The organic acids in tea plants. A study of the non‐volatile organic acids separated on silica gel

Succinic, oxalic, malic, citric, isocitric, and five unknown acids have been found at appreciable levels (>0·1 μequiv./g. fresh wt.) in tea shoot tips. The major acids quantitatively were oxalic, malic and citric acids. The acids studied were recovered quantitatively from plant extracts, but they accounted for less than one‐fourth the total acidity present in tea shoot tips. The acid levels in shoot tips varied quantitatively between clones and between sampling dates, and also both quantitatively and qualitatively between different parts of the tea plant. Changes in the levels of organic acids take place in tea shoot tips during the manufacture of tea which are typical of senescing plant tissues. Notably, the levels of succinic and malic acids are markedly reduced during withering. The level of oxalic acid, however, remains nearly constant throughout manufacture. Studies with 14 CO 2 on intact plants showed that all of the organic acids studied are metabolically active except oxalic acid.