The amount of total sugars in the mango juice samples was
determined using a modified version of the phenol–sulphuric acid
assay described by Nielson (2010). Accurately 1 mL of the diluted
juice sample was mixed with 1 mL of 5% phenol solution and 5mL
of 96% sulphuric acid(rapidly added)in each tube.The tubes were
vortexed and allowed to stand at room temperature for 20 min.
The concentrated sulphuric acid converts all non-reducing sugars
to reducing sugars,so the method deter mines the concentration of
the total sugars present in the sample.A blank was prepared by
substituting distilled water for the juice sample.The absorption of
the characteristic yellow-orange colour produced as a result of the
interaction between the sugars and the phenol was measured at
490 nm using a spectrophotometer.The typical colour of this reaction is stable for several hours.The concentration of the total sugars present in each sample was calculated by referring to a standard sucrose curve.