The reaction was started by the addition of 100 mL of banana juice extract to 2.9 mL of incubation medium containing 1.5 mL of 0.5 g/100 mL pectin aqueous solution as substrate, 0.4 mL 0.1 mol/L phosphate-citrate buffer pH 6.0 and 1 mL of 0.1 mol/L calcium chloride aqueous solution.