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Effect of added carbohydrates on the quality of cereal kvass and kvass bread
Stoklásková, Olga ; Vítová, Eva (referee) ; Diviš, Pavel (advisor)
The aim of this bachelor thesis was to characterize selected chemical, senzoric and rheologic properties of sourdough breads with added particular saccharides in the dough. In the theoretical part, processes during mixing, proofing and scaling of the sourdough in fixed conditions are analysed; researched sugars are characterized and their influence on the sourdough product, resulting from present research, is discussed. The experimental part focuses on particular analyses, that influence the quality of sourdough product and determine so its market demand. According to the analysis, sourdough fortification of low honey concentration tends to the maximal volume of the loaf and the most tender crumb at the same time. Higher additions of white table sugar increase the total acidity of the dough the most significantly; unlike, a malt flour provides a smooth, sweetish aroma to the bread. This is because of inhibition of acetic acid production by maltose during sourdough fermentation. Unfortunately, lower concentration of acetate and higher content of remaining sugars in the same time is a factor of shortening the microbial shelf-life of the bread after its baking.
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Možnosti regulace kyselin v hroznových moštech a vínech
Pribilová, Lenka
The aim of this thesis was to describe the selected organic acids in wines and musts . The most important acids in grapes are tartaric acid and malic acid . Then describe the physiological characteristics of the grapes ripening affecting acidity . According to them, it is possible to determine exactly when in the vineyard may apply specific agro-technical interventions . Although there is a quality wine in the vineyard , it is very important technological processing . In grades where there is non-ideal malic acid and tartaric acid in musts and wines is applicable regulation acids , increasing or decreasing acidity. Acidification can be achieved by means of tartaric acid , lactic acid and citric acid. Conversely common acidification can be de-acidified using blending wines , hydrogen carbonate calcium and other conventional methods or modern viticultural biodegradation acids , which are in sharp taste degrade malic acid to softer lactic acid .
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Základní parametry moštů révy vinné
Výmola, Tomáš
In this bachelor´s work was after studying the collected domestic and foreign sources analysed consisted of the basic parameters of the must of the vine, wine production and subsequently to frequent diseases and defects of the wine where we can meet. To the overall quality of the wine occurs in the vineyard, during the processing of the grapes, fementation of the mas hor even in the achal wine during his training or after the subsequent filling into bottles.
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Influence of selected coffee bean roasting technology on its chemical composition
Šajdlerová, Kristýna ; Mikulíková, Renata (referee) ; Diviš, Pavel (advisor)
The subject of this diploma thesis is the monitoring of chemical changes taking place in the coffee bean during roasting using various devices. For these purposes an industrial coffee roaster and a home roaster were used in the practical part. The theoretical part deals mainly with the characterization of coffee beans in terms of the content of various compounds and a description of the changes that occur during roasting. Different types of roasting machines are also presented. In the experimental part the roasting of coffee beans and the determination of the concentration of selected substances in the samples taken during roasting were performed. The monitored parameters included the concentration of sucrose, organic acids (citric, acetic, lactic, malic, formic and chlorogenic), caffeine and aromatic substances. One of the biggest differences found between the both roasters is the reduction in the concentration of chlorogenic acid, which decreased by 33 % for domestic equipment, while the decrease was almost doubled for industrial roasters. Another significant difference was also observed in the change in sucrose content. Sucrose degradation occurred in 94 % of coffee bean samples roasted on an industrial roaster, while only 75 % of the second type of roaster.
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Production and characterization of mead produced by different technologies
Kilian, David ; Vítová, Eva (referee) ; Pořízka, Jaromír (advisor)
This diploma thesis is focused on the technology of producing mead from the chosen kind of honey with a variety of sugar concentrations with the use of modern producing technological procedures with the cold and hot process. The theoretical part is focused on the history of mead and its technological development. It focuses, in detail, on modern large scale technologies – both cold and also the hot process. In the practical part of the thesis, the production of samples of mead with various sugar concentrations from three kinds of honey with the use of two technological processes (hot and cold process) was conducted firstly. Secondly, the characteristics of the samples were conducted from the view of the volume of HMF – Hydroxymethylfurfural, ethanol, glucose, fructose, the chosen organic acids and elements with sensory analysis. The prepared samples were compared and discussed concerning differences to find out the differences of the use of the two manufacturing technologies (cold and hot process), the chosen kinds of honey and the influence of sugar before the fermentation on the final product.
