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The addition of carbon dioxide to milk for cheese production
Králová, Petra ; Hrstka, Miroslav (referee) ; Kvasnička, Miloš (advisor)
This work deals with the addition of carbon dioxide to milk for cheese production. The first aim was to elaborate a literary search focused on chemical composition of milk and its changes after addition of carbon dioxide and to describe production processes, with or without addition of carbon dioxide. The opening part was in particular focused on production of cheese with carbon dioxide and what all this gas causes during production. Carbon dioxide significantly decreases pH, thereby preventing from multiplication of undesirable microorganisms, it is also very important for shortening of production time, because it shortens the coagulation time. The main aim of experimental part was to determine the optimum addition of carbon dioxide to milk for production of Balkan cheese and using several analytical methods to compare cheese produced with and without addition of carbon dioxide. The sensory methods suitable for following of sensory differences of produced cheeses were also chosen and applied. By request of Dairy in Polná Ltd., the operation economy was calculated, which revealed that production with carbon dioxide is very useful and can reduce production costs of Balkan cheese, which would certainly be positive. The advantages and disadvantages of cheese production with carbon dioxide for consumers as well as for producer are evaluated as conclusion of this work.
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Study of fruit ripening and storage
Langová, Jiřina ; Zemanová, Jana (referee) ; Babák, Libor (advisor)
There are many changes in fruit quality during its ripening and storage. The following four apple varieties were studied: Champion, Glostr, Golden Delicious and Idaret. Amount of reducing sugars, total amount of sugars, quantities of acids, refractive solids and loss of starch were monitored. The changes of parameters, the differences between the varieties and differences in storage were compared. Parameters were monitored from mid-August 2008, when the apples ripened. After the harvest, apples were stored in a cool box at 2 - 3 ° C and at room temperature 20 - 23 ° C. Apples stored in the cool box were analyzed till the end of March 2009, and apples stored at room temperature until the beginning of January 2009. Total quantity of sugars in all varieties increases before harvest, while it decreases after picking the apples. The quantity of reducing sugars in apples rises gradually and after their picking it falls significantly in apples stored at 20 - 23 ° C. In apples stored in the cool box it continues rising until the end of November, and then it also decreases. Losses of starch are considerable and they are accelerated after the harvest. The quantity of acids also decreases throughout and amounts of refractive solids increases. For all varieties there are significant changes in storage at 20 - 23 ° C. Temperature, therefore, significantly affects processing of sugars and acids in fruit respiration.
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Study of selected technological properties of licorice mass
Gajdušek, Martin ; Vítová, Eva (referee) ; Vespalcová, Milena (advisor)
This bachelor thesis deals with the study of selected technological properties of liquorice matter. By microscopic observation it was found that at a content of more than 10% of the boiled starch grains or more than 30% of the non-swollen grains, the mass does not achieve the desired properties for further processing. Technological loss during drying depends mainly on time, but also on location in the oven, both in height and space. The highest technological loss was achieved mainly in the highest positions in the oven. By liquid chromatography was determined 11.8% glucose, 9.2% fructose, 23.3% sucrose in liquorice mass prior to cooking; 11.9% glucose, 9.4% fructose, 22.6% sucrose in cooked matter; 12.7% glucose, 10.8% fructose and 20.1% sucrose in dried liquorice products.
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Basic chemical characteristics of juices from selected red currants varieties
Rucká, Markéta ; Jurečková, Zuzana (referee) ; Vespalcová, Milena (advisor)
This bachelor thesis is focused on the determination of basic chemical characteristics of selected red currants varieties from the Research and Breeding Institute of Pomology Holovousy Ltd. The theoretical part concentrates on general information about red currant, such as history of cultivation, origin and its expansion. There is also mention of the general characteristics of currant, currant building and significance of red currant cultivation. Chapter "Individual varieties" deals with the analysed varieties of red currants, especially its description and its biological properties, followed by an overview of the main substances contained in red currants and their brief description. Bachelor thesis also presents examples of the processing and the utilization of red currant in the food industry. The final chapter provides information about the individual determinations of the chemical characteristics of red currants, which include juice yield, soluble solids content, total dry matter content, pH, titratable acidity, formol number and reducing sugars. The experimental part describes the specific conditions and methods of individual determinations, followed by a summary of the results and their discussion. Variety Jesan showed the highest juice yield (63 ml per 100 g) and the highest pH value (3,16). The highest soluble solids content (13,94 %) and the highest formol number (22,83 ml of 0,1 M NaOH per 100 g) was determined in a variety Jonkheer van Tets. The highest dry matter value was detected for variety Rovada (14,48 %). The titratable acids content was highest in variety NŠLS 11/6 (403,88 mmol•kg-1). The highest concentration of reducing sugars was found in variety Tatran (8,17 %).
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Basic chemical characteristics of chokeberry juices
Zámorská, Vendula ; Veselá, Mária (referee) ; Vespalcová, Milena (advisor)
This bachelor thesis deals wirh characteristics of berries and assessment of basic chemical parameters of chokeberry juices (Aronia melanocarpa). The theoretical part is about the basic botanical description of selected varieties of Aronia and its taxonomic status. The following are important substances contained in fruits and their part in human nutrition and use for food purposes. The end of the theoretical part of bachelor thesis is about basic methods of determining the nutritional parameters of berries. In the experimental part solids content of the fruit. Furthermore soluble dry matter content, pH, titratable acidity, formol number, reducing sacharides and ascorbic acid by spectrofotometry were determined. Based on the results, juices were compared.
