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The quality of eggs - general, functional and nutritional properties
PECH, Miloslav
This bachelor's thesis, processed in the form of a literary review, focuses on a comprehensive view of hen's eggs, analyzing their general, functional, and nutritional properties. After the introduction, a literary review follows, mapping the biological origin and domestication of the chicken, and then summarizing the current state of chicken farming. The thesis then delves into the formation and development of eggs, examining the structure and chemical composition of the yolk and albumen, including their proteins, lipids, carbohydrates, pigments, vitamins, and minerals. The physicochemical properties of eggs are also analyzed, including a total of seven properties such as specific gravity, freezing point, or refractive index. A detailed examination of the functional properties of eggs follows, which represent a key element in understanding their wide use in the food and culinary industries. The thesis focuses on analyzing the mechanisms through which hen's eggs can form gels, foams, and emulsions, which are properties that play an important role in various food processes and recipes. These properties are essential for the production of various foods, such as gelatin desserts, leavened doughs in baking, sauces, and mayonnaises. Eggs are also recognized as functional food because they are a rich source of nutrients, including vitamins, minerals, and biologically active substances that can contribute to overall health. These substances can, for example, help reduce the risk of heart disease and improve eye health. In the next section, the thesis focuses on the nutritional properties of eggs, examining microbial contamination, egg allergies, and biologically active substances such as choline, immunoglobulin Y (IgY), and lutein and their impact on human health. An overview of this section provides a deeper understanding of hen's eggs and their influence on human nutrition and health.
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Development of quality indicators of hens eggs from different types of breeding over time
ŠTĚPÁN, Stanislav
This thesis dealt with the determination of quality indicators of hen eggs from diffe-rent types of breeding - free range (domestic), litter house and enriched cage bree-ding, their comparison with each other and with our own results from 2021. 10 samples from each breeding were evaluated. There was no significant difference (p>0.05) between the eggs from each type of rearing in terms of volume, shape index, air bubble height, solid white index, Haugh units and yolk index. The shell was intact in all samples. There were differences in egg weight (p<0.001) and shell thickness (p<0.05). When compared with the 2021 results, the largest differences were in the litter-reared eggs, which were different in all parameters except shape index. For free-range (home-reared) eggs, there were differences in weight, shell thickness (p<0.001) and egg shape index (p<0.05). Eggs from enriched cage rearing differed in weight (p<0.001) and yolk index (p<0.01).
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Analýza faktorů ovlivňujících reprodukční vlastnosti nandu pampového
Muchová, Tereza
Focus of this diploma thesis is the analysis of partial influences having impact on the reproduction of Greater rhea. It captures a detailed description of the most common factors, such as housing, nourishment, season’s effect, climatic conditions, genetics and subsequent breeding of chickens. Included is an anatomical description of reproductive organs of both sexes and getting the reader acquainted with the social behavior of this animal. Thesis also consists of ethological observations of defined individuals with focus on the influence of the season on various daily activities. Finally, an analysis of the eggs is performed that includes the overall laying capabilities of the female, along with hatchability, fertilization and mortality of embryos. As an appendix of the diploma thesis you can find recommended precautions increasing the possibility to improve the level of reproduction for the breeders.
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Zařazení barevné pšenice "AF ZORA" s vysokým obsahem antokyanů na parametry užitkovosti nosnic na konci snáškového cyklu
Schořová, Michaela
The hypothesis of the experiment was to determine the effect of anthocyanins from the black AF Zora wheat variety on the reproductive parameters of weaned hens (>72 weeks of age). 120 laying hens of the breed Rhode Island White were used for the experiment and were divided into two groups - control and experimental in six repetitions. The experimental group was fed with a feed mixture containing 60% AF Zora black wheat and the control group 60% ordinary wheat of the Vanessa red variety. The experiment lasted 18 weeks, dur-ing which feed consumption, egg laying, egg quality, bone strength, antioxidant activity and phytoestrogen activity were monitored. The positive effect of anthocyanins was evident on egg-laying (P<0.05) in the experimental group, but at the same time, the weight of one egg in this group was about 1 g less and the quality of the shell deteriorated. Furthermore, the eggs of the experimental group had higher haugh units (P<0.01). The effect of anthocyanins on the antioxidant activity determined using the FRAP method was not confirmed. Phytoes-trogenic activity determined by mRNA expression of vitellogenin (VTG 1 and VTG 2) was not confirmed.
