The Effect of Water Content on the Compaction Behaviour of Potato Starch

Ollett, A.-L.; Kirby, Andrew R.; Clark, Sybil A.; Parker, Roger; Smith, Andrew C.

doi:10.1002/star.19930450205

Cited by 12 publications

(4 citation statements)

References 15 publications

(13 reference statements)

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“…Ollet et al [24] observed that in the region of the glass transition (at ambient temperatures with a water content of 20% the elastic modulus is extremely sensitive to water content. Above 20% they found that starch granules were rubbery and allowed extensive elastic deformation in response to the stress, whilst below 18% the elastic modulus was more typical of a glass and only relatively small elastic deformations could occur.…”

Section: Discussionmentioning

confidence: 99%

Holes in Starch Granules: Confocal, SEM and Light Microscopy Studies of Starch Granule Structure

et al. 1994

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Following an initial observation of putative holes within potato starch granules during observation in a medium with the same refractive index, the internal architecture of starch granules has been investigated using confocal, scanning electron and light microscopy. These complimentary microscopy techniques confirmed the existence of holes at the hilum of potato, rice and wheat starch granules. Observations were made with minimal sample preparation to avoid the generation of artifactual holes. Using image analysis we have quantitatively measured the occurrence and the size distribution of holes and linked their appearance to the drying of the granule.

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Section: Discussionmentioning

confidence: 99%

Holes in Starch Granules: Confocal, SEM and Light Microscopy Studies of Starch Granule Structure

et al. 1994

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“…[8][9][10] The mechanical properties of starch are well documented in the literature. [11][12][13][14] It has been reported that pregelatinised starch, which is produced by heating an aqueous slurry of starch, followed by a thermic dehydration process 4) (e.g.…”

mentioning

confidence: 99%

“…[11][12][13][14] The plasticity of starch was found to be dependent on particle size, size distribution, particle shape, moisture content and compaction speed. 8,15) Also, starch is extremely sensitive to the softening effects of alkaline stearate lubricants and thus, it has a high strain sensitivity index.…”

mentioning

confidence: 99%

Influence of Physical Parameters and Lubricants on the Compaction Properties of Granulated and Non-granulated Cross-linked High Amylose Starch.

Rahmouni

Lenaerts²,

Massuelle

et al. 2002

CHEMICAL & PHARMACEUTICAL BULLETIN

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“…In one study (Ollett ot ail., 1991), the Young's modulus of wheat starch was found to decrease from 1500 MPa to 50 MPa when the water content was increased from 16 to 20%. Although the starches were reported to exhibit limited yielding (Rees and Rue, 1978), electron microscopic investigation shows that this is relatively insensitive to water content for potato starch (Ollett et al, 1993b). The large variation in deformation stress determined from the Heckel plot is predominantly due to the changes in elastic modulus with water content.…”

Section: Resultsmentioning

confidence: 98%

Compaction and flow of potato starch and potato granules Compactación y flujo de almidón de patata y gránulos de patata

Halliday

Smith

1997

Food sci. technol. int.

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Potato starch and potato granules are materials that are often used in extrusion processes. It is important to quantify their rheology for modelling and prediction of process performance. The compaction behaviour of potato starch was examined at water contents of 4-18% wwb (wet weight basis) for pressures between 1 and 85 MPa. The Heckel deformation stress decreased as the water content increased up to 12% but became inaccurate at 18%. This decrease agreed qualitatively with other observations of the decrease in stiffness of starchy materials over this water content range. Potato granules were examined at water contents of 25-45% wwb and aspects of their rheological behaviour characterized using different approaches. A first approximation used the shear viscosity-shear rate power law which produced a law exponent for the resulting pastes (0.1-0.2). The classical Benbow equation was used to estimate yield and wall shear stresses in capillary flow. The latter indicates the presence of slip which was examined more fully as a function of wall shear stress. The Mooney technique was used together with a variation of the method where the shear rate for each die was subtracted from that for a non-slip flow, which was approximated using rough dies. A critical wall shear stress for slip was found to be 0.05-0.1 MPa, making it consistent with published results for other materials.El almidón y (os grannies de patata son materias usadas frecuentenmente en procesos de extrusion. Es importante cuantificar sus reologia para el control y prediccion del rendimiento de sus procesos. En este trabajo se ha estudiado el comportamiento de la compactacion de almidein de patata con un contenido de humedad de 4 a 18% (en peso base humeda) sometido de 1 a 85 MPa de presion.Se observo una disminucion en el esfuerzo de deformaci6n de Heckel con el incremento del contenido de humedad, hasta un 12%, sin embargo para un 18% perdio la exactitud.Tal decremento concuerda cualitativamente con observaciones previas en la disminucion de la rigidez de materiales almidonados en el intervalo de humedades mencionado. Tambi6n se examinaron granulos de patata con una humedad del 25 al 45%. (en peso base humeda) y se estudiaron sus -caracteristicas reol6gicas mediante diferentes modelos. Mediante el modelo de la ley de la potencia ' se obtuvo un bajo exponente para las pastas, del orden de 0.1 a 0.2. La ecuacion clasica de Benbow se emp]e6 para estimar los esfuerzos de corte y los de fluencia en tlujo capilar. Se observo un arrastre viscoso que se analiz6 que en fiinci6n del esfuerzo de corte en la pared. La tecnica de Mooney se utilizó, con la modificaci6n de que la velocidad de deformaci6n se substrae de la del flujo de no arrastre, usando orificios rugosos. Se encontro un esfuerzo critico de corte para el . arrastre viscoso del orden de 0.05 a 0.1 MPa, que concuerda con los valores publicados para otros materiales.Palabras claie: compactación, flujo, reologfa, extrusion, almidón de patata, griiiulos de patata * To aolrorrr correspolldcllcc slioiild be sm...

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The Effect of Water Content on the Compaction Behaviour of Potato Starch

Cited by 12 publications

References 15 publications

Holes in Starch Granules: Confocal, SEM and Light Microscopy Studies of Starch Granule Structure

Holes in Starch Granules: Confocal, SEM and Light Microscopy Studies of Starch Granule Structure

Influence of Physical Parameters and Lubricants on the Compaction Properties of Granulated and Non-granulated Cross-linked High Amylose Starch.

Compaction and flow of potato starch and potato granules Compactación y flujo de almidón de patata y gránulos de patata

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