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Disinfectants in food
Romanská, Veronika ; Vítová, Eva (referee) ; Vránová, Dana (advisor)
The aim the of bachelor thesis is description of chemical disinfection, which is used in food industry to eliminate microbial contaminations of food, food intermediates and foodborne diseases, which can occur if hygienic regulations are not observed correctly. The experimental part of the bachelor thesis characterizes the method which was used to specify the disinfecting effect. This method was used to determine two types of disinfectants which contain two different active ingredients. Based on the results, two disinfectants were evaluated and compared.
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Investigation of yeast properties during the beer fermentation
Kociánová, Lenka ; Vítová, Eva (referee) ; Omelková, Jiřina (advisor)
In this diploma thesis, the properities of brewery’s yeasts during the operation beer fermentation in the selected brewery and dependences of diferent agents and their influence on viability and vitality of the yeasts were studied. Other observed properities were physiological state, pH, temperature, a value of soft and coarse sludges, a value of dissolved oxygen in wort, the level of wort’s fermentation. It were collected the samples of fermenting wort and washing yeasts for determination. The used yeasts were observed from the first time until thein last used (generally 4 times). pH, temperature, apparent fermenting and total numer of yeast cells were measured in the collected samples. The used yeasts were washed before every other application and vitality was determined. The number of death cells were observed by this method. The number of death cells never fell bellow 5 %. The value of dissolved oxygen in wort is also the important agent for the growth of yeasts. The touchs with low number of oxygen showed that the time for fermentation had to be longer (by about 3 or 4 days more). The touchs with higher number of sludges showed that the sludges haven’t any influence on the yeasts and the procces of fermentation. Confirm the accuracy of the repeated used of the yeasts was the object of this thesis.
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The assessment of fatty acids in cheeses
Rajnochová, Veronika ; Omelková, Jiřina (referee) ; Vítová, Eva (advisor)
This bachelor thesis deals with the determination of fatty acids in natural Edam cheese. The theoretical part briefly characterize the natural Edam cheese, main attention is paid to lipids, fatty acids and the possibility of their determination by gas chromatography. In the experimental part the content of fatty acids in the model samples of natural Edam cheese produced at Tomas Bata University in Zlín was determined. The method according to ISO 1735 was chosen for extraction of lipids from the samples , the method according to ISO 5509 using methanol solution of potassium hydroxide was chosen for the esterification of fatty acids ,. The resulting methyl esters were determined by gas chromatography with FID detection.
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Analysis of selected nutritional parameters in the new varieties of gooseberries
Nováková, Jana ; Vítová, Eva (referee) ; Vespalcová, Milena (advisor)
Diploma thesis deals with the new varieties of gooseberries. The theoretical part characterizes gooseberry from a biological point of view, what is the content of healthful nutrients and states food technology aspects. Furthermore, the theoretical part deals with the main parameters examined nutrition: vitamin C, anthokyanům and antioxidant activity. In the experimental part was measured both weight solids content and soluble solids. Vitamin C was measured by HPLC, anthocyanins using a pH differential method and for antioxidant activity determination was selected method by Kanedy known also as DPPH.
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Characterisation of elderberry fruits
Christovová, Silvia ; Diviš, Pavel (referee) ; Vítová, Eva (advisor)
This master's thesis deals with the characterization of elderberry fruit (Sambucus nigra L.) with emphasis on the aroma active compounds (AAC) and vitamin C (ascorbic acid (AA), dehydroascorbic acid (DHA)). The theoretical part gives a brief outlook on the chemical composition and attributes of Sambucus berries, its healing properties and the means of processing. The rest of the theoretical part thoroughly examines the AAC and vitamin C. The suitable assessment methods are also discussed. The experimental part of the work consists of two main tasks. The first one was to assess the aroma profile of Sambucus berries using the HS-SPME-GC-FID. 18 samples were examined (the wild elderberry and 17 cultivated varieties). In total, 24 different volatile aroma active compounds were identified and quantified, 12 of which belonged to alcohols, 5 to aldehydes, 4 to esters, 1 to acids and 2 “other” compounds (linalool and -damascenone). The chemical composition of the individual samples was not uniform; no single sample contained all of the identified compounds. The second task was to assess the total vitamin C content (the sum of DHA and AA) using the HPLC. For the purpose of reducing DHA to AA three reducing agents were examined (DTT, TCEP and L-cysteine) at two different pH levels (7 and 4). TCEP at pH 4 turned out to be most efficient and was subsequently applied on the samples of 5 selected elderberry varieties. The measured vitamin C content was within the range of 5,1 – 13,0 mg per 100 g of fruit.
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The selection and optimization of the method for assessment of free fatty acids
Koval, Dominik ; Vespalcová, Milena (referee) ; Vítová, Eva (advisor)
This master´s thesis deals with optimization and validation of method for determination of free fatty acids. The theoretical part is focused on possibilities of extraction, extract separation, esterification, gas chromatography determination and brief description of the most important validation parameters. All with main emphasis on applying on free fatty acids. The experimental part describes the selection and procedure of optimizing individual steps of the method. Extraction of lipids was performed by solvent mixture (diethylether/petroleumether), based on the standard ČSN EN ISO 1735, for the extraction of free fatty acid solid phase extraction was tested. The acid catalyzed esterification based on ČSN EN ISO 5509 using methanolic solution BF3 was used for derivatization of free fatty acids and a gas chromatograph with a flame ionization detector was used for their determination. Subsequently, selected validation parameters of the method were verified: repeatability, reproducibility, linearity, limits of detection and quantitation. Sunflower oil and emmental type cheese, bought in common food market, were used as model samples for selection and optimatization of the method.
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Growth characteristics of thermophilic microorganisms
Kuchtová, Ludmila ; Vítová, Eva (referee) ; Babák, Libor (advisor)
The aim of this work was focused on study of influence of cultivation conditions on growth of thermophilic bacteria Thermus aquaticus, Thermus scotoductus, Geobacillus thermodenitrificans and Geobacillus thermocatenulatus in cultivation medium recommended by Czech Collection of Microorganisms (CCM). The change of concentration of biomass during cultivation with various pH of media, cultivation temperature, agitation rate and with addition of glucose to medium during cultivation in Erlenmayer flasks was observed. Results served for determination of optimal growth conditions for each microorganism. After optimal growth conditions were obtained, cultivations in fermenter were performed. Growth curves were made from values of absorbance and dry weight of samples.
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Assessment of aroma active compounds in chosen fruit types
Rodzíková, Martina ; Vespalcová, Milena (referee) ; Vítová, Eva (advisor)
This bachelor thesis deals with the assessment of aroma active compounds in less known berries, gooseberries. In the theoretical part the general characteristics, biological signs and properties of selected varieties, chemical composition and structure of the components, drug effects, the possibility of processing and use of gooseberries are mainly described. The main aim of this thesis was to determine aroma active substances in selected varieties of gooseberry fruits using SPME-GC method. Aroma active compounds were first extracted by solid-phase microextraction and then assessed by gas chromatography.
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Microbiology of raw milk and milk after treatment
Pláničková, Jana ; Vítová, Eva (referee) ; Omelková, Jiřina (advisor)
The aim of this bachelor thesis is microbiology of raw milk and heat treatment milk, pasteurized and UHT treatment. There are described the most important and the most common microorganisms that contaminate milk, spoilage and pathogenic in the theoretical part. Practical part was provided in laboratory of diary factory. There were determined counts of microorganisms in raw, pasteurized and UHT milk by microbiological analysis.
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The assessment of aroma active compounds in cheeses
Ryglová, Hana ; Diviš, Pavel (referee) ; Vítová, Eva (advisor)
This work deals with aroma active compounds of Edam cheese, i.e. natural hard cheese with low heat curd. Aroma active compounds contribute to overal aroma of cheese. They are volatile compounds, which include alcohols, aldehydes, ketones, fatty acids, esters, lactones, terpenes etc. These compounds were identified and quantified using SPME/GC/FID method in the model samples of Edam cheese, produced at Tomas Bata University in Zlin. In total 18 volatile compounds were identified, 3 aldehydes, 4 ketones, 7 alcohols, 1 ester and 3 acids. Differences in number of compounds identified, as well as in the contents of them, were found between samples. Low number of compounds and also their low total content correspond to the initial phase of cheese ripening.
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