Effects of harvest maturity on the storage life of Japanese type plums

Abstract

Summary. Plums are highly perishable and once harvested have a short commercial life. Hence, this crop would benefit from the determination of conditions which permit extended storage. This study investigates the effects of fruit maturity at harvest on the physical and chemical characteristics of the plum cultivars, Radiant, Gulfruby and Shiro, after periods of cool storage. Fruit from these cultivars were separated into 3 maturity categories according to either skin colour at harvest or time after pit hardening. The storage disorders, internal breakdown and gel breakdown, were measured after periods of storage at 0°C and subsequent ripening at 20°C. Skin colour, flesh firmness, concentration of soluble solids and titratable acidity were measured at harvest and after ripening. Internal breakdown and gel breakdown, symptoms of chilling injury, developed after 2 weeks cool storage in Gulfruby and Shiro and after 4 weeks in Radiant. These symptoms were most severe in the oldest fruit. Significant differences were also found in skin colour, firmness, soluble solids and acidity during ripening and after cool storage. Fruit harvested at an earlier maturity withstand cold storage better than more mature fruit. However, these less mature fruit initially have a poorer quality than those which are more mature. Therefore, it is important for the grower to be able to determine the precise stage of crop development in order to allow harvesting at a time which is optimal for the storage process.