Vol 117 (2004): Proceedings of the Florida State Horticultural Society
Handling & Processing

Pre- and postharvest application of retain® to 'Red Lady' papaya fruit: effects on harvest maturity, ripening and quality

Steven A. Sargent
University of Florida
Published December 1, 2004
  • carica papaya,
  • ripening delay,
  • postharvest


Papaya (Carica papaya L.) is becoming an important fruit for fresh and processed products. Tropical fruits, such as papaya, encounter greater problems during transport and storage due to increased perishability. ReTain®, a commercial formulation of aminoethoxyvinylglycine (aviglycine HCL, or AVG), inhibits the synthesis of ethylene. AVG has been reported to delay abscission which increased fruit color, retarded softening, and increased vegetative growth when applied as a preharvest spray in apple; it also delayed softening and decreased ethylene production in peach when applied pre-or postharvest. The first experiment investigated the postharvest application of ReTain® (0, 250, 500, and 750 ppm) on subsequent fruit ripening and quality of 'Red Lady' papaya, an elongated, red-fleshed type. Fruits were harvested at colorbreak stage and held overnight at 20 C (68 F); the next day they were immersed, stored for 7 days at 13 C, and then transferred to 20 C and 90% relative humidity for ripening. The papaya fruit reached full-ripe stage 15 days after harvest and there were no significant differences between treatments for the quality parameters tested. Soluble solids content was 10.8 to 10.9 Brix, total titratable acidity was 0.14 to 0.17% and pH was 5.2 to 5.3. Firmness was 13.2 to 17.4 N and variable due to the erratic presence of hard sections in the ripe pulp. In a related experiment, ReTain® was applied at 300 ppm (0.5 g) per papaya plant in a commercial orchard. The objective was to determine if ReTain® application delayed harvest maturity. For the next 21 days fruit maturation was assessed every three days until the fruit reached commercial harvest maturity (colorbreak). Preharvest ReTain® sprays had only a slight tendency to delay papaya fruit maturation under the conditions tested, not enough to be commercially important. Results from both studies indicated that AVG applications had little effect on delaying harvest maturity or postharvest ripening of 'Red Lady' papaya.