Articles
EXTRACTION, IDENTIFICATION AND QUANTIFICATION OF THE POLYPHENOLS OF GREEN AND BLACK TUNISIAN TEA DECOCTIONS COMMERCIALIZED AS “GARDEN OF TEA”
Article number
853_23
Pages
199 – 206
Language
English
Abstract
The dried tea leaves of Camellia sinensis is a popular beverage commonly consumed throughout the world.
This research was conducted to determine the decoction time effect on the total phenolic content of green and black tea commercialized as Garden of Tea decoction in comparison to their infusions.
During the experiment period, green and black tea leaves (40 g/L of water) were cooked for 15, 30 and 60 minutes continuously and discontinuously.
After recovering by adding 3v of cold acetone, followed by rota-evaporation at 40°C under vacuum, the remaining aqueous extracts were evaluated for their total phenolics using the Folin-Ciocalteu method.
The green tea cooked for 15 min had the highest quantity of polyphenols (1388±52 mg Gallic acid equivalent (GAE)/100 ml of tea decoction); while for the black tea, the highest phenolic content (953±40 mg Gallic acid equivalent (GAE)/100 ml of tea decoction) was obtained when cooking continuously for 30 minutes.
The antioxidant and antimicrobial activities were also investigated.
The antioxidant activity was evaluated by ABTS method using Trolox as reference.
The strongest properties corresponded to the extracts obtained from green tea cooked for 15 minutes with a 4975±40 mg equivalent Trolox/100 ml of decoction.
The antimicrobial potential of the tea phenolic extracts against a range of microorganism strains showed that Staphylococcus aureus and Staphylococcus epidermidis were the most sensitive.
This research was conducted to determine the decoction time effect on the total phenolic content of green and black tea commercialized as Garden of Tea decoction in comparison to their infusions.
During the experiment period, green and black tea leaves (40 g/L of water) were cooked for 15, 30 and 60 minutes continuously and discontinuously.
After recovering by adding 3v of cold acetone, followed by rota-evaporation at 40°C under vacuum, the remaining aqueous extracts were evaluated for their total phenolics using the Folin-Ciocalteu method.
The green tea cooked for 15 min had the highest quantity of polyphenols (1388±52 mg Gallic acid equivalent (GAE)/100 ml of tea decoction); while for the black tea, the highest phenolic content (953±40 mg Gallic acid equivalent (GAE)/100 ml of tea decoction) was obtained when cooking continuously for 30 minutes.
The antioxidant and antimicrobial activities were also investigated.
The antioxidant activity was evaluated by ABTS method using Trolox as reference.
The strongest properties corresponded to the extracts obtained from green tea cooked for 15 minutes with a 4975±40 mg equivalent Trolox/100 ml of decoction.
The antimicrobial potential of the tea phenolic extracts against a range of microorganism strains showed that Staphylococcus aureus and Staphylococcus epidermidis were the most sensitive.
Authors
K. Dhaouadi, S. Fattouch, M.H. Hamdaoui
Keywords
antimicrobial, antioxidant, RP-HPLC
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