Increase in low molecular size uronic acid in ripening banana fruit

Abstract

AbstractUronic acid soluble in ethanol/water (4:1 v/v) increased from 9 ± 1 mg kg−1 fresh weight in pulp of unripe banana fruit. Musa (AAA Group, Cavendish subgroup) ‘Williams’, to 53 ± 13 mg kg−1 fresh weight in fruit ripened for 13 days. This increase began within the first 2 days of ripening. Uronic acid soluble in phenol/acetic acid/water (2:1:1 w/v/v) increased from 15 ± 5 to 86 ± 17 mg kg−1 fresh weight during the first 8 days of ripening, accompanied by a decrease in cell wall uronic acid from 10·2 ± 0·8 to 4·4 ± 0·4 g kg−1 fresh weight. Most or all of the uronic acid in extracts of ripe pulp cochromatographed with monogalacturonic acid. The results were consistent with hydrolysis of cell wall polyuronides by exopolygalacturonase (EC 3.2.1.67).