduction behavior in germanium ferrite additive with transition metal

    PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 4 2007
    S. A. Fayek
    Abstract The effects of adding transition metals (Ni and Co) on the optical and electrical properties of four thin films Ni1.25Fe1.5Ge0.25O4, Ni1.5Fe1Ge0.5O4, Co1Fe1Ge0.5O4 and Co1.25Fe1.5Ge0.25O4 are reported. X-ray diffraction was used to ascertain the amorphization nature of the deposited films. The optical absorption behavior of these films was studied from the transmission and reflection in the range 200,1100 nm. It was found that the optical band gap increases on increasing GeO2 and arises from direct forbidden transitions. The opposite trend was found with the band tail width of the localized state. Optical constant parameters such as refractive index and absorption index were obtained for the films. The results for the alternating-current (ac) conductivity and the dielectric constant of the four films are presented over the temperature range 277,357 K and the frequency range 0.1 to 1000 kHz. The ac conductivity increases with temperature and frequency and decreases with the increase in Ni2+ or Co2+ content. The effect of composition and temperature on the dielectric constant was also studied. The frequency variation of the dielectric constant does not have a peak, unlike many semiconductor glasses. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    VISCOUS PROPERTIES OF TARO FLOUR EXTRUDED WITH WHEY PROTEINS TO SIMULATE WEANING FOODS,

    JOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 3 2002
    C. I. ONWULATA
    Taro flour, derived from the corm of Colocasia Esculenta cv. Lehua, a root tuber grown in the tropical regions of the world, was extruded with whey protein concentrate (WPC), whey protein isolate (WPI) or lactalbumin (LAC), to derive blends containing 20% protein, simulating the protein content of some weaning foods. Taro flour is unique because of its extremely small particle size (1,5 micron) and high mucilage or gum content, making it a possible replacement for corn or wheat starch in weaning foods. Extrusion processing temperatures were from 100 to 130C and moisture of the feed blends was held constant at 18%. The extrudates were pulverized, made into powders, and rehydrated to make a paste. Viscosities of the feed blends before extrusion and the pastes made from the extrudates were determined using a Rapid Visco Analyzer (RVA) to determine peak, final, and breakdown viscosities. Water solubility and absorption indices were also determined. Extrudates made from taro containing whey products expanded more than taro alone; were easier to grind into powders; and rehydrated readily in water to form pastes. Before extrusion, the peak viscosities of the blends were 5000, 2600, 1600, 1600 cP for taro flour, taro with WPI, taro with WPC, or taro with LAC, respectively. After extrusion cooking, the viscosities for taro flour, taro with WPI, taro with WPC, or taro with LAC were 110, 65, 70 or 90 cP, respectively. Taro extrudates without protein absorbed the most water, and were more soluble than products containing whey proteins or LAC. The addition of whey proteins reduced peak viscosities, but WPI and taro pastes were characteristic of weaning foods. Both extrusion cooking and the [source]

    Evolutionary population synthesis for binary stellar population at high spectral resolution: integrated spectral energy distributions and absorption-feature indices

    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2005
    Fenghui Zhang
    ABSTRACT Using evolutionary population synthesis, we present high-resolution (0.3 Å) integrated spectral energy distributions from 3000 to 7000 Å and absorption-line indices defined by the Lick Observatory Image Dissector Scanner (Lick/IDS) system, for an extensive set of instantaneous-burst binary stellar populations with binary interactions. The ages of the populations are in the range 1,15 Gyr and the metallicities are in the range 0.004,0.03. These high-resolution synthesis results can satisfy the needs of modern spectroscopic galaxy surveys, and are available on request. By comparing the synthetic continuum of populations at high and low resolution, we show that there is good agreement for solar metallicity and tolerable disagreement for non-solar metallicity. The strength of the Balmer lines at high spectral resolution is greater than that at low resolution for all metallicities. The comparison of Lick/IDS absorption-line indices at low and high resolution, both of which are obtained by the fitting functions, shows that the discrepancies in all indices except for TiO1 and TiO2 are insignificant for populations with Z= 0.004 and 0.02. The high-resolution Ca4227, Fe5015 and Mgb indices are redder than the corresponding low-resolution ones for populations with Z= 0.01 and 0.03; this effect lowers the derived age and metallicity of the population. The high-resolution Mg1, Fe5709 and Fe5782 indices are bluer than those at low resolution; this effect raises the age and metallicity. The discrepancy in these six indices is greater for populations with Z= 0.03 in comparison to Z= 0.01. At high resolution we compare the Lick/IDS spectral absorption indices obtained by using the fitting functions with those measured directly from the synthetic spectra. We find that the Ca4455, Fe4668, Mgb and Na D indices obtained by the use of the fitting functions are redder for all metallicities, Fe5709 is redder at Z= 0.03 and becomes bluer at Z= 0.01 and 0.004, and the other indices are bluer for all metallicities than the corresponding values measured directly from the synthetic spectra. [source]