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Effect of Camellia sp. on dairy matrix digestion
Scholzová, Tereza ; Potůčková, Miroslava (advisor) ; Vladimír, Vladimír (referee)
The aim of this bachelor thesis is to summarise of current knowledge about the effects and biological properties of the substances contained in leaves of Camellia sinensis, their digestion and their effect on the digestion of dairy matrices. Camellia sinensis is a plant, which is used to tea production. Tea is manufactured by fermentation of tea leaves and according to its degree it is possible to prepare different kinds of this product. The best known are green, black and oolong tea. Beverages prepared from tea leaves contain many bioactive compounds, including alkaloids, free amino acids, proteins and vitamins. However, the most important are polyphenolic substances flavonoids, which are also the major bioactive constituents of tea. These compounds have many pharmacological properties such as antiatherosclerotic, antibacterial, anticancer, antiviral, hypolipidemic and hypocholesterolemic.
The effect of milk on the biological activity of tea polyphenols has been a subject of many studies but the mechanism by which the antioxidant activity of this compounds affect milk and dairy products and especially their digestion process has not been fully understood yet. It was found that flavonoids can interact with proteins rich in prolin, including also casein, via covalent and noncovalent interactions, especially by hydrophobic interactions and hydrogen bonds. The resulting complexes may destabilize protein molecules and cause their precipitation, thereby their digestibility is improved. On the contrary, stable complexes protect polyphenols from autooxidation. Interesting is also crosslinking effect of green tea flavonoids on milk proteins. These substances also have the ability to form complexes with lipids and lipolytic enzymes and so decrease lipids digestion and absorption, including the milk fat and its accompanying components such as cholesterol. It was also observed reduced absorption of other fat-soluble substances like persistent organic compounds.
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