Dynamic and steady: shear rheological properties of xanthan and guar gums dispersed in yellow passion fruit pulp (Passiflora edulis f. flavicarpa)
Yellow passion fruit pulp is unstable, presenting phase separation that can be avoided by the addition of hydrocolloids. For this purpose, xanthan and guar gum [0.3, 0.7 and 1.0% (w/w)] were added to yellow passion fruit pulp and the changes in the dynamic and steady - shear rheological behavior eva...
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Brazilian Society of Chemical Engineering
2011-09-01
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doaj-4669a9b89fec49788ac14caf39301afc2020-11-24T22:34:16ZengBrazilian Society of Chemical EngineeringBrazilian Journal of Chemical Engineering0104-66321678-43832011-09-0128348349410.1590/S0104-66322011000300014Dynamic and steady: shear rheological properties of xanthan and guar gums dispersed in yellow passion fruit pulp (Passiflora edulis f. flavicarpa)I. C. F MoraesL. H FasolinR. L CunhaF. C MenegalliYellow passion fruit pulp is unstable, presenting phase separation that can be avoided by the addition of hydrocolloids. For this purpose, xanthan and guar gum [0.3, 0.7 and 1.0% (w/w)] were added to yellow passion fruit pulp and the changes in the dynamic and steady - shear rheological behavior evaluated. Xanthan dispersions showed a more pronounced pseudoplasticity and the presence of yield stress, which was not observed in the guar gum dispersions. Cross model fitting to flow curves showed that the xanthan suspensions also had higher zero shear viscosity than the guar suspensions, and, for both gums, an increase in temperature led to lower values for this parameter. The gums showed different behavior as a function of temperature in the range of 5 - 35ºC. The activation energy of the apparent viscosity was dependent on the shear rate and gum concentration for guar, whereas for xanthan these values only varied with the concentration. The mechanical spectra were well described by the generalized Maxwell model and the xanthan dispersions showed a more elastic character than the guar dispersions, with higher values for the relaxation time. Xanthan was characterized as a weak gel, while guar presented a concentrated solution behavior. The simultaneous evaluation of temperature and concentration showed a stronger influence of the polysaccharide concentration on the apparent viscosity and the G' and G" moduli than the variation in temperature.http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322011000300014Yellow passion fruitXanthanGuarRheology |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
I. C. F Moraes L. H Fasolin R. L Cunha F. C Menegalli |
spellingShingle |
I. C. F Moraes L. H Fasolin R. L Cunha F. C Menegalli Dynamic and steady: shear rheological properties of xanthan and guar gums dispersed in yellow passion fruit pulp (Passiflora edulis f. flavicarpa) Brazilian Journal of Chemical Engineering Yellow passion fruit Xanthan Guar Rheology |
author_facet |
I. C. F Moraes L. H Fasolin R. L Cunha F. C Menegalli |
author_sort |
I. C. F Moraes |
title |
Dynamic and steady: shear rheological properties of xanthan and guar gums dispersed in yellow passion fruit pulp (Passiflora edulis f. flavicarpa) |
title_short |
Dynamic and steady: shear rheological properties of xanthan and guar gums dispersed in yellow passion fruit pulp (Passiflora edulis f. flavicarpa) |
title_full |
Dynamic and steady: shear rheological properties of xanthan and guar gums dispersed in yellow passion fruit pulp (Passiflora edulis f. flavicarpa) |
title_fullStr |
Dynamic and steady: shear rheological properties of xanthan and guar gums dispersed in yellow passion fruit pulp (Passiflora edulis f. flavicarpa) |
title_full_unstemmed |
Dynamic and steady: shear rheological properties of xanthan and guar gums dispersed in yellow passion fruit pulp (Passiflora edulis f. flavicarpa) |
title_sort |
dynamic and steady: shear rheological properties of xanthan and guar gums dispersed in yellow passion fruit pulp (passiflora edulis f. flavicarpa) |
publisher |
Brazilian Society of Chemical Engineering |
series |
Brazilian Journal of Chemical Engineering |
issn |
0104-6632 1678-4383 |
publishDate |
2011-09-01 |
description |
Yellow passion fruit pulp is unstable, presenting phase separation that can be avoided by the addition of hydrocolloids. For this purpose, xanthan and guar gum [0.3, 0.7 and 1.0% (w/w)] were added to yellow passion fruit pulp and the changes in the dynamic and steady - shear rheological behavior evaluated. Xanthan dispersions showed a more pronounced pseudoplasticity and the presence of yield stress, which was not observed in the guar gum dispersions. Cross model fitting to flow curves showed that the xanthan suspensions also had higher zero shear viscosity than the guar suspensions, and, for both gums, an increase in temperature led to lower values for this parameter. The gums showed different behavior as a function of temperature in the range of 5 - 35ºC. The activation energy of the apparent viscosity was dependent on the shear rate and gum concentration for guar, whereas for xanthan these values only varied with the concentration. The mechanical spectra were well described by the generalized Maxwell model and the xanthan dispersions showed a more elastic character than the guar dispersions, with higher values for the relaxation time. Xanthan was characterized as a weak gel, while guar presented a concentrated solution behavior. The simultaneous evaluation of temperature and concentration showed a stronger influence of the polysaccharide concentration on the apparent viscosity and the G' and G" moduli than the variation in temperature. |
topic |
Yellow passion fruit Xanthan Guar Rheology |
url |
http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322011000300014 |
work_keys_str_mv |
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