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Qualitative indicators of eggs from different types of feeding
HUBKOVÁ, Michaela
This bachelor thesis dealt with the influence of rearing forms on selected qualitative characteristics of hen eggs. The observed egg samples were from litter, free-range, organic and home rearing. The parameters evaluated were - shell breakage and cleanliness, height, stability and position of air bubble, white transparency and firmness, yolk post-movement and position, embryo visibility, weight, evidence of cleaning, incidence of flesh spots, yolk and firm white index, Haugh units and shell thickness. The values found were not significantly different and were close to the average values.
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Reologické vlastnosti žloutků slepičích vajec v průběhu skladování
Pavková, Lucie
The thesis deals with the influence of storage time on particular physical and rheolo-gical properties of a yolk of chicken eggs. Monitored eggs were stored at 6 °C for 8 weeks. The thesis describes the influence of storage time on physical characteristics of a whole egg, such as weight and shape index. As expected, the weight loss of chicken eggs was demonstrated during eight weeks storing. Egg yolk (colour, height, width, weight, index and density) was also described and evaluated in detail. According to our estimates, there are no significant changes in weight during yolk storing. But yolk index is distinctly decreased. During the final part of monitoring rheological properties were evaluated - apparent viscosity, time dependence of viscosity and dependence of shear stress on the shear rate (flow curves). The experiments have proved Newtonian behaviour of egg yolk throughout the storage. The storage time has also clear impact on flow properties of yolk. The results of each experiment were modelled using the power law (Ostwald-de Waele) model.
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Vývoj spotřebitelských preferencí na trhu vajec v ČR
Němcová, Monika
The Bachelor Thesis deals with what are the consumer preferences on the eggs market. By way of introduction discusses the agricultural fair, specifics of demand and also selected commodity, which means eggs. Eggs are very important food in the nutrition and so are parts of a diet of most people. The aim of this thesis is to find out what information is of interest to consumers when buying eggs. These information is get through questionnaire survey and is focused on basic characteristics, such a price, colour of shell, or whether information mentioned on wraps are sufficient for the consumer sufficient, or what extra information would be welcomed.
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Změny mikrobiální kontaminace vajec v průběhu skladování
Zemanová, Aneta
This masters thesis deals of microbial contamination of chicken eggs in storage. Test samples were tracked for the following microbial indicators: Total Viable Count (TVC), bacteria of the Enterobacteriaceae family, bacteria of the Enterococcus genus, psychrotrophic microorganisms, yeasts and molds. Microbial analysis was made for eggs acquired from market chains, originating from three different farming environments: enriched cages, cage-free and free range. Samples were stored in three different temperature environments: refrigerated at 5 °C for the whole storage period, stored in a thermostated box at 28 °C for the whole storage period and alternating between 5 °C and 28 °C temperature environments with one week storage periods each. The analysis of acquired test samples shows that TVC did not change significantly between different farming environments and storage temperature environments. Cage-free eggs show increasing TVC in long time storage (21 days). Cage-free and free range eggs also show higher count for Enterobacteriaceae. Enterobacteriaceae counts show significant differences between samples stored at constant 28 °C and alternating temperatures. Lowest microorganism count for bacteria of the Enterobacteriaceae family was observed at alternating temperatures. Long time storage resulted in elevated Enterobacteriaceae count in cage-free eggs. Presence of Enterococcus, psychotrophic microorganism and molds was detected in a low number of samples.
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