Physicochemical Changes during Date Ripening Related to Ethylene Production
Some physicochemical parameters related to ripening and their relationship with ethylene were studied in date fruits ( Phoenix dactyliferaL. type Negros). Dates were harvested and classified into sixteen ripening stages according to their color, ranging from yellow-greenish to dark brown. Fruit firmness decreased through the different ripening stages, while the ripening index, expressed as the relation between soluble solids and acidity, increased. The greatest loss of fruit firmness correlated with the greatest increases in both polygalacturonase and •-galactosidase activities. In early ripening stages, a small peak in ethylene production was detected, followed by a peak in respiration rate, suggesting that a date could be considered as a climacteric fruit, with the plant hormone ethylene being responsible for changes in color, fruit firmness, soluble solids content and acidity.