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Biologically active substances contained in tea, coffee and cocoa
Marková, Kristýna ; Hejtmánková, Alena (advisor) ; Jadrná, Petra (referee)
This bachelor thesis deals with the effects and chemical structures of selected biologically active substances contained in tea, coffee, and cocoa. The tea plant (Camellia) belongs to the family Theaceae. Several varieties are cultivated, but all of them are referred to as the Camellia sinensisvariety. The main products of the tea plant are leaves from which tea is produced. Catechins (8 - 18 %) are the most meaningful substances in tea, they belong to the group of polyphenolic substances, which have strong antioxidant properties.
The coffee plant (Coffea) belongs to the family Rubiaceae. The most significant varieties from this family are Coffeaarabica and Coffearobusta; their beans are used for the production of coffee. Coffee is a sought-after stimulating beverage. Caffeine (0.7 - 2.5 %) is the most important substance, it is included in the group of alkaloids. Itis a central nervous system stimulant, affecting the heart beat and the cardiovascular system.
The cocoa tree (Theobroma) belongs to the family Sterculiaceae. A significant representative of this family is Theobroma cacao and its groups Criollo, Forastero, and Trinitario. Cocoa is particularly rich in flavonoids (20 %) which also belong to the group of polyphenolic substances. They are strong antioxidants; in adequate quantity, they have positive effects on health.
Tea, coffee, and cocoa also contain vitamins and minerals. In the organism, they may form part of a structure of somatic cells and enzymes, some of them are activators of enzymes, and they also act as molecule transporters in metabolic reactions. Vitamin C and vitamin E are most frequently present; minerals potassium and phosphorus have the highest content in these stimulating products.
The total concentration of biologically active substances is primarily affected by the family of the relevant type and form of processing. Raw materials that have not undergone fermentation or roasting contain more biologically active substances than those that have been treated.
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