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The effect of a storage conditions on aroma compounds in processed cheese
Štouračová, Anna ; Buňka, František (referee) ; Vítová, Eva (advisor)
The aim of this diploma thesis was to monitor influence of storage conditions (temperature and time) on content of aroma substances in sterilized processed cheeses and also on their flavour. The part of cheeses was stored at 6°C, second part at room temperature 23 °C and third part at 40 °C. Processed cheeses were produced by Madeta, a. s., sterilized at 117 °C 20 min. The analysis was made at regular intervals, cheeses stored 16 and 23 months were analysed in this work. The aroma compounds were isolated by SPME and subsequently identified and quantified by gas chromatography. In total 37 aroma compounds were identified and quantified, 7 aldehydes, 7 ketones, 6 acids, 12 alcohols and 5 esters. Total content of aroma compounds increases with higher storage temperature. The time of storage has also influence on content of aroma compounds, we may say, that content is increasing, although sharp growth was registered only after 23 months, namely in the thermostat. Simultaneously sensory analysis of cheeses was made. Ranking test and evaluation using scale were used. Cheeses from a fridge were always evaluated as the best in all categories. Cheeses stored at room temperature were evaluated worse and cheeses from thermostat were the worst. So it is apparent, that high temperature supports undesirable chemical changes in cheeses and certainly is related to their flavour.
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The effect of a storage conditions on fatty acids in processed cheese
Němcová, Tereza ; Zemanová, Jana (referee) ; Vítová, Eva (advisor)
This diploma thesis deals with the changes in content of fatty acids in long-lasting stored sterilized processed cheeses. Cheeses were stored under different temperatures 6 ± 2 °C, 23 ± 2 °C and 40 ± 2 °C during 23 months. Measurements was made in 16th and 23rd month of storage. The samples of sterilized processed cheeses were extracted by using mixture of solvents (ethanol, diethylether and petrolether). The obtained fat was then saponified by methanolic solution of potassium hydroxide. The methylesthers were analyzed by gas chromatography with flame ionization detection. Lauric, myristic, palmitic, oleic and stearic acids were the most abundant in cheeses. The yield was measured in these main acids. To summarize the content of fatty acids decreased during time of storage and also by influence of storage temperature higher than in refrigerator.
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