|
|
Acidobasic behavior of carboxymethylcellulose solutions
Teslíková, Ivana ; Kislinger, Jiří (referee) ; Janeček, Jiří (advisor)
This work concerns with the study of acidobasic behavior of solutions of sodium salts of carboxymethylcellulose (CMC-Na). This behavior was investigated using acidimetric titrations of the salt solutions with potentiometric and conductometric indications. In order to determine the content of carboxylic groups in two different samples of CMC-Na (M1=90 kDa, DS1=0.7; M2=700 kDa, DS2=0.9), we employed the method of Ray von Wandruzska, originally proposed for the determination of the acidity of humic substances. The values of the degree of substitution (DS) obtained using this method correspond to the values declared by the producer. The small differences (of the order few percentage points) can be attributed to the humidity of the samples. The acidimetric titrations were performed also for solutions with different ionic strengths. There is an apparent effect of the ionic strength on the shape of titration curves; nevertheless these data were not used for any theoretical interpretation.
|
|
|
Využití polyaspartátu draselného pro zajištění krystalické stability vín
Meredová, Karin
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.
|
|
|
Acidobasic behavior of carboxymethylcellulose solutions
Teslíková, Ivana ; Kislinger, Jiří (referee) ; Janeček, Jiří (advisor)
This work concerns with the study of acidobasic behavior of solutions of sodium salts of carboxymethylcellulose (CMC-Na). This behavior was investigated using acidimetric titrations of the salt solutions with potentiometric and conductometric indications. In order to determine the content of carboxylic groups in two different samples of CMC-Na (M1=90 kDa, DS1=0.7; M2=700 kDa, DS2=0.9), we employed the method of Ray von Wandruzska, originally proposed for the determination of the acidity of humic substances. The values of the degree of substitution (DS) obtained using this method correspond to the values declared by the producer. The small differences (of the order few percentage points) can be attributed to the humidity of the samples. The acidimetric titrations were performed also for solutions with different ionic strengths. There is an apparent effect of the ionic strength on the shape of titration curves; nevertheless these data were not used for any theoretical interpretation.
|
|
|
Porovnání přípravků k zajištění koloidní stability bílých vín před lahvováním
Polehňa, Jan
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.
|
guest ::
