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Design of coffee maker
Švancarová, Jana ; Chorý, Tomáš (referee) ; Rubínová, Dana (advisor)
The subject of this diploma thesis is the design of a coffee machine. The design focuses on a professional automatic high-load coffee machine intended for use in dayrooms and meeting rooms of companies. The final proposal should meet all constructional, technological, aesthetic and ergonomic requirements. The aim of the thesis is to design a coffee machine following the expected requirements while the visual appearance and functionality of the device corresponds to the individual needs of its users and operators.
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Design of home automatic coffee machine
Kajstura, Bogdan ; Křenek, Ladislav (referee) ; Haltof, Vladimír (advisor)
The aim of this Bachelor’s thesis is to design an automatic coffee maker, which could be used in a household. Implementation of a modern technology as designing a machine, which would fulfill technologic and ergonomic requirements are main goals for this kind of product. Based on a wide analysis there was created an automatic coffee machine, which deals with these challenges in its own, original way.
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Design of coffee maker
Stejskal, Pavel ; Sládek, Josef (referee) ; Zvonek, Miroslav (advisor)
The aim of this thesis is to create a modern design of coffee maker, which would bring the one hand, an unusual look at the overall shape of the body. At the same time offered an improved process of preparing the coffee, which would facilitate its operation. The final option is designed to meet the requirements needed for the production and end-use in the home.
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Determination of acrylamide in coffee by high performance liquid chromatography
Vajdíková, Tereza ; Vítová, Eva (referee) ; Diviš, Pavel (advisor)
The bachelor's thesis aimed to optimize the method of determining acrylamide in coffee using high-efficiency liquid chromatography with a diode-array detector. In the theoretical part of the bachelor's thesis, attention was paid to the taxonomic distribution of coffee, it's processing and chemical composition. Part of the theoretical frequency of the work involved describing the formation of acrylamide in coffee and possible methods of determining it. The practical part looked at validating the method, which was used in the analysis of coffee samples. The individual samples of coffee varied in the type of coffee and the societies where the coffee was obtained. Determination of the acrylamide content has been carried out on commercial, franchised, and selective coffees of the arabica species. Finally, the determination of acrylamide was made in the coffee of various types, in robusta and arabica.
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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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Isolation of antimicrobial compounds from spent coffee grounds
Kurzová, Pavlína ; Veselá, Mária (referee) ; Kovalčík, Adriána (advisor)
Coffee grounds are one of the very valuable lignocellulosic wastes that have been able to be processed and used for isolated phenolic substances. Many phenolic substances isolated from lignocellulosic wastes have antimicrobial properties. Aim of this thesis is isolation phenolic substances from spent coffee grounds extract and their available antimicrobial properties. Two isolation ways were applied to receive phenolic substances from spent coffee grounds: 1) solvent extraction (hexane, 75% ethanol, 70% acetone, diethyl ether, and ethyl acetate) and 2) release of active substances by alcoholic fermentation. All isolated materials were characterized by the viewpoint of concentration of reducing sugars, polyphenols and flavonoids. Subsequently, their antimicrobial activity was determined by using agar diffusion and broth dilution methods. Two gram-positive bacteria (Bacillus subtilis and Micrococcus luteus), one gram-negative bacteria (Serratia marcescens) and two yeasts (Candida glabrata and Saccharomyces cerevisiae) were used for antimicrobial testing. High-performance liquid chromatography (HPLC) was used to identify phenolic substances in the extracts. First, the results showed that the isolated sample with the highest antimicrobial activity was 70% acetone extract. This extract contained chlorogenic acid, gallic acid, caffeic acid and coumaric acid according to HPLC. The ethyl acetate extract showed the lowest antimicrobial activity. Second, after lyophilization, the isolated materials also revealed high antimicrobial activity. The highest antimicrobial activity displayed the materials obtained by the extraction with 70% ethanol. This sample contained chlorogenic acid, gallic acid and caffeic acids. Next, samples with phenolic compounds were obtained by the alcoholic fermentation of spent coffee grounds. These samples showed similarly to the previous solution extracts significant antimicrobial activity. Interestingly, the unfiltered samples received directly after alcoholic fermentation also showed antifungal properties. The characterization of phenolic compounds by HPLC showed similarly as in previous examples that chlorogenic, caffeic and gallic acids were present in these samples.
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Content of selected alkaloids in tea and coffee
Trenzová, Kristina ; Divišová,, Radka (referee) ; Diviš, Pavel (advisor)
This master thesis deals with content of selected alkaloids in tea and coffee samples. Theoretical part of this paper focuses on basic characteristic of Camellia sinensis and Coffea arabica/canephora, its processing technology and chemical composition. Furthermore, there is discussion about effects of methylxanthines on the human body, the effects on health and metabolism in plants capable of accumulating methylxanthines. The samples were extracted into an organic solvent and also prepared in the aqueous phase according to the recommended preparation. This thesis focuses on xanthine alkaloids - caffeine, theobromine and theophylline. Of the coffees, Robusta coffee from India had the highest caffeine concentration (1730 mg/l), which corresponds to 1,72 % in coffee. From Arabica samples, the highest caffeine concentration was measured for Honduras coffee (1115 mg/l), which is 1,11 %. The highest values of tea samples were measured for Ceylon types, the highest caffeine concentration was measured for black Ceylon 2087 mg/l, which is 2,08 %. The highest concentration of theobromine was in Ceylon gunpowder (175,4 mg/l). Alkaloids passed into aqueous solutions with almost 100 % efficiency, depending on temperature and time. The best penetration was for coffees prepared by a mocha teapot and for pu-erh teas. The worst for green teas and maté samples.
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Design of coffee grinder
Krčma, Martin ; Buganská, Tamara (referee) ; Ondra, Martin (advisor)
Subject of this bachelor thesis is desing of a coffee grinder. This product is studied from historical, technical and designer points of view. Then, based on the completed analysis, a new product is designed, one that meets ergonomical, technical, aestetic and social requirements.
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Study of changes in the chemical composition of coffee during roasting
Kohoutová, Lenka ; Vítová, Eva (referee) ; Diviš, Pavel (advisor)
This bachelor thesis deals with monitoring of changes in acrylamide and hydroxymethylfurfural levels in coffee during the process of roasting. Green coffee was roasted using two separate roasting modes (medium roast: temperature 210 °C for duration of 14 minutes, City roast: temperature 220 °C for 17 minutes). Concentration of acrylamide and hydroxymethylfurfural for various roasting durations was determined by high performance liquid chromatography. For the determination of acrylamide, linear growth of the concentration was observed. The final levels of acrylamide corresponded with levels given by the literature, although the characteristic trend of acrylamide formation was not observed. Typical trend of hydroxymethylfurfural formation was observed in samples roasted with City roast mode, while the first part of the trend was also apparent in samples roasted with medium roast mode. Final levels of hydroxymethylfurfural in roasted coffee were within the limits given by the literature.
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