For determining the content of red colorant in FRP, the pericarp
after removal of seed and stalk were extracted with acetone until
the color was exhausted. The combined extracts were evaporated
to remove acetone and water (from FRP) under reduced pressure
with a rotary evaporator at 45
C. A residual cream was obtained.
Then it was dissolved with acetone into a determinate volume for
absorbance determination.