IJUP08 - Universidade do Porto

HPLC separation and quantification of Catechins in green tea
home prepared: comparison with commercial soft drinks
C. Petisca1, A. Melo2, O. Pinho1,2, I.M.P.L.V.O. Ferreira 2
1 Faculdade de Ciências da Nutrição e Alimentação, Universidade do Porto, Portugal
2 REQUIMTE – Departamento de Bromatologia, Faculdade de Farmácia, Universidade do Porto,
Portugal
Tea is produced from the leaves of the plant Camelia sinensis. Tea composition varies with
climate, season, horticultural practices, variety, type of soil and the age of the leaves [1].
The high concentration of catechins and theaflavins in tea, coupled with its broad
consumption, make tea a significant dietary source of these flavonoids. These compounds
are potent natural antioxidants. Epidemiological and experimental evidence have
highlighted potential therapeutic and health-protective activities of tea catechins and
related derivatives [2].
Green tea samples were prepared using an aqueous extraction procedure which simulated
usual brewing conditions for a cup of tea. A precisely known amount of green tea leaves
was steeped at different temperatures (100°C, 95°C, 90°C, 85°C, 80°C, 75°C and 70°C)
for 5 and 10 minutes respectively and compared with ideal conditions for catechins
extraction (80°C during 80min) to adquire maximum concentration of catechins. The
amount of catechins present in commercial soft drinks containing green tea was also
studied and the results were compared. Separation and quantification of catechins was
performed by reverse-phase HPLC with Diode array detection. The samples were filtered
through a 0,45μm polyester filter before analysis.
Evaluation of time/temperature relation in green tea samples prepared using home
conditions, showed that samples prepared at 100°C for 10minutes, contained more
catechins than the other time/temperature relations evaluated, but has about 10 times less
catechins than the ideal conditions for catechins extraction. Comparison with the levels of
catechins in comercial soft drinks revelead that “Lipton Linea” infusion contained higher
amounts of catechins. However, this infusion presented less galic acid when compared
with tea at 100°C for 10min. Cold “Lipton Linea” also contained high levels of catechins.
The others comercial soft drinks analized presented lower amounts of catechins.
In conclusion the ideal time/temperature to extract the highest amount of catechins is 80°C
for 80min, but , despite being the most accurate way, people at home don’t take so much
time to prepare tea. When comparing catechin content present in tea prepared at home
conditions, we concluded that some comercial soft drinks have more amount of catechins.
References:
[1] Yang, D.J., Hwang, L.S. and Lin, J.T. (2007), Effects of different steeping methods and storage
on caffeine, catechins and gallic acid in bag tea infusions, Journal of Chromatography, 1156 (1-2),
312-320.
[2] Neilson, A.P., Green, R.J., Wood K.V. and Ferruzzi, M.G. (2006), High-throughput analysis of
catechins and theaflavins by high performance liquid chromatography with diode array detection,
Journal of Chromatography, 1132 (1-2), 132-140.
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