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The use of thin layer chromatography for fractionation of lipids in cheese matrix
Pop, Zdeněk ; Vespalcová, Milena (referee) ; Vítová, Eva (advisor)
This bachelors thesis is focused on the use of thin layer chromatography for fractionation of lipids in the cheese matrix. Milk fat, lipids, fatty acids, the possibility of determination of lipid compounds, thin-layer chromatography and gas chromatography are characterized in theoretical part. In the experimental part the conditions for the fractionation of lipids using thin layer chromatography were optimized, selected validation parameters were evaluated, lipid fractions obtained from the solid-phase extraction were verified and fatty acids in lipid fractions in the sample of processed cheese were quantified. The method according to ISO 1735 was chosen for extraction of lipids from the samples. Lipids fractionation was performed on commercially available plates for thin-layer chromatography. The method accrording to ISO 5509 using methanol solution of boron trifluoride as catalyst was chosen for the esterification of fatty acids. The resulting methyl esters were determined by gas chromatography with FID detection.
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Monitoring of sensory active compounds during cheese production
Ryglová, Hana ; Buňka, František (referee) ; Vítová, Eva (advisor)
This work deals with monitoring of sensory active compounds during production of Edam cheeses, i.e. natural hard cheeses with low heat curd, and of processed cheeses, which were produced from Edam cheeses. Sensory active compounds contribute to overal flavour 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 cheeses and processed cheeses, produced at Tomas Bata University in Zlin. In total 42 volatile compounds were identified, 6 aldehydes, 7 ketones, 15 alcohols, 6 esters and 8 acids. Differences in number of compounds identified, as well as in the contents of them, were found between samples. Effect of pasteurization on the contents and composition of the identified compounds was the most obvious in the samples of matured cheeses. In the samples of processed cheeses the effect of pasteurization was the most obvious in combination with prolonged heating during melting.
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Comparison of aroma active compounds of selected types of cheese
Brožová, Michaela ; Zemanová, Jana (referee) ; Vítová, Eva (advisor)
This diploma thesis deals with the determination of aroma active substances in selected white mold cheeses, which are/are not awarded with the „Protected Designation of the European Union“ and their mutual comparison. In the theoretical part cheeses are characterised , including general production technology. The white mold cheeses are then described in detail. This is followed by the literary search dealing with the problematic of aroma active substances in cheeses. In conclusion of the theoretical part the method of their determination using solid phase microextraction and gas chromatography with mass detection is described. The SPME-GC- MS method was chosen for the experimental part of the determination of aroma active substances in selected white mold cheeses. A total of 12 cheeses were analyzed, of which 6 were Czech and Slovak and 6 were French with a protected designation of origin. The differences between individual samples were found in the number and type of the identified volatile compounds. A total of 78 volatiles were identified in selected cheeses, of which 20 were alcohols, 19 esters, 12 ketones, 11 acids, 4 sulfur compounds, 3 hydrocarbons, 3 lactones, 2 aldehydes, 2 phenols, 1 nitrogen compound. The cheeses were compared in terms of the identified compounds, and finally the results were statistically evaluated by the PCA method.
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Assessment of fatty acids in selected type of cheese
Těšíková, Karolína ; Sůkalová, Kateřina (referee) ; Vítová, Eva (advisor)
This bachelor’s thesis is focused on identification and quantification of free and bound fatty acids in model cheeses of „Moravský bochník“, made at Tomáš Baťa University in Zlín. Theoretical part is dealing with characteristics of lipids and fatty acids. Furthermore, the classification of cheese types and description of their production and composition are discussed. Finally, the gas chromatography is described as a most commonly used method for assessment of fatty acids. The experimental part focuses on comparing the content of free and bound fatty acids in four model cheeses in relation to the use of different microbial cultures. The method according to the ČSN EN ISO 1735:2005 was employed for extraction of lipids from cheese samples. The present fatty acids were identified and quantified by gas chromatography with flame ionization detector after conversion to methylesters using acid-catalysed esterification with a methanolic solution of boron trifluoride. In total, 32 bound and 20 free fatty acids were identified in cheese samples.
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The effect of nutritionally desirable ingredients on selected sensory properties of dairy products
HRADILOVÁ, Kristina
The aim of this Master's thesis was to assess the chemical composition and selected properties of cheeses and yogurts, to which various amounts of skimmed milk powder (SMP) were added. The literature review discusses the characteristics and division of cheeses and yogurts, their nutritional significance, rheology and its changes after the addition of proteins. In the experimental part of the thesis, the chemical composition of yogurts and cheeses was determined by spectrophotometry. Further, other laboratory methods were used to determine their acidity, viscosity, colour and hardness. Our research has shown that there are correlations between SMP content and the protein, fat, lactose and dry matter in yogurts and cheeses, between SMP content and the hardness, acidity and colour of cheeses, and between SMP content and the acidity and viscosity of yogurts. The results of this work enable determining the ideal amount of SMP to cheeses and yogurts in order to improve their nutritional and sensory properties.
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Využití bakterií mléčného kysání s probiotickými účinky ve výrobě čerstvých sýrů
Fialová, Pavla
This bachelor thesis focuses on characteristics of lactic acid bacteria and its use mainly in the dairy industry. It also includes characteristic of prebiotics and lactic acid bacteria with probiotic effects, otherwise known as probiotics. Probiotics can have a number of positive effects on human health. The thesis describes use of probiotics in the surrounding states, observes the demands placed upon milk used for production of fresh cheese, and the process of production of fresh cheese, describes different types of fresh cheese and use of probiotic bacteria in production of fresh cheese. The bachelor thesis also monitors the current assortment of fresh cheese in our market. The monitoring of assortment of fresh cheese is focused on the range of fresh cheese found in selected wholesale chains and it ascertains whether fresh cheese with probiotic culture can be bought in the Czech Republic. The results were put down into tables and evaluated.
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