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Characterization of proteins, soluble gums and phenolic compounds isolated from flaxseed (Linum usitatissimum L.)
JAROŠOVÁ, Markéta
Flax (Linum usitatissimum L.) is one of the oldest domesticated crops. Its cultivation for fibre, oil or medicinal purposes was already widespread in ancient times. Nowadays, the growing of flax for the production of high-quality flaxseed oil prevails compared to fibres. However, using flaxseed as a functional food in the food industry and dietary applications has become more popular recently. Flaxseed contains bioactive components, including polyunsaturated fatty acids representing the major proportion of flaxseed oil, as well as functional proteins and peptides, lignans and dietary fibre in the forms of soluble mucilaginous polysaccharides and insoluble lignocellulose. This dissertation presents the results focused on characterisation of three significant constituents of flaxseed - proteins, polysaccharides and lignans. These groups of compounds exhibit interesting functional properties and biological activities that may be useful in a wide range of food or medical applications. This work highlights the importance and potential use of flaxseed oil cake, which is an important source of these components. In addition to the results, this thesis also provides a comprehensive literature review of previous and current research on flaxseed proteins, mucilages and lignans. The results of this work can be primarily applied to breeding new oilseed flax cultivars or in the food and processing industries. However, due to the important nutritional aspects and biological activities of the mentioned components, the obtained findings can also be used in dietary applications and medicine. In general, this work aims to expands the spectrum of knowledge on the subject and to open up the scope for further research. Two review articles represent the first part of the results. The first publication focused on the hydrocolloids of flaxseed in the form of flaxseed mucilage representing 4-15% of the flaxseed content and protein representing 20% of its weight. In this manuscript, the structure, extraction methods, functional and biological properties and possible applications of both types of hydrocolloids for the fortification of various foods or other food applications are described in detail. This manuscript is followed by a short review article summarising current trends in food and dietary applications of flaxseed mucilage. The first publication describes more likely the traditional use of flaxseed mucilage for food fortification to enhance the technological, nutritional or sensory quality of foods or to provide health benefits. The second review paper focuses exclusively on the potential use of flaxseed mucilage in recent and innovative food industry and nutrition areas. In modern applications, flaxseed mucilage can be applied, for instance for preparing films, for food protection, as a structural component in oleogels, cryogels or aerogels, and it may modify the functional properties of proteins within composites. From the point of nutrition, flaxseed mucilage can serve as an encapsulating agent for probiotics or biologically active compounds. Flaxseed mucilage has the characteristics of a prebiotic and may increase the proportion of beneficial probiotic microorganisms. As a result, both review articles highlight the significant potential of flaxseed proteins and flaxseed mucilage for various recent and future applications. The second part of this thesis represents a first-authorship original manuscript focused on researching the influence of variety and growing conditions on yield parameters, chemical composition, lignan content and antioxidant potential of flaxseeds.
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Analysis of functional properties of protein isolates
Vojtasová, Tereza ; Diviš, Pavel (referee) ; Pořízka, Jaromír (advisor)
Proteins are an important part of the human diet, and a lack of them can lead to many health problems. Therefore, they are often added to enrich foods. For food applications, it is desirable to know the functional properties of the proteins used, as they can significantly affect the resulting quality of the final product. This bachelor thesis was focused on the determination of functional properties of some commercially available protein powders: pea, beef, hemp, rice, egg, soy, whey, and laboratory-prepared wheat bran protein powder, and their possible application in food industry. The theoretical part of the thesis described proteins, their functional properties, production, quality assessment, then plant and animal proteins and methods of characterization of protein isolates and concentrates. In the experimental part, individual determinations of functional properties were performed and their applications in food industry were discussed. The solubility of tested protein powders was variable, with the highest solubility observed in powders of animal origin. The lowest solubility was found at pH 3–5, where the isoelectric point of most proteins was located. Soy protein isolate showed the best water-holding capacity of 10.65 gH2O/g, foaming capacity of 109.6% and emulsion properties. It was followed by pea protein with a WHC of 5.32 gH2O/g. Wheat bran concentrate had the best oil holding capacity of 2.18 goil/g. Foaming properties varied considerably but showed a positive correlation with water-holding capacity. The emulsion activity was very similar for most of the protein powders, except for beef, hemp and rice protein which exhibited no good functional properties. Only the beef hydrolyzed collagen was fully soluble. The emulsion layer increased slightly after heat treatment for the proteins, which already formed quite stable emulsions, except for wheat bran powder. Hemp and bran protein powders were the most distinctive in color, while egg and beef protein powders were the lightest. Soy and pea protein isolates showed foaming and emulsion properties similar to egg white proteins, indicating their potential use as partial or total replacements for egg white proteins in food products. In conclusion, selecting protein isolates with suitable functional and sensory properties for a specific food application is crucial for successful consumer acceptance of the protein-enriched product.
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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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Production of enzyme hydrolysates from flaxseed proteins and evaluation of their properties
HAŠKOVÁ, Kateřina
This thesis focuses on effect on antioxidant properties and chosen functional properties: solubility, water and fat holding capacity, emulsification activity and stability caused by hydrolysis of protein isolates (PI) made from three different flax varieties (Libra, Agriol and Raciol). Part of this work was production of PI from flax seed. For hydrolysis trypsin, alcalase and papain were used - hydrolysis by trypsin was the mildest, while hydrolysis by papain was the most intensive one. Dynamics and degree of hydrolysis were also observed. Solubility of PI and hydrolysates was discovered to be very high (almost 100%). On the contrary water holding capacity was lower (3,93 g/g and less) than fat holding capacity (4,34 g/g), which increased upon hydrolysis for most enzymes, while water holding capacity decreased. Emulsification activity rised (1,47×) under the effect of hydrolysis, however stability dropped (1,3×). The best emulsifiction properties were found out in trypsin hydrolysates. Hydrolysis caused great impact on content of polyphenols which were in alcalase hydrolysates up to 3× higher and on antioxidant activity which grew in papain hydrolysates up to 2,5×.
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Amalgam Spaces
Peša, Dalimil ; Pick, Luboš (advisor)
In this thesis we introduce the concept of Wiener-Luxemburg amalgam spaces which are a modification of the more classical Wiener amalgam spaces intended to address some of the shortcomings the latter face in the context of rearrangement invariant Banach function spaces. We first provide some new results concerning quasinormed spaces. Then we illustrate the asserted shortcomings of Wiener amalgam spaces by provid- ing counterexamples to certain properties of Banach function spaces as well as rearrangement invariance. We introduce the Wiener-Luxemburg amalgam spaces and study their properties, including (but nor limited to) their normability, em- beddings between them and their associate spaces. Finally we provide some applications of this general theory. 1
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Amalgam Spaces
Peša, Dalimil ; Pick, Luboš (advisor)
In this thesis we introduce the concept of Wiener-Luxemburg amalgam spaces which are a modification of the more classical Wiener amalgam spaces intended to address some of the shortcomings the latter face in the context of rearrangement invariant Banach function spaces. We first provide some new results concerning quasinormed spaces. Then we illustrate the asserted shortcomings of Wiener amalgam spaces by provid- ing counterexamples to certain properties of Banach function spaces as well as rearrangement invariance. We introduce the Wiener-Luxemburg amalgam spaces and study their properties, including (but nor limited to) their normability, em- beddings between them and their associate spaces. Finally we provide some applications of this general theory. 1
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Amalgam Spaces
Peša, Dalimil ; Pick, Luboš (advisor) ; Nekvinda, Aleš (referee)
In this thesis we introduce the concept of Wiener-Luxemburg amalgam spaces which are a modification of the more classical Wiener amalgam spaces intended to address some of the shortcomings the latter face in the context of rearrangement invariant Banach function spaces. We first provide some new results concerning quasinormed spaces. Then we illustrate the asserted shortcomings of Wiener amalgam spaces by provid- ing counterexamples to certain properties of Banach function spaces as well as rearrangement invariance. We introduce the Wiener-Luxemburg amalgam spaces and study their properties, including (but nor limited to) their normability, em- beddings between them and their associate spaces. Finally we provide some applications of this general theory. 1
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