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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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Analysis of phenolics in different kinds of coffee
Jašková, Martina ; Halienová, Andrea (referee) ; Márová, Ivana (advisor)
The aim of this bachelor thesis was examining the quantity of biologically significant substances in selected types of roasted ground coffee, instant coffee and coffee extract. The particular kinds of coffee differed in technological processing, degree of roasting and composition. In the practical part total phenolics and flavonoids by using spectrophotometry methods. The total antioxidant activity in the individual coffee extracts was determined by ABTS method. Qualitative and quantitative analysis of some individual antioxidants and caffeine was performed using RP-HLPC with spectrophotometric detection. As a part of the work sensory analysis of all coffee samples was realized and consumer questionnaires were completed.
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Design of Coffeemaker
Enenkelová, Sylvie ; Řezníček, Svatopluk (referee) ; Rubínová, Dana (advisor)
The topic of my Bachelor 's thesis is a design of a coffee machine. Specifically, I focused on designing automatic espresso machine suitable for households. The purpose was to create such a product that will be able to compete with a wide offer of the other products on the market. It should be as technically good as it 's design will be.
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Design of Table Coffee Machine
Skotnica, Vojtěch ; Rubínová, Dana (referee) ; Zvonek, Miroslav (advisor)
The aim of this thesis is to create a new design of table coffee machine, that provides all construction, engineering, aesthetic and ergonomic requirements. This thesis focuses on the uniqueness of the product, which is key for definition among a wide range of current products. Thesis also describes in text form and in the form of visualization the entire design process.
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Development of organic UV filtres based on natural extracts
Káčeríková, Martina ; Kovalčík, Adriána (referee) ; Márová, Ivana (advisor)
This diploma thesis is focused on the development of organic UV filters. Organic UV filters were extracted from natural resources and encapsulated into nanomaterial-like delivery systems such as liposomes and nanofibres. SPF of particular extracts and carriers with encapsulated extracts were measured. All of the prepared extracts as well as carriers were characterised for their content of natural substances like phenolic compounds and their antioxidant acitvity, stability, cytotoxicity, micriobial acitivity and their safety were studied too. All of the prepared materials were evaluated as suitable for use in comestic industry. However, in a future, it would be appropriate to add to the study other experimental methods to increase the active substances and at the same time increase the SPF protection factor.
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Studying the authenticity of coffee of various geographical origins
Flegr, Šimon ; Pořízka, Jaromír (referee) ; Diviš, Pavel (advisor)
This diploma thesis researches coffee authenticity problematice, mainly focusing on the authenticity of geographic origin. In the theoretical part of this work, botanical classification is described as well as production technology and processes. The work also includes chemical composition of coffee, describing the major components and changes during production phases. It describes major production areas of the world, in terms of general description and brief history. Problematics with coffee fraud and its identification are also described. Theoretical part also includes general geological description of 17 studied coffee growing regions. Experimental part is devoted to trace amount analysis of selected elements and volatile compounds. The element analysis was conducted using mass spectrometry or optical emission spectrometry, volatile compounds were determined using gas chromatography combined with mass spectrometry detection. Results were statistically described and analyzed, resulting in several discrimination models based on geographic origin.
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Vliv zpracování kávy na obsah kofeinu a jeho účinky na lidský organismus
Odehnalová, Barbora
This diploma thesis focuses on the comparison of caffeine content in coffee processed in different ways. It involves dry and wet processing, where in the first mentioned case the coffee beans are dried in the sun to the ideal moisture level after collection and sorting. In the wet method, the coffee is fermented in vats with added microorganisms and then dried. The work also includes the effects of caffeine on the human organism.
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Porovnání množství vázaného uhlíku v nadzemní i podzemní biomase v různých typech využití půdy v okolí města Oxapampa, Peru
Chalupová, Karolína
The present work compares amount of sequestered carbon in different types of land use in the vicinity of Oxapampa in Peru. Research was conducted in the autumn of 2022 with focus on three main types of land use: coffee agroforestry plantations, montane tropical forests and silvopastoral systems. Data collection was carried out with Field-Map technology, where 47 study plots on 6 transects were compared. To estimate aboveground and belowground biomass allometric equations were used. The evaluation of soil carbon stocks was determined based on soil analysis using a Soli-TOC device (Elementar). The results showed that there was no statistically significant difference between the amount of carbon bound in the biomass of agroforestry coffee plantations and forest ecosystems. Soil carbon stocks were highest in forest stands in the upper soil layers. At lower depths (20–30 cm) the difference between the studied ecosystems was no longer registered. Average soil carbon values (%) for coffee agroforestry systems and particular depths were as follows: H (7,6 ± 3,8); 0–10 (5,1 ± 1,8); 10–20 (3,8 ± 0,8); 20–30 (3,4 ± 0,7). For study plots in forest ecosystems: H (34,2 ± 12,1); 0–10 (22,4 ± 14,7); 10–20 (9,5 ± 6,2); 20–30 (7,3 ± 5,8). Soil carbon stocks values for silvopasture systems were: H (12,1 ± 4,7); 0–10 (7,3 ± 3,3); 10–20 (5,3 ± 2,3); 20–30 (3,7 ± 2,1).
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