Total polyphenol was measured using a modified Folin and Ciocalteu
method described by Vasco, Ruales, and Kamal-Eldin (2008).
Briefly, an aliquot (0.5 ml) of the banana juice blank or standard
was placed in a 25 ml flask and 0.5 ml of the Folin–Ciocalteu reagent
was added. The mixture was allowed to react for 5 min with
stirring. 10 ml of solution of sodium carbonate (concentration 75 g/
l) was added and mixed well. Distilled water was added to make up
the volume of the solution to 25 ml and then it was kept at room
temperature for 1 h. The absorbance was then measured at
750 nm using a spectrophotometer (M/s Perkin Elmer, Connecticut,
USA). The results were expressed as mg of gallic acid equivalents
per 100 ml.