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Beer bioflavouring by dry hopping using czech cultivars of hops
Gajdušek, Martin ; Štursa, Václav (referee) ; Pořízka, Jaromír (advisor)
This diploma thesis deals with the influence of dry hopping on selected analytical and sensory properties of beer. The effect of dry hopping was observed using Czech hop varieties Kazbek and Uran, which were added to the wort during the main fermentation phase in doses of 3 and 6 gdm-3. The contact time of hops with wort was 3, 6 and 9 days. The experimental part describes the technology of preparation of the reference beer, in which dry hopping were subsequently performed. A parallel measurement was performed on each sample. In terms of the basic parameters of beer, the effect of dry hopping, especially its length, on the ethanol content was observed. With a longer period of dry hopping, the concentration of ethanol in beer increased. The higher alcohol concentration was also associated with a decrease in the apparent extract. In terms of color and pH of beer, the effect of dry hopping has not been proven. Elemental analysis performed by optical emission spectrometry with inductively coupled plasma revealed an increase in the concentration of calcium, magnesium, and iron due to dry hopping. No statistically significant difference was observed for manganese and barium compared to the reference. In terms of bitterness, a significant increase was identified in dry hopped beers compared to the reference, the value being dependent on the dose of hops used. The effect of the hop variety has not been proved. Concentrations of organic acids determined by ion-exchange chromatography with a conductivity detector were affected by dry hopping only in the case of lactic acid and acetic acid. An increase in lactic acid was observed compared to the reference, also related to the degree of fermentation. While in the acetic acid content the hop samples showed a lower concentration than the reference sample. The concentrations of myrcene, humulene and geraniol were determined by gas chromatography with a mass detector. These are volatile components of hop essential oils. Dry hopped samples recorded significantly higher concentrations of all aromatic substances compared to the reference. In terms of hop time, the highest concentrations were shown by samples hopped for three days. The results of the sensory analysis show that the overall best rated sample is a sample hopped with the Kazbek variety with a dose of 3 gdm-3 for three days. Beer which was dry hopped for the shortest time also showed the lowest intensity of bitterness, which was perceived positively.
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Use of analytical methods and chemometry to verify the geographical authenticity of honey
Marková, Lucie ; Křikala, Jakub (referee) ; Diviš, Pavel (advisor)
The teoretical part of this bachelor thesis is focused on the process of producing the honey by bees, its composition and means of its adulteration or ways to detect substandard products. The experimental part describes methodes, which were used to observe the samples. Sacharides, organic acids, mineral content, the amount of dry matter, titration acidity and conductivity were meassured. Obtained data were used for differentiation the Czech and foreign honey. The result of the statistical analysis shows the calcium, copper and glucose content are suitable paramteres to differentiate the Czech honey from that externals. Theese parameters could be used to distinguish the two different geographical origin of honey. Nevertheless, the total evaluation seems to be insufficient for differentiation these two groups. The efficiency could be icreased by the including more samples for analysis, or meassuring more parameters. Finally, some of the parameters were used for quality control of honey.
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Study of geographical authenticity of Moravian white wines
Horáková, Kristýna ; Křikala, Jakub (referee) ; Diviš, Pavel (advisor)
The aim of this bachelor thesis was to verify geographical autenticity of Moravian white wines based on elemental analysis. This data were completed with the analysis of organic acids, fenolic compounds and atioxidants in wines. There were used two spektrometric methods for the elemental analysis (ICP-MS and ICP-OES). The concentration of organic acids was mesured by Ion chromatography. To determine the concentration of phenolic compounds in wines there was used the high performance liquid chromatography (HPLC-DAD), the content of antioxidants and the total content of phenols was measured on spectrophotometer. In total there were 33 samples of wine from 4 Moravian subregions. For the purpose of determination the samples in groups the dataset was firstly corrected by Grubbs test for remote results. From those data the box plots were created which represents the minimal, maximal and mean concentrations of each measured component. Furthermore the analysis of variance was applied, which picked up 12 statisticly valuable parameters from the whole 47. By appliyng the multidimensional statistical methods (Pearson correlation analysis (PCA) and discriminant analysis (DA)) were compiled mathematical models for the division of Moravian wines according to geographical origin. The success rate of the discrimination test was 96,97%. The cross-validation test showed an 81,82% success rate for classifying unknown samples.
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Influence of coffee making process on chemical composition of brewed coffee
Trenzová, Kristina ; Divišová, Radka (referee) ; Diviš, Pavel (advisor)
This bachelor thesis deals with the influence of baristic coffee preparations on the chemical composition of the obtained beverage. Teoretical part of this thesis focuses on coffee growing, processing technology and the chemical composition of coffee beans. In the experimental part were measured samples of espresso coffee, samples prepared by moca pot, flip-drip method, filtrated coffee, samples prepared by french-press technique, vacuum pot samples and boiled coffee. The samples were prepared according to the baristic techniques at first and later with adjusted water and amount of coffee so these methods could be compared with each other. This work focuses on the determination of caffeine and acrylamide content by liquid chromatography, validation of HPLC method, determination of total phenolic content by Folin-Ciocalteu reagent, determination of organic acids by ion chromatography, determination of selected macro and micro elements by inductively coupled plasma in optical emission spectrometry and analysis of aromatic substances using gas chromatography. Based on the processed results and compared methods, it was shown that the moca pot had the greatest influence on the content of caffeine, acrylamide, organic acids and total phenolic substances, and the flip-drip with vacuum pot method had the greatest influence on the content of aromatic substances. From a baristic point of view the highest concentration of caffeine was 3689 mg/l in coffee based on flip-drip method, and concentration of acrylamide was 25,4 mg/l in the coffee based on the same method. The highest value of total phenolic content was determined in moka pot to c = 5,23 g/l. Regarding the mineral representation, the mineral decomposition of coffee beans and espresso were compared, and the highest values were reached by potassium, namely the concentration was 577 mg/l per 1 g of mineralized sample, in the cup of espresso the potassium concentration was 2461 mg/l. The highest content of organic acids was determined in the beverage prepared by moca pot, in terms of selected acids, the largest representation had the succinic acid with the concentration 599,8 mg/l. The highest content of aromatic substances was found in coffee from a moca pot and in coffee by flip-drip method. The biggest part was~made by furfuryl alcohol.
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Hodnocení kvality siláží vyrobených z pícnin čeledi lipnicovitých
Richterová, Bára
The thesis is focused on the assessment of the quality of the fermentation process in various grass species. In the literary part we characterize grasses of the family Poaceae. The next part is devoted to the conservation of silage grasses with possible threats to ensilage and the use of silage additives in production. In the practical part, a total of 12 grass samples were monitored. They were founded in two variants, fertilized and non-fertilized with nitrogen, treated and untreated with silage additive. Grasses were harvested from the microsilage vessels after 60 days and analyzed for selected parameters. The results were evaluated by graphs. Ammonia, pH, LA, AA, biogenic amines were further processed by ANOVA. Using the values from the analyzes, we evaluated the quality of the fermentation process, when the samples of festulolium, festulolium N were the best, among which there was a statistically significant difference at 95 % confidence level. In the analytical evaluation the worst sample of the lobed fur without treatment was found to have poor quality silage fermentation. It also contained the most biogenic amines but there were no statistically significant differences between the samples (p <0.05). For samples of the lobed foot treated with a chemical additive, we can conclude that the use of the chemical preservative SoftAcid improved the quality of the fermentation.
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