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Basic chemical characteristics of juices from selected blackcurrant varieties
Maňásková, Eva ; Pořízka, Jaromír (referee) ; Vespalcová, Milena (advisor)
This thesis deals with the basic characteristic of juices of the selected varieties of blackcurrant. The theoretical part presents the history and origin of this fruit cultivation, basic botanical description of each species and selected varieties and also features active substances contained in fruits. Conclusion the theoretical part then describes procedures basic methods of determining the various chemical parameters of fruits. In the experimental part was set tentative determination juice yield, soluble solids content, pH, titratable acidity and formol number. Based on the results were different varieties compared.
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Basic chemical characteristics of cranberry juice
Cao, Ha Thuy ; Hrstka, Miroslav (referee) ; Vespalcová, Milena (advisor)
This bachelor thesis is about lingonberries and cranberries. It is mainly about berries which were used for chemical analysis. The berries are from the Research and Breeding Institute of Pomology Holovousy Ltd. and they have delivered six cultivars of lingonberries and three cultivars of cranberries. There is a research of general information about classification, botanical description, important chemical substances such as vitamins, natural colorants and products made in the industry. Furthermore there is descriprion of chemical methods for basic analysis. The next part of bachelor thesis is about how all these methods were applied to berry juice. What instruments and chemicals were used. First assessment was profit of juice which was about 50,00–60,00 %, but lingonberry Runo bilawskie has at least 31,49 % and cranberries have less profit too. Total solids were determined in the range of 11,40 % (Pilgrim) to 18,50 % (Runo bielawskie) and solitable solids are in range of 10,00 % (Pilgrim) to 16,08 % (Korál). Lingonberry contains more reducing sugars (8,81–12,92 %) than cranberry (7,90–9,03 %). Titratable acids are about 32,04–49,60 mmol.l-1 for lingonberry and about 55,40–60,67 mmol.l-1 for cranberry. The measurements show that pH of both berries are about 3. The most phenolic substances are found in range of 2187,11–3476,75 mg.l-1. Berries content anthocyans colorants in range of 54,91-65,29 mg.l-1 and the most in cranberry. All results are shown in charts and in the end there is a discussion and conclusion about methods and results.
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Burning pellets from non-wood biomass in boilers II
Linda, Matúš ; Baláš, Marek (referee) ; Zejda, Vojtěch (advisor)
Bachelor thesis is divided into four main chapters. The first chapter deals with issue of combustion of agropellets in boilers. This section specifies types of pellets, their production and problems of combustion in boilers associated with formation of emissions. The second chapter specifies valid legislation and emissions limits. The third chapter describes fuel analysis of agropellets samples. This includes an analysis in order to determine the properties and chemical composition of agropellets resulting in determination of gross heat and calorific value. The fourth chapter evaluates agropellets influence on boilers and emissions creation on the basis of data and knowledge. The results are compared with data of other commonly used solid fuel found in literature sources.
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Corelation of transport and viscoelastic properties of hydrogels with diffusion gradient
Ščotková, Romana ; Sedláček, Petr (referee) ; Smilek, Jiří (advisor)
The aim of the presented bachelor thesis was to prepare hydrogels with diffusion gradient and to demonstrate the gradient structure of hydrogels in terms of viscoelastic and transport properties. With regard to potential biomedical applications, the cationic polysaccharide chitosan was selected for the preparation, especially for its antimicrobial and biocompatible properties. The resulting gradient hydrogels were subsequently characterized by oscillation tests to observe the differences using different concentrations and molecular weights of chitosan, crosslinking agent concentrations, dispersion environments for chitosan dissolution, and different gel crosslinking times. The samples were also subjected to drying experiments to confirm the gradient structure formed. The ability of the hydrogels to transport the active species was confirmed by visually evaluating the permeation of the anionic dye (bromothymol blue) during the gelation process. From the results obtained during the experimental part of the bachelor thesis it can be concluded that the viscoelastic properties of hydrogels can be modified by changing selected parameters during the preparation itself. It was also confirmed the assumption that with better mechanical properties of hydrogels there is a deterioration of transport properties. By controlled diffusion method, it was possible to prepare a hydrogel with a gradual gradient of crosslinking density, thus modifying the viscoelastic and transport properties.
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Bioactive substances contained in elderberry pomace
Šimšová, Veronika ; Diviš, Pavel (referee) ; Vespalcová, Milena (advisor)
This bachelor thesis deals with the determination of selected chemical characteristics in the elderberry juice, compote and in the extracts of elderberry marc. The theoretical part describes the botanical characteristics of elderberry (Sambucus nigra L.) including its occurrence, the possibility of utilization of individual parts of the plant in the food industry and in the healing therapies and chemical composition of the berries. The biggest attention is given to the bioactive compounds contained in these fruits. The second chapter deals with the dry matter and the methods of its determination. The last chapter of the theoretical part describes vitamin C, its importance for the human organism and manual methods for determination of vitamin C. Among the selected chemical characteristics, set out in the experimental part, was the determination of reducing sugars by gravimetric method and Berthrand method, titratable acids, total anthocyanins by pH-differential method, total phenolic compounds by the Folin-Ciocalteu method and determination of the dry matter by drying and refractometric method. Analyzes have proven that extracts made of elderberry marc under suitable conditions have, in most cases, chemical characteristics comparable to the elderberry juice and compote. However, extracts are much better source of anthocyanic and phenolic compounds than juice and compote.
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