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Trendy ve využití složek vajec
Doležalová, Eliška
Eggs are now recognised not only as a dietary ingredient but also as a starting material providing many valuable bioactive compounds that are used primarily in food processing but also in medicine, veterinary medicine, pharmacology and biotechnology. Egg yolk is an important source of antioxidants, aromatic amino acids, carotenoids, vitamins, phospholipids and proteins. Egg white is an excellent natural source of high quality protein that is rich in essential amino acids. Eggshell mainly contains calcium and other minerals. Hen egg yolk has a number of technological functions, including emulsifying, gelling and film-forming. Different types of modification can be used to improve the functional properties of egg components. For example, enzymatic hydrolysis can be used to modify the egg yolk and deamidation is used to modify the egg white. Eggshells are primarily considered as zero-value waste, although they are rich in organic and inorganic compounds that can be used in various forms.
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The content of the micronutrients in consumer eggs
DUŠOVÁ, Hana
The aim of the diploma work was to analyticly verify the actual status of the micronutrients (iodine, copper, zinc and manganese) in consumer eggs. The results of the research gives information about the content of the observed micronutrients in egg yolk and the importance of eggs as a source of these micronutrients for the nutrition of people. The eggs came from 13 small flocks and 7 large flocks in both 2007 and 2008. The average content of iodine in fresh matter of yolk of the eggs from the large flocks in 2007 was 1285,2 {$\pm$} 861,6 {$\mu$}g{$\bullet$}kg-1, zinc 63,71 {$\pm$} 31,08 mg{$\bullet$}kg-1, copper 7,42 {$\pm$} 4,88 mg{$\bullet$}kg-1 and manganese 1,02 {$\pm$} 0,84 mg{$\bullet$}kg-1. The average content of iodine in fresh matter of yolk of the eggs from the small flocks in 2007 was 387,1 {$\pm$} 214,3 {$\mu$}g{$\bullet$}kg-1, Cu 10,90 {$\pm$} 5,28 mg{$\bullet$}kg-1, Zn 73,54 {$\pm$} 44,33 mg{$\bullet$}kg-1 a Mn 1,28 {$\pm$} 0,75 mg{$\bullet$}kg-1. In 2008 the average concentration of iodine in fresh matter of yolk of the eggs from the large flocks was 1071,9 {$\pm$} 543,9 {$\mu$}g{$\bullet$}kg-1, Cu 20,63 {$\pm$} 8,85 mg{$\bullet$}kg-1, Zn 29,59 {$\pm$} 8,67 mg{$\bullet$}kg-1 a Mn 1,42 {$\pm$} 0,62 mg{$\bullet$}kg-1. In 2008 the average concentration of iodine in fresh matter of yolk of the eggs from the small flocks was 340,7 {$\pm$} 330,6 {$\mu$}g{$\bullet$}kg-1, Cu 17,95 {$\pm$} 6,19 mg{$\bullet$}kg-1, Zn 33,10 {$\pm$} 7,97 mg{$\bullet$}kg-1 and Mn 1,22 {$\pm$} 0,54 mg{$\bullet$}kg-1. The Eggs from the large flocks cover 6,8 {--} 13,5% of the daily iodine requirement in adults, 13 {--} 17,3% of copper, only 2,5 {--} 3,1% of zinc and 0,4 {--} 1,1% of manganese. The gained results imply that only the content of iodine in the egg yolk is evidently affected by the intake of it in the feeding rations, the intensity of the egg production and the stage of the laying cycle. The stated relations were not definite with the other elements. The concentration of iodine in the egg yolk was assessed spectrophotometrically by the method of Sandell {--} Kolthoff, modified by Bednář et al., (1964). The content of zinc, manganese and copper in the egg yolk were assessed by the method of atomic absorption spectroscopy (AAS).
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Lead soaps in paintings: symptoms and the role of humidity
Garrappa, Silvia ; Švarcová, Silvie ; Kočí, Eva ; Hradilová, J. ; Bezdička, Petr ; Hradil, David
In this study, an overview of the symptoms of lead soaps reported in artworks in combination\nwith the study of the role of humidity on the formation of these degradation products have\nbeen thoroughly investigated. The use of optical microscopy, scanning electron microscopy\n(SEM) in combination with Fourier-transform infrared spectroscopy (FTIR) proved to be an\nefficient analytical approach to highlight both the saponified area of artworks’ samples and the\nformation of metal carboxylates within mock-up model systems. Optical microscopy revealed\nto be very useful for the first screening of samples embedded in resin, while SEM helped in\nthe detection and distribution of elements within the cross-sections. On the other hand, FTIR\nmicroscope proved to be a very powerful instrument for high-resolution point measurements\nperformed in the attenuated total reflection mode (ATR) mode with mercury-cadmium-telluride\n(MCT) detector, as well as for chemical imaging of larger area of both artworks’ and mock-up\nsamples performed in the ATR mode with focal plane arrays (FPA) detector. This study provides\nnew useful insights contributing to better understanding of factors affecting the paints‘ stability,\nwhich is neccesary for developing new efficient strategies for preservation and restoration of\nfatty-based painted artworks.
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