Abstract
Citric acid metabolism in Satsuma mandarin fruits (Citrus unshiu MARCOVITCH, cv. KATAYAMA) with or without curing was investigated during 90 days by injecting with citrate-1, 5-14C (0.1μCi, pH 3.5) into the fruit segments.
1. It was found that the injected citrate-14C was readily translocated to the areas of peel which was in contact with the injected segment. No radioactivity was found in all segments except the injected segment of the fruit throughout the storage period.
2. The content of titratable acid in each segment of a fruit continued to decrease independently during storage. Therefore it made a great difference in the titratable acid content in each segment of a fruit at the end of storage.
3. The cumulative radioactivity of respired 14CO2 continued to increase after injection with the substrate and the curve leveled off within 10 days. The cumulative radioactivity evolved by cured fruits was lower than that of non-cured fruits during 10 days after injection.
4. The injected citrate-14C was decarboxylated rapidly within 10 days and the radioactivities in ethanol soluble fractions in the peels and pulps decreased gradually for the subsequent 80 days.
It may be concluded that the endogenous acids or their salts in the vesicles of the segment were not translocated into another segments and were catabolized in si-tu during storage of Satsuma mandarin fruits.
