Physical and chemical changes in French prunes during maturation in coastal valleys

Abstract

does not appear. First page follows. Introduction In 1951 and 1952, physical and chemical changes of French prunes during maturation on the tree were studied in the Sacramento Valley (Claypool and Kilbuck, 1956).7 In the warm interior valleys of California, French prunes usually remain firmly attached to the tree long after they attain maturity and, since shaking removes fruits of all maturities with about equal facility, a tree is completely harvested in one operation. For dried prunes of good quality, however, shaking must be delayed until all or nearly all fruits are mature. In the cooler, coastal valleys attachment of French prunes to the tree usually becomes less firm as the fruits mature and therefore considerable numbers of ripe prunes may drop to the ground. Mature fruit is readily harvested by lightly shaking the main branches. Commercial harvesting operations involve two to four pickings, in contrast to the single picking in the interior valleys. During 1956 and 1957, extensive tests on the effect of various harvesting procedures on quality of dried fruit were conducted in seven coastal valley orchards. In addition, fruits were tagged for study of physical and chemical changes during maturation. The latter study is reported here and compared with the previous study on interior valley prunes by (Claypool and Kilbuck (1956)). Procedure Two orchards were selected for study: in 1956, one in the southern part of the