Description of Extrudate Characteristics in Relation to the Shear Stress of Plasticised Starches Determined In-line

Bindzus, Wolfgang; Fayard, Gilles; Lengerich, Bernhard van; Meuser, F.

doi:10.1002/1521-379x(200206)54:6<252::aid-star252>3.0.co;2-v

Cited by 12 publications

(6 citation statements)

References 10 publications

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“…Different starches underwent different amounts of molecular degradation, as evidenced by changes in gel permeation chromatograms. However degradation of starch increases with the specific mechanical energy applied during extrusion cooking (Bindzus, Fayard, van Lengerich & Meuser, 2002). In the case of microfluidisation of heated and sheared starches, there is an increase in the depolymerisation of the starch chain with increasing microfluidisation pressure, but only increasing passes at the higher pressure (80 MPa) resulted in a further small increase in degradation.…”

Section: Apparent Molecular Weightmentioning

confidence: 99%

Functional performance of a resistant starch ingredient modified using a microfluidiser

Augustin

Sanguansri

Htoon

2008

Innovative Food Science & Emerging Technologies

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Section: Apparent Molecular Weightmentioning

confidence: 99%

Functional performance of a resistant starch ingredient modified using a microfluidiser

Augustin

Sanguansri

Htoon

2008

Innovative Food Science & Emerging Technologies

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“…The lower cold swelling peak and end viscosity depicted in the RVA pasting profiles for wheats extruded at high SME indicated that a high extrusion regime had caused greater macromolecular breakdown of starch polysaccharides than low SME processing. Indeed a lower molecular weight is known to decrease the cold paste viscosity of the extrudate (Bindzus et al, 2002).…”

Section: Effect Of Extrusionmentioning

confidence: 99%

Physicochemical changes to starch granules during micronisation and extrusion processing of wheat, and their implications for starch digestibility in the newly weaned piglet

White

Doucet

Hill

et al. 2008

Animal

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Two trials were performed to assess changes in the physicochemical properties of precisely processed (micronised v. extruded) wheats, prior to inclusion in piglet diets. The in vitro data obtained were subsequently related to biological responses of newly weaned piglets over 14 days. The effects of the severity of micronisation (Trial 1) or extrusion (Trial 2) on the nutritional value of two wheats (varying in endosperm texture) were examined. Extrusion, in contrast to micronisation, drastically disrupted the structural properties of wheat starch granules through melting of crystallites and macromolecular degradation of starch polysaccharides. These structural changes strongly improved the hydration characteristics of starch and its digestibility. The amount of starch digested in vitro was approximately 0.20, 0.70 and 0.90 for the unprocessed, micronised and extruded samples, respectively. This enhanced in vitro digestibility correlated well with, and helped to explain, the significant improvement in the apparent digestibility of starch at both the 0.5 region (mean coefficients for extruded wheat were 0.869 and 0.959 v. raw 0.392; P 5 0.017) and 0.75 region (extruded 0.973 v. raw 0.809; P 5 0.009) of the small intestine, when compared with piglets fed an unprocessed wheat diet. Extrusion and, to a lesser extent, micronisation lessened the reduction in apparent starch digestibility on day 4 post-weaning, typically seen at the 0.5 intestinal region in piglets fed an unprocessed wheat diet. Processing variables influenced both in vitro and in vivo data, with for instance, a positive relationship between specific mechanical energy (SME) input during extrusion and starch digestibility at the 0.5 region. The higher digestibility coefficient observed at the 0.5 region for the high SME diet suggests enhanced digestion and more rapid release of starch. However, it remains to be seen whether a diet containing rapidly digestible, as opposed to slowly digestible, starch is more beneficial for piglets. This rate of starch breakdown in the piglet is an important finding, which may have implications in helping to alleviate the post-weaning growth check, particularly in the absence of in-feed antibiotic growth promoters. Processing did not appear to offer any benefit over unprocessed wheat with regard to daily live-weight gain or the apparent digestibility of nitrogen in the small intestine over the 14-day period. Based on the enhanced in vivo starch digestibility, performance might be improved over a longer period, although future studies are required to confirm this. Precise processing variables for raw materials must be stated in all animal trials.

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“…Therefore, the degradation of the starch polymers caused by extrusion-cooking resulted in a decrease in the shear stress of the plasticised material in the range of extrusion conditions under investigation [26,38]. It has already been demonstrated that the development of the functional properties (CWS and CPV) of starch extrudates is determined by degradation of the starch polymers [3].…”

Section: Relationship Between Shear Stress and The Product Characterimentioning

confidence: 99%

Application of an In-line Viscometer to Determine the Shear Stress of Plasticised Wheat Starch

Bindzus¹,

Fayard²,

Lengerich³

et al. 2002

Starch/Stärke

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An in-line viscometer was designed and constructed to enable determination of the shear stress of plasticised wheat starch during extrusion cooking. The viscometer was installed between the end of the barrel section and the extruder die plate so that the shear stress could be determined for the plasticised material, irrespective of the geometrical shape into which it was subsequently moulded by the extruder die. The extrusion conditions were described in terms of the process parameters, i. e. water content, barrel temperature, screw speed and screw configuration; and of the system parameters, which were the specific mechanical energy input (SME), product temperature (PT) and mean residence time (MRT). The parameters were measured and the results evaluated using statistical methods. Regression equations were used to describe functional relationships between the shear stress and the extrusion conditions on the one hand, and between the shear stress and the product characteristics of the extrudates on the other. The shear stress of plasticised wheat starch determined in-line can be used to predict the morphological structure (volumetric expansion) and the functional properties (cold paste viscosity and cold water solubility) of extruded, directly expanded starch with a high degree of accuracy. The measurement technique used and the results of the extrusion tests undertaken for this project will therefore enable the shear stress of plasticised material in an extruder to be used as the principle parameter for controlling extruders on-line.

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Description of Extrudate Characteristics in Relation to the Shear Stress of Plasticised Starches Determined In-line

Abstract: The configuration of the twin-screw laboratory extruder (Bühler AG, Uzwil, Switzerland, type DNDL-44) and the in-line viscometer used for the determination and on-line measurement of the shear stress of the plasticised materials have already been described [1,2].

Cited by 12 publications

References 10 publications

Functional performance of a resistant starch ingredient modified using a microfluidiser

Functional performance of a resistant starch ingredient modified using a microfluidiser

Physicochemical changes to starch granules during micronisation and extrusion processing of wheat, and their implications for starch digestibility in the newly weaned piglet

Application of an In-line Viscometer to Determine the Shear Stress of Plasticised Wheat Starch

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