Field and post-harvest requirements for optimizing Carica papaya L fruit yields

Carica papaya L fruit (pawpaw) is a growing export crop due to its high demand. Success of this crop in the global market requires extended shelf-life of the fruit. This study assessed fruit firmness and colour change as time-related factors for harvesting in conjunction with the effects of pre-treatment with heat, chlorine or salt solution and storage conditions on the shelf-life of pawpaw. Two hundred and fifty pawpaw trees were studied from bloom to harvest in two fruiting seasons. Number of fruits per tree at peak fruiting, proportion of matured to immature fruits and number of harvest visits were recorded. Fruits were handpicked and only certified healthy fruits were studied for quality and acceptability. Range of matured fruits on trees was 8-25 with average per harvest of 5 fruits per tree. The proportion of matured to immature fruits at each harvest visit was 2:3. Harvested fruits that have not attained full maturity indicated by first colour break either failed to ripe or ripen unevenly. Matured fruits with early sign of ripening preserved for 3-7 and 9-12 days at 27-32° C and 19- 230 C respectively. Treatments with salt solution prior storage produced poorly ripe and disfigured fruits and encouraged the growth of moulds (Aspergillus spp., Penicillium spp., Mucor spp., Colletotrichum gloeosporoides, Alternaria spp., Rhizopus stolonifer). Heat treatment and dip in chlorine water gave the upper range of shelf-life. Timing of harvest, post-harvest handling and storage at low temperature are critical in determining the post-harvest shelf-life of C. papaya fruits