Seasonal Variation of Chemical Components of Juice at Maturing Stage in Very Early Ripening Mutants of Satsuma Mandarin with Special Reference to Limonoid Compounds

Abstract

Seasonal changes in the physical properties and chemical constituents of fruits during the maturing stage were examined in 5 strains of very early ripening mutants of Satsuma mandarin (Citrus unshiu Marc. var praecox Tanaka) with special reference to the limonoid compounds.
The fruit size showed no significance during harvests performed 5 times successively. The proportion of peel of 'Hashimoto wase' was higher than other strains and peel-puffing was occurred. The Brix value increased in almost all the strains during fruit maturation and the sucrose contents mainly increased among the sugar constituents. Organic acid contents decreased, in particular citric acid as in the case of Wase satsuma mandarin. Both contents of limonin and nomilin were reduced with fruit maturation, but the rate of decrease of nomilin was faster than that of limonin. In the fruits harvested late, juice processing was optimal in terms of chemical components except for 'Hashimoto wase'.
Since the correlation coefficients between the Brix value, citric acid or rind color a-value and limonoid compounds were very high, bitterness due to the presence of limonoids in the juice products could be predicted from several parameters. Based on the principal component analysis of the juice characteristics, 'Hashimoto wase' displayed different properties compared with the other strains. Based on this statistical method, it may become possible to develop a new classification of very early ripening mutants of Satsuma mandarin.