02204nas a2200205   4500008004100000022001400041245003400055210003400089260009900123300001200222490000700234520159000241653001901831653001301850653001401863100001701877700001601894700002101910856006701931       2006                        eng d  a0260-877400aStudies on shrikhand rheology0 aStudies on shrikhand rheology  aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLANDbELSEVIER SCI LTDcMAY  a169-1770 v743 a<p>Shrikhand, a popular Indian dessert made from yogurt, is manufactured on an industrial scale using several chemical engineering unit operations such as mixing, filtration and heat transfer. Understanding the rheology of shrikhand is not only relevant for designing large scale mixers but can also provide quantitative means for linking the microstructure of shrikhand to its perception of texture, consistency and taste. We show here that shrikhand exhibits a combination of several rheological properties such as weak gel-like viscoelasticity, an apparent yield stress, thixotropy and long structural recovery time scales. For instance, the elastic modulus is always higher than the loss modulus over the measurable frequency range and that both moduli show only weak frequency dependence that is a characteristic of gel-like consistency. Forward and reverse rate sweep tests show a distinct hysteresis loop, which is a signature of thixotropic character. In an attempt to trace the origins of these rheological properties in shrikhand we characterized its microstructure and showed that there exist two different microstructures: one composed of crystallites of milk fats having a length scale of similar to 50-100 mu m, and the other composed of aggregates of colloidal cascin micelles of similar to 0.5-10 mu m size. Our studies show that while the temperature sensitivity of the viscoelastic parameters is dominated by the semicrystalline milk fat microstructure, the shear sensitivity is largely dictated by the protein network. (c) 2005 Elsevier Ltd. All rights reserved.</p>10aMicrostructure10aRheology10ashrikhand1 aKulkarni, C.1 aBelsare, N.1 aLele, Ashish, K.  uhttp://library.ncl.res.in/content/studies-shrikhand-rheology-002271nas a2200253   4500008004100000022001400041245006300055210006300118260000800181300001200189490000700201520153700208653002001745653001501765653000801780653001901788653001301807653001701820100002101837700002301858700002101881700002101902856009401923       2020                        eng d  a0035-451100aMicrostructure and yielding of capillary force induced gel0 aMicrostructure and yielding of capillary force induced gel  cMAY  a291-3060 v593 a<p>We have investigated the rheology and structure of a gel formed from a mixture of non-Brownian particles and two immiscible liquids. The suspension of particles in a liquid undergoes gelation upon the addition of a small content of second, wetting liquid which forms liquid bridges between particles leading to a sample spanning network. The rheology of this gel primarily exhibits a yield stress at low shear rates followed by a linear variation of shear stress at high shear rates. The apparent yield stress extracted from the flow curves increases rapidly with volume fraction of the second liquid before saturation, while it exhibits a monotonic increase with increasing particle concentration. Rescaling of the yield stress curves using suitable shift factors results in an empirical expression for the yield stress showing squared dependence on liquid fraction and a rapid increase with particle fraction above a certain value, both combined in a highly non-linear manner. The microstructural variations with changing secondary liquid content and particle fractions are captured using three-dimensional X-ray tomography technique. The microstructure is observed to show increased local compactness with increased liquid content and increased spatial homogeneity with increased particle fractions. The images from X-ray tomography are analysed to obtain the distributions of particle-particle bonds (coordination number) in the system which serve to explain the observed yield stress behaviour in a qualitative manner.</p>
10aCapillary force10aFlow curve10agel10aMicrostructure10aRheology10aYield stress1 aHuprikar, Sameer1 aUsgaonkar, Saurabh1 aLele, Ashish, K.1 aOrpe, Ashish, V.  uhttp://library.ncl.res.in/content/microstructure-and-yielding-capillary-force-induced-gel