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Viscosity and acidity of selected type of natural yoghur
BÁRTOVÁ, Zuzana
The aim of the thesis was to evaluate the acidity and viscosity of natural yoghurt depending on the different addition of skimmed milk powder and using of the methods of sensory analysis to evaluate the perception of these properties by young consumers. Part of this work was to analyse acidity and viscozity in selected kinds of natural yoghurts purchased in the market network of the Czech Republic (CR). The literature search mentions basic characteristic of yoghurts and their classification, acidity and rheological properities of yoghurts including the factors, which affect them and sensory analysis. In the experimental part of the study the acidity value, total solids and viscosity measurements were detected by physico-chemical analyses of samples of natural yoghurts. At samples of yoghurts with different content of skimmed milk powder the sensory evaluation was also subjected and the graphs of sensory profile were compiled. The observed results showed, that from the samples of yoghurts made in the laboratory was the most satisfactory sample containing 10 % of skimmed milk powder. At samples purchased in the market network of CR were detected very low leveles of titratable acidity.
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Technological characteristics of meat - viscosity
DIBĎÁK, Tomáš
This bachelor thesis is focused on the technological characteristics of meat, mainly viscosity of meat. At the beginning I dealt with construction of meat and various types of meat: beef, veal, pork, mutton, rabbit, poultry and venison. Then I described basic chemical composition of meat and it?s characteristic. In detail I dealt with viscosity of meat. Viscosity is the ability of meat to bind water both own and added. I mentioned influences, which effects viscosity and I presented the possibilities, how to measure viscosity of meat. The last chapter describes the process of post mortem changes in meat both normal and abnormal.
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Povaha toku modelových suspenzí
Kulaviak, Lukáš ; Večeř, Marek ; Růžička, Marek ; Drahoš, Jiří ; Hladil, Jindřich
The main object of the present investigation is to test the settling abilities of mixtures of solid particles in liquids. The key quantity here is the magnitude of the viscosity, both of the carrying liquid (water-glycerol solutions) and the effective viscosity of the two-phase mixture. Few model systems were used (glass and polystyrene pellets), to study the settling process. The sedimentation were recorded by a video camera and the resulting deposit structure was photographed. Besides, also a real suspension was tested, of geological materials (calcite, quartz, mixed geological powder, etc.). Immersion rotary viscometer Brookfield with special spindles (RVT and V spindles) was used to measure the effective viscosity of the dispersion.
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Empirický model zohledňující lokální extrém průběhu viskozity
Filip, Petr ; David, Jiří ; Pivokonský, Radek
Almost all empirical models dealing with the flow curves of non- Newtonian fluids can be applied only in the case of monotonous course of these curves. Exceptionally it is possible to model viscosity behaviour of rheologically more complex materials if there appears, in the course of a flow curve, a global extreme. The 8-parameter model proposed enables a description of viscosity behaviour in dependence on shear rate or shear stress also for the case when an extreme (maximum or minimum) is only local.
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K charakterizaci Vočadlova modelu pomocí postupu zpětného vytlačování
Filip, Petr ; David, Jiří ; Pivokonský, Radek
Back extrusion represents one of the cheapest and time-saving experimental methods how to determine rheological characteristics of the fluids studied. This method is based on plunging of a circular rod into an axisymmetrically located circular cup containing the experimental sample. Formerly this method was successfully applied to power-law, Bingham and Herschel-Bulkley fluids. The aim of this contribution is to present a sufficiently simple user-friendly procedure how to determine the individual rheological parameters appearing in the Vočadlo model (sometimes called Robertson-Stiff one) - yield stress, consistency parameter and flow behaviour index.
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