Packing Characteristics of Starch Granules

Willett, J. L.

doi:10.1094/cchem.2001.78.1.64

Cited by 24 publications

(16 citation statements)

References 19 publications

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“…Thus the packing fraction f c of rice starch was approximately 0.067/0.16 < 0.42. This value is in very good agreement with the value of 0.45 obtained by Willett [21] for rice starch, using a different method.…”

Section: Viscosity Determination From the Swelling Measurementssupporting

confidence: 91%

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Viscosity, Swelling and Starch Leaching During the Early Stages of Pasting of Normal and Waxy Rice Starch Suspensions Containing Different Milk Protein Ingredients

et al. 2007

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The effects of three milk protein ingredients, sodium caseinate (NaCAS), whey protein isolate (WPI) and skim milk powder (SMP), on the swelling and leaching behaviour of normal and waxy rice starch solutions, during the early stages of pasting, were investigated. It was found that the swelling onset temperature for both starches was increased by NaCAS and SMP but was not affected by WPI. Furthermore, onset temperature determined by the swelling measurements was lower than the onset temperature determined from viscosity measurements. However, the calculated viscometric onset temperature, using the Maron-Pierce equation and the results of the swelling measurements, was found to be in very good agreement with the measured viscometric onset temperature. This study also showed that the quantity of leached polysaccharides during the early stages of starch pasting was very small, indicating that significant leaching of polysaccharides during pasting primarily occurs after the breakup of the sheared starch granules.Starch/Stärke 59 (2007) 379-387 379 Recently, Noisuwan et al. [13] investigated the effect of the addition of NaCAS, WPI and skim milk powder (SMP) on the pasting behaviour of normal and waxy rice starches, and found that all three milk protein ingredients affected markedly and differently the pasting behaviour of the two rice starches. In the case of normal rice starch, SMP and NaCAS shifted the temperature of the peak viscosity to higher temperatures, whereas WPI reduced the temperature of the peak viscosity. For waxy rice starch, SMP, NaCAS and WPI increased the temperature of the peak viscosity. In addition, although the gelatinisa-

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Section: Viscosity Determination From the Swelling Measurementssupporting

confidence: 91%

“…2 and 3 at 507C). As the density of rice starch is 1.5 g/cm 3 [21], the exact volume fraction occupied by the starch was 10 %/1.5 = 6.7 %, because the starch was added at a weight fraction of 10 %. Thus the packing fraction f c of rice starch was approximately 0.067/0.16 < 0.42.…”

Section: Viscosity Determination From the Swelling Measurementsmentioning

confidence: 99%

Viscosity, Swelling and Starch Leaching During the Early Stages of Pasting of Normal and Waxy Rice Starch Suspensions Containing Different Milk Protein Ingredients

et al. 2007

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“…The critical packing fraction φ cr is the value at which the cornstarch suspension dynamically jams. It must lie in between the 060401-3 static, sedimented (0.44) and the maximally compacted (0.57) value [19]. From creating the densest, still flowing cornstarch suspension in our laboratory, we estimate that φ cr = 0.46 at most.…”

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confidence: 85%

Nonmonotonic settling of a sphere in a cornstarch suspension

et al. 2011

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Cornstarch suspensions exhibit remarkable behavior. Here, we present two unexpected observations for a sphere settling in such a suspension: In the bulk of the liquid the velocity of the sphere oscillates around a terminal value, without damping. Near the bottom the sphere comes to a full stop, but then accelerates again toward a second stop. This stop-go cycle is repeated several times before the object reaches the bottom. We show that common shear thickening or linear viscoelastic models cannot account for the observed phenomena, and propose a minimal jamming model to describe the behavior at the bottom. Concentrated particulate suspensions consist of a homogeneous fluid containing particles, larger than 1 μm. They can be found everywhere, and their flow is important in nature, industry, and even health care [1]. In spite of their significance, many aspects of the flow of these dense suspensions remain poorly understood. In order to study these materials, people have used methods inspired by classical rheology, and typically characterized them in terms of a constitutive relation of stress versus shear rate [2][3][4][5][6]. A general result is that, when increasing the shear rate, dense suspensions first tend to become less viscous (shear thinning) and subsequently shear thicken.Probably the most conspicuous example of a dense suspension is formed by a high concentration of cornstarch in water. Recent rheological experiments in cornstarch have revealed the existence of a mesoscopic length scale [6,7], a shear thinning regime that terminates in a sudden shear thickening [8], a dynamic jamming point [4], and fracturing [9]. Merkt et al. [10] observed in a vertically shaken, thin layer of cornstarch suspension that, among other exotic phenomena, stable oscillating holes can be formed at certain frequencies and amplitudes [10,11], which were subsequently described using a phenomenological model based on a hysteretic constitutive equation [12]. At present, however, we are still far from a detailed understanding of dense suspensions.In this Rapid Communication we subject a cornstarch suspension to a basic experiment, in which we observe and describe the settling of a spherical object in a deep bath of suspension. This yields two interesting observations. In the bulk, we find that the object velocity is oscillating in addition to going toward a terminal value. Near the bottom we observe a second phenomenon: The object comes to a full stop before the bottom, but then accelerates again, and this stop-go cycle can repeat up to seven times. We will show that both bulk and bottom behavior are conceptually different from that observed in a wide range of other fluids. We propose a jamming model for the stop-go cycles near the bottom that specifically includes the liquid-grain interactions.Experiment. Our experimental setup is shown in Fig. 1(a). It consists of a 12 × 12 × 30 cm 3 glass container containing a mixture of cornstarch and liquid. For the liquid we use either demineralized water or an aqueous solution of CsCl with...

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“…f c is the packing fraction of the rice starch granules in the capillary tube; it is calculated using f 0 ¼ 0.033 and 1.5 g cm À3 as the density of rice starch (Willett, 2001). As the concentration by weight of the added starch is 2%, the volume fraction is 0.02/1.5 ¼ 0.0133 and the packing fraction is f c ¼ 0.013/ 0.033E0.40, which is very close to the value of 0.42 reported by Noisuwan et al (2007).…”

Section: Article In Pressmentioning

confidence: 99%