Wpływ warunków parzenia na zawartość antyoksydantow w naparach różnych rodzajów herbat Influence of brewing conditions on antioxidant content in different kinds of tea infusions
Tea has been consumed all over the World for over two thousand years
and now it is the most popular caffeine-containing beverage. Its worldwide
consumption is second only to water [1–3]. The tea is not only important
because of its popularity but also due to its beneficial influence on human
health [4]. The biological benefits of tea are due to their flavanol content
[5–13]. Tea flavanols are a group of natural polyphenols (Fig. 2). Therapeutic effects
of tea have been extensively examined in many in vitro and in vivo tests. It was
confirmed that tea leaves ingredients have antibacterial, antifungial, antiviral properties,
they also prevent cell mutations and they inhibit progress of heart diseases.
Moreover, tea can stimulate neural system and regulate its functions [14–20]. All
this activities are mostly due to antioxidant ability of tea polyphenols (Fig. 4).
Tea production process can be run in different ways and this affects of the tea
taste, aroma, colour and antioxidants content. According to fermentation degree,
different tea kinds can be obtained (Fig. 1). During the manufacturing process of
black and oolong teas, tea leaves are crushed to allow polyphenol oxidase to catalyze
the oxidation and polymerization of catechins to polymers called theaflavins
and thearubigins (Fig. 3) [21–23]. Green or white teas are obtained through shorter
fermentation, so the catechin concentration remains higher. Tea is prepared by infusing
tea leaves in hot water. Brewing process conditions like temperature, brewing
time, pH, besides other factors has a significant influence on polyphenols content
[24-32]. Many studies have determined total flavonoids content and antioxidant
activity according to different tea type and brewing conditions, tea plantation type
or fermentation process. The amount of total polyphenol was determined using
the F-C method, catechins, caffeine and polyphenolic acids were analysed using
High Performance Liquid Chromatography with reversed phase. Obtained results
let compare how different production and brewing processes affect the tea quality
[33–56].
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