The thesis on comparing products to ensure the colloidal stability of white wines before bottling in the theoretical part examined the definition of colloid division of disperse systems and their relation to wine. Further described is the main cataracts occurring in wines and methods to prevent them, focusing on the practice of the most commonly used products: Metatartaric acid, gum arabic and carboxymethylcellulose (CMC). In the practical part of these products in different variations, combinations and concentrations added to white wine, which was a non-stabilized against the tartar and proteins. This wine was in the wake of bottling and variants of the same stored for one year in two different storage temperatures. In the course of storage was observed formation of cataracts in individual bottles. After a year all variants were opened and evaluated was total sensory analysis with qualification and quantification of turbidity, sediment filtration and weighing, measuring conductivity and pH. The results were statistically processed and evaluated with recommendations for practice.

The theoretical part of this thesis deals with cellulolytic enzymes, their microbial producers, the possibilities of using such enzymes in the industry and how can be enzymes - not only cellulolytic - immobilized. Experimental part examines the preparations created by immobilizing various amounts of the commercially used cellulolytic complex Cellulast 1.5L onto various synthetic carriers made of polyethylene terephthalate - commercially used Sorsilen, PET carrier and glutaraldehyde-treated PET carrier. Enzyme activity of these preparations was determined by Somogyi - Nelson method by spectrophotometry. For the highest activity immobilized preparation was determined the temperature- and the pH-optimum. The difference in effects change between the free and immobilized enzyme by measuring viscosity decrease of the substrate depending on the degradation of glycosidic bonds was also studied.

The thesis on „Utilization of potassium polyaspartate to ensure wines crystal stability“ is divided in two section, as theoretical so practical part. Theoretic part examined general colloid definition and division of disperse systems. This part further described various kind of turbidities in connection to the wine itself. It comprising detailed turbidity description together with methods and prevention option through the most commonly used stabilizers (e.g. carboxymethylcellulose, metatartaric acid, gum arabic etc.). Experimental, is theoretical parts dealt with the experiment execution itself. The experiment focused on already known and in practice used preparations and their comparison with new potassium polyaspartate-based preparation. Stabilisers were added in different concentration, variants and combinations in non-stable wine. The wines were immediately botteled in with proper preparations and stored in two variants (cellar and indoor temperature). The parameters such as wine color variation and crystal turbidity formation were examined throughout the entire storage period for each option separately. From each variant were eastablished three equal bottles in order to verify potential opening and time-dependent differeneces of already used preparations. The wines were subjected various methods of evaluation (visual check, gravimetry, evaluation at Alpha machine, pH, turbidity) and the results were statistically evaluated and processed. In the end was the follow-up reseach recommended with the same subject of focus.

This diploma thesis is focused on two parts. The first one deals with rheological behavior of sodium carboxymethylcellulose (CMC-Na) solutions in the presence of sodium and calcium ions. The solutions of various concentrations were prepared by solubilization in aqueous solutions of NaCl or CaCl2. The effect of monovalent and bivalent ions on apparent viscosity and viscoelastic properties of these solutions was studied. It was found that in the case of low concentrations of CMC-Na in the sample (up to 0.5% w/w) the elastic character increases. At the same time the stiffness of the sample is higher with higher concentration of calcium ion in the solution. This increase might indicate the formation of gel network. On the other hand the viscosity of these solutions decreases with higher concentration of calcium ions. In case of solutions with concentration higher than 1.5% w/w changes of viscosity did not happen by influence of addition ions. Rheological behavior was compared also with solutions prepared without adding an electrolyte as well as with acid form of carboxymethylcellulose (CMC-H). In terms of second part the molecular dynamic simulations of hyaluronan tetramer both sodium and calcium in aqueous medium were performed. Structure and arrangement of water molecules in the surrounding of hyaluronan chain were studied. Structure was described by formalism of radial distribution functions. In the case of system containing sodium ions only, the obtained results are in accordance with earlier published data. Presence of calcium ions does not cause qualitative changes during the radial distribution functions in comparison with the system with sodium ions.