Lugol s solution

Starch degradation was measured from 15 apples after harvest, which were cut into halves orthogonally to the apple core. The freshly cut site was dried with a paper towel and dipped into an iodine/potassium iodate solution (Lugol’s solution, 3.3 g/L iodine and 6.7 g/L potassium iodide; Carl Roth, Karlsruhe, Germany) and allowed to rest for 5 min. The color intensity of the blue starch-iodine complex represents the degree of ripening in terms of the apple starch degradation. The coloration pattern was matched with the corresponding degradation grade on a 1–10 point scale (EUROFRU, Ctifl—Centre Technique Interprofessionel des Fruits et Legumes, Paris, France) [17 (link)], where grade 1 corresponds to no starch degradation and grade 10 to complete starch degradation in the apple fruits. The mean was calculated from 15 apple halves.

To follow the degradation of starch during maturation and ripening, five apples per harvest were cut into halves orthogonally to the apple core. The freshly cut site was dried with a paper towel and dipped into an iodine/potassium iodate solution (Lugol’s solution, 3.3 g/L iodine and 6.7 g/L potassium iodide; Carl Roth, Karlsruhe, Germany) and allowed to rest for 5 min. The color intensity of the blue starch-iodine complex represents the degree of ripening in terms of the apple starch degradation. The coloration pattern was matched with the corresponding degradation grade on a 1–10 point scale (EUROFRU, Ctifl—Centre Technique Interprofessionel des Fruits et Legumes, Paris, France) [17 ], where grade 1 corresponds to no starch degradation and grade 10 to complete starch degradation in the apple fruits. The mean and standard deviation were calculated from 5 apple halves for each harvest date.