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Crystallization of coating systems based on epoxy resins.
Seidlová, Michaela ; Dohnálek,, Pavel (referee) ; Petránek, Vít (referee) ; Drochytka, Rostislav (referee) ; Bydžovský, Jiří (advisor)
Crystallisation of epoxy resins based on bisphenol A and bisphenol F is the natural property of these oligomers. However, manufacturers of paints and other systems based on these epoxy resins, strive to slow down the crystallisation process as much as possible, thereby prolonging the shelf life and improving the competitiveness of their products. The main aim of the thesis is generalisation of the factors influencing the crystallisation process of epoxy resins based on bisphenol A and bisphenol F, verifying new approaches to the possibility of influencing the crystallisation process and determining the possibility of using a certain degree of epoxy resins crystallinity based on bisphenol A and bisphenol F in the preparation and production of epoxy resinbased coating systems.
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The content of antioxidants in raw materials and their stability in enriched foods depending on the processing technology
BEDRNÍČEK, Jan
Oxidation reactions, that can negatively affect safety and sensory properties, take place during food storage. To inhibit such an unwanted process, natural polyphenolic antioxidants can be added to food. The aim of this thesis was to study the effects of the addition of polyphenol rich plant materials on chemical and sensory properties of commonly consumed food products. Two types of polyphenol rich plant material were chosen: onion (Allium cepa L.) peel, which is processing by-product and rosemary (Rosmarinus officinalis L.) extract Inolens 4. The addition of polyphenol rich material (both, onion peel and rosemary extract) increased antioxidant activity of food and also delayed lipid oxidation in meat products. Unfortunately, in some cases the addition caused deterioration of sensory properties leading to poor consumers' acceptance. This was observed mainly after the addtition of onion peel powder in higher amounts. The addtition negatively affected hardness of texture. On the other hand, onion peel powder can effectively cover or reduce formation of unpleasant fishy odour, that is typical for fish products stored for long period of time. Additionally, several coumpounds occurring only in onion peel were identified (4 types of quercetin dimer and 1 type of trimer) and their stability during thermal treatment of fortified food was elucidated. This was first study that described this phenomenon. Overall, it can be concluded that plant polyphenols have the potential to extend shelf life of food products.
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Crystallization of coating systems based on epoxy resins.
Seidlová, Michaela ; Dohnálek,, Pavel (referee) ; Petránek, Vít (referee) ; Drochytka, Rostislav (referee) ; Bydžovský, Jiří (advisor)
Crystallisation of epoxy resins based on bisphenol A and bisphenol F is the natural property of these oligomers. However, manufacturers of paints and other systems based on these epoxy resins, strive to slow down the crystallisation process as much as possible, thereby prolonging the shelf life and improving the competitiveness of their products. The main aim of the thesis is generalisation of the factors influencing the crystallisation process of epoxy resins based on bisphenol A and bisphenol F, verifying new approaches to the possibility of influencing the crystallisation process and determining the possibility of using a certain degree of epoxy resins crystallinity based on bisphenol A and bisphenol F in the preparation and production of epoxy resinbased coating systems.
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Methods for prolonging the shelf life of minced fish meat
KUBÍK, Michal
The initial part of this work sums up the methods of mechanical mincing of fish meat and food safety. The fish meat processing methods are described in detail and supplemented with the respective legislative. The primary factors affecting the quality and usability of the product are the changes caused by proteolysis and autolysis, the occurrence of microorganisms and biogenic amines. These processes are natural; they may only be delayed or reduced in intensity. Despite the possibility of using different preservatives, we need to pay attention to the basic hygienic and technological processes particularly in shortening their duration and storage conditions, especially the temperature. The major part of the research focuses on the possibility of using the enzyme preparation of SEA-i and its impact on the occurrence of biogenic amines, coliform bacteria and the total number of microorganisms in separated carp meat in smoking and liquid smoke treatment. Using SEA-i has proved to be a suitable means for preventing the development of biogenic amines. He was able to suppress the development of histamine below the detectable limit and the amount of putrescine decreased to 24 mg.kg-1 compared to the control group with the appearance of 89 mg.kg-1. For other biogenic amines has also demonstrated potent inhibitory effect. Its effect was also demonstrated in the total number of microorganisms.
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