Ripening-associated changes in the amounts of starch and non-starch polysaccharides and their contributions to fruit softening in three banana cultivars.

BACKGROUND: Fruit softening is generally attributed to cell wall degradation in the majority of fruits. However, unripe bananas contain a large amount of starch, and different banana cultivars vary in the amount of starch remaining in ripe fruits. Since studies on changes in pulp firmness carried out with bananas are usually inconclusive, the cell wall carbohydrates and the levels of starch and soluble cell wall monosaccharides from the pulps of three banana cultivars were analysed at different ripening stages.
RESULTS: Softening of Nanicão and Mysore bananas seemed to be more closely related to starch levels than to cell wall changes. For the plantain Terra, cell wall polysaccharide solubilisation and starch degradation appeared to be the main contributors.
CONCLUSION: Banana softening is a consequence of starch degradation and the accumulation of soluble sugars in a cultivar-dependent manner. However, contributions from cell wall-related changes cannot be disregarded.