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Impact of the Soak and the Malt on the Physicochemical Properties of the Sorghum Starches  [PDF]
Irakoze Pierre Claver,Haihua Zhang,Qin Li,Kexue Zhu,Huiming Zhou
International Journal of Molecular Sciences , 2010, DOI: 10.3390/ijms11083002
Abstract: Starches were isolated from soaked and malted sorghum and studied to understand their physicochemical and functional properties. The swelling power (SP) and the water solubility index (WSI) of both starches were nearly similar at temperatures below 50 °C, but at more than 50 °C, the starch isolated from malted sorghum showed lower SP and high WSI than those isolated from raw and soaked sorghum. The pasting properties of starches determined by rapid visco-analyzer (RVA) showed that malted sorghum starch had a lower viscosity peak value (86 BU/RVU) than raw sorghum starch (454 BU/RVU). For both sorghum, X-ray diffractograms exhibited an A-type diffraction pattern, typical of cereal starches and the relative degrees of crystallinity ranged from 9.62 to 15.50%. Differential scanning calorimetry (DSC) revealed that raw sorghum starch showed an endotherm with a peak temperature (Tp) at 78.06 °C and gelatinization enthalpies of 2.83 J/g whereas five-day malted sorghum starch had a Tp at 47.22 °C and gelatinization enthalpies of 2.06 J/g. Storage modulus (G′) and loss modulus (G″) of all starch suspensions increased steeply to a maximum at 70 °C and then decreased with continuous heating. The structural analysis of malted sorghum starch showed porosity on the granule’s surface susceptible to the amylolysis. The results showed that physicochemical and functional properties of sorghum starches are influenced by soaking and malting methods.
Effect of chemical modification type on physicochemical and rheological characteristics of banana starch
Guerra-DellaValle, D.;Sánchez-Rivera, M. M.;Zamudio-Flores, P. B.;Méndez-Montealvo, G.;Bello-Pérez, L. A.;
Revista mexicana de ingeniería química , 2009,
Abstract: isolation of non-conventional starches has increased in the last decade; chemical modification of these no conventional starches may produce starches with improved physicochemical and functional properties that are not available from commercial starches. banana starch was acetylated and oxidized and the thermal, pasting and rheological characteristics were evaluated. the low carbonyl and carboxyl groups might be due to the starch source. the acetylated banana starch obtained had a low degree of substitution (0.04). the acetylated banana starch had lower temperature and enthalpy of gelatinization than oxidized and native banana starches, had higher peak viscosity in the viscoamylographic profile than its native counterpart. the oxidized starch produced the peak viscosity during the cooling step and the three starches had higher viscosity during the cooling step, showing a gel conformation. the native, acetylated and oxidized starches showed a non-newtonian behavior of the shear-thinning type. the rotational test showed that oxidized banana starch had a firmer gel than acetylated starch, which agrees with the viscoamylographic results.
Effect of enzymatic hydrolysis on some physicochemical properties of root and tuber granular starches
Rocha, Thaís de Souza;Carneiro, Ana Paula de Almeida;Franco, Celia Maria Landi;
Ciência e Tecnologia de Alimentos , 2010, DOI: 10.1590/S0101-20612010000200039
Abstract: enzymatic hydrolysis of granular starch is an important tool to provide information about granule structure. cassava, sweet potato, peruvian carrot, and potato starches were hydrolyzed by bacterial α-amylase at 37 °c for 48 hours, and the physicochemical properties of the residues from hydrolysis were determined. cassava starch was the most susceptible to enzyme displaying 20.9% of hydrolysis, whereas potato starch was the most resistant with 5.9%. the granule average size varied from 10.8 to 23.4 μm for peruvian carrot and potato starches, respectively. with the use of sem, a smooth granule surface was observed for all native starches. cassava and sweet potato starches displayed an a-type x-ray diffraction pattern, while peruvian carrot and potato starches showed a b-type pattern. after hydrolysis, cassava, sweet potato, and peruvian carrot starches showed some well degraded granules, whereas potato starch presented a slight sign of degradation. the amylose content of the starches decreased with hydrolysis for cassava, sweet potato, and peruvian carrot starches and was kept unchanged for the potato starch. as expected, intrinsic viscosity and pasting properties decreased for all hydrolyzed starches. there is no difference between thermal properties of native and hydrolyzed starches. these results suggested that hydrolysis occurred in amorphous and crystalline areas of the granules. the b type diffraction pattern in conjunction with the big granule size of the potato starch may have contributed to the greatest resistance of this starch to hydrolysis.
PHYSICOCHEMICAL CHARACTERIZATION OF NATURAL AND ACETYLATED THERMOPLASTIC CASSAVA STARCH
MINA,JOSE; VALADEZ-GONZáLEZ,ALEX; HERRERA-FRANCO,PEDRO; ZULUAGA,FABIO; DELVASTO,SILVIO;
DYNA , 2011,
Abstract: thermoplastic starch (tps) was obtained from natural and acetylated cassava starch using a twin screw extruder and then conditioned at 25 oc and 54 % of relative humidity. it was found that the crystallinity index, calculated as the ratio of the ir peaks at 1047 (crystalline phase) and 1022 cm-1 (amorphous phase), decreases due to the effect of a plasticization process. also, as expected, sem micrographs show that the plasticization process destroyed the starch granular structure almost completely and an amorphous mass was obtained. the tga results indicated that the activation energy, ea, was also reduced by the plasticization process. the acetylated tps shows a decrease in tg, in tensile strength and in the percentage of moisture absorption compared to natural tps but a larger strain at the breaking point. this behavior suggests that the chemical modification reduces the secondary interactions between starch chains due to the substitution of the hydroxyl groups by acetates.
Intrinsic and Extrinsic Galaxy Alignment  [PDF]
Paolo Catelan,Marc Kamionkowski,Roger D. Blandford
Physics , 2000, DOI: 10.1046/j.1365-8711.2001.04105.x
Abstract: We show with analytic models that the assumption of uncorrelated intrinsic ellipticities of target sources that is usually made in searches for weak gravitational lensing due to large-scale mass inhomogeneities (``field lensing'') is unwarranted. If the orientation of the galaxy image is determined either by the angular momentum or the shape of the halo in which it forms, then the image should be aligned preferentially with the component of the tidal gravitational field perpendicular to the line of sight. Long-range correlations in the tidal field will thus lead to long-range ellipticity-ellipticity correlations that mimic the shear correlations due to weak gravitational lensing. We calculate the ellipticity-ellipticity correlation expected if halo shapes determine the observed galaxy shape, and we discuss uncertainties (which are still considerable) in the predicted amplitude of this correlation. The ellipticity-ellipticity correlation induced by angular momenta should be smaller. We consider several methods for discriminating between the weak-lensing (extrinsic) and intrinsic correlations, including the use of redshift information. An ellipticity--tidal-field correlation also implies the existence of an alignment of images of galaxies near clusters. Although the intrinsic alignment may complicate the interpretation of field-lensing results, it is inherently interesting as it may shed light on galaxy formation as well as on structure formation.
Physicochemical and Functional Properties of Some Cultivars of Irish Potato and Cassava Starches
P.D. Mbougueng,D. Tenin,J. Scher,C. Tchiegang
Journal of Food Technology , 2013,
Abstract: In this study, starches were extracted from two cultivars of local Irish potatos (Solanum tuberosum) and tree cultivars of local Cassava (Manihot esculanta). These starches and a commercial Irish Potato Starch (IPS), where characterized with respect to their physico-chemical and functional properties. Significant differences (p< 0.05) were observed among starches as far as their proximate composition were concerned. The commercial starch showed the highest phosphorus content. The amylose content was observed to be significantly lower (p< 0.05) in the cassava starches than in the local Irish potato starches. The highest (p< 0.05) gelatinisation parameters were those of 2425 starch cultivar. Potato starch granules exhibited the largest granule size at 10, 50 and 90% diameter compared to those of cassava starches. Potato starches had wider particle size distribution compared to cassava starches. There were apparent differences, between species (Cassava and potatoes) with respect to granule morphology and size. No significant colour difference (p>0.05) was observed between the Sipiera starch cultivars and the Irish potatoes commercial starch.
Intrinsic and extrinsic geometry of random surfaces  [PDF]
Thordur Jonsson
Physics , 1991, DOI: 10.1016/0370-2693(92)90716-H
Abstract: We prove that the extrinsic Hausdorff dimension is always greater than or equal to the intrinsic Hausdorff dimension in models of triangulated random surfaces with action which is quadratic in the separation of vertices. We furthermore derive a few naive scaling relations which relate the intrinsic Hausdorff dimension to other critical exponents. These relations suggest that the intrinsic Hausdorff dimension is infinite if the susceptibility does not diverge at the critical point.
Extrinsic and intrinsic determinants of nerve regeneration
Toby A. Ferguson,Young-Jin Son
Journal of Tissue Engineering , 2011, DOI: 10.1177/2041731411418392
Abstract: After central nervous system (CNS) injury axons fail to regenerate often leading to persistent neurologic deficit although injured peripheral nervous system (PNS) axons mount a robust regenerative response that may lead to functional recovery. Some of the failures of CNS regeneration arise from the many glial-based inhibitory molecules found in the injured CNS, whereas the intrinsic regenerative potential of some CNS neurons is actively curtailed during CNS maturation and limited after injury. In this review, the molecular basis for extrinsic and intrinsic modulation of axon regeneration within the nervous system is evaluated. A more complete understanding of the factors limiting axonal regeneration will provide a rational basis, which is used to develop improved treatments for nervous system injury.
Intrinsic and extrinsic properties of quantum systems  [PDF]
P. Hajicek,J. Tolar
Physics , 2008,
Abstract: The paper attempts to convince that the orthodox interpretation of quantum mechanics does not contradict philosophical realism by throwing light onto certain properties of quantum systems that seem to have escaped attention as yet. The exposition starts with the philosophical notions of realism. Then, the quantum mechanics as it is usually taught is demoted to a mere part of the theory called phenomenology of observations, and the common impression about its contradiction to realism is explained. The main idea of the paper, the physical notion of intrinsic properties, is introduced and many examples thereof are given. It replaces the irritating dichotomy of quantum and classical worlds by a much softer difference between intrinsic and extrinsic properties, which concern equally microscopic and macroscopic systems. Finally, the classicality and the quantum measurement are analyzed and found to present some still unsolved problems. A possible way of dealing with the Schr\"{o}dinger cat is suggested that is based on the intrinsic properties. A simple quantum model of one classical property illustrates how our philosophy may work.
Intrinsic and extrinsic measure for Brownian motion  [PDF]
Pavel Castro-Villarreal
Statistics , 2014, DOI: 10.1088/1742-5468/2014/05/P05017
Abstract: Based upon the Smoluchowski equation on curved manifolds three physical observables are considered for the Brownian displacement, namely, geodesic displacement, $s$, Euclidean displacement, $\delta{\bf R}$, and projected displacement $\delta{\bf R}_{\perp}$. The Weingarten-Gauss equations are used to calculate the mean-square Euclidean displacements in the short-time regime. Our findings show that from an extrinsic point of view the geometry of the space affects the Brownian motion in such a way that the particle's diffusion is decelerated, contrasting with the intrinsic point of view where dynamics is controlled by the sign of the Gaussian curvature [J. Stat. Mech. P08006 (2010)]. Furthermore, it is possible to give exact formulae for $\left<\delta{\bf R}\right>$ and $\left<\delta{\bf R}^{2}\right>$ on spheres and minimal surfaces, which are valid for all values of time. In the latter case, surprisingly, Brownian motion corresponds to the usual diffusion in flat geometries, albeit minimal surfaces have non-zero Gaussian curvature. Finally, the two-dimensional case is emphasized due to its close relation to surface self-diffusion in fluid membranes.
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