A key objective indicator of apple storability is flesh firmness, measured in kg/cm² using a penetrometer with an 11 mm diameter plunger. To assess storage potential, the iodine-starch test, which determines the degree of starch degradation, and the refractometric index of soluble solids content are also used.
This trait varies significantly depending on the cultivar's genetics: winter cultivars have the capacity for long-term storage, whereas summer and early autumn cultivars are characterized by rapid quality loss. The final level of storability is expressed as the percentage of marketable yield relative to the total volume placed in storage.
Storability is significantly influenced by growing conditions, in particular excessive nitrogen fertilization and high humidity before harvest, which increase the risk of developing physiological and microbiological disorders. Optimal harvest timing is a determining factor, as early picking leads to yield loss, while overripening on the tree critically shortens the fruit's shelf life.
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Keeping quality.