2.7. Soluble tannin's determination
Soluble tannin's were measured according to Taira (1996). Five grams of fruit tissue (including skin and flesh) was homogenized with 25 ml of 80% methanol in a blender and then centrifuged. The supernatant was collected and the precipitant was re-extracted with 80% methanol and centrifuged. The combined supernatant was brought to 100 ml with distilled water. One ml of sample solution was mixed with 6 ml distilled water and 0.5 ml FolinCiocalteureagent (previously diluted 10-fold with distilled water). After 3 min, 1 ml of saturated sodium carbonate and 1.5 ml of distilled water was added and kept for 1 h at ambient temperature before measuring absorbance at 750 nm using a UV-Vis Spectrophotometer. The blank contains only water and the reagents. Soluble tannin's were quantified from a calibration curve obtained by measuring the absorbance of known concentrations of gallic acid.