The
resulting solution was filtered with anhydrous sodium
sulphate and read on a spectrophotometer (Hitachi,
U-2000, Japan) at 450-nm against petroleum ether as a
blank. A standard graph was plotted using synthetic
crystalline beta-carotene (Fluka, Germany) dissolved
in petroleum ether and its optical density measured at
450 nm. From the standard graph, the concentration
in microgram per ml was determined and this was used
for the calculation of beta-carotene in the sample. All
the analytical work were repeated three times.