Dietary fibre composition in developing apple fruits

Changes in dietary fibre composition of 'Delicious', 'Golden Delicious', and 'Stayman' apples were studied over the course of fruit development. Fruit were analysed every 15 d starting 30 d after full bloom (DAFB) up to 150 DAFB in 'Delicious', 135 DAFB in 'Golden Delicious', and 120 DAFB in 'Stayman'. Nonstarch cell wall materials (NSCWM) and nonstarch polysaccharides (NSP) content of apple flesh of all the cultivars decreased during development. During the period between 30 DAFB and 120 DAFB, NSP content of 'Delicious', 'Golden Delicious', and 'Stayman' fruit decreased by 25.2%, 29.0%, and 19.3%, respectively. Relative amount of monosaccharides present in apple fibre also changed during development. Proportions of rhamnose, arabinose, mannose, and galactose decreased during development while the proportions of xylose, glucose and uronic acid increased. Firmness of apple flesh was positively correlated with its NSP content. Firmness was also strongly correlated with the amounts of galactose, glucose, arabinose, mannose, and rhamnose present in the hydrolyzates of apple fibre.