The type of calcium (Ca) compounds in plant tissues and their changes during storage were determined in several kinds of fruits and vegetables. The four types of Ca compounds extracted were as follows: water soluble Ca(F-I: mainly water soluble organic acid salts and Ca ion), 1N-sodium chloride soluble Ca(F-II: Ca-pectate and Ca-carbonate), 2%-acetic acid soluble Ca(F-III: Ca-phosphate), and 5%-hydrochloric acid soluble Ca(F-IV: Ca-oxalate).
1. The composition of the four types of Ca compound was different in the various fruits and vegetables. The predominant types were as follows: F-IV in spinach, F-I in parsley, radish seedling and mume (Japanese apricot) fruit and F-I and F-II in banana and tomato fruits.
2. In spinach leaves, the composition varied with the age of leaves; relatively high levels of F-II and F-III as well as F-IV were found in young (inner) leaves, while the level of F-IV increased in mature (outer) leaves.
3. During storage at 20°C for one week, the composition of Ca did not change in radish seedlings, but in banana and tomato fruits F-I increased with ripening.
4. In spinach which contains much F-IV Ca, and in parsley which contains much F-I Ca, changes in the content of ascorbic acid and in the composition of Ca compounds were determined during storage at 1°C and 20°C. In both species there was no clear change in Ca compounds at 1°C. However, in stored at 20°C there were a sharp decrease in F-I Ca and an increase in F-IV Ca, accompanied by a decrease in ascorbic acid content. In spinach stored at 20°C, Ca compounds did not change, while ascorbic acid content decreased.