Dichromate
ðCr2O2
7 Þ is yellowish in color and the reduced chromic product
(Cr+++) is intensely green. A calibration curve was made with
pure ethanol at different concentrations and the absorbance of
the samples was read at 490 nm. The ethanol production was calculated
as the percent (v/v) of ethanol present in the body fraction
per volume of fermentation broth.