a study of the quality of a local herbal tea and volatiles of parinari ...

3.6 Determination of theaflavins, thearubigins, colour and brightness of
F. ancylantha and Lipton control teas
3.6.1 Preparation of tea samples
The water bath was set to 90 ºC and tea samples (0.200 g) were weighed in a 10ml glass
extraction tube. Tripple distilled water (1L) was heated in a 90 ºC water bath for 30 min
for equilibration. An extraction tube containing tea sample was placed in a water bath and
triple distilled water (5 ml) was added. A stopper was placed on the extraction tube and
mixing was done on a vortex. The mixture was kept in a water bath for 10 min and
vortexed after 5 min and after 10 min. Tubes were removed from the water bath and left
for 5 min to cool down to room temperature. The stopper was removed and mixture was
centrifuged for 10 min at 3500 rpm. The supernatant was decanted into a 10 ml
volumetric flask and set aside. The process was repeated and the supernatant was added
to the previously collected supernatant and made up to 10 ml with cold triple distilled
water. The extracted tea supernatant was filtered using a 0.22 µM filter coupled to a
10 ml syringe.
3.6.2 Extraction of theaflavins and thearubigins
Determination of the content of thearubigins, theaflavins, colour and brightness was done
by the method of Robert and Smith (1963).
Theaflavins and thearubigins contribute to brightness, colour and strength of tea (Sud and
Baru, 2000). Thearubigins has been broken down into three fractions, fraction SII
precipitated by ether from methanol solution, fraction SI precipitated by ether from
acetone solution, and a filtrate fraction left in solution after successive precipitations of SI
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