Rheological behavior of two commercial brands of stirred yogurt were investigated using a Haake RV 20 rotational viscometer. For samples from both brands, the upward shear-rate flow behavior generally followed the Herschel-Bulkley model and the downward flow curves were linear. They demonstrated progressive structural degradation with repeated shearing. In the steady shear runs, all samples exhibited apparent thixotropic behavior and did not attain the equilibrium condition even after 60 min of continuous shearing. The time-dependent stress decay behavior of all samples were accurately described by Weltman's logarithmic time model. The rheological properties of both yogurt brands were qualitatively similar. Both Arrhenius and Turian models were found suitable to assess the temperature influence in the range 10-25$ sp circ$C. / The influence of pectin (0.0 to 0.5%) and fruit concentrates (raspberry and strawberry) (64$ sp circ$B, 0 to 10%) on the rheology of stirred yogurt were evaluated. The influence of storage time at 2$ sp circ$C up to a period of four weeks on the rheological properties of the two brands were evaluated.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.60520 |
| Date | January 1991 |
| Creators | Basak, Sarmistha |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Department of Food Science and Agricultural Chemistry.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001246090, proquestno: AAIMM72088, Theses scanned by UMI/ProQuest. |
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