The objective of this work was to evaluate the pectinmethylesterase (PME) activity in papaya (Carica papaya L.) fruits cv. Sunrise Solo and Tainung, and to correlate its changes with the pulp firmness loss during fruit ripening. Fruits were collected daily from a commercial farm localized in Aracruz - ES, and stored under room temperature (approximately 25 °C) until the period of analysis. The pulp firmness loss of the fruits in both cultivars began at the 4th day after harvest (DAH); however, the cv. Sunrise Solo presented highest reduction than the cv. Tainung. The PME activity of cv. Sunrise Solo was higher at the 1st DAH, and decreased slowly at the 4th DAH, reaching its smallest value. At the 5th DAH the activity increased, remaining practically the same at the 8th DAH. In the cv. Tainung, the PME activity increased until the 3rd DAH and decreased at the 4th DAH. In the 5th DAH, its activity increased again reaching its higher value at the 6th DAH. From this on, the enzyme activity decreased significantly, maintaining the same value until the last day of analysis (8th DAH). The correlation coefficient obtained between the PME activity and the pulp firmness in the cv. Sunrise Solo after the 4th DAH was R = - 0,84, indicating that during this period, the pulp firmness of the fruits decreased when the PME activity increased. On the other hand, there was no significant correlation between these two characteristics in the cv. Tainung.
post harvest; pectinmethylesterase; firmness; papaya; pulp
