A review of the factors affecting senescent sweetening in potatoes

Cultivars differ in their susceptibility to senescent sweetening. Although the cultivars that are most susceptible to senescent sweetening tend to have short dormancy there are important exceptions to this rule such as Maris Piper and Record.

Growth and storage conditions affect timing of sweetening: early planting, stress and warm storage temperatures all speed up its onset. The most widely accepted hypothesis for the mechanisms of senescent sweetening is that tissue senescence in terms of a breakdown of cellular function occurs and that this is responsible for sweetening. Damage at the cellular level, especially membrane damage, facilitates enzyme access to starch granules thereby speeding up starch breakdown resulting in senescent sweetening. Physiological aging of tubers is associated with increasing oxidative damage. The process of oxidative damage, and how tissues may protect themselves against it, is considered in some detail given its importance in the process of cell senescence. Strategies to assess physiological age and hence storage quality at harvest and during storage are considered.

A link between senescent sweetening and changes in the ability to protect against oxidative damage (antioxidant capacity) was established. This provides possible strategies to follow tuber damage and give an early indication of senescent sweetening. Ascorbate concentration in particular should be investigated as a simple indicator of changes in capacity for oxidative protection.