Criteria for picking plums ( Prunus domestica L.) at the optimum maturity stage for the fresh fruit market.

摘要

Norwegian plum growers and marketing organizations wish to improve the status of plums in the fresh fruit market. To assure only high quality plums of uniform quality and ripeness are marketed, grading machines have been introduced at the packing houses. However, the pickers have to be trained to judge the maturity stage of the plums when picking. Methods, to help the pickers and the marketing people have a similar understanding of maturity, have been tested. Colour charts with pictures showing different maturity stages of the major plum cultivars grown in Norway, have been developed. The best way to judge the maturity of fruit of the plum cultivar 'Jubileum', however, is by firmness. The portable Durofel firmness tester is well suited for training pickers to judge maturity in 'Jubileum' plums. Threshold values for firmness related to different maturity stages, as measured by the Durofel firmness tester, have been established.