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Hodnocení fyzikálně-chemických parametrů zrajících sýrů
Strojilová, Hana
The diploma thesis on the topic "Evaluation of Physicochemical Parameters of Ri-pened Cheeses" deals with the topic of the history of cheeses and their composition in its theoretical part. The thesis also mentions the importance of dairy products in nutri-tion. Other chapters are devoted to the technological production of cheeses with low-heated and high-heated cheese curd and their important representatives. In the last chapters of the theoretical part there is a general description of the used methods for the determination of fatty acids in the formulas. The experimental part of the thesis is focused on basic analytical methods that allow control of individual components of cheese with its packaging. At the same time, a comparison of sampling of Gouda chee-se and Edam cheese was made. Additionally, an experiment was carried out in the ex-perimental part, during which individual fatty acids were extracted. The extraction of fatty acids was carried out according to the method of Hara and Radin. The samples were derivatized and analysed by using a gas chromatograph. Individual percentage values of acids were compared in all samples together. Furthermore, the content of individual fatty acids was evaluated with samples compared by type of cheese. For the experimental part, samples of cheeses with low-heated cheese curd were used there.
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Vliv receptury a délky zrání na obsah polyaminů ve zrajících sýrech
Kolková, Andrea
The theoretical part of my thesis was focused on the characteristics of polyamines, their synthesis, degradation and effect in the organism. The practical part was involved on determining the content of polyamines (putrescine, spermine and spermidine) in ripening cheese without addition and with the addition of laccase. The high-performance liquid chromatography method was used for the analysis. Quantitatively, the most significant polyamine in all tested cheese variants was spermine (laccase in cheese grains 16.6 mg/kg > control 15.5 mg/kg > surface laccase 14.8 mg/kg; p < 0.05). Spermidine content was in the range (surface laccase 8.8 mg/kg > laccase in cheese grains 2.9 mg/kg > control 2.4 mg/kg; p < 0.05). Putrescine was detected only in low precipitation (laccase in cheese grains 2.1 mg/kg > control 1.3 mg/kg > laccase in surface 0.7 mg/kg; p < 0.05). During storage (X; weeks), the total PA content (Y; mg/kg) in the control cheese sample without the addition of laccase increased according to the equations: y = 256.93 + 207.38x (R² = 0.8955; p = 0.0021 ), the amount of PA in the sample of cheese with laccase in the cheese grains also increased linearly according to equation: y = 196.05 + 228.22x (R² = 0.8226; p = 0.0024). The total PA content in the cheese sample with laccase on the surface increased up to 4 weeks and then decreased according to the equation: y = 629.1 + 621.45x - 59.539x2 (R² = 0.8984; p = 0.0163). The effect of laccase on the degradation of amines described in the literature has not been proven. However, this is a pilot experiment that investigates the effect of laccase on the content of polyamines in ripening cheeses. For a better understanding of this problematics, will be needed more extensive research.
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Vliv receptury a délky zrání na obsah biogenních aminů ve zrajících sýrech
Trusinová, Adéla
The diploma thesis is focused on the content of biogenic amines (cadaverine, histamine, 2-phenylethylamine, tyramine and tryptamine) depending on the ripening time in 3 varieties of maturing cheeses (control sample, sample with laccase in the cheese dough, sample with laccase on the surface of the cheese). Furthermore, the work focuses on the effect of adding laccase to the dough and on the surface of the cheeses. The theoretical part is focused on the importance and occurrence of biogenic amines in food, including possible toxic effects on the organism. The practical part monitored the effect of ripening time on the content of biogenic amines in 3 variants of the same type of cheese in the ripening process. Biogenic amines were determined after derivatization with dansyl chloride by HPLC. The most quantitatively represented biogenic amine was cadaverine, which reached the highest concentration values after 14 days of ripening in cheese with laccase on the surface. The value of the concentration was 336 μg/100 g. The amount of laccase on the surface showed an opposite trend (p ˂0.05) when evaluating the storage time on the content of the concentration of biogenic amines, an opposite trend against cheeses with laccase in the dough. The concentration of the sum of biogenic amines in all cheese samples with laccase in the dough first decreased, then increased according to the equation y = 556.03–165.51x + 22.593x2 (R² = 0.4904; p = 0.14). The concentration of the sum of biogenic amines in cheeses with laccase on the surface, depending on the ripening time, first increased and then decreased according to the equation y = 150.42 + 631.63x - 97.921x2 (R² = 0.1999; p = 0.57). Most of the values measured in this work do not correspond to the normal content of individual biogenic amines in the literature, this fact may be caused by an inappropriate selection of the type of cheese for the determination of biogenic amines, an incorrect technological procedure during production or the fact that the filtration of the supernatants was very difficult and lengthy and with large losses. The influence of laccases on the formation of biogenic amines could not be unequivocally demonstrated due to the great variability of the data and few reference values with which the measured values can be compared. Laccases in food are a relatively new issue that is not sufficiently supported by literature sources and requires further investigation.
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Stanovení biogenních aminů v sortimentu zrajících sýrů
Bubelová, Kristýna
The diploma thesis focuses on the content of biogenic amines (BA: tyramine, histamine, kadaverine, tryptamine, phenylethylamine) and polyamines (PA: putrescine, spermine, spermidine) in eidam, emmental and parmesan cheese. The theoretical part describes the origin, occurrence and importance of BA and PA, and the various factors influencing their occurrence. In the practical part, the influence of the type of cheese, temperature and storage time on the content of individual amines was monitored. The most significant amines in all types of tested cheeses were tyramine (eidam 173,3 mg/kg > emmental 4,4 mg/kg = parmesan 10,9 mg/kg) and putrescine (eidam 188,4 mg/kg > emmental 77,5 mg/kg = parmesan 36,4 mg/kg). When compared to all types of monitored cheeses stored for 3 weeks, there was a tendency (p > 0,05) to increase the BA content and decrease the PA content in the cheeses stored at 20 °C compared to the cheese stored at 5 °C (tyramine 128,1 mg/kg vs. 62,9 mg/kg, putrescine 61 mg/kg vs. 100,8 mg/kg). During storage (X, weeks), the tyramine content (Y; mg/kg) in eidam and emmental was increased by the following equation: y = 82,2 + 28,9x (R2 = 0,34, p = 0,005) and y = -10,7 + 5,17x (R2 = 0,23, p = 0,025). The corresponding regression for the content of PUT (on the other hand, the reduction of content) in emmental and parmesan was as follows: y = 230,1 – 63,63x + 4.249x2 (R2 = 0,92, p < 0,001) and y = 48,6 – 6,07x2 (R2 = 0,24, p = 0,024).
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Biogenní aminy ve fermentovaných mléčných výrobcích
Bubelová, Kristýna
This bachelor thesis is focused on biogenic amines in fermented dairy products, particularly in cheeses. Biogenic amines are low molecular weight nitrogenous base formed mainly by decarboxylation of free amino acids by treatment with bacterial de-carboxylation enzymes. The most important bacteria forming biogenic amines in cheese are part of contaminating microflora (e.g. Enterococcus) and starter cultures (e.g. Lactobacillus). The cheeses are most prone to histamine, tyramine, cadaverine, putrescine. Furthermore, the work described effects, factors affecting the incidence and methods of determination